Myeloperoxidase and Other Markers of Neutrophil Activation Associate With Malaria and Malaria/HIV Coinfection in the Human Placenta

Introduction

Placental malaria (PM) is characterized by accumulation of inflammatory leukocytes in the placenta, leading to poor pregnancy outcomes. Understanding of the underlying mechanisms remains incomplete. Neutrophils respond to malaria parasites by phagocytosis, generation of oxidants, and externalization of Neutrophil Extracellular Traps (NETs). NETs drive inflammation in malaria but evidence of NETosis in PM has not been reported. Neutrophil activity in the placenta has not been directly investigated in the context of PM and PM/HIV-co-infection.

Methods

Using peripheral and placental plasma samples and placental tissue collected from Kenyan women at risk for malaria and HIV infections, we assessed granulocyte levels across all gravidities and markers of neutrophil activation, including NET formation, in primi- and secundigravid women, by ELISA, western blot, immunohistochemistry and immunofluorescence.

Results

Reduced peripheral blood granulocyte numbers are observed with PM and PM/HIV co-infection in association with increasing parasite density and placental leukocyte hemozoin accumulation. In contrast, placental granulocyte levels are unchanged across infection groups, resulting in enhanced placental: peripheral count ratios with PM. Within individuals, PM- women have reduced granulocyte counts in placental relative to peripheral blood; in contrast, PM stabilizes these relative counts, with HIV coinfection tending to elevate placental counts relative to the periphery. In placental blood, indicators of neutrophil activation, myeloperoxidase (MPO) and proteinase 3 (PRTN3), are significantly elevated with PM and, more profoundly, with PM/HIV co-infection, in association with placental parasite density and hemozoin-bearing leukocyte accumulation. Another neutrophil marker, matrix metalloproteinase (MMP9), together with MPO and PRTN3, is elevated with self-reported fever. None of these factors, including the neutrophil chemoattractant, CXCL8, differs in relation to infant birth weight or gestational age. CXCL8 and MPO levels in the peripheral blood do not differ with infection status nor associate with birth outcomes. Indicators of NETosis in the placental plasma do not vary with infection, and while structures consistent with NETs are observed in placental tissue, the results do not support an association with PM.

Conclusions

Granulocyte levels are differentially regulated in the peripheral and placental blood in the presence and absence of PM. PM, both with and without pre-existing HIV infection, enhances neutrophil activation in the placenta. The impact of local neutrophil activation on placental function and maternal and fetal health remains unclear. Additional investigations exploring how neutrophil activation and NETosis participate in the pathogenesis of malaria in pregnant women are needed.

Characterization of the Gene Expression Patterns in the Murine Liver Following Intramuscular Administration of Baculovirus

Intramuscular administration of wild-type baculovirus is able to both protect against Plasmodium sporozoite challenge and eliminate liver-stage parasites via a Toll-like receptor 9-independent pathway. To investigate its effector mechanism(s), the gene expression profile in the liver of baculovirus-administered mice was characterized by cDNA microarray analysis. The ingenuity pathway analysis gene ontology module revealed that the major gene subsets induced by baculovirus were immune-related signaling, such as interferon signaling. A total of 40 genes commonly upregulated in a Toll-like receptor 9-independent manner were included as possible candidates for parasite elimination. This gene subset consisted of NT5C3, LOC105246895, BTC, APOL9a/b, G3BP3, SLC6A6, USP25, TRIM14, and PSMB8 as the top 10 candidates according to the special unit. These findings provide new insight into effector molecules responsible for liver-stage parasite killing and, possibly, the development of a new baculovirus-mediated prophylactic and therapeutic biopharmaceutical for malaria.

Malaria and intestinal parasite co-infection and its association with anaemia among people living with HIV in Buea, Southwest Cameroon: A community-based retrospective cohort study

Background

Both malaria and intestinal parasites are endemic in Cameroon, and their co-infection can be of great impact on anaemia among people living with HIV (PLWH). This community-based retrospective cohort study determined the prevalence and association of infections with anaemia in PLWH and HIV-negative individuals in Buea, Cameroon from March to August 2019.

