1
|
Holla P, Bhardwaj J, Tran TM. Mature beyond their years: young children who escape detection of parasitemia despite living in settings of intense malaria transmission. Biochem Soc Trans 2024; 52:1025-1034. [PMID: 38752830 PMCID: PMC11209762 DOI: 10.1042/bst20230401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Revised: 05/01/2024] [Accepted: 05/02/2024] [Indexed: 05/18/2024]
Abstract
Despite having the highest risk of progressing to severe disease due to lack of acquired immunity, the youngest children living in areas of highly intense malaria transmission have long been observed to be infected at lower rates than older children. Whether this observation is due to reduced exposure to infectious mosquito bites from behavioral and biological factors, maternally transferred immunity, genetic factors, or enhanced innate immunity in the young child has intrigued malaria researchers for over half a century. Recent evidence suggests that maternally transferred immunity may be limited to early infancy and that the young child's own immune system may contribute to control of malarial symptoms early in life and prior to the development of more effective adaptive immunity. Prospective studies of active and passive detection of Plasmodium falciparum blood-stage infections have identified young children (<5 years old) who remain uninfected through a defined surveillance period despite living in settings of highly intense malaria transmission. Yet, little is known about the potential immunological basis for this 'aparasitemic' phenotype. In this review, we summarize the observational evidence for this phenotype in field studies and examine potential reasons why these children escape detection of parasitemia, covering factors that are either extrinsic or intrinsic to their developing immune system. We discuss the challenges of distinguishing malaria protection from lack of malaria exposure in field studies. We also identify gaps in our knowledge regarding cellular immunity in the youngest age group and propose directions that researchers may take to address these gaps.
Collapse
Affiliation(s)
- Prasida Holla
- Ryan White Center for Global Health and Pediatric Infectious Diseases, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN 46202, U.S.A
| | - Jyoti Bhardwaj
- Division of Infectious Diseases, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN 46202, U.S.A
| | - Tuan M. Tran
- Ryan White Center for Global Health and Pediatric Infectious Diseases, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN 46202, U.S.A
- Division of Infectious Diseases, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN 46202, U.S.A
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202, U.S.A
| |
Collapse
|
2
|
Partey FD, Obiri D, Bonney EY, Pobee ANA, Damptey IK, Ennuson K, Akwetea-Foli J, Nuokpem FY, Courtin D, Kusi KA, Mensah BA. Efficient transplacental transfer of SARS-CoV-2 antibodies between naturally exposed mothers and infants in Accra, Ghana. Sci Rep 2024; 14:10772. [PMID: 38730052 PMCID: PMC11087586 DOI: 10.1038/s41598-024-61496-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Accepted: 05/06/2024] [Indexed: 05/12/2024] Open
Abstract
We aimed to determine SARS-CoV-2 antibody seropositivity among pregnant women and the transplacental transfer efficiency of SARS-CoV-2-specific antibodies relative to malaria antibodies among SARS-CoV-2 seropositive mother-cord pairs. This cross-sectional study was conducted in Accra, Ghana, from March to May 2022. Antigen- specific IgG antibodies against SARS-CoV-2 (nucleoprotein and spike-receptor binding domain) and malarial antigens (circumsporozoite protein and merozoite surface protein 3) in maternal and cord plasma were measured by ELISA. Plasma from both vaccinated and unvaccinated pregnant women were tested for neutralizing antibodies using commercial kit. Of the unvaccinated pregnant women tested, 58.12% at antenatal clinics and 55.56% at the delivery wards were seropositive for both SARS-CoV-2 nucleoprotein and RBD antibodies. Anti-SARS-CoV-2 antibodies in cord samples correlated with maternal antibody levels (N antigen rs = 0.7155, p < 0.001; RBD rs = 0.8693, p < 0.001). Transplacental transfer of SARS-CoV-2 nucleoprotein antibodies was comparable to circumsporozoite protein antibodies (p = 0.9999) but both were higher than transfer rates of merozoite surface protein 3 antibodies (p < 0.001). SARS-CoV-2 IgG seropositivity among pregnant women in Accra is high with a boost of SARS-CoV-2 RBD-specific IgG in vaccinated women. Transplacental transfer of anti-SARS-CoV-2 and malarial antibodies was efficient, supporting vaccination of mothers as a strategy to protect infants against SARS-CoV-2.
Collapse
Affiliation(s)
- Frederica D Partey
- Department of Epidemiology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, P.O BOX LG 581, Legon, Accra, Ghana
| | - Dorotheah Obiri
- Department of Epidemiology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, P.O BOX LG 581, Legon, Accra, Ghana
| | - Evelyn Yayra Bonney
- Department of Epidemiology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, P.O BOX LG 581, Legon, Accra, Ghana
| | - Abigail Naa Adjorkor Pobee
- Department of Epidemiology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, P.O BOX LG 581, Legon, Accra, Ghana
| | - Isaac Kumi Damptey
- Department of Epidemiology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, P.O BOX LG 581, Legon, Accra, Ghana
| | - Keren Ennuson
- Department of Epidemiology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, P.O BOX LG 581, Legon, Accra, Ghana
| | - Jayln Akwetea-Foli
- Department of Epidemiology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, P.O BOX LG 581, Legon, Accra, Ghana
| | | | - David Courtin
- Department of Epidemiology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, P.O BOX LG 581, Legon, Accra, Ghana
- Université Paris Cité, IRD, MERIT, 75006, Paris, France
| | - Kwadwo A Kusi
- Department of Epidemiology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, P.O BOX LG 581, Legon, Accra, Ghana
| | - Benedicta A Mensah
- Department of Epidemiology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, P.O BOX LG 581, Legon, Accra, Ghana.
| |
Collapse
|
3
|
Asare KK, Agrah B, Ofori-Acquah FS, Kudzi W, Aryee NA, Amoah LE. Immune responses to P falciparum antibodies in symptomatic malaria patients with variant hemoglobin genotypes in Ghana. BMC Immunol 2024; 25:14. [PMID: 38336647 PMCID: PMC10858493 DOI: 10.1186/s12865-024-00607-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Accepted: 02/02/2024] [Indexed: 02/12/2024] Open
Abstract
BACKGROUND Haemoglobin (Hb) variants such as sickle cell trait (SCT/HbAS) play a role in protecting against clinical malaria, but little is known about the development of immune responses against malaria parasite (Plasmodium falciparum surface protein 230 (Pfs230) and Plasmodium falciparum erythrocyte binding antigen 175 region-3 (PfEBA175-3R)) and vector (on the An. gambiae Salivary Gland Protein-6 peptide 1 (gSG6-P1)) antigens in individuals with variants Hb genotypes. This study assessed antibody (IgG) responses against malaria parasite, Pfs230 and PfEBA175-3R and vector, gSG6-P1 in febrile individuals with variant Hb genotypes. METHODS The study was conducted on symptomatic malaria patients attending various healthcare facilities throughout Ghana. Microscopy and ELISA were used to determine the natural IgG antibody levels of gSG6-P1, PfEBA175-3R & Pfs230, and Capillarys 2 Flex Piercing was used for Hb variants determination. RESULTS Of the 600 symptomatic malaria patients, 50.0% of the participants had malaria parasites by microscopy. The majority 79.0% (398/504) of the participants had Hb AA, followed by HbAS variant at 11.3% (57/504) and HbAC 6.7% (34/504). There were significantly (p < 0.0001) reduced levels of gSG6-P1 IgG in individuals with both HbAC and HbAS genotypes compared to the HbAA genotype. The levels of gSG6-P1 IgG were significantly (p < 0.0001) higher in HbAS compared to HbAC. Similarly, Pfs230 IgG and PfEBA-175-3R IgG distributions observed across the haemoglobin variants were significantly higher in HbAC relative to HbAS. CONCLUSION The study has shown that haemoglobin variants significantly influence the pattern of anti-gSG6-P1, Pfs230, and PfEBA-175 IgG levels in malaria-endemic population. The HbAS genotype is suggested to confer protection against malaria infection. Reduced exposure to infection ultimately reduces the induction of antibodies targeted against P. falciparum antigens.
Collapse
Affiliation(s)
- Kwame Kumi Asare
- Department of Biomedical Science, School of Allied Health Sciences, University of Cape Coast, Cape Coast, Ghana
- Biomedical and Clinical Research Centre, College of Allied Health Sciences, University of Cape Coast, Cape Coast, Ghana
| | - Benjamin Agrah
- Department of Medical Biochemistry, College of Health Sciences, University of Ghana Medical School, University of Ghana, Korle- Bu, Accra, Ghana
| | | | - William Kudzi
- West Africa Genetic Medicine Centre, University of Ghana, Accra, Ghana
| | - Nii Ayite Aryee
- Department of Medical Biochemistry, College of Health Sciences, University of Ghana Medical School, University of Ghana, Korle- Bu, Accra, Ghana
| | - Linda Eva Amoah
- Department of Immunology, Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana.
| |
Collapse
|
4
|
Mortazavi SE, Lugaajju A, Nylander M, Danielsson L, Tijani MK, Beeson JG, Persson KEM. Acquisition of complement fixing antibodies targeting Plasmodium falciparum merozoites in infants and their mothers in Uganda. Front Immunol 2023; 14:1295543. [PMID: 38090561 PMCID: PMC10715273 DOI: 10.3389/fimmu.2023.1295543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2023] [Accepted: 11/10/2023] [Indexed: 12/18/2023] Open
Abstract
Background Antibody-mediated complement fixation has previously been associated with protection against malaria in naturally acquired immunity. However, the process of early-life development of complement-fixing antibodies in infants, both in comparison to their respective mothers and to other immune parameters, remains less clear. Results We measured complement-fixing antibodies in newborns and their mothers in a malaria endemic area over 5 years follow-up and found that infants' complement-fixing antibody levels were highest at birth, decreased until six months, then increased progressively until they were similar to birth at five years. Infants with high levels at birth experienced a faster decay of complement-fixing antibodies but showed similar levels to the low response group of newborns thereafter. No difference was observed in antibody levels between infant cord blood and mothers at delivery. The same result was found when categorized into high and low response groups, indicating placental transfer of antibodies. Complement-fixing antibodies were positively correlated with total schizont-specific IgG and IgM levels in mothers and infants at several time points. At nine months, complement-fixing antibodies were negatively correlated with total B cell frequency and osteopontin concentrations in the infants, while positively correlated with atypical memory B cells and P. falciparum-positive atypical memory B cells. Conclusion This study indicates that complement-fixing antibodies against P. falciparum merozoites are produced in the mothers and placentally-transferred, and they are acquired in infants over time during the first years of life. Understanding early life immune responses is crucial for developing a functional, long lasting malaria vaccine.
Collapse
Affiliation(s)
- Susanne E. Mortazavi
- Department of Laboratory Medicine, Lund University, Lund, Sweden
- Department of Infectious Diseases, Skåne University Hospital, Lund, Sweden
| | - Allan Lugaajju
- College of Health Sciences, Makerere University, Kampala, Uganda
| | - Maria Nylander
- Department of Laboratory Medicine, Lund University, Lund, Sweden
| | - Lena Danielsson
- Department of Laboratory Medicine, Lund University, Lund, Sweden
- Clinical Chemistry and Pharmacology, Laboratory Medicine, Office for Medical Services, Region Skåne, Lund, Sweden
| | - Muyideen Kolapo Tijani
- Department of Laboratory Medicine, Lund University, Lund, Sweden
- Cellular Parasitology Program, Cell Biology and Genetics Unit, Department of Zoology, University of Ibadan, Ibadan, Nigeria
| | - James G. Beeson
- The Burnet Institute, Melbourne, VIC, Australia
- Department of Infectious Diseases, University of Melbourne, Melbourne, VIC, Australia
- Central Clinical School and Department of Microbiology, Monash University, Melbourne, VIC, Australia
| | - Kristina E. M. Persson
- Department of Laboratory Medicine, Lund University, Lund, Sweden
- Clinical Chemistry and Pharmacology, Laboratory Medicine, Office for Medical Services, Region Skåne, Lund, Sweden
| |
Collapse
|
5
|
Archer NM, Gnangnon B, Mikdar M, Ciuculescu MF, Petersen N, Staffa SJ, Duraisingh MT. F-erythrocytes promote Plasmodium falciparum proliferation in sickle cell disease. Am J Hematol 2023; 98:1598-1605. [PMID: 37584425 PMCID: PMC11145631 DOI: 10.1002/ajh.27042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 07/09/2023] [Indexed: 08/17/2023]
Abstract
BACKGROUND Sickle cell disease (SCD) remains prevalent because heterozygous carriers (HbAS) are partially resistant to Plasmodium falciparum malaria. Sickle hemoglobin (HbS) polymerization in low and intermediate oxygen (O2 ) conditions is the main driver of HbAS-driven resistance to P. falciparum malaria. However, epidemiological studies have reported mixed malaria morbidity and mortality outcomes in individuals with sickle cell disease (SCD). While maximum-tolerated dose hydroxyurea has been shown to lower malaria incidence, fetal hemoglobin (HbF), an inhibitor of HbS polymerization that is variably packaged in F-erythrocytes, might provide hemoglobin that is accessible to the parasite for feeding. METHODS To explore that risk, we examined the effect of variable mean corpuscular fetal hemoglobin (MCHF) on P. falciparum proliferation, invasion, and development in HbSS RBCs. RESULTS We found that greater MCHF in HbSS red blood cells (RBCs) is associated with increased P. falciparum proliferation in O2 environments comparable with the microcirculation. Moreover, both parasite invasion and intracellular growth, the major components of proliferation, occur predominantly in F-erythrocytes and are augmented with increasing MCHF. CONCLUSIONS HbF modifies P. falciparum infection in HbSS RBCs, further highlighting the complexity of the molecular interactions between these two diseases. Other inhibitors of HbS polymerization that do not increase HbF or F-erythrocytes should be independently assessed for their effects on P. falciparum malaria proliferation in HbSS RBCs.
Collapse
Affiliation(s)
- Natasha M. Archer
- Pediatric Hematology/Oncology Dana-Farber/Boston Children’s Cancer and Blood Disorders Center, Harvard Medical School, Boston, Massachusetts, USA
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
| | - Bénédicte Gnangnon
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
- Center for Communicable Diseases Dynamics, Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
| | - Mahmoud Mikdar
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
| | - Marioara F. Ciuculescu
- The TransLab, Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Nicole Petersen
- Pediatric Hematology/Oncology Dana-Farber/Boston Children’s Cancer and Blood Disorders Center, Harvard Medical School, Boston, Massachusetts, USA
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
| | - Steven J. Staffa
- Department of Anesthesiology, Critical Care and Pain Medicine, Boston Children’s Hospital, Boston, Massachusetts, USA
| | - Manoj T. Duraisingh
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
| |
Collapse
|
6
|
Rent S, Bauserman M, Laktabai J, Tshefu AK, Taylor SM. Malaria in Pregnancy: Key Points for the Neonatologist. Neoreviews 2023; 24:e539-e552. [PMID: 37653081 DOI: 10.1542/neo.24-9-e539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
Abstract
In malaria-endemic regions, infection with the malaria parasite Plasmodium during pregnancy has been identified as a key modifiable factor in preterm birth, the delivery of low-birthweight infants, and stillbirth. Compared with their nonpregnant peers, pregnant persons are at higher risk for malaria infection. Malaria infection can occur at any time during pregnancy, with negative effects for the pregnant person and the fetus, depending on the trimester in which the infection is contracted. Pregnant patients who are younger, in their first or second pregnancy, and those coinfected with human immunodeficiency virus are at increased risk for malaria. Common infection prevention measures during pregnancy include the use of insecticide-treated bed nets and the use of intermittent preventive treatment with monthly doses of antimalarials, beginning in the second trimester in pregnant patients in endemic areas. In all trimesters, artemisinin-combination therapies are the first-line treatment for uncomplicated falciparum malaria, similar to treatment in nonpregnant adults. The World Health Organization recently revised its recommendations, now listing the specific medication artemether-lumefantrine as first-line treatment for uncomplicated malaria in the first trimester. While strong prevention and detection methods exist, use of these techniques remains below global targets. Ongoing work on approaches to treatment and prevention of malaria during pregnancy remains at the forefront of global maternal child health research.
Collapse
Affiliation(s)
- Sharla Rent
- Department of Pediatrics, Duke University School of Medicine, Durham, NC
| | | | | | - Antoinette K Tshefu
- Kinshasa School of Public Health, Kinshasa, Democratic Republic of the Congo
| | - Steve M Taylor
- Department of Medicine, Duke University School of Medicine, Durham, NC
| |
Collapse
|
7
|
Leonard CM, Uhomoibhi P, Abubakar A, Ogunniyi A, Mba N, Greby SM, Okoye MI, Iriemenam NC, Ihekweazu C, Steinhardt L, Rogier E. Dynamics of IgG antibody response against Plasmodium antigens among Nigerian infants and young children. Front Immunol 2023; 14:1208822. [PMID: 37691957 PMCID: PMC10484571 DOI: 10.3389/fimmu.2023.1208822] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Accepted: 07/24/2023] [Indexed: 09/12/2023] Open
Abstract
Background Plasmodium falciparum malaria is a leading cause of child mortality in Nigeria. Neonates are born with maternal antibodies from placental transfer which may protect against malaria infection in the first months of life. The IgG dynamics of the transition from passively transferred antimalarial antibodies to actively acquired IgG from natural exposure have not been well elucidated. Methods Blood samples collected during a 2018 Nigeria nationwide HIV/AIDS household survey were available for 9,443 children under 5 years of age, with a subset of infants under 2 months of age having maternal samples available (n=41). Samples were assayed for the P. falciparum HRP2 antigen and anti-malarial IgG antibodies. LOESS regression examined the dynamics in IgG response in the first 5 years of life. Correlation with maternal IgG levels was assessed for mother/child pairs. Results Consistent decreases were observed in median IgG levels against all Plasmodium spp. antigen targets for the first months of life. At a population level, P. falciparum apical membrane antigen-1 (AMA1) and merozoite surface protein-1 19kD (PfMSP1) IgG decreased during the first 12 months of life before reaching a nadir, whereas IgGs to other targets only declined for the first 4 months of life. Seropositivity showed a similar decline with the lowest seropositivity against AMA1 and PfMSP1 at 10-12 months, though remaining above 50% during the first 2 years of life in higher transmission areas. No protective association was observed between IgG positivity and P. falciparum infection in infants. Maternal antibody levels showed a strong positive correlation with infant antibody levels for all P. falciparum antigens from birth to 2 months of age, but this correlation was lost by 6 months of age. Discussion Maternally transferred anti-malarial IgG antibodies rapidly decline during the first 6 months of life, with variations among specific antigens and malaria transmission intensity. From 3-23 months of age, there was a wide range in IgG levels for the blood-stage antigens indicating high individual variation in antibody production as children are infected with malaria. Non-falciparum species-specific antigens showed similar patterns in waning immunity and correlation with paired mother's IgG levels compared to P. falciparum antigens.
Collapse
Affiliation(s)
- Colleen M. Leonard
- Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, United States
- Oak Ridge Institute for Science and Education, U.S. Department of Energy, Oak Ridge, TN, United States
| | - Perpetua Uhomoibhi
- National Malaria Elimination Programme, Federal Ministry of Health, Abuja, Nigeria
| | - Ado Abubakar
- Institute of Human Virology (IHVN), Abuja, Nigeria
| | | | - Nwando Mba
- Nigeria Centre for Disease Control (NCDC), Abuja, Nigeria
| | - Stacie M. Greby
- Division of Global HIV and Tuberculosis, Center for Global Health, Centers for Disease Control and Prevention, Abuja, Nigeria
| | - McPaul I. Okoye
- Division of Global HIV and Tuberculosis, Center for Global Health, Centers for Disease Control and Prevention, Abuja, Nigeria
| | - Nnaemeka C. Iriemenam
- Division of Global HIV and Tuberculosis, Center for Global Health, Centers for Disease Control and Prevention, Abuja, Nigeria
| | | | - Laura Steinhardt
- Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, United States
| | - Eric Rogier
- Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, United States
| | - NMS4 Technical Working Group
- Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, United States
| |
Collapse
|
8
|
Mohan K, Omar BJ, Chacham S. Malaria in newborn: A missed entity for primary care physician. J Family Med Prim Care 2023; 12:1511-1515. [PMID: 37767407 PMCID: PMC10521827 DOI: 10.4103/jfmpc.jfmpc_2332_22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 05/20/2023] [Accepted: 05/29/2023] [Indexed: 09/29/2023] Open
Abstract
Neonatal malaria and congenital malaria, though thought to be a rare entity in non-endemic areas but incidences from epidemic countries are eye openers. It is still thought by primary care physicians that its existence among neonates is not common even in endemic areas due to a low index of suspicion. In order to attain the objective set out in the global technical strategy against malaria 2016-2030, it is important to have a gravity of this disease in all age groups, especially in children and neonates in which misconception of low burden of infection results in underestimation of its morbidity and mortality in these age groups. This disease is only the tip of the iceberg due to unidentified, underreported and neglected illness and being a pointer towards higher circulation among society and pregnant women. So this review article highlights pathophysiology, epidemiology, clinical features, complications, prognosis, treatment and prevention of malaria in newborns and intends to bring awareness among the caregivers to understand the need for attention towards this neglected disease of neonates so that they should be able to identify and manage the disease in this vulnerable age group.
Collapse
Affiliation(s)
- Kriti Mohan
- Department of Pediatrics, All India Institute of Medical Sciences, Gorakhpur, Uttar Pradesh, India
| | - Balram J. Omar
- Department of Microbiology, All India Institute of Medical Sciences, Rishikesh, Uttarakhand, India
| | - Swathi Chacham
- Department of Pediatrics, All India Institute of Medical Sciences, Rishikesh, Uttarakhand, India
| |
Collapse
|
9
|
Andronescu LR, Buchwald AG, Sharma A, Bauleni A, Mawindo P, Liang Y, Gutman JR, Mathanga DP, Chinkhumba J, Laufer MK. Plasmodium falciparum infection and disease in infancy associated with increased risk of malaria and anaemia in childhood. Malar J 2023; 22:217. [PMID: 37496052 PMCID: PMC10369742 DOI: 10.1186/s12936-023-04646-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Accepted: 07/11/2023] [Indexed: 07/28/2023] Open
Abstract
BACKGROUND Infants under 6 months of age are often excluded from malaria surveillance and observational studies. The impact of malaria during early infancy on health later in childhood remains unknown. METHODS Infants from two birth cohorts in Malawi were monitored at quarterly intervals and whenever they were ill from birth through 24 months for Plasmodium falciparum infections and clinical malaria. Poisson regression and linear mixed effects models measured the effect of exposure to malaria in infancy on subsequent malaria incidence, weight-for-age z-scores (WAZ), and haemoglobin concentrations after 6 months. RESULTS Infants with at least one P. falciparum infection during their first 6 months had increased incidence ratio (IRR) of P. falciparum infection (IRR = 1.27, 95% CI, 1.06-1.52) and clinical malaria (IRR = 2.37, 95% CI, 2.02-2.80) compared to infants without infection. Infants with clinical malaria had increased risk of P. falciparum infection incidence between 6 and 24 months (IRR = 1.64, 95% CI, 1.38-1.94) and clinical malaria (IRR = 1.85, 95% CI, 1.48-2.32). Exposure to malaria was associated with lower WAZ over time (p = 0.02) and lower haemoglobin levels than unexposed infants at every time interval (p = 0.02). CONCLUSIONS Infants experiencing malaria infection or clinical malaria are at increased risk of subsequent infection and disease, have poorer growth, and lower haemoglobin concentrations.
Collapse
Affiliation(s)
- Liana R Andronescu
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, 21201, USA
| | - Andrea G Buchwald
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, 21201, USA
| | - Ankur Sharma
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, 21201, USA
| | - Andy Bauleni
- Malaria Alert Center, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Patricia Mawindo
- Malaria Alert Center, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Yuanyuan Liang
- Department of Epidemiology and Public Health, University of Maryland School of Medicine, Baltimore, 21201, USA
| | - Julie R Gutman
- Malaria Branch, Centers for Disease Control and Prevention, Atlanta, 30333, USA
| | - Don P Mathanga
- Malaria Alert Center, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Jobiba Chinkhumba
- Malaria Alert Center, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Miriam K Laufer
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, 21201, USA.
| |
Collapse
|
10
|
Malaria Vaccines. Infect Dis (Lond) 2023. [DOI: 10.1007/978-1-0716-2463-0_536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/10/2023] Open
|
11
|
Archer NM, Pasvol G, Wilson I, Duraisingh MT. Does fetal hemoglobin inhibit the malarial parasite Plasmodium falciparum? Am J Hematol 2022; 97:E325-E327. [PMID: 35834276 PMCID: PMC9428829 DOI: 10.1002/ajh.26661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Accepted: 06/01/2022] [Indexed: 11/11/2022]
Affiliation(s)
- Natasha M. Archer
- Pediatric Hematology/Oncology Dana-Farber/Boston Children’s Cancer and Blood Disorders Center, Harvard Medical School, 300 Longwood Avenue, Boston MA 02115
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, 651 Huntington Avenue, FXB Building, Room 205, Boston MA, 02115
| | - Geoffrey Pasvol
- Imperial College London, Dept. of Life Sciences, 6th Floor Sir Alexander Fleming Building, Exhibition Road, South Kensington, London SW7 2AZ
| | - Iain Wilson
- University of Edinburgh, School of Biological Sciences, Ashworth Laboratories, King’s Buildings EH9 3JT
| | - Manoj T. Duraisingh
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, 651 Huntington Avenue, FXB Building, Room 205, Boston MA, 02115
| |
Collapse
|
12
|
Suspected Severe Malaria in a Sudanese Patient Affected by Sickle Cell Disease Who Was Treated with Hydroxyurea. Pathogens 2021; 10:pathogens10080985. [PMID: 34451449 PMCID: PMC8398986 DOI: 10.3390/pathogens10080985] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 07/27/2021] [Accepted: 08/03/2021] [Indexed: 11/21/2022] Open
Abstract
Sickle cell disease (SCD) is the most common genetic disease in sub-Saharan Africa. The signs and symptoms of SCD usually begin in early childhood. Characteristic features of this disorder include anaemia, repeated infections, and periodic episodes of pain. Malaria is one of the infections that can occur in patients with SCD in endemic countries. Many guidelines recommend antimalarial chemoprophylaxis in these patients, although the debate on which drug should be used is still ongoing. Hydroxyurea (HU), which is considered a safe and effective treatment for both children and adults with SCD, seems to affect the incidence and severity of malaria, although these impacts have yet to be fully demonstrated. We report a case of an eight-and-a-half-year-old Sudanese boy with SCD treated with HU admitted for suspected severe malaria who showed a recrudescence after first-line treatment. Although he had undergone splenectomy and thus belonged to a category of patients at high risk for infectious complications, he was not receiving any malaria chemoprophylaxis. This case emphasises the importance of the routine administration of malaria prophylaxis to children with SCD living in endemic areas, even when they are treated with HU, and especially if they are at high risk for infectious complications because they have undergone splenectomy. There is an urgent need for further research to evaluate the most appropriate regimen and its optimal duration.
Collapse
|
13
|
Botwe AK, Oppong FB, Gyaase S, Owusu-Agyei S, Asghar M, Asante KP, Färnert A, Osier F. Determinants of the varied profiles of Plasmodium falciparum infections among infants living in Kintampo, Ghana. Malar J 2021; 20:240. [PMID: 34051822 PMCID: PMC8164218 DOI: 10.1186/s12936-021-03752-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Accepted: 05/07/2021] [Indexed: 11/22/2022] Open
Abstract
Background Understanding why some infants tolerate infections, remaining asymptomatic while others succumb to repeated symptomatic malaria is beneficial for studies of naturally acquired immunity and can guide control interventions. This study compared demographic, host and maternal factors associated with being either parasite negative or having asymptomatic infections versus developing symptomatic malaria in the first year of life. Methods A birth cohort (n = 1264) was monitored longitudinally over two years for malaria infections in Kintampo, Ghana. Symptomatic and asymptomatic infections were detected actively through monthly home visits, complemented by passive case detection. Light microscopy was used to detect parasitaemia. Based on data from a minimum of eight monthly visits within the first year of life, infants were classified into one of four groups: “parasite negative”, “only-asymptomatic”, “only-symptomatic” or “alternating” i.e., sometimes symptomatic and other times asymptomatic. The host and maternal characteristics and demographic factors in relation to these four groups were compared. Results The parasite negative group formed 36% of the cohort, whilst the only-symptomatic were 35%. The alternating group were 22% and the only-asymptomatic were 7% of the cohort. There were significant associations between residence, socio-economic status (SES), parity, IPTp doses, delivery place of infant and having or not having malaria parasites. Maternal factors such as early commencement and frequency of ante-natal care (ANC) were significantly higher in the parasite negative group compared to all others. ITN use in pregnancy increased the odds of infant having only asymptomatic infections (“protected against disease”). Placental malaria was more common in the groups of infants with symptomatic malaria. Urban residence was significantly higher in the parasite negative group, while birth in the malaria transmission season were significantly more common in the alternating and parasite negative groups. Risk factors for infants with symptomatic malaria included low SES, birth in private maternity homes, sickle cell normal variant, lower MUAC, reported intake of anti-malarials and increased morbidity before the first microscopic infection was detected. Conclusion Strengthening ANC by encouraging early and regular attendance, the use of IPTp, maternal bed nets and improving the nourishment of infants help reduce the frequency of symptomatic malaria over the first year of life. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-021-03752-9.
Collapse
Affiliation(s)
- Akua Kyerewaa Botwe
- Kintampo Health Research Centre, Ghana Health Service, Kintampo, Ghana. .,Division of Infectious Diseases, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden. .,Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya.
| | | | - Stephaney Gyaase
- Kintampo Health Research Centre, Ghana Health Service, Kintampo, Ghana
| | - Seth Owusu-Agyei
- Kintampo Health Research Centre, Ghana Health Service, Kintampo, Ghana.,Institute of Health Research, University of Health and Allied Sciences, Ho, Ghana
| | - Muhammad Asghar
- Division of Infectious Diseases, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden.,Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Kwaku Poku Asante
- Kintampo Health Research Centre, Ghana Health Service, Kintampo, Ghana
| | - Anna Färnert
- Kintampo Health Research Centre, Ghana Health Service, Kintampo, Ghana.,Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden.,Department of Infectious Diseases, Karolinska University Hospital, Stockholm, Sweden
| | - Faith Osier
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya.,Centre for Infectious Diseases, Parasitology, Heidelberg University Hospital, Heidelberg, Germany
| |
Collapse
|
14
|
Zehner N, Adrama H, Kakuru A, Andra T, Kajubi R, Conrad M, Nankya F, Clark TD, Kamya M, Rodriguez-Barraquer I, Dorsey G, Jagannathan P. Age-related Changes in Malaria Clinical Phenotypes During Infancy are Modified by Sickle Cell Trait. Clin Infect Dis 2021; 73:1887-1895. [PMID: 33738485 PMCID: PMC8599196 DOI: 10.1093/cid/ciab245] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Indexed: 12/02/2022] Open
Abstract
Background Infants are protected against Plasmodium falciparum malaria. Mechanisms that drive this protection remain unclear due to a poor understanding of malaria clinical phenotypes during infancy. Methods We enrolled a birth cohort of 678 infants in Busia, Uganda, an area of high malaria transmission. We followed infants through 12 months of age and quantified protection against parasitemia and clinical disease. Results Symptomatic malaria incidence increased from 1.2 to 2.6 episodes per person-year between 0 and <6 months and between 6 and 12 months of age, while the monthly probability of asymptomatic parasitemia given infection decreased from 32% to 21%. Sickle cell trait (HbAS) was protective against symptomatic malaria (incidence rate ratio = 0.57 comparing HbAS vs hemoglobin AA (HbAA); 95% confidence interval, 0.44–0.74; P < .001), but age modified this relationship (Pint = <0.001), with nonlinear protection that waned between 0 and 9 months of age before increasing. Increasing age was associated with higher parasite densities at the time of infection and, in infants with HbAS, a reduced ability to tolerate high parasite densities without fever. Conclusions Age-dependent changes in HbAS protective efficacy in infancy were accompanied by differential loss of antiparasite and antidisease protection among HbAS and HbAA infants. This provides a framework for investigating the mechanisms that underlie infant protection against malaria. Clinical Trials Registration NCT02793622.