Methods

The study population comprised of 190 PLWH and 216 consenting HIV-negative individuals from the Buea community. Participants were examined clinically, the collected blood sample was used for malaria parasite (MP) detection, HIV diagnosis and haemoglobin (Hb) measurement while stool samples were examined for the detection of intestinal parasites (IPs). Proportions were compared using Pearson’s Chi-square test and association of anaemia with independent variables was evaluated using logistic regression analysis.

Results

Out of the 406 participants, MP, IPs and MP/IP co-infection prevalences were 15.5%, 13.0% and 3.0% respectively. PLWH had a higher prevalence of MP (16.3%, P = 0.17), IPs (23.7%, P ˂ 0.001) and MP/IPs co-infection (3.7%, P = 0.04) when compared with HIV-negative participants. Similarly, PLWH had significantly lower mean haemoglobin value (11.10 ± 1.54 g/dL) than their HIV-negative counterparts (12.45 ± 2.06 g/dL). Also, PLWH co-infected with MP and IPs were observed to have a significantly lower mean haemoglobin value (10.6 ± 1.21 g/dL). PLWH had a significantly (P ˂ 0.001) higher prevalence of mild (56.8%), moderate (18.4%) and severe (1.6%) anaemia when compared with HIV-negative counterparts. The significant risk factors associated with anaemia included being febrile (P = 0.03), MP-infected only (P = 0.001), HIV-infected only (P < 0.001), having dual (P < 0.001) or triple-infections (P = 0.03).

Conclusion

Malaria and intestinal parasites remain public health concerns among PLWH and anaemia as a serious haematological abnormality gets exacerbated even with the viral load suppression. Hence, routine medical check-ups among PLWH are recommended.

Metagenomic next-generation sequencing of samples from pediatric febrile illness in Tororo, Uganda

Febrile illness is a major burden in African children, and non-malarial causes of fever are uncertain. In this retrospective exploratory study, we used metagenomic next-generation sequencing (mNGS) to evaluate serum, nasopharyngeal, and stool specimens from 94 children (aged 2–54 months) with febrile illness admitted to Tororo District Hospital, Uganda. The most common microbes identified were Plasmodium falciparum (51.1% of samples) and parvovirus B19 (4.4%) from serum; human rhinoviruses A and C (40%), respiratory syncytial virus (10%), and human herpesvirus 5 (10%) from nasopharyngeal swabs; and rotavirus A (50% of those with diarrhea) from stool. We also report the near complete genome of a highly divergent orthobunyavirus, tentatively named Nyangole virus, identified from the serum of a child diagnosed with malaria and pneumonia, a Bwamba orthobunyavirus in the nasopharynx of a child with rash and sepsis, and the genomes of two novel human rhinovirus C species. In this retrospective exploratory study, mNGS identified multiple potential pathogens, including 3 new viral species, associated with fever in Ugandan children.

Antibiotic prescriptions for inpatients having non-bacterial diagnosis at medicine departments of two private sector hospitals in Madhya Pradesh, India: a cross-sectional study

OBJECTIVES

To present and compare antibiotic prescribing for inpatients among the most common non-bacterial diagnoses groups at medicine departments of a teaching (TH) and a non-teaching hospital (NTH) in central India.

SETTING

An observational cross-sectional study was conducted at two tertiary care settings in Ujjain district, Madhya Pradesh, India.

DATA AND PARTICIPANTS

The data were collected manually, using a customised form. Complete records of all inpatients, who were >15 years of age and had stayed for at least one night in either of the hospitals during 2008-2011, were analysed.

OUTCOME MEASURES

Inpatients were grouped according to the presence or absence of a bacterial infectious diagnosis, viral/malaria fever or cardiovascular disease. Classes of antibiotics prescribed to these groups and adherence to the available prescribing guidelines were compared between the hospitals using the notes from the patient files and the diagnoses.

RESULTS

Of 20 303 inpatients included in the study, 66% were prescribed antibiotics. Trade name prescribing and use of broad-spectrum antibiotics were more frequent at the NTH than at the TH (p<0.001). At the TH a significantly higher proportion of patients having fever without registered bacterial infection were prescribed antibiotics (82%) compared with the NTH (71%, p<0.001). Patients admitted for cardiovascular diagnosis without registered bacterial infections received antibiotic prescriptions at both hospitals (NTH 47% and TH 37%) but this was significantly higher at the NTH (p<0.001). None of the diagnoses were confirmed by microbiology reports.

CONCLUSIONS

Prescribing antibiotics, including broad-spectrum antibiotics, to inpatients without bacterial infections-that is, viral fever, malaria and cardiovascular disease, was common at both hospitals, which increases the risk for development of bacterial resistance, a global public health threat. In view of the overprescribing of antibiotics, the main recommendations are development and implementation of local prescription guidelines, encouragement to use laboratory facilities and prescription analysis, with antibiotic stewardship programmes.

Optimal insecticide-treated bed-net coverage and malaria treatment in a malaria-HIV co-infection model

We propose and study a mathematical model for malaria-HIV co-infection transmission and control, in which malaria treatment and insecticide-treated nets are incorporated. The existence of a backward bifurcation is established analytically, and the occurrence of such backward bifurcation is influenced by disease-induced mortality, insecticide-treated bed-net coverage and malaria treatment parameters. To further assess the impact of malaria treatment and insecticide-treated bed-net coverage, we formulate an optimal control problem with malaria treatment and insecticide-treated nets as control functions. Using reasonable parameter values, numerical simulations of the optimal control suggest the possibility of eliminating malaria and reducing HIV prevalence significantly, within a short time horizon.

Malaria parasitaemia among febrile under-five children at Nnamdi Azikiwe University Teaching Hospital, Nnewi, South-East, Nigeria

BACKGROUND

Malaria is an infectious disease caused by Plasmodium and transmitted by the bite of an infected female Anopheles mosquito. It continues to be a global challenge with about half of the world's population being at risk of the disease and under–5 children being the most vulnerable.

AIMS AND OBEJECTIVES

To determine the prevalence of malaria parasitaemia and some associated symptoms among febrile under-five children presenting at Nnamdi Azikiwe University Teaching Hospital Nnewi, Nigeria.

MATERIALS AND METHODS

A total of 200 children under the age of five years were recruited for the study. Data on socio-demographic characteristics and symptoms were collected through interviewer administered questionnaire. They were physically examine and blood sample was collected from each of them. The Blood smear was Giemsa stained and examined microscopically for malaria parasite.

RESULT

There were 118 males and 82 females, giving a male: female ratio of 1.44:1. Their ages ranged from 3-59 months and the average age was 27+17.49 months. Those in the age range of 12-23 months and 24-35 months constitute the highest number (23%) each. Forty-seven (23.5%) came from the rural area while 153(76.5%) came from the urban area. Average number of days the subjects had fever before presentation were 3.78+1.95 days with a range of 1-30 0 days. Body temperature ranged from 35.9-40.4 C with average of 37.7+0.8oC. Forty (20%) were positive to microscopy. Those in the age range of 47-59 months have the highest prevalence of malaria. Parasite density ranged from 40-136,000/μL with a mean of 18,687.2+3360/μL. All the children who are positive by microcopy had Plasmodium falciparium as the specie causing malaria.

CONCLUSION

Malaria parasitaemia among these under-5 children is 20%.