Collapse
Affiliation(s)
| | - Harriet Adrama
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Abel Kakuru
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Teddy Andra
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Richard Kajubi
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Melissa Conrad
- Department of Medicine, University of California, San Francisco, USA
| | | | - Tamara D Clark
- Department of Medicine, University of California, San Francisco, USA
| | - Moses Kamya
- Infectious Diseases Research Collaboration, Kampala, Uganda.,Department of Medicine, Makerere University College of Health Sciences, Kampala, Uganda
| | | | - Grant Dorsey
- Department of Medicine, University of California, San Francisco, USA
| | | |
Collapse
|
15
|
Natama HM, Rovira-Vallbona E, Krit M, Guetens P, Sorgho H, Somé MA, Traoré-Coulibaly M, Valéa I, Mens PF, Schallig HDFH, Berkvens D, Kestens L, Tinto H, Rosanas-Urgell A. Genetic variation in the immune system and malaria susceptibility in infants: a nested case-control study in Nanoro, Burkina Faso. Malar J 2021; 20:94. [PMID: 33593344 PMCID: PMC7885350 DOI: 10.1186/s12936-021-03628-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 02/03/2021] [Accepted: 02/05/2021] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Genetic polymorphisms in the human immune system modulate susceptibility to malaria. However, there is a paucity of data on the contribution of immunogenetic variants to malaria susceptibility in infants, who present differential biological features related to the immaturity of their adaptive immune system, the protective effect of maternal antibodies and fetal haemoglobin. This study investigated the association between genetic variation in innate immune response genes and malaria susceptibility during the first year of life in 656 infants from a birth cohort survey performed in Nanoro, Burkina Faso. METHODS Seventeen single nucleotide polymorphisms (SNPs) in 11 genes of the immune system previously associated with different malaria phenotypes were genotyped using TaqMan allelic hybridization assays in a Fluidigm platform. Plasmodium falciparum infection and clinical disease were documented by active and passive case detection. Case-control association analyses for both alleles and genotypes were carried out using univariate and multivariate logistic regression. For cytokines showing significant SNP associations in multivariate analyses, cord blood supernatant concentrations were measured by quantitative suspension array technology (Luminex). RESULTS Genetic variants in IL-1β (rs1143634) and FcγRIIA/CD32 (rs1801274)-both in allelic, dominant and co-dominant models-were significantly associated with protection from both P. falciparum infection and clinical malaria. Furthermore, heterozygote individuals with rs1801274 SNP in FcγRIIA/CD32 showed higher IL-1RA levels compared to wild-type homozygotes (P = 0.024), a cytokine whose production is promoted by the binding of IgG immune complexes to Fcγ receptors on effector immune cells. CONCLUSIONS These findings indicate that genetic polymorphisms in genes driving innate immune responses are associated to malaria susceptibility during the first year of life, possibly by modulating production of inflammatory mediators.
Collapse
Affiliation(s)
- Hamatandi Magloire Natama
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium.
- Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de La Santé, Nanoro, Burkina Faso.
- Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium.
| | | | - Meryam Krit
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
| | - Pieter Guetens
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
| | - Hermann Sorgho
- Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de La Santé, Nanoro, Burkina Faso
| | - M Athanase Somé
- Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de La Santé, Nanoro, Burkina Faso
| | - Maminata Traoré-Coulibaly
- Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de La Santé, Nanoro, Burkina Faso
| | - Innocent Valéa
- Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de La Santé, Nanoro, Burkina Faso
| | - Petra F Mens
- Department of Medical Microbiology-Parasitology Unit, Academic Medical Centre, Amsterdam University Medical Centres, Amsterdam, The Netherlands
| | - Henk D F H Schallig
- Department of Medical Microbiology-Parasitology Unit, Academic Medical Centre, Amsterdam University Medical Centres, Amsterdam, The Netherlands
| | - Dirk Berkvens
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
| | - Luc Kestens
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
- Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
| | - Halidou Tinto
- Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de La Santé, Nanoro, Burkina Faso
- Centre Muraz, Bobo Dioulasso, Burkina Faso
| | - Anna Rosanas-Urgell
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium.
| |
Collapse
|
16
|
Parra M, Yang J, Weitner M, Akkoyunlu M. Neonatal mice resist Plasmodium yoelii infection until exposed to para-aminobenzoic acid containing diet after weaning. Sci Rep 2021; 11:90. [PMID: 33420157 PMCID: PMC7794322 DOI: 10.1038/s41598-020-79703-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 12/04/2020] [Indexed: 12/03/2022] Open
Abstract
We developed a newborn (NB) mouse Plasmodium yoelii NL infection model to study malaria in early age. Surprisingly, the onset of parasitemia in P. yoelii challenged NB mice was delayed compared to adults and coincided with the weaning date when weanlings switched from maternal milk to normal chow diet. Also, compared to adult mice, parasitemia resolved much later (48 days vs 20 days post challenge) and the peak parasitemia was twice as high in weanlings. Concurrently, weanlings’ germinal center reaction was delayed and diminished compared to adult mice. Maternal milk is deficient in para-aminobenzoic acid (PABA), which is required for de novo folate synthesis by Plasmodium. Suggesting a possible role for the protection afforded by PABA-deficient maternal milk, mice fed with a PABA-deficient diet after the weaning continued to control parasitemia. Despite the reduced parasitemia, these mice developed robust T follicular helper (Tfh) responses and were protected from a second P. yoelii challenge. The NB malaria model provides mechanistic insight into the human infant malaria manifestations where a diet solely based on breast-feeding reduces the incidence of severe malaria in infants. NB mice experiments also support further studies to investigate dietary PABA restriction in the management of severe malaria in infants.
Collapse
Affiliation(s)
- Marcela Parra
- Center for Biologics Evaluation and Research, Division of Bacterial Allergenic and Parasitic Diseases, US Food and Drug Administration, Silver Spring, MD, USA
| | - Jiyeon Yang
- Center for Biologics Evaluation and Research, Division of Bacterial Allergenic and Parasitic Diseases, US Food and Drug Administration, Silver Spring, MD, USA
| | - Megan Weitner
- Center for Biologics Evaluation and Research, Division of Bacterial Allergenic and Parasitic Diseases, US Food and Drug Administration, Silver Spring, MD, USA.,Viral & Rickettsial Diseases Department (NMRC VRDD), Naval Medical Research Center, Silver Spring, MD, USA
| | - Mustafa Akkoyunlu
- Center for Biologics Evaluation and Research, Division of Bacterial Allergenic and Parasitic Diseases, US Food and Drug Administration, Silver Spring, MD, USA. .,DBPAP, US FDA, CBER, 10903 New Hampshire Ave., Building 52/72, Room, 5214, Silver Spring, MD, 209903, USA.
| |
Collapse
|
17
|
Profiles of Plasmodium falciparum infections detected by microscopy through the first year of life in Kintampo a high transmission area of Ghana. PLoS One 2020; 15:e0240814. [PMID: 33075074 PMCID: PMC7571695 DOI: 10.1371/journal.pone.0240814] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Accepted: 10/02/2020] [Indexed: 11/24/2022] Open
Abstract
Although malaria mortality among children under five years of age is high, the characteristics of their infection patterns are not well described. The aim of this study was to examine the longitudinal sequence pattern of Plasmodium falciparum infections in the first year of life within a birth cohort in Kintampo, Ghana (N = 1855). Infants were monitored at home with monthly sampling and also at the clinic for any febrile illness between 2008 and 2011. Light microscopy was performed on monthly scheduled visits and febrile ill visits over twelve months of follow-ups (n = 19231). Microscopy-positive visits accompanied with or without symptoms were rare during the first five months of life but were common from six to twelve months of age. Among 1264 infants with microscopy data over a minimum of eight monthly visits and also throughout in sick visits, some were microscopy negative (36%), and others positive: only-symptomatic (35%), alternating (22%) and only-asymptomatic (7%). The median age of microscopic infection was seven months for the alternating group and eight months for both the only-symptomatic and only-asymptomatic groups. The alternating group had the highest cumulative incidence of microscopic infections, the lowest age at first infection and 87 different infection patterns. Parasite densities detected by microscopy were significantly higher for symptomatic versus asymptomatic infection. We conclude that infants in malaria endemic areas experience diverse infection profiles throughout their first year of life. Further investigations should include submicroscopic reservoir and may shed more light on the factors that determine susceptibility to malaria during infancy.
Collapse
|
18
|
Hartley MA, Hofmann N, Keitel K, Kagoro F, Antunes Moniz C, Mlaganile T, Samaka J, Masimba J, Said Z, Temba H, Gonzalez I, Felger I, Genton B, D’Acremont V. Clinical relevance of low-density Plasmodium falciparum parasitemia in untreated febrile children: A cohort study. PLoS Med 2020; 17:e1003318. [PMID: 32956354 PMCID: PMC7505590 DOI: 10.1371/journal.pmed.1003318] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 08/13/2020] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND Low-density (LD) Plasmodium infections are missed by standard malaria rapid diagnostic tests (standard mRDT) when the blood antigen concentration is below the detection threshold. The clinical impact of these LD infections is unknown. This study investigates the clinical presentation and outcome of untreated febrile children with LD infections attending primary care facilities in a moderately endemic area of Tanzania. METHODS/FINDINGS This cohort study includes 2,801 febrile pediatric outpatients (median age 13.5 months [range 2-59], female:male ratio 0.8:1.0) recruited in Dar es Salaam, Tanzania between 01 December 2014 and 28 February 2016. Treatment decisions were guided by a clinical decision support algorithm run on a mobile app, which also collected clinical data. Only standard mRDT+ cases received antimalarials. Outcomes (clinical failure, secondary hospitalization, and death) were collected in follow-up visits or interviews on days 3, 7, and 28. After patient recruitment had ended, frozen blood from all 2,801 patients was tested for Plasmodium falciparum (Pf) by ultrasensitive-quantitative polymerase chain reaction (qPCR), standard mRDT, and "ultrasensitive" mRDT. As the latter did not improve sensitivity beyond standard mRDT, it is hereafter excluded. Clinical features and outcomes in LD patients (standard mRDT-/ultrasensitive-qPCR+, not given antimalarials) were compared with those with no detectable (ND) parasitemia (standard mRDT-/ultrasensitive-qPCR-) or high-density (HD) infections (standard mRDT+/ultrasensitive-qPCR+, antimalarial-treated). Pf positivity rate was 7.1% (n = 199/2,801) and 9.8% (n = 274/2,801) by standard mRDT and ultrasensitive qPCR, respectively. Thus, 28.0% (n = 76/274) of ultrasensitive qPCR+ cases were not detected by standard mRDT and labeled "LD". LD patients were, on average, 10.6 months younger than those with HD infections (95% CI 7.0-14.3 months, p < 0.001). Compared with ND, LD patients more frequently had the diagnosis of undifferentiated fever of presumed viral origin (risk ratio [RR] = 2.0, 95% CI 1.3-3.1, p = 0.003) and were more often suffering from severe malnutrition (RR = 3.2, 95% CI 1.1-7.5, p = 0.03). Despite not receiving antimalarials, outcomes for the LD group did not differ from ND regarding clinical failures (2.6% [n = 2/76] versus 4.0% [n = 101/2,527], RR = 0.7, 95% CI 0.2-3.5, p = 0.7) or secondary hospitalizations (2.6% [n = 2/76] versus 2.8% [n = 72/2,527], RR = 0.7,95% CI 0.2-3.2, p = 0.9), and no deaths were reported in any Pf-positive groups. HD patients experienced more secondary hospitalizations (10.1% [n = 20/198], RR = 0.3, 95% CI 0.1-1.0, p = 0.005) than LD patients. All the patients in this cohort were febrile children; thus, the association between parasitemia and fever cannot be investigated, nor can the conclusions be extrapolated to neonates and adults. CONCLUSIONS During a 28-day follow-up period, we did not find evidence of a difference in negative outcomes between febrile children with untreated LD Pf parasitemia and those without Pf parasitemia. These findings suggest LD parasitemia may either be a self-resolving fever or an incidental finding in children with other infections, including those of viral origin. These findings do not support a clinical benefit nor additional risk (e.g. because of missed bacterial infections) to using ultrasensitive malaria diagnostics at a primary care level.
Collapse
Affiliation(s)
- Mary-Anne Hartley
- Centre for Primary Care and Public Health, University of Lausanne, Lausanne Switzerland
- EPFL, Machine Learning and Optimization Laboratory, Lausanne, Switzerland
| | - Natalie Hofmann
- Swiss Tropical and Public Health Institute, University of Basel, Basel, Switzerland
| | - Kristina Keitel
- Swiss Tropical and Public Health Institute, University of Basel, Basel, Switzerland
| | - Frank Kagoro
- Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania
| | - Clara Antunes Moniz
- Swiss Tropical and Public Health Institute, University of Basel, Basel, Switzerland
| | - Tarsis Mlaganile
- Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania
| | - Josephine Samaka
- Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania
- Amana hospital, Dar es Salaam, United Republic of Tanzania
| | - John Masimba
- Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania
| | - Zamzam Said
- Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania
| | - Hosiana Temba
- Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania
| | - Iveth Gonzalez
- Foundation for Innovative New Diagnostics (FIND), Geneva, Switzerland
| | - Ingrid Felger
- Swiss Tropical and Public Health Institute, University of Basel, Basel, Switzerland
| | - Blaise Genton
- Centre for Primary Care and Public Health, University of Lausanne, Lausanne Switzerland
- Swiss Tropical and Public Health Institute, University of Basel, Basel, Switzerland
| | - Valérie D’Acremont
- Centre for Primary Care and Public Health, University of Lausanne, Lausanne Switzerland
- Swiss Tropical and Public Health Institute, University of Basel, Basel, Switzerland
| |
Collapse
|
19
|
Nhama A, Varo R, Bassat Q. Highlighting the burden of malarial infection and disease in the neonatal period: making sense of different concepts. Malar J 2020; 19:311. [PMID: 32859200 PMCID: PMC7456000 DOI: 10.1186/s12936-020-03394-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Accepted: 08/25/2020] [Indexed: 11/10/2022] Open
Affiliation(s)
- Abel Nhama
- Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique
- Instituto Nacional de Saúde (INS), Maputo, Mozambique
| | - Rosauro Varo
- Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique
- ISGlobal, Hospital Clínic, Universitat de Barcelona, Barcelona, Spain
| | - Quique Bassat
- Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique.
- ISGlobal, Hospital Clínic, Universitat de Barcelona, Barcelona, Spain.
- ICREA, Pg. Lluís Companys 23, Barcelona, 08010, Spain.
- Pediatric Infectious Diseases Unit, Pediatrics Department, Hospital Sant Joan de Déu (University of Barcelona), Barcelona, Spain.
- Consorcio de Investigación Biomédica en Red de Epidemiología y Salud Pública (CIBERESP), Madrid, Spain.