Presence of Plasmodium falciparum DNA in Plasma Does Not Predict Clinical Malaria in an HIV-1 Infected Population

BACKGROUND

HIV-1 and Plasmodium falciparum malaria cause substantial morbidity in Sub-Saharan Africa, especially as co-infecting pathogens. We examined the relationship between presence of P. falciparum DNA in plasma samples and clinical malaria as well as the impact of atazanavir, an HIV-1 protease inhibitor (PI), on P. falciparum PCR positivity.

METHODS

ACTG study A5175 compared two NNRTI-based regimens and one PI-based anti-retroviral (ARV) regimen in antiretroviral therapy naïve participants. We performed nested PCR on plasma samples for the P. falciparum 18s rRNA gene to detect the presence of malaria DNA in 215 of the 221 participants enrolled in Blantyre and Lilongwe, Malawi. We also studied the closest sample preceding the first malaria diagnosis from 102 persons with clinical malaria and randomly selected follow up samples from 88 persons without clinical malaria.

RESULTS

PCR positivity was observed in 18 (8%) baseline samples and was not significantly associated with age, sex, screening CD4+ T-cell count, baseline HIV-1 RNA level or co-trimoxazole use within the first 8 weeks. Neither baseline PCR positivity (p = 0.45) nor PCR positivity after initiation of antiretroviral therapy (p = 1.0) were significantly associated with subsequent clinical malaria. Randomization to the PI versus NNRTI ARV regimens was not significantly associated with either PCR positivity (p = 0.5) or clinical malaria (p = 0.609). Clinical malaria was associated with a history of tuberculosis (p = 0.006) and a lower BMI (p = 0.004).

CONCLUSION

P. falciparum DNA was detected in 8% of participants at baseline, but was not significantly associated with subsequent development of clinical malaria. HIV PI therapy did not decrease the prevalence of PCR positivity or incidence of clinical disease.

Gammaherpesvirus Co-infection with Malaria Suppresses Anti-parasitic Humoral Immunity

Immunity to non-cerebral severe malaria is estimated to occur within 1-2 infections in areas of endemic transmission for Plasmodium falciparum. Yet, nearly 20% of infected children die annually as a result of severe malaria. Multiple risk factors are postulated to exacerbate malarial disease, one being co-infections with other pathogens. Children living in Sub-Saharan Africa are seropositive for Epstein Barr Virus (EBV) by the age of 6 months. This timing overlaps with the waning of protective maternal antibodies and susceptibility to primary Plasmodium infection. However, the impact of acute EBV infection on the generation of anti-malarial immunity is unknown. Using well established mouse models of infection, we show here that acute, but not latent murine gammaherpesvirus 68 (MHV68) infection suppresses the anti-malarial humoral response to a secondary malaria infection. Importantly, this resulted in the transformation of a non-lethal P. yoelii XNL infection into a lethal one; an outcome that is correlated with a defect in the maintenance of germinal center B cells and T follicular helper (Tfh) cells in the spleen. Furthermore, we have identified the MHV68 M2 protein as an important virus encoded protein that can: (i) suppress anti-MHV68 humoral responses during acute MHV68 infection; and (ii) plays a critical role in the observed suppression of anti-malarial humoral responses in the setting of co-infection. Notably, co-infection with an M2-null mutant MHV68 eliminates lethality of P. yoelii XNL. Collectively, our data demonstrates that an acute gammaherpesvirus infection can negatively impact the development of an anti-malarial immune response. This suggests that acute infection with EBV should be investigated as a risk factor for non-cerebral severe malaria in young children living in areas endemic for Plasmodium transmission.