- Barcelona Institute for Global Health, Carrer Roselló 132, Barcelona, Sobreátic, 08036, Spain.
| |
Collapse
|
20
|
Kurtis JD, Raj DK, Michelow IC, Park S, Nixon CE, McDonald EA, Nixon CP, Pond-Tor S, Jha A, Taliano RJ, Kabyemela ER, Friedman JF, Duffy PE, Fried M. Maternally-derived Antibodies to Schizont Egress Antigen-1 and Protection of Infants From Severe Malaria. Clin Infect Dis 2020; 68:1718-1724. [PMID: 30165569 DOI: 10.1093/cid/ciy728] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Accepted: 08/21/2018] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND In holoendemic areas, children suffer the most from Plasmodium falciparum malaria, yet newborns and young infants express a relative resistance to both infection and severe malarial disease (SM). This relative resistance has been ascribed to maternally-derived anti-parasite immunoglobulin G; however, the targets of these protective antibodies remain elusive. METHODS We enrolled 647 newborns at birth from a malaria-holoendemic region of Tanzania. We collected cord blood, measured antibodies to Plasmodium falciparum Schizont Egress Antigen-1 (PfSEA-1), and related these antibodies to the risk of severe malaria in the first year of life. In addition, we vaccinated female mice with PbSEA-1, mated them, and challenged their pups with P. berghei ANKA parasites to assess the impact of maternal PbSEA-1 vaccination on newborns' resistance to malaria. RESULTS Children with high cord-blood anti-PfSEA-1 antibody levels had 51.4% fewer cases of SM compared to individuals with lower anti-PfSEA-1 levels over 12 months of follow-up (P = .03). In 3 trials, pups born to PbSEA-1-vaccinated dams had significantly lower parasitemia and longer survival following a P. berghei challenge compared to pups born to control dams. CONCLUSIONS We demonstrate that maternally-derived, cord-blood anti-PfSEA-1 antibodies predict decreased risk of SM in infants and vaccination of mice with PbSEA-1 prior to pregnancy protects their offspring from lethal P. berghei challenge. These results identify, for the first time, a parasite-specific target of maternal antibodies that protect infants from SM and suggest that vaccination of pregnant women with PfSEA-1 may afford a survival advantage to their offspring.
Collapse
Affiliation(s)
- Jonathan D Kurtis
- Center for International Health Research, Brown University Medical School, Providence.,Department of Pathology and Laboratory Medicine, Brown University Medical School, Providence
| | - Dipak K Raj
- Center for International Health Research, Brown University Medical School, Providence.,Department of Pathology and Laboratory Medicine, Brown University Medical School, Providence
| | - Ian C Michelow
- Center for International Health Research, Brown University Medical School, Providence.,Department of Pediatrics, Rhode Island Hospital, Brown University Medical School, Providence
| | - Sangshin Park
- Center for International Health Research, Brown University Medical School, Providence.,Department of Pediatrics, Rhode Island Hospital, Brown University Medical School, Providence
| | - Christina E Nixon
- Center for International Health Research, Brown University Medical School, Providence.,Department of Pathology and Laboratory Medicine, Brown University Medical School, Providence
| | - Emily A McDonald
- Center for International Health Research, Brown University Medical School, Providence.,Department of Pediatrics, Rhode Island Hospital, Brown University Medical School, Providence
| | - Christian P Nixon
- Center for International Health Research, Brown University Medical School, Providence.,Department of Pathology and Laboratory Medicine, Brown University Medical School, Providence
| | - Sunthorn Pond-Tor
- Center for International Health Research, Brown University Medical School, Providence.,Department of Pathology and Laboratory Medicine, Brown University Medical School, Providence
| | - Ambrish Jha
- Center for International Health Research, Brown University Medical School, Providence
| | - Ross J Taliano
- Department of Pathology and Laboratory Medicine, Brown University Medical School, Providence
| | - Edward R Kabyemela
- Mother Offspring Malaria Studies (MOMS) Project, Seattle Biomedical Research Institute, Washington.,Muheza Designated District Hospital.,Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania
| | - Jennifer F Friedman
- Center for International Health Research, Brown University Medical School, Providence.,Department of Pediatrics, Rhode Island Hospital, Brown University Medical School, Providence
| | - Patrick E Duffy
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland
| | - Michal Fried
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland
| |
Collapse
|
21
|
Lufungulo Bahati Y, Delanghe J, Bisimwa Balaluka G, Sadiki Kishabongo A, Philippé J. Asymptomatic Submicroscopic Plasmodium Infection Is Highly Prevalent and Is Associated with Anemia in Children Younger than 5 Years in South Kivu/Democratic Republic of Congo. Am J Trop Med Hyg 2020; 102:1048-1055. [PMID: 32124722 DOI: 10.4269/ajtmh.19-0878] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
One of the most important problems in controlling malaria is the limited access to effective and accurate diagnosis of malaria parasitemia. In the Democratic Republic of Congo (DRC), malaria is one of the leading causes of morbidity and mortality. The purpose of this study was to assess the prevalence of anemia and the relationship with asymptomatic submicroscopic Plasmodium infection. A cross-sectional study was carried out among 1,088 apparently healthy children aged between 6 and 59 months selected at random in the health zone of Miti Murhesa in South Kivu/DRC. Capillary blood was obtained for hemoglobin (Hb) concentration measurement by Hemocue® Hb 301. Malaria detection was performed by microscopy and the loop-mediated isothermal amplification (LAMP) assay. Anemia was defined as Hb < 11g/dL. We applied the chi-square test for comparisons, and multiple logistic regression was used to identify the risk factors for anemia and submicroscopic Plasmodium infection. The prevalence of anemia was 39.6%, and the prevalence of parasitemia was 15.9% and 34.0% using microscopy and LAMP test, respectively. Submicroscopic Plasmodium infection was found in 22.3% of the children. The independent risk factors for anemia are Plasmodium infection, children younger than 24 months, low middle-upper arm circumference, and history of illness two weeks before. Otherwise, children with submicroscopic malaria infection have a significantly increased risk for anemia, with a need of transfusion. The prevalence of malaria infection was underestimated, when microscopy was used to diagnose malaria. Children with low parasitemia detected by LAMP but not by microscopy showed a significantly increased prevalence of anemia.
Collapse
Affiliation(s)
- Yvette Lufungulo Bahati
- Department of Diagnostic Sciences, Ghent University, Ghent, Belgium.,Department of Pediatrics, Catholic University of Bukavu, Bukavu, Democratic Republic of Congo
| | - Joris Delanghe
- Department of Diagnostic Sciences, Ghent University, Ghent, Belgium
| | | | | | - Jan Philippé
- Department of Diagnostic Sciences, Ghent University, Ghent, Belgium
| |
Collapse
|
22
|
Saghir S, Moukit M, Kouach J, Assoufi N, Abilkassem R, Agadr A. What about the treatment of asymptomatic forms of congenital malaria: case report and review of the literature. Pan Afr Med J 2020; 35:116. [PMID: 32637014 PMCID: PMC7320767 DOI: 10.11604/pamj.2020.35.116.16628] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2018] [Accepted: 08/06/2018] [Indexed: 11/11/2022] Open
Abstract
We report in this manuscript a case of newborn baby with asymptomatic form of congenital malaria; the screening of the peripheral blood smear of the baby after a positive result in the mother allowed the diagnosis. The authors were permitted through this case to discuss the therapeutic possibility in these cases.
Collapse
Affiliation(s)
| | - Mounir Moukit
- Obstetrics and Gynecology Department, Military Hospital Mohammed V, Rabat, Morocco
| | - Jaouad Kouach
- Obstetrics and Gynecology Department, Military Hospital Mohammed V, Rabat, Morocco
| | - Naoufal Assoufi
- Department of Internal Medicine, Military Hospital Mohammed V, Rabat, Morocco
| | | | - Aomar Agadr
- Pediatric Department, Military Hospital Mohammed V, Rabat, Morocco
| |
Collapse
|
23
|
Tatu T. Wide range of F cell levels in healthy Thai adults: Influence of Swiss-type hereditary persistence of foetal haemoglobin & β-haemoglobinopathy. Indian J Med Res 2020; 150:161-166. [PMID: 31670271 PMCID: PMC6829780 DOI: 10.4103/ijmr.ijmr_1954_17] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Background & objectives: Swiss-type hereditary persistence of foetal haemoglobin (HPFH) has been shown to be responsible for the wide range of F cell levels in healthy Thai adults. However, a survey for F cells in healthy Thai adults has not been performed. This study was conducted to determine the F cell distribution in adult Thai blood donors and to assess the possible involvement of β-thalassaemia and haemoglobin E (HbE) carriers in increased HbF levels. Methods: Thai blood donors (n=375, 205 males and 170 females) were included in the study. Blood samples were collected for measuring haemoglobin (Hb) concentration and haematocrit (Hct) and F cell levels. Hb and Hct levels were determined by automated blood counter, while F cells were quantified by flow cytometric analysis of F cells stained by fluorescein isothiocyanate-conjugated anti γ-globin monoclonal antibody. Finally, F cell levels were compared between blood samples having mean corpuscular volume (MCV) <80 fl and ≥80 fl as well as between β-haemoglobinopathies (HbE and β-thalassaemia carriers) and normal adults. Results: F cell levels varied markedly spanning 0.80-39.2 per cent with a positively skewed distribution. Thirty two per cent of these individuals had F cell levels more than the 4.5 per cent cut-off point. F cell levels in females were significantly higher than those in males (P<0.05). F cell levels in individuals having MCV <80 fl were significantly higher than those having MCV ≥80 fl (P<0.05). β-haemoglobinopathy (HbE and β-thalassaemia carriers) had significantly higher F cell levels than normal individuals (P<0.05). Interpretation & conclusions: The present results showed that besides Swiss-type HPFH, the β-haemoglobinopathy was expected to be involved in increased F cell levels in adult Thais. Thus, influence of β-haemoglobinopathy must be considered in interpreting F cell levels in area endemic of this globin disorder.
Collapse
Affiliation(s)
- Thanusak Tatu
- Department of Medical Technology, Division of Clinical Microscopy, Research Center for Hematology & Health Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai, Thailand
| |
Collapse
|
24
|
Kivisi CA, Muthui M, Hunt M, Fegan G, Otto TD, Githinji G, Warimwe GM, Rance R, Marsh K, Bull PC, Abdi AI. Exploring Plasmodium falciparum Var Gene Expression to Assess Host Selection Pressure on Parasites During Infancy. Front Immunol 2019; 10:2328. [PMID: 31681266 PMCID: PMC6798654 DOI: 10.3389/fimmu.2019.02328] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 09/16/2019] [Indexed: 11/13/2022] Open
Abstract
In sub-Saharan Africa, children below 5 years bear the greatest burden of severe malaria because they lack naturally acquired immunity that develops following repeated exposure to infections by Plasmodium falciparum. Antibodies to the surface of P. falciparum infected erythrocytes (IE) play an important role in this immunity. In children under the age of 6 months, relative protection from severe malaria is observed and this is thought to be partly due to trans-placental acquired protective maternal antibodies. However, the protective effect of maternal antibodies has not been fully established, especially the role of antibodies to variant surface antigens (VSA) expressed on IE. Here, we assessed the immune pressure on parasites infecting infants using markers associated with the acquisition of naturally acquired immunity to surface antigens. We hypothesized that, if maternal antibodies to VSA imposed a selection pressure on parasites, then the expression of a relatively conserved subset of var genes called group A var genes in infants should change with waning maternal antibodies. To test this, we compared their expression in parasites from children between 0 and 12 months and above 12 months of age. The transcript quantity and the proportional expression of group A var subgroup, including those containing domain cassette 13, were positively associated with age during the first year of life, which contrasts with above 12 months. This was accompanied by a decline in infected erythrocyte surface antibodies and an increase in parasitemia during this period. The observed increase in group A var gene expression with age in the first year of life, when the maternal antibodies are waning and before acquisition of naturally acquired antibodies with repeated exposure, is consistent with the idea that maternally acquired antibodies impose a selection pressure on parasites that infect infants and may play a role in protecting these infants against severe malaria.
Collapse
Affiliation(s)
- Cheryl A Kivisi
- KEMRI Wellcome Trust Research Programme, Kilifi, Kenya.,Pwani University Biosciences Research Centre, Pwani University, Kilifi, Kenya.,Department of Biological Sciences, Pwani University, Kilifi, Kenya
| | | | - Martin Hunt
- Wellcome Sanger Institute, Cambridge, United Kingdom
| | - Greg Fegan
- KEMRI Wellcome Trust Research Programme, Kilifi, Kenya
| | | | | | - George M Warimwe
- KEMRI Wellcome Trust Research Programme, Kilifi, Kenya.,Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, United Kingdom
| | - Richard Rance
- Pwani University Biosciences Research Centre, Pwani University, Kilifi, Kenya
| | - Kevin Marsh
- KEMRI Wellcome Trust Research Programme, Kilifi, Kenya.,Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, United Kingdom
| | - Peter C Bull
- KEMRI Wellcome Trust Research Programme, Kilifi, Kenya
| | - Abdirahman I Abdi
- KEMRI Wellcome Trust Research Programme, Kilifi, Kenya.,Pwani University Biosciences Research Centre, Pwani University, Kilifi, Kenya
| |
Collapse
|
25
|
Archer NM, Petersen N, Duraisingh MT. Fetal hemoglobin does not inhibit Plasmodium falciparum growth. Blood Adv 2019; 3:2149-2152. [PMID: 31311778 PMCID: PMC6650726 DOI: 10.1182/bloodadvances.2019000399] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Accepted: 06/03/2019] [Indexed: 11/20/2022] Open
Abstract
P falciparum growth is not inhibited in either cord or heterozygote hereditary persistence of fetal hemoglobin erythrocytes. P falciparum growth in fetal hemoglobin erythrocytes is oxygen independent.
Collapse
Affiliation(s)
- Natasha M Archer
- Pediatric Hematology/Oncology, Dana-Farber/Boston Children's Cancer and Blood Disorders Center, Dana-Farber Cancer Institute and Boston Children's Hospital, Boston, MA; and
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Harvard University, Boston, MA
| | - Nicole Petersen
- Pediatric Hematology/Oncology, Dana-Farber/Boston Children's Cancer and Blood Disorders Center, Dana-Farber Cancer Institute and Boston Children's Hospital, Boston, MA; and
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Harvard University, Boston, MA
| | - Manoj T Duraisingh
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Harvard University, Boston, MA
| |
Collapse
|
26
|
Saelens JW, Taylor SM. Born to sweet delight: Using natural models of malaria protection to understand and neutralize P. falciparum pathogenesis. PLoS Pathog 2019; 15:e1007770. [PMID: 31220180 PMCID: PMC6586352 DOI: 10.1371/journal.ppat.1007770] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- Joseph W. Saelens
- Division of Infectious Diseases, Duke University School of Medicine, Durham, North Carolina, United States of America
| | - Steve M. Taylor
- Division of Infectious Diseases, Duke University School of Medicine, Durham, North Carolina, United States of America
- Duke Global Health Institute, Duke University, Durham, North Carolina, United States of America
- * E-mail:
| |
Collapse
|
27
|
Bendabenda J, Patson N, Hallamaa L, Ashorn U, Dewey KG, Ashorn P, Maleta K. Does anthropometric status at 6 months predict the over-dispersion of malaria infections in children aged 6-18 months? A prospective cohort study. Malar J 2019; 18:143. [PMID: 31010435 PMCID: PMC6477714 DOI: 10.1186/s12936-019-2778-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 04/13/2019] [Indexed: 12/02/2022] Open
Abstract
BACKGROUND In malaria-endemic settings, a small proportion of children suffer repeated malaria infections, contributing to most of the malaria cases, yet underlying factors are not fully understood. This study was aimed to determine whether undernutrition predicts this over-dispersion of malaria infections in children aged 6-18 months in settings of high malaria and undernutrition prevalence. METHODS Prospective cohort study, conducted in Mangochi, Malawi. Six-months-old infants were enrolled and had length-for-age z-scores (LAZ), weight-for-age z-scores (WAZ), and weight-for-length z-scores (WLZ) assessed. Data were collected for 'presumed', clinical, and rapid diagnostic test (RDT)-confirmed malaria until 18 months. Malaria microscopy was done at 6 and 18 months. Negative binomial regression was used for malaria incidence and modified Poisson regression for malaria prevalence. RESULTS Of the 2723 children enrolled, 2561 (94%) had anthropometry and malaria data. The mean (standard deviation [SD]) of LAZ, WAZ, and WLZ at 6 months were - 1.4 (1.1), - 0.7 (1.2), and 0.3 (1.1), respectively. The mean (SD) incidences of 'presumed', clinical, and RDT-confirmed malaria from 6 to 18 months were: 1.1 (1.6), 0.4 (0.8), and 1.3 (2.0) episodes/year, respectively. Prevalence of malaria parasitaemia was 4.8% at 6 months and 9.6% at 18 months. Higher WLZ at 6 months was associated with lower prevalence of malaria parasitaemia at 18 months (prevalence ratio [PR] = 0.80, 95% confidence interval [CI] 0.67 to 0.94, p = 0.007), but not with incidences of 'presumed' malaria (incidence rate ratio [IRR] = 0.97, 95% CI 0.92 to 1.02, p = 0.190), clinical malaria (IRR = 1.03, 95% CI 0.94 to 1.12, p = 0.571), RDT-confirmed malaria (IRR = 1.00, 95% CI 0.94 to 1.06, p = 0.950). LAZ and WAZ at 6 months were not associated with malaria outcomes. Household assets, maternal education, and food insecurity were significantly associated with malaria. There were significant variations in hospital-diagnosed malaria by study site. CONCLUSION In children aged 6-18 months living in malaria-endemic settings, LAZ, WAZ, and WLZ do not predict malaria incidence. However, WLZ may be associated with prevalence of malaria. Socio-economic and micro-geographic factors may explain the variations in malaria, but these require further study. Trial registration NCT00945698. Registered July 24, 2009, https://clinicaltrials.gov/ct2/show/NCT00945698 , NCT01239693. Registered Nov 11, 2010, https://clinicaltrials.gov/ct2/show/NCT01239693.
Collapse
Affiliation(s)
- Jaden Bendabenda
- Department of Public Health, School of Public Health, University of Malawi College of Medicine, Mahatma Gandhi Road, Private Bag 360, Blantyre 3, Malawi
- Faculty of Medicine and Life Sciences, Center for Child Health Research, University of Tampere, Tampere, Finland
| | - Noel Patson
- Department of Public Health, School of Public Health, University of Malawi College of Medicine, Mahatma Gandhi Road, Private Bag 360, Blantyre 3, Malawi
- School of Public Health, University of the Witwatersrand, Johannesburg, South Africa
| | - Lotta Hallamaa
- Faculty of Medicine and Life Sciences, Center for Child Health Research, University of Tampere, Tampere, Finland
| | - Ulla Ashorn
- Faculty of Medicine and Life Sciences, Center for Child Health Research, University of Tampere, Tampere, Finland
| | - Kathryn G Dewey
- Department of Nutrition, University of California, Davis, Davis, CA, USA
| | - Per Ashorn
- Faculty of Medicine and Life Sciences, Center for Child Health Research, University of Tampere, Tampere, Finland
| | - Kenneth Maleta
- Department of Public Health, School of Public Health, University of Malawi College of Medicine, Mahatma Gandhi Road, Private Bag 360, Blantyre 3, Malawi.
| |
Collapse
|
28
|
Natama HM, Rovira-Vallbona E, Somé MA, Zango SH, Sorgho H, Guetens P, Coulibaly-Traoré M, Valea I, Mens PF, Schallig HDFH, Kestens L, Tinto H, Rosanas-Urgell A. Malaria incidence and prevalence during the first year of life in Nanoro, Burkina Faso: a birth-cohort study. Malar J 2018; 17:163. [PMID: 29650007 PMCID: PMC5898041 DOI: 10.1186/s12936-018-2315-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Accepted: 04/09/2018] [Indexed: 12/22/2022] Open
Abstract
Background Infants are thought to be protected against malaria during the first months of life mainly due to passage of maternal antibodies. However, in high transmission settings, malaria in early infancy is not uncommon and susceptibility to the infections varies between individuals. This study aimed to determine malaria morbidity and infection during early childhood in rural Burkina Faso. Methods Malariometric indices were determined over 1-year follow-up in a birth cohort of 734 infants living in Nanoro health district. Clinical malaria episodes were determined by passive case detection at peripheral health centres while asymptomatic malaria infections were identified during 4 cross-sectional surveys at 3, 6, 9 and 12 months of age. Plasmodium falciparum infections were detected by rapid diagnostic test and/or light microscopy (LM) and quantitative PCR (qPCR). Results In total, 717 clinical episodes were diagnosed by qPCR over 8335.18 person-months at risk. The overall malaria incidence was 1.03 per child-year and increased from 0.27 per child-year at 0–3 months of age to 1.92 per child-year at 9–12 months of age. Some 59% of children experienced at least one clinical episode with a median survival time estimated at 9.9 months, while 20% of infants experienced the first episode before 6 months of age. The majority of the clinical episodes were attributable to microscopic parasitaemia (84.2%), and there was a positive correlation between parasite density and age (Spearman’s rho = 0.30; P < 0.0001). Prevalence of asymptomatic infections was similar at 3, 6 and 9 months of age (17.7–20.1%) and nearly 1.6 times higher at 12 months (31.3%). Importantly, gametocyte prevalence among the LM-positive study population was 6.7%, but increased to 10% among asymptomatic infections. In addition, 46% of asymptomatic infections were only detected by qPCR suggesting that infants below 1 year are a potential reservoir for sustaining malaria transmission. Both symptomatic and asymptomatic infections showed marked seasonal distribution with the highest transmission period (July to December) accounting for about 89 and 77% of those infections, respectively. Conclusions These findings indicate high and marked age and seasonal-dependency of malaria infections and disease during the first year of life in Nanoro, calling for intensified efforts to control malaria in rural Burkina Faso.
Collapse
Affiliation(s)
- Hamtandi Magloire Natama
- Department of Biomedical Sciences, Institute of Tropical Medicine, 2000, Antwerp, Belgium. .,Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de la Santé, Nanoro, BP 218, Burkina Faso. .,Department of Biomedical Sciences, University of Antwerp, 2610, Antwerp, Belgium.
| | - Eduard Rovira-Vallbona
- Department of Biomedical Sciences, Institute of Tropical Medicine, 2000, Antwerp, Belgium
| | - M Athanase Somé
- Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de la Santé, Nanoro, BP 218, Burkina Faso
| | - Serge Henri Zango
- Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de la Santé, Nanoro, BP 218, Burkina Faso.,Centre Muraz, Bobo Dioulasso, BP 390, Burkina Faso
| | - Hermann Sorgho
- Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de la Santé, Nanoro, BP 218, Burkina Faso
| | - Pieter Guetens
- Department of Biomedical Sciences, Institute of Tropical Medicine, 2000, Antwerp, Belgium
| | - Maminata Coulibaly-Traoré
- Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de la Santé, Nanoro, BP 218, Burkina Faso
| | - Innocent Valea
- Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de la Santé, Nanoro, BP 218, Burkina Faso
| | - Petra F Mens
- Department of Medical Microbiology-Parasitology Unit, Academic Medical Centre, 1105 AZ, Amsterdam, The Netherlands
| | - Henk D F H Schallig
- Department of Medical Microbiology-Parasitology Unit, Academic Medical Centre, 1105 AZ, Amsterdam, The Netherlands
| | - Luc Kestens
- Department of Biomedical Sciences, Institute of Tropical Medicine, 2000, Antwerp, Belgium.,Department of Biomedical Sciences, University of Antwerp, 2610, Antwerp, Belgium
| | - Halidou Tinto
- Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de la Santé, Nanoro, BP 218, Burkina Faso.,Centre Muraz, Bobo Dioulasso, BP 390, Burkina Faso
| | - Anna Rosanas-Urgell
- Department of Biomedical Sciences, Institute of Tropical Medicine, 2000, Antwerp, Belgium
| |
Collapse
|
29
|
Novel use Of Hydroxyurea in an African Region with Malaria (NOHARM): a trial for children with sickle cell anemia. Blood 2017; 130:2585-2593. [PMID: 29051184 DOI: 10.1182/blood-2017-06-788935] [Citation(s) in RCA: 95] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2017] [Accepted: 08/18/2017] [Indexed: 11/20/2022] Open
Abstract
Hydroxyurea treatment is recommended for children with sickle cell anemia (SCA) living in high-resource malaria-free regions, but its safety and efficacy in malaria-endemic sub-Saharan Africa, where the greatest sickle-cell burden exists, remain unknown. In vitro studies suggest hydroxyurea could increase malaria severity, and hydroxyurea-associated neutropenia could worsen infections. NOHARM (Novel use Of Hydroxyurea in an African Region with Malaria) was a randomized, double-blinded, placebo-controlled trial conducted in malaria-endemic Uganda, comparing hydroxyurea to placebo at 20 ± 2.5 mg/kg per day for 12 months. The primary outcome was incidence of clinical malaria. Secondary outcomes included SCA-related adverse events (AEs), clinical and laboratory effects, and hematological toxicities. Children received either hydroxyurea (N = 104) or placebo (N = 103). Malaria incidence did not differ between children on hydroxyurea (0.05 episodes per child per year; 95% confidence interval [0.02, 0.13]) vs placebo (0.07 episodes per child per year [0.03, 0.16]); the hydroxyurea/placebo malaria incidence rate ratio was 0.7 ([0.2, 2.7]; P = .61). Time to infection also did not differ significantly between treatment arms. A composite SCA-related clinical outcome (vaso-occlusive painful crisis, dactylitis, acute chest syndrome, splenic sequestration, or blood transfusion) was less frequent with hydroxyurea (45%) than placebo (69%; P = .001). Children receiving hydroxyurea had significantly increased hemoglobin concentration and fetal hemoglobin, with decreased leukocytes and reticulocytes. Serious AEs, sepsis episodes, and dose-limiting toxicities were similar between treatment arms. Three deaths occurred (2 hydroxyurea, 1 placebo, and none from malaria). Hydroxyurea treatment appears safe for children with SCA living in malaria-endemic sub-Saharan Africa, without increased severe malaria, infections, or AEs. Hydroxyurea provides SCA-related laboratory and clinical efficacy, but optimal dosing and monitoring regimens for Africa remain undefined. This trial was registered at www.clinicaltrials.gov as #NCT01976416.
Collapse
|
30
|
Awasthi V, Chattopadhyay D, Das J. Potential Hemoglobin A/F role in clinical Malaria. Bioinformation 2017; 13:269-273. [PMID: 28959096 PMCID: PMC5609292 DOI: 10.6026/97320630013269] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2017] [Revised: 08/18/2017] [Accepted: 08/19/2017] [Indexed: 11/24/2022] Open
Abstract
The Malarial parasite resides in the host RBC during its erythrocytic cycle. Plasmodium meets its entire nutritional requirement from RBC. It scavenges the hemoglobin of RBCs to meet its amino acid requirement. The host hemoglobin is made of different chains and it is dependent on age. Hemoglobin F (HbF), which has two-alpha and two gamma chain persists in children upto six years, and hemoglobin A (HbA) made of two alpha and two beta chains dominates. Therefore, it is of interest to compare the compositional features of HbA with HbF. Isoleucine is present in hemoglobin of children (gamma chain of HbF) while it is absent in adult hemoglobin (HbA). The presence of Isoleucine (I) makes HbF ideally suitable for the growth of parasite, as it does not have to depend upon the exogenous supply of the isoleucine, which might be responsible for making children more vulnerable to malaria as compared to adults.
Collapse
Affiliation(s)
- Vikky Awasthi
- Immunology Division, ICMR-National Institute of Malaria Research, Dwarka, New Delhi; Present Address: Regional Medical Research Centre, Belagavi, Nehru Nagar, National Highway No.4, Belagavi-590010, Karnataka, India
| | | | - Jyoti Das
- Immunology Division, ICMR-National Institute of Malaria Research, Dwarka, New Delhi; Present Address: Regional Medical Research Centre, Belagavi, Nehru Nagar, National Highway No.4, Belagavi-590010, Karnataka, India
| |
Collapse
|
31
|
Gonçalves BP, Walker PG, Cairns M, Tiono AB, Bousema T, Drakeley C. Pregnant Women: An Overlooked Asset to Plasmodium falciparum Malaria Elimination Campaigns? Trends Parasitol 2017; 33:510-518. [DOI: 10.1016/j.pt.2017.03.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Revised: 01/20/2017] [Accepted: 03/01/2017] [Indexed: 01/28/2023]
|
32
|
Del Castillo M, Szymanski AM, Slovin A, Wong ECC, DeBiasi RL. Congenital Plasmodium falciparum Malaria in Washington, DC. Am J Trop Med Hyg 2017; 96:167-169. [PMID: 28077745 PMCID: PMC5239687 DOI: 10.4269/ajtmh.15-0630] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Accepted: 06/03/2016] [Indexed: 11/07/2022] Open
Abstract
Congenital malaria is rare in the United States, but is an important diagnosis to consider when evaluating febrile infants. Herein, we describe a case of congenital Plasmodium falciparum malaria in a 2-week-old infant born in the United States to a mother who had emigrated from Nigeria 3 months before delivery.
Collapse
Affiliation(s)
- Melissa Del Castillo
- Division of Pediatric Infectious Diseases, Children's National Medical Center, Washington, District of Columbia
- Office of Vaccines Research and Review, Food and Drug Administration, Silver Spring, Maryland
| | - Ann Marie Szymanski
- Division of General Pediatrics, Children's National Medical Center, Washington, District of Columbia
| | - Ariella Slovin
- Division of General Pediatrics, Children's National Medical Center, Washington, District of Columbia
| | - Edward C C Wong
- Division of Laboratory Medicine, Children's National Medical Center, Washington, District of Columbia
- Department of Pediatrics, The George Washington University School of Medicine and Health Sciences, Washington, District of Columbia
- Department of Pathology, The George Washington University School of Medicine and Health Sciences, Washington, District of Columbia
| | - Roberta L DeBiasi
- Division of Pediatric Infectious Diseases, Children's National Medical Center, Washington, District of Columbia.
- Department of Pediatrics, The George Washington University School of Medicine and Health Sciences, Washington, District of Columbia
- Department of Microbiology, Immunology, and Tropical Medicine, The George Washington University School of Medicine and Health Sciences, Washington, District of Columbia
| |
Collapse
|
33
|
Oxidative insult can induce malaria-protective trait of sickle and fetal erythrocytes. Nat Commun 2016; 7:13401. [PMID: 27824335 PMCID: PMC5105170 DOI: 10.1038/ncomms13401] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Accepted: 09/29/2016] [Indexed: 01/06/2023] Open
Abstract
Plasmodium falciparum infections can cause severe malaria, but not every infected person develops life-threatening complications. In particular, carriers of the structural haemoglobinopathies S and C and infants are protected from severe disease. Protection is associated with impaired parasite-induced host actin reorganization, required for vesicular trafficking of parasite-encoded adhesins, and reduced cytoadherence of parasitized erythrocytes in the microvasculature. Here we show that aberrant host actin remodelling and the ensuing reduced cytoadherence result from a redox imbalance inherent to haemoglobinopathic and fetal erythrocytes. We further show that a transient oxidative insult to wild-type erythrocytes before infection with P. falciparum induces the phenotypic features associated with the protective trait of haemoglobinopathic and fetal erythrocytes. Moreover, pretreatment of mice with the pro-oxidative nutritional supplement menadione mitigate the development of experimental cerebral malaria. Our results identify redox imbalance as a causative principle of protection from severe malaria, which might inspire host-directed intervention strategies.
Collapse
|
34
|
Anyanwu JN, Williams O, Sautter CL, Kasirye P, Hume H, Opoka RO, Latham T, Ndugwa C, Ware RE, John CC. Novel Use of Hydroxyurea in an African Region With Malaria: Protocol for a Randomized Controlled Clinical Trial. JMIR Res Protoc 2016; 5:e110. [PMID: 27339303 PMCID: PMC4937184 DOI: 10.2196/resprot.5599] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Accepted: 04/03/2016] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Sickle cell anemia (SCA), one of most prevalent monogenic diseases worldwide, is caused by a glutamic acid to valine substitution on the beta globin protein of hemoglobin, which leads to hemolytic anemia. Hydroxyurea, the only disease-modifying therapy approved by the Food and Drug Administration for SCA, has proven to be a viable therapeutic option for SCA patients in resource-rich settings, given clinical improvements experienced while taking the medication and its once-daily oral dosing. Significant studies have demonstrated its safety and clinical efficacy among children and adults in developed countries. In Sub-Saharan Africa, however, the risk of malaria, hematologic toxicities, and safety of hydroxyurea in children with SCA living in malaria-endemic areas are unknown. OBJECTIVES Study objectives include determining the incidence of malaria in SCA patients taking hydroxyurea versus placebo; establishing the frequency of hematologic toxicities and adverse events (AEs) in children with SCA treated with hydroxyurea versus placebo; and defining the relationships between hydroxyurea treatment and fetal hemoglobin, soluble intracellular adhesion molecule-1, and nitric oxide levels, and between levels of these factors and risk of subsequent malaria. METHODS Novel use Of Hydroxyurea in an African Region with Malaria (NOHARM, NCT01976416) is a prospective, randomized, placebo-controlled, double-blinded phase III trial to compare risk of malaria with oral hydroxyurea versus placebo. Children will be recruited from the Mulago Hospital Sickle Cell Clinic in Kampala, Uganda. RESULTS Two hundred Ugandan children aged between 1.00 and 3.99 years with confirmed SCA will be randomized into treatment groups by order of entry in the study, based on a predetermined blinded randomization list. The primary outcome of the trial is malaria incidence in the 2 study groups, defined as episodes of clinical malaria occurring over the 1-year randomized study treatment period. CONCLUSION NOHARM will be the first prospective randomized, placebo-controlled clinical trial investigating the use of hydroxyurea for children with SCA in a malaria-endemic region within Africa. The results of this trial have the potential to significantly advance understanding of how to safely and effectively use hydroxyurea in children with SCA in malaria-endemic areas. TRIAL REGISTRATION Clinicaltrials.gov NCT01976416; https://clinicaltrials.gov/ct2/show/NCT01976416 (Archived by WebCite at http://www.webcitation.org/6hmoilZnp).
Collapse
|
35
|
Przyborski JM, Nyboer B, Lanzer M. Ticket to ride: export of proteins to the Plasmodium falciparum-infected erythrocyte. Mol Microbiol 2016; 101:1-11. [PMID: 26996123 DOI: 10.1111/mmi.13380] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/17/2016] [Indexed: 12/28/2022]
Abstract
The malaria parasite Plasmodium falciparum exports numerous proteins to its chosen host cell, the mature human erythrocyte. Many of these proteins are important for parasite survival. To reach the host cell, parasites must cross multiple membrane barriers and then furthermore be targeted to their correct sub-cellular localisation. This novel transport pathway has received much research attention in the past decades, especially as many of the mechanisms are expected to be parasite-specific and thus potential targets for drug development. In this article we summarize some of the most recent advances in this field, and highlight areas in which further research is needed.
Collapse
Affiliation(s)
- Jude M Przyborski
- Parasitology, Faculty of Biology, Philipps University Marburg, Karl von Frisch Strasse 8, 35043, Marburg, Germany
| | - Britta Nyboer
- Center of Infectious Diseases, Parasitology, Heidelberg University, Im Neuenheimer Feld 324, 69120, Heidelberg, Germany
| | - Michael Lanzer
- Center of Infectious Diseases, Parasitology, Heidelberg University, Im Neuenheimer Feld 324, 69120, Heidelberg, Germany
| |
Collapse
|
36
|
Helms G, Dasanna AK, Schwarz US, Lanzer M. Modeling cytoadhesion of Plasmodium falciparum-infected erythrocytes and leukocytes-common principles and distinctive features. FEBS Lett 2016; 590:1955-71. [PMID: 26992823 PMCID: PMC5071704 DOI: 10.1002/1873-3468.12142] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Revised: 02/01/2016] [Accepted: 02/07/2016] [Indexed: 12/25/2022]
Abstract
Cytoadhesion of Plasmodium falciparum‐infected erythrocytes to the microvascular endothelial lining shares striking similarities to cytoadhesion of leukocytes. In both cases, adhesins are presented in structures that raise them above the cell surface. Another similarity is the enhancement of adhesion under physical force (catch bonding). Here, we review recent advances in our understanding of the molecular and biophysical mechanisms underlying cytoadherence in both cellular systems. We describe how imaging, flow chamber experiments, single‐molecule measurements, and computational modeling have been used to decipher the relevant processes. We conclude that although the parasite seems to induce processes that resemble the cytoadherence of leukocytes, the mechanics of erythrocytes is such that the resulting behavior in shear flow is fundamentally different.
Collapse
Affiliation(s)
- Gesa Helms
- Department of Infectious Diseases, Heidelberg University, Germany
| | - Anil Kumar Dasanna
- BioQuant, Heidelberg, Germany.,Institute for Theoretical Physics, Heidelberg University, Germany
| | - Ulrich S Schwarz
- BioQuant, Heidelberg, Germany.,Institute for Theoretical Physics, Heidelberg University, Germany
| | - Michael Lanzer
- Department of Infectious Diseases, Heidelberg University, Germany
| |
Collapse
|
37
|
Activated Neutrophils Are Associated with Pediatric Cerebral Malaria Vasculopathy in Malawian Children. mBio 2016; 7:e01300-15. [PMID: 26884431 PMCID: PMC4791846 DOI: 10.1128/mbio.01300-15] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Most patients with cerebral malaria (CM) sustain cerebral microvascular sequestration of Plasmodium falciparum-infected red blood cells (iRBCs). Although many young children are infected with P. falciparum, CM remains a rare outcome; thus, we hypothesized that specific host conditions facilitate iRBC cerebral sequestration. To identify these host factors, we compared the peripheral whole-blood transcriptomes of Malawian children with iRBC cerebral sequestration, identified as malarial-retinopathy-positive CM (Ret+CM), to the transcriptomes of children with CM and no cerebral iRBC sequestration, defined as malarial-retinopathy-negative CM (Ret-CM). Ret+CM was associated with upregulation of 103 gene set pathways, including cytokine, blood coagulation, and extracellular matrix (ECM) pathways (P < 0.01; false-discovery rate [FDR] of <0.05). Neutrophil transcripts were the most highly upregulated individual transcripts in Ret+CM patients. Activated neutrophils can modulate diverse host processes, including the ECM, inflammation, and platelet biology to potentially facilitate parasite sequestration. Therefore, we compared plasma neutrophil proteins and neutrophil chemotaxis between Ret+CM and Ret-CM patients. Plasma levels of human neutrophil elastase, myeloperoxidase, and proteinase 3, but not lactoferrin or lipocalin, were elevated in Ret+CM patients, and neutrophil chemotaxis was impaired, possibly related to increased plasma heme. Neutrophils were rarely seen in CM brain microvasculature autopsy samples, and no neutrophil extracellular traps were found, suggesting that a putative neutrophil effect on endothelial cell biology results from neutrophil soluble factors rather than direct neutrophil cellular tissue effects. Meanwhile, children with Ret-CM had lower levels of inflammation, higher levels of alpha interferon, and upregulation of Toll-like receptor pathways and other host transcriptional pathways, which may represent responses that do not favor cerebral iRBC sequestration. There were approximately 198 million cases of malaria worldwide in 2013, with an estimated 584,000 deaths occurring mostly in sub-Saharan African children. CM is a severe and rare form of Plasmodium falciparum infection and is associated with high rates of mortality and neurological morbidity, despite antimalarial treatment. A greater understanding of the pathophysiology of CM would allow the development of adjunctive therapies to improve clinical outcomes. A hallmark of CM is cerebral microvasculature sequestration of P. falciparum-infected red blood cells (iRBCs), which results in vasculopathy in some patients. Our data provide a global analysis of the host pathways associated with CM and newly identify an association of activated neutrophils with brain iRBC sequestration. Products of activated neutrophils could alter endothelial cell receptors and coagulation to facilitate iRBC adherence. Future studies can now examine the role of neutrophils in CM pathogenesis to improve health outcomes.
Collapse
|
38
|
Abstract
Malaria is one of the most serious infectious diseases with most of the severe disease
caused by Plasmodium falciparum (Pf). Naturally acquired immunity
develops over time after repeated infections and the development of antimalarial
antibodies is thought to play a crucial role. Neonates and young infants are relatively
protected from symptomatic malaria through mechanisms that are poorly understood. The
prevailing paradigm is that maternal antimalarial antibodies transferred to the fetus in
the last trimester of pregnancy protect the infant from early infections. These
antimalarial antibodies wane by approximately 6 months of age leaving the infant
vulnerable to malaria, however direct evidence supporting this epidemiologically based
paradigm is lacking. As infants are the target population for future malaria vaccines,
understanding how they begin to develop immunity to malaria and the gaps in their
responses is key. This review summarizes the antimalarial antibody responses detected in
infants and how they change over time. We focus primarily on Pf antibody responses and
will briefly mention Plasmodium vivax responses in infants.
Collapse
|
39
|
Contrasting Patterns of Serologic and Functional Antibody Dynamics to Plasmodium falciparum Antigens in a Kenyan Birth Cohort. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2015; 23:104-16. [PMID: 26656119 PMCID: PMC4744923 DOI: 10.1128/cvi.00452-15] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Accepted: 11/20/2015] [Indexed: 11/20/2022]
Abstract
IgG antibodies to Plasmodium falciparum are transferred from the maternal to fetal circulation during pregnancy, wane after birth, and are subsequently acquired in response to natural infection. We examined the dynamics of malaria antibody responses of 84 Kenyan infants from birth to 36 months of age by (i) serology, (ii) variant surface antigen (VSA) assay, (iii) growth inhibitory activity (GIA), and (iv) invasion inhibition assays (IIA) specific for merozoite surface protein 1 (MSP1) and sialic acid-dependent invasion pathway. Maternal antibodies in each of these four categories were detected in cord blood and decreased to their lowest level by approximately 6 months of age. Serologic antibodies to 3 preerythrocytic and 10 blood-stage antigens subsequently increased, reaching peak prevalence by 36 months. In contrast, antibodies measured by VSA, GIA, and IIA remained low even up to 36 months. Infants sensitized to P. falciparum in utero, defined by cord blood lymphocyte recall responses to malaria antigens, acquired antimalarial antibodies at the same rate as those who were not sensitized in utero, indicating that fetal exposure to malaria antigens did not affect subsequent infant antimalarial responses. Infants with detectable serologic antibodies at 12 months of age had an increased risk of P. falciparum infection during the subsequent 24 months. We conclude that serologic measures of antimalarial antibodies in children 36 months of age or younger represent biomarkers of malaria exposure rather than protection and that functional antibodies develop after 36 months of age in this population.
Collapse
|
40
|
Hockham C, Piel FB, Gupta S, Penman BS. Understanding the contrasting spatial haplotype patterns of malaria-protective β-globin polymorphisms. INFECTION, GENETICS AND EVOLUTION : JOURNAL OF MOLECULAR EPIDEMIOLOGY AND EVOLUTIONARY GENETICS IN INFECTIOUS DISEASES 2015; 36:174-183. [PMID: 26394108 PMCID: PMC4653953 DOI: 10.1016/j.meegid.2015.09.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Revised: 09/04/2015] [Accepted: 09/06/2015] [Indexed: 12/24/2022]
Abstract
The malaria-protective β-globin polymorphisms, sickle-cell (β(S)) and β(0)-thalassaemia, are canonical examples of human adaptation to infectious disease. Occurring on distinct genetic backgrounds, they vary markedly in their patterns of linked genetic variation at the population level, suggesting different evolutionary histories. β(S) is associated with five classical restriction fragment length polymorphism haplotypes that exhibit remarkable specificity in their geographical distributions; by contrast, β(0)-thalassaemia mutations are found on haplotypes whose distributions overlap considerably. Here, we explore why these two polymorphisms display contrasting spatial haplotypic distributions, despite having malaria as a common selective pressure. We present a meta-population genetic model, incorporating individual-based processes, which tracks the evolution of β-globin polymorphisms on different haplotypic backgrounds. Our simulations reveal that, depending on the rate of mutation, a large population size and/or high population growth rate are required for both the β(S)- and the β(0)-thalassaemia-like patterns. However, whilst the β(S)-like pattern is more likely when population subdivision is high, migration low and long-distance migration absent, the opposite is true for β(0)-thalassaemia. Including gene conversion has little effect on the overall probability of each pattern; however, when inter-haplotype fitness variation exists, gene conversion is more likely to have contributed to the diversity of haplotypes actually present in the population. Our findings highlight how the contrasting spatial haplotype patterns exhibited by β(S) and β(0)-thalassaemia may provide important indications as to the evolution of these adaptive alleles and the demographic history of the populations in which they have evolved.
Collapse
Affiliation(s)
| | | | - Sunetra Gupta
- Department of Zoology, University of Oxford, Oxford, UK.
| | | |
Collapse
|
41
|
Kangoye DT, Mensah VA, Murungi LM, Nkumama I, Nebie I, Marsh K, Cisse B, Bejon P, Osier FHA, Sirima SB. Dynamics and role of antibodies to Plasmodium falciparum merozoite antigens in children living in two settings with differing malaria transmission intensity. Vaccine 2015; 34:160-6. [PMID: 26541134 PMCID: PMC4683095 DOI: 10.1016/j.vaccine.2015.10.058] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Revised: 09/26/2015] [Accepted: 10/12/2015] [Indexed: 11/17/2022]
Abstract
BACKGROUND Young infants have reduced susceptibility to febrile malaria compared with older children, but the mechanism for this remains unclear. There are conflicting data on the role of passively acquired antibodies. Here, we examine antibody titres to merozoite surface antigens in the protection of children in their first two years of life in two settings with differing malaria transmission intensity and compare these titres to previously established protective thresholds. METHODS Two cohorts of children aged four to six weeks were recruited in Banfora, Burkina and Keur Soce, Senegal and followed up for two years. Malaria infections were detected by light microscopic examination of blood smears collected at active and passive case detection visits. The titres of antibodies to the Plasmodium falciparum recombinant merozoite proteins (AMA1-3D7, MSP1-19, MSP2-Dd2, and MSP3-3D7) were measured by enzyme-linked immunosorbent assay at 1-6, 9, 12, 15 and 18 months of age and compared with the protective thresholds established in Kenyan children. RESULTS Antibody titres were below the protective thresholds throughout the study period and we did not find any association with protection against febrile malaria. Antibodies to AMA1 and MSP1-19 appeared to be markers of exposure in the univariate analysis (and so associated with increasing risk) and adjusting for exposure reduced the strength and significance of this association. CONCLUSION The antibody levels we measured are unlikely to be responsible for the apparent protection against febrile malaria seen in young infants. Further work to identify protective antibody responses might include functional assays and a wider range of antigens.
Collapse
Affiliation(s)
- David Tiga Kangoye
- Centre National de Recherche et de Formation sur le Paludisme (CNRFP), 01 BP 2208, Ouagadougou 01, Burkina Faso; Kenya Medical Research Institute, Centre for Geographic Medicine Research Coast (KEMRI-CGMRC), P.O. Box 230, Kilifi 80108, Kenya.
| | | | - Linda Muthoni Murungi
- Kenya Medical Research Institute, Centre for Geographic Medicine Research Coast (KEMRI-CGMRC), P.O. Box 230, Kilifi 80108, Kenya
| | - Irene Nkumama
- Kenya Medical Research Institute, Centre for Geographic Medicine Research Coast (KEMRI-CGMRC), P.O. Box 230, Kilifi 80108, Kenya
| | - Issa Nebie
- Centre National de Recherche et de Formation sur le Paludisme (CNRFP), 01 BP 2208, Ouagadougou 01, Burkina Faso
| | - Kevin Marsh
- Kenya Medical Research Institute, Centre for Geographic Medicine Research Coast (KEMRI-CGMRC), P.O. Box 230, Kilifi 80108, Kenya; Nuffield Department of Medicine, Centre for Clinical Vaccinology and Tropical Medicine, University of Oxford, Churchill Hospital, Oxford, United Kingdom
| | - Badara Cisse
- Service de Parasitologie, Université Cheikh Anta Diop (UCAD), BP 5005 UCAD, Dakar, Senegal
| | - Philip Bejon
- Kenya Medical Research Institute, Centre for Geographic Medicine Research Coast (KEMRI-CGMRC), P.O. Box 230, Kilifi 80108, Kenya; Nuffield Department of Medicine, Centre for Clinical Vaccinology and Tropical Medicine, University of Oxford, Churchill Hospital, Oxford, United Kingdom
| | - Faith Hope Among'in Osier
- Kenya Medical Research Institute, Centre for Geographic Medicine Research Coast (KEMRI-CGMRC), P.O. Box 230, Kilifi 80108, Kenya
| | - Sodiomon Bienvenu Sirima
- Centre National de Recherche et de Formation sur le Paludisme (CNRFP), 01 BP 2208, Ouagadougou 01, Burkina Faso
| |
Collapse
|
42
|
Anemia and Red Blood Cell Abnormalities in HIV-Infected and HIV-Exposed Breastfed Infants: A Secondary Analysis of the Kisumu Breastfeeding Study. PLoS One 2015; 10:e0141599. [PMID: 26529316 PMCID: PMC4631368 DOI: 10.1371/journal.pone.0141599] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 10/09/2015] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Anemia results in increased morbidity and mortality, underscoring the need to better understand its pathophysiology amongst HIV-exposed and infected children in sub-Saharan Africa, the region where most infant HIV exposure and infections occur. METHODS This analysis used samples obtained from children in the Kisumu Breastfeeding Study (KiBS). KiBS was a longitudinal phase IIB, open-label, one-arm clinical trial, designed to investigate the safety, tolerability and effectiveness of a maternal triple-antiretroviral (ARV) regimen for prevention of mother-to-child transmission (PMTCT) of HIV, during late pregnancy and early infancy while breastfeeding. Blood samples from 482 children were obtained at birth, 2, 6, 10 and 14 weeks and 6, 9, 12, 18 and 24 months. Severity of anemia was graded using the NIH Division of AIDS (DAIDS) toxicity tables. We describe the proportion of children with anemia and anomalies in red blood cell parameters at various time points over 24 months and compare rates of anemia between HIV-infected and HIV-uninfected children and by mothers' ARV regimen and infant malaria infection. RESULTS The proportion of children with anemia significantly increased after the breastfeeding period in both HIV-infected and HIV-uninfected children with higher proportion among HIV-infected children compared to HIV-uninfected children (RR: 1.72; CI: 1.22-2.44, p = 0.002). Maternal triple-antiretroviral regimen was not associated with infant anemia (p = 0.11). There was no significant difference in mean hemoglobin between HIV-uninfected children with and without malaria at each time point except at 24 months. CONCLUSION A relatively lower proportion of children with severe anemia during the breastfeeding period suggest that exposure to mother's triple antiretroviral combinations through breast milk, posed minimal risk of hematologic toxicity.
Collapse
|
43
|
Shelton JMG, Corran P, Risley P, Silva N, Hubbart C, Jeffreys A, Rowlands K, Craik R, Cornelius V, Hensmann M, Molloy S, Sepulveda N, Clark TG, Band G, Clarke GM, Spencer CCA, Kerasidou A, Campino S, Auburn S, Tall A, Ly AB, Mercereau-Puijalon O, Sakuntabhai A, Djimdé A, Maiga B, Touré O, Doumbo OK, Dolo A, Troye-Blomberg M, Mangano VD, Verra F, Modiano D, Bougouma E, Sirima SB, Ibrahim M, Hussain A, Eid N, Elzein A, Mohammed H, Elhassan A, Elhassan I, Williams TN, Ndila C, Macharia A, Marsh K, Manjurano A, Reyburn H, Lemnge M, Ishengoma D, Carter R, Karunaweera N, Fernando D, Dewasurendra R, Drakeley CJ, Riley EM, Kwiatkowski DP, Rockett KA. Genetic determinants of anti-malarial acquired immunity in a large multi-centre study. Malar J 2015; 14:333. [PMID: 26314886 PMCID: PMC4552443 DOI: 10.1186/s12936-015-0833-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Accepted: 08/03/2015] [Indexed: 01/01/2023] Open
Abstract
Background Many studies report associations between human genetic factors and immunity to malaria but few have been reliably replicated. These studies are usually country-specific, use small sample sizes and are
not directly comparable due to differences in methodologies. This study brings together samples and data collected from multiple sites across Africa and Asia to use standardized methods to look for consistent genetic effects on anti-malarial antibody levels. Methods Sera, DNA samples and clinical data were collected from 13,299 individuals from ten sites in Senegal, Mali, Burkina Faso, Sudan, Kenya, Tanzania, and Sri Lanka using standardized methods. DNA was extracted and typed for 202 Single Nucleotide Polymorphisms with known associations to malaria or antibody production, and antibody levels to four clinical grade malarial antigens [AMA1, MSP1, MSP2, and (NANP)4] plus total IgE were measured by ELISA techniques. Regression models were used to investigate the associations of clinical and genetic factors with antibody levels. Results Malaria infection increased levels of antibodies to malaria antigens and, as expected, stable predictors of anti-malarial antibody levels included age, seasonality, location, and ethnicity. Correlations between antibodies to blood-stage antigens AMA1, MSP1 and MSP2 were higher between themselves than with antibodies to the (NANP)4 epitope of the pre-erythrocytic circumsporozoite protein, while there was little or no correlation with total IgE levels. Individuals with sickle cell trait had significantly lower antibody levels to all blood-stage antigens, and recessive homozygotes for CD36 (rs321198) had significantly lower anti-malarial antibody levels to MSP2. Conclusion Although the most significant finding with a consistent effect across sites was for sickle cell trait, its effect is likely to be via reducing a microscopically positive parasitaemia rather than directly on antibody levels. However, this study does demonstrate a framework for the feasibility of combining data from sites with heterogeneous malaria transmission levels across Africa and Asia with which to explore genetic effects on anti-malarial immunity. Electronic supplementary material The online version of this article (doi:10.1186/s12936-015-0833-x) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Jennifer M G Shelton
- Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, UK.
| | - Patrick Corran
- London School of Hygiene and Tropical Medicine, Keppel Street, London, UK. .,National Institute for Biological Standards and Controls, South Mimms, Hertfordshire, UK.
| | - Paul Risley
- National Institute for Biological Standards and Controls, South Mimms, Hertfordshire, UK.
| | - Nilupa Silva
- National Institute for Biological Standards and Controls, South Mimms, Hertfordshire, UK.
| | - Christina Hubbart
- Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, UK.
| | - Anna Jeffreys
- Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, UK.
| | - Kate Rowlands
- Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, UK.
| | - Rachel Craik
- Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, UK.
| | - Victoria Cornelius
- Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, UK.
| | - Meike Hensmann
- Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, UK.
| | - Sile Molloy
- Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, UK.
| | - Nuno Sepulveda
- London School of Hygiene and Tropical Medicine, Keppel Street, London, UK.
| | - Taane G Clark
- London School of Hygiene and Tropical Medicine, Keppel Street, London, UK.
| | - Gavin Band
- Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, UK.
| | - Geraldine M Clarke
- Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, UK.
| | - Christopher C A Spencer
- Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, UK.
| | - Angeliki Kerasidou
- Nuffield Department of Population Health, The Ethox Centre, University of Oxford, Richard Doll Building, Old Road Campus, Oxford, OX3 7LF, UK.
| | - Susana Campino
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SA, UK.
| | - Sarah Auburn
- Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, UK.
| | - Adama Tall
- Infectious Diseases Epidemiology Unit, Institut Pasteur, BP 220, Dakar, Senegal.
| | - Alioune Badara Ly
- Infectious Diseases Epidemiology Unit, Institut Pasteur, BP 220, Dakar, Senegal.
| | - Odile Mercereau-Puijalon
- Parasite Molecular Immunology Unit, Institut Pasteur, 28 rue du Docteur Roux, 75724, Paris Cedex 15, France.
| | - Anavaj Sakuntabhai
- Unité de Génétique Fonctionnelle des Maladies Infectieuses, Institut Pasteur, 28 rue du Docteur Roux, 75724, Paris Cedex 15, France. .,Centre National de la Recherche Scientifique, URA3012, 28 rue du Docteur Roux, 75724, Paris Cedex 15, France.
| | - Abdoulaye Djimdé
- Department of Epidemiology of Parasitic Diseases, Faculty of Medicine, Pharmacy and Odonto-Stomatology, Malaria Research and Training Center, USTTB, BP 1805, Bamako, Mali.
| | - Boubacar Maiga
- Department of Epidemiology of Parasitic Diseases, Faculty of Medicine, Pharmacy and Odonto-Stomatology, Malaria Research and Training Center, USTTB, BP 1805, Bamako, Mali.
| | - Ousmane Touré
- Department of Epidemiology of Parasitic Diseases, Faculty of Medicine, Pharmacy and Odonto-Stomatology, Malaria Research and Training Center, USTTB, BP 1805, Bamako, Mali.
| | - Ogobara K Doumbo
- Department of Epidemiology of Parasitic Diseases, Faculty of Medicine, Pharmacy and Odonto-Stomatology, Malaria Research and Training Center, USTTB, BP 1805, Bamako, Mali.
| | - Amagana Dolo
- Department of Epidemiology of Parasitic Diseases, Faculty of Medicine, Pharmacy and Odonto-Stomatology, Malaria Research and Training Center, USTTB, BP 1805, Bamako, Mali.
| | - Marita Troye-Blomberg
- Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm University, Svante Arrheniusväg 20B, 106 91, Stockholm, Sweden.
| | - Valentina D Mangano
- Department of Public Health and Infectious Diseases, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185, Rome, Italy.
| | - Frederica Verra
- Department of Public Health and Infectious Diseases, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185, Rome, Italy.
| | - David Modiano
- Department of Public Health and Infectious Diseases, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185, Rome, Italy.
| | - Edith Bougouma
- Centre de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso.
| | - Sodiomon B Sirima
- Centre de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso.
| | - Muntaser Ibrahim
- Institute of Endemic Diseases, University of Khartoum, Medical Sciences Campus, Qasser Street, Khartoum, Sudan.
| | - Ayman Hussain
- Institute of Endemic Diseases, University of Khartoum, Medical Sciences Campus, Qasser Street, Khartoum, Sudan.
| | - Nahid Eid
- Institute of Endemic Diseases, University of Khartoum, Medical Sciences Campus, Qasser Street, Khartoum, Sudan.
| | - Abier Elzein
- Institute of Endemic Diseases, University of Khartoum, Medical Sciences Campus, Qasser Street, Khartoum, Sudan.
| | - Hiba Mohammed
- Institute of Endemic Diseases, University of Khartoum, Medical Sciences Campus, Qasser Street, Khartoum, Sudan.
| | - Ahmed Elhassan
- Institute of Endemic Diseases, University of Khartoum, Medical Sciences Campus, Qasser Street, Khartoum, Sudan.
| | - Ibrahim Elhassan
- Institute of Endemic Diseases, University of Khartoum, Medical Sciences Campus, Qasser Street, Khartoum, Sudan.
| | - Thomas N Williams
- KEMRI-Wellcome Trust Research Programme, CGMRC, PO Box 230-80108, Kilifi, Kenya. .,Department of Medicine, Imperial College, St Mary's Campus, Norfolk Place, London, W2 1PG, UK.
| | - Carolyne Ndila
- KEMRI-Wellcome Trust Research Programme, CGMRC, PO Box 230-80108, Kilifi, Kenya.
| | - Alexander Macharia
- KEMRI-Wellcome Trust Research Programme, CGMRC, PO Box 230-80108, Kilifi, Kenya.
| | - Kevin Marsh
- KEMRI-Wellcome Trust Research Programme, CGMRC, PO Box 230-80108, Kilifi, Kenya.
| | - Alphaxard Manjurano
- London School of Hygiene and Tropical Medicine, Keppel Street, London, UK. .,Kilimanjaro Christian Medical College, Tumaini University, Moshi, Tanzania.
| | - Hugh Reyburn
- London School of Hygiene and Tropical Medicine, Keppel Street, London, UK. .,Kilimanjaro Christian Medical College, Tumaini University, Moshi, Tanzania.
| | - Martha Lemnge
- National Institute for Medical Research, Ocean Road, Dar es Salaam, Tanzania.
| | - Deus Ishengoma
- National Institute for Medical Research, Ocean Road, Dar es Salaam, Tanzania.
| | - Richard Carter
- Division of Biological Sciences, Ashworth Laboratories, University of Edinburgh, West Mains Rd., Edinburgh, EH9 3JT, UK.
| | - Nadira Karunaweera
- Department of Parasitology, Faculty of Medicine, University of Colombo, Kynsey Road, Colombo, Sri Lanka.
| | - Deepika Fernando
- Department of Parasitology, Faculty of Medicine, University of Colombo, Kynsey Road, Colombo, Sri Lanka.
| | - Rajika Dewasurendra
- Department of Parasitology, Faculty of Medicine, University of Colombo, Kynsey Road, Colombo, Sri Lanka.
| | - Christopher J Drakeley
- London School of Hygiene and Tropical Medicine, Keppel Street, London, UK. .,Kilimanjaro Christian Medical College, Tumaini University, Moshi, Tanzania.
| | - Eleanor M Riley
- London School of Hygiene and Tropical Medicine, Keppel Street, London, UK. .,Kilimanjaro Christian Medical College, Tumaini University, Moshi, Tanzania.
| | - Dominic P Kwiatkowski
- Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, UK. .,Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SA, UK.
| | - Kirk A Rockett
- Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, UK. .,Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SA, UK.
| | | |
Collapse
|
44
|
Mmbando BP, Mgaya J, Cox SE, Mtatiro SN, Soka D, Rwezaula S, Meda E, Msaki E, Snow RW, Jeffries N, Geller NL, Makani J. Negative Epistasis between Sickle and Foetal Haemoglobin Suggests a Reduction in Protection against Malaria. PLoS One 2015; 10:e0125929. [PMID: 25965586 PMCID: PMC4428884 DOI: 10.1371/journal.pone.0125929] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Accepted: 03/26/2015] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Haemoglobin variants, Sickle (HbS) and foetal (HbF) have been associated with malaria protection. This study explores epistatic interactions between HbS and HbF on malaria infection. METHODS The study was conducted between March 2004 and December 2013 within the sickle cell disease (SCD) programme at Muhimbili National Hospital, Tanzania. SCD status was categorized into HbAA, HbAS and HbSS using hemoglobin electrophoresis and High Performance Liquid Chromatography (HPLC). HbF levels were determined by HPLC. Malaria was diagnosed using rapid diagnostic test and/or blood film. Logistic regression and generalized estimating equations models were used to evaluate associations between SCD status, HbF and malaria. FINDINGS 2,049 individuals with age range 0-70 years, HbAA 311(15.2%), HbAS 241(11.8%) and HbSS 1,497(73.1%) were analysed. At enrolment, malaria prevalence was significantly higher in HbAA 13.2% compared to HbAS 1.24% and HbSS 1.34% (p<0.001). Mean HbF was lower in those with malaria compared to those without malaria in HbAA (0.43% vs 0.82%) but was the reverse in HbSS (8.10% vs 5.59%). An increase in HbF was associated with a decrease in risk of malaria OR=0.50 (95%CI: 0.28, 0.90; p=0.021) in HbAA, whereas for HbSS the risk of malaria increased OR=2.94 (1.44, 5.98; p=0.003). A similar pattern was seen during multiple visits; HbAA OR=0.52 (0.34, 0.80; p=0.003) vs HbSS OR=2.01 (1.27, 3.23; p=0.003). CONCLUSION Higher prevalence of malaria in HbAA compared to HbAS and HbSS confirmed the protective effect of HbS. Lower prevalence of malaria in HbAA with high HbF supports a protective effect of HbF. However, in HbSS, the higher prevalence of malaria with high levels of HbF suggests loss of malaria protection. This is the first epidemiological study to suggest a negative epistasis between HbF and HbS on malaria.
Collapse
Affiliation(s)
- Bruno P. Mmbando
- Muhimbili University of Health and Allied Sciences, Dar-es-Salaam, Tanzania
- National Institute for Medical Research, Tanga, Tanzania
- * E-mail:
| | - Josephine Mgaya
- Muhimbili University of Health and Allied Sciences, Dar-es-Salaam, Tanzania
| | - Sharon E. Cox
- Muhimbili University of Health and Allied Sciences, Dar-es-Salaam, Tanzania
- London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Siana N. Mtatiro
- Muhimbili University of Health and Allied Sciences, Dar-es-Salaam, Tanzania
| | - Deogratias Soka
- Muhimbili University of Health and Allied Sciences, Dar-es-Salaam, Tanzania
| | | | - Elineema Meda
- Muhimbili National Hospital, Dar-es-Salaam, Tanzania
| | - Evarist Msaki
- Muhimbili University of Health and Allied Sciences, Dar-es-Salaam, Tanzania
| | - Robert W. Snow
- KEMRI-Wellcome Trust Programme, Nairobi, Kenya
- University of Oxford, Oxford, United Kingdom
| | - Neal Jeffries
- National Heart, Lung, and Blood Institute (NHLBI), National Institutes of Health (NIH), Bethesda, Maryland, United States of America
| | - Nancy L. Geller
- National Heart, Lung, and Blood Institute (NHLBI), National Institutes of Health (NIH), Bethesda, Maryland, United States of America
| | - Julie Makani
- Muhimbili University of Health and Allied Sciences, Dar-es-Salaam, Tanzania
- University of Oxford, Oxford, United Kingdom
| |
Collapse
|
45
|
The relationship between Plasmodium infection, anaemia and nutritional status in asymptomatic children aged under five years living in stable transmission zones in Kinshasa, Democratic Republic of Congo. Malar J 2015; 14:83. [PMID: 25880427 PMCID: PMC4336722 DOI: 10.1186/s12936-015-0595-5] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Accepted: 01/30/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Malaria is preventable and treatable when recommended interventions are properly implemented. Thus, diagnosis and treatment focus on symptomatic individuals while asymptomatic Plasmodium infection (PI) plays a role in the sustainability of the transmission and may also have an impact on the morbidity of the disease in terms of anaemia, nutritional status and even cognitive development of children. The objective of this study was to assess PI prevalence and its relationship with known morbidity factors in a vulnerable but asymptomatic stratum of the population. METHODS A simple random sample, household survey in asymptomatic children under the age of five was conducted from April to September 2012 in two health areas of the health zone of Mont Ngafula 1, Kinshasa, Democratic Republic of Congo. RESULTS The PI prevalence were 30.9% (95% CI: 26.5-35.9) and 14.3% (95% CI: 10.5-18.1) in Cité Pumbu and Kindele health areas, respectively, (OR: 2.7; p <0.001). All were Plasmodium falciparum infected and 4% were co-infected with Plasmodium malariae. In Cité Pumbu and Kindele, the prevalence of anaemia (haemoglobin <11 g/dL) was 61.6% (95% CI: 56.6-66.5) and 39.3% (95% CI: 34.0-44.6), respectively, (OR: 2.5; p <0.001). The health area of Cité Pumbu had 32% (95% CI: 27.5-37.0) of chronic malnutrition (HAZ score ≤ -2SD) compared to 5.1% (95% CI: 2.8-7.6) in Kindele. PI was predictor factor for anaemia (aOR: 3.5, p =0.01) and within infected children, there was an inverse relationship between parasite density and haemoglobin level (β = -5*10(-5), p <0.001). Age older than 12 months (aOR: 3.8, p = 0.01), presence of anaemia (aOR: 3.4, p =0.001), chronic malnutrition (aOR: 1.8, p = 0.01), having a single parent/guardian (aOR: 1.6, p =0.04), and the non-use of insecticide-treated nets (aOR: 1.7, p = 0.04) were all predictors for PI in the overall population. CONCLUSION PI in asymptomatic children was correlated with anaemia and chronic malnutrition and was thus a harmful condition in the study population. Malaria control initiatives should not only focus on treatment of symptomatic infections but also take into consideration asymptomatic but infected children.
Collapse
|
46
|
K'Oyugi BO. Effects of bed nets and anti-malaria drugs use on childhood mortality in Kenya's malaria endemic and epidemic areas. BMC Public Health 2015; 15:34. [PMID: 25631099 PMCID: PMC4314758 DOI: 10.1186/s12889-015-1398-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Accepted: 01/12/2015] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND The Kenya Demographic and Health Surveys (KDHS) data collected since 1989 indicate that malaria prone areas have consistently recorded the highest childhood mortality rates. Malaria control programme information also indicates that malaria contributes to about 20 per cent of the deaths among under-five year old children. The 2009-2017 National Malaria Strategy is being implemented to reduce malaria morbidity and mortality. Its key interventions include: bed nets use; anti-malaria drugs use during pregnancy for prevention; and, prompt treatment using anti-malaria drugs of children with fever. This study seeks to establish differentials in childhood mortality rates by these interventions in three malaria prone areas defined as highland epidemic, coast endemic and lake endemic. It also seeks to determine the effects of these interventions on childhood mortality. METHODS The data used is drawn from the 2008/9 KDHS. The study sample consists of 3,728 children born less than 60 months prior to the survey. The direct demographic method for estimation of childhood mortality rates and multivariate Poisson regression models are used to analyse the data. RESULTS The findings show that use of bed nets and anti-malaria drugs are not high in Kenya's malaria prone areas. On the average, only about 60% of the children are found to be in higher use category for each of the three intervention measures. The childhood mortality rates show that higher use of prompt treatment with anti-malaria drugs for children with fever has lower infant and under-five mortality rates in all malaria epidemic and endemic areas compared to lower use. Higher bed nets use has lower childhood mortality rates compared to lower use in coast and lake endemic areas. Higher use of anti-malaria drugs during pregnancy for prevention has lower childhood mortality rates in highland epidemic and lake endemic areas compared to lower use. The regression models fitted show that in highland epidemic area, higher use of anti-malaria drugs during pregnancy for prevention has significant reduction effect on childhood mortality compared to lower use in the presence of breastfeeding duration, toilet facility type and age of child variables. The regression models also show that in combined malaria prone areas, higher prompt treatment of children with fever using anti-malaria drugs has significant reduction effect on both infant and child mortality compared to lower prompt treatment in the presence of breastfeeding duration and toilet facility type variables. CONCLUSION This study underscore the need for increasing uptake of malaria interventions and complementing them with longer breastfeeding duration and improved toilet facility in efforts towards reducing infant and child mortality rates in Kenya's malaria prone areas. There is also need to improve quality of individual household data for malaria module in future KDHS undertakings.
Collapse
Affiliation(s)
- Boniface O K'Oyugi
- Population Studies and Research Institute, University of Nairobi, P.O. Box 30197, 00100, Nairobi, Kenya.
| |
Collapse
|
47
|
Abstract
PURPOSE OF REVIEW Multiple red cell variants are known to confer protection from malaria. Here, we review advances in identifying new variants that modulate malaria risk and in defining molecular mechanisms that mediate malaria protection. RECENT FINDINGS New red cell variants, including an innate variant in the red cell's major Ca²⁺ pump and the acquired state of iron deficiency, have been associated with protection from clinical falciparum malaria. The polymorphisms hemoglobin C (HbC) and hemoglobin S (HbS) - known to protect carriers from severe falciparum malaria - enhance parasite passage to mosquitoes and may promote malaria transmission. At the molecular level, substantial advances have been made in understanding the impact of HbS and HbC upon the interactions between host microRNAs and Plasmodium falciparum protein translation; remodeling of red cell cytoskeletal components and transport of parasite proteins to the red cell surface; and chronic activation of the human innate immune system, which induces tolerance to blood-stage parasites. Several polymorphisms have now been associated with protection from clinical vivax malaria or reduced Plasmodium vivax density, including Southeast Asian ovalocytosis and two common forms of glucose-6-phosphate dehydrogenase deficiency. SUMMARY Red cell variants that modulate malaria risk can serve as models to identify clinically relevant mechanisms of pathogenesis, and thus define parasite and host targets for next-generation therapies.
Collapse
|
48
|
Amoako N, Asante KP, Adjei G, Awandare GA, Bimi L, Owusu-Agyei S. Associations between red cell polymorphisms and Plasmodium falciparum infection in the middle belt of Ghana. PLoS One 2014; 9:e112868. [PMID: 25470251 PMCID: PMC4254276 DOI: 10.1371/journal.pone.0112868] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Accepted: 10/20/2014] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND Red blood cell (RBC) polymorphisms are common in malaria endemic regions and are known to protect against severe forms of the disease. Therefore, it is important to screen for these polymorphisms in drugs or vaccines efficacy trials. This study was undertaken to evaluate associations between clinical malaria and RBC polymorphisms to assess biological interactions that may be necessary for consideration when designing clinical trials. METHOD In a cross-sectional study of 341 febrile children less than five years of age, associations between clinical malaria and common RBC polymorphisms including the sickle cell gene and G6PD deficiency was evaluated between November 2008 and June 2009 in the middle belt of Ghana, Kintampo. G6PD deficiency was determined by quantitative methods whiles haemoglobin variants were determined by haemoglobin titan gel electrophoresis. Blood smears were stained with Giemsa and parasite densities were determined microscopically. RESULTS The prevalence of clinical malarial among the enrolled children was 31.9%. The frequency of G6PD deficiency was 19.0% and that for the haemoglobin variants were 74.7%, 14.7%, 9.1%, 0.9% respectively for HbAA, HbAC, HbAS and HbSS. In Multivariate regression analysis, children with the HbAS genotype had 79% lower risk of malaria infection compared to those with the HbAA genotypes (OR = 0.21, 95% CI: 0.06-0.73, p = 0.01). HbAC genotype was not significantly associated with malaria infection relative to the HbAA genotype (OR = 0.70, 95% CI: 0.35-1.42, p = 0.33). G6PD deficient subgroup had a marginally increased risk of malaria infection compared to the G6PD normal subgroup (OR = 1.76, 95% CI: 0.98-3.16, p = 0.06). CONCLUSION These results confirm previous findings showing a protective effect of sickle cell trait on clinical malaria infection. However, G6PD deficiency was associated with a marginal increase in susceptibility to clinical malaria compared to children without G6PD deficiency.
Collapse
Affiliation(s)
- Nicholas Amoako
- Kintampo Health Research Centre, Kintampo, Brong Ahafo Region, Ghana
| | - Kwaku Poku Asante
- Kintampo Health Research Centre, Kintampo, Brong Ahafo Region, Ghana
| | - George Adjei
- Kintampo Health Research Centre, Kintampo, Brong Ahafo Region, Ghana
| | - Gordon A Awandare
- Infectious Diseases Research Laboratory, Department of Biochemistry, Cell and Molecular Biology. University of Ghana, Legon, Ghana
| | - Langbong Bimi
- Department of Animal Biology and Conservation Science, University of Ghana, Legon, Ghana
| | - Seth Owusu-Agyei
- Kintampo Health Research Centre, Kintampo, Brong Ahafo Region, Ghana
| |
Collapse
|
49
|
Sauerzopf U, Honkpehedji YJ, Adgenika AA, Feugap EN, Ngoma GM, Mackanga JR, Lötsch F, Loembe MM, Kremsner PG, Mordmüller B, Ramharter M. In vitro growth of Plasmodium falciparum in neonatal blood. Malar J 2014; 13:436. [PMID: 25406504 PMCID: PMC4242501 DOI: 10.1186/1475-2875-13-436] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2014] [Accepted: 11/03/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Children below the age of six months suffer less often from malaria than older children in sub-Saharan Africa. This observation is commonly attributed to the persistence of foetal haemoglobin (HbF), which is considered not to permit growth of Plasmodium falciparum and therefore providing protection against malaria. Since this concept has recently been challenged, this study evaluated the effect of HbF erythrocytes and maternal plasma on in vitro parasite growth of P. falciparum in Central African Gabon. METHODS Umbilical cord blood and peripheral maternal blood were collected at delivery at the Albert Schweitzer Hospital in Gabon. Respective erythrocyte suspension and plasma were used in parallel for in vitro culture. In vitro growth rates were compared between cultures supplemented with either maternal or cord erythrocytes. Plasma of maternal blood and cord blood was evaluated. Parasite growth rates were assessed by the standard HRP2-assay evaluating the increase of HRP2 concentration in Plasmodium culture. RESULTS Culture of P. falciparum using foetal erythrocytes led to comparable growth rates (mean growth rate = 4.2, 95% CI: 3.5 - 5.0) as cultures with maternal red blood cells (mean growth rate =4.2, 95% CI: 3.4 - 5.0) and those from non-malaria exposed individuals (mean growth rate = 4.6, 95% CI: 3.8 - 5.5). Standard in vitro culture of P. falciparum supplemented with either maternal or foetal plasma showed both significantly lower growth rates than a positive control using non-malaria exposed donor plasma. CONCLUSIONS These data challenge the concept of HbF serving as intrinsic inhibitor of P. falciparum growth in the first months of life. Erythrocytes containing HbF are equally permissive to P. falciparum growth in vitro. However, addition of maternal and cord plasma led to reduced in vitro growth which may translate to protection against clinical disease or show synergistic effects with HbF in vivo. Further studies are needed to elucidate the pathophysiology of innate and acquired protection against neonatal malaria.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | | | | | | | - Michael Ramharter
- Department of Medicine I, Division of Infectious Diseases and Tropical Medicine, Medical University of Vienna, Vienna, Austria.
| |
Collapse
|
50
|
Plasmodium falciparum malaria in children aged 0-2 years: the role of foetal haemoglobin and maternal antibodies to two asexual malaria vaccine candidates (MSP3 and GLURP). PLoS One 2014; 9:e107965. [PMID: 25238160 PMCID: PMC4169582 DOI: 10.1371/journal.pone.0107965] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Accepted: 08/07/2014] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND Children below six months are reported to be less susceptible to clinical malaria. Maternally derived antibodies and foetal haemoglobin are important putative protective factors. We examined antibodies to Plasmodium falciparum merozoite surface protein 3 (MSP3) and glutamate-rich protein (GLURP), in children in their first two years of life in Burkina Faso and their risk of malaria. METHODS A cohort of 140 infants aged between four and six weeks was recruited in a stable transmission area of south-western Burkina Faso and monitored for 24 months by active and passive surveillance. Malaria infections were detected by examining blood smears using light microscopy. Enzyme-linked immunosorbent assay was used to quantify total Immunoglobulin G to Plasmodium falciparum antigens MSP3 and two regions of GLURP (R0 and R2) on blood samples collected at baseline, three, six, nine, 12, 18 and 24 months. Foetal haemoglobin and variant haemoglobin fractions were measured at the baseline visit using high pressure liquid chromatography. RESULTS A total of 79.6% of children experienced one or more episodes of febrile malaria during monitoring. Antibody titres to MSP3 were prospectively associated with an increased risk of malaria while antibody responses to GLURP (R0 and R2) did not alter the risk. Antibody titres to MSP3 were higher among children in areas of high malaria risk. Foetal haemoglobin was associated with delayed first episode of febrile malaria and haemoglobin CC type was associated with reduced incidence of febrile malaria. CONCLUSIONS We did not find any evidence of association between titres of antibodies to MSP3, GLURP-R0 or GLURP-R2 as measured by enzyme-linked immunosorbent assay and early protection against malaria, although anti-MSP3 antibody titres may reflect increased exposure to malaria and therefore greater risk. Foetal haemoglobin was associated with protection against febrile malaria despite the study limitations and its role is therefore worthy further investigation.
Collapse
|