Association between immunoglobulin GM and KM genotypes and placental malaria in HIV-1 negative and positive women in western Kenya

Immunoglobulin (Ig) GM and KM allotypes, genetic markers of γ and κ chains, are associated with humoral immune responsiveness. Previous studies have shown the relationships between GM6-carrying haplotypes and susceptibility to malaria infection in children and adults; however, the role of the genetic markers in placental malaria (PM) infection and PM with HIV co-infection during pregnancy has not been investigated. We examined the relationship between the gene polymorphisms of Ig GM6 and KM allotypes and the risk of PM infection in pregnant women with known HIV status. DNA samples from 728 pregnant women were genotyped for GM6 and KM alleles using polymerase chain reaction-restriction fragment length polymorphism method. Individual GM6 and KM genotypes and the combined GM6 and KM genotypes were assessed in relation to PM in HIV-1 negative and positive women, respectively. There was no significant effect of individual GM6 and KM genotypes on the risk of PM infection in HIV-1 negative and positive women. However, the combination of homozygosity for GM6(+) and KM3 was associated with decreased risk of PM (adjusted OR, 0.25; 95% CI, 0.08-0.8; P = 0.019) in HIV-1 negative women while in HIV-1 positive women the combination of GM6(+/-) with either KM1-3 or KM1 was associated with increased risk of PM infection (adjusted OR, 2.10; 95% CI, 1.18-3.73; P = 0.011). Hardy-Weinberg Equilibrium (HWE) tests further showed an overall significant positive F(is) (indication of deficit in heterozygotes) for GM6 while there was no deviation for KM genotype frequency from HWE in the same population. These findings suggest that the combination of homozygous GM6(+) and KM3 may protect against PM in HIV-1 negative women while the HIV-1 positive women with heterozygous GM6(+/-) combined with KM1-3 or KM1 may be more susceptible to PM infection. The deficit in heterozygotes for GM6 further suggests that GM6 could be under selection likely by malaria infection.

Effects of cotrimoxazole prophylactic treatment on adverse health outcomes among HIV-exposed, uninfected infants

BACKGROUND

The World Health Organization guidelines recommend cotrimoxazole prophylactic treatment (CPT) for all HIV-exposed infants from age 6 weeks to the cessation of breastfeeding and the exclusion of HIV infection. There are limited data on the effects of CPT among this population of infants. We examined the effects of CPT on adverse health outcomes among HIV-exposed infants during the first 36 weeks of life using data from the Breastfeeding, Antiretrovirals and Nutrition study, a large clinical trial of antiretroviral drugs given to the mother or infant for the prevention of HIV transmission during breastfeeding.

METHODS

For the analysis, we assigned a status of CPT-exposed to infants who were participating in the study after the CPT program started. We estimated unadjusted and adjusted hazard ratios for the effect of CPT status on time to incident malaria, severe illness or death, anemia, and weight-for-age Z score < -2.0. Participation in the study was limited to focus exclusively on HIV-exposed, uninfected infants.

RESULTS

The hazard ratio for the effect of CPT on incident malaria was 0.35 (95% confidence interval: 0.21, 0.57) during the first 10 weeks of CPT exposure and 0.93 (95% confidence interval: 0.67, 1.29) for the remaining 20 weeks. CPT was not associated with the other outcomes examined.

CONCLUSIONS

CPT offered temporary protection against malaria among HIV-exposed, uninfected infants. However, CPT offered no protection against anemia, low weight for age or the collapsed outcome of severe illness or death.

Early age at time of primary Epstein-Barr virus infection results in poorly controlled viral infection in infants from Western Kenya: clues to the etiology of endemic Burkitt lymphoma

BACKGROUND

Infection with Epstein-Barr virus (EBV) early in life and repeated malaria exposure have been proposed as risk factors for endemic Burkitt lymphoma (eBL).

METHODS

Infants were enrolled from 2 rural sites in Kenya: the Kisumu District, where malaria transmission is holoendemic and risk for eBL is high, and the Nandi District, where malaria transmission is limited and the risk for eBL is low. Blood samples were taken from infants through 2 years of age to measure EBV viral load, EBV antibodies, and malaria parasitemia.

RESULTS

We observed a significantly younger age at time of primary EBV infection in children from Kisumu compared with children from Nandi (mean age, 7.28 months [±0.33 SEM] in Kisumu vs 8.39 months [±0.26 SEM] in Nandi), with 35.3% of children in Kisumu infected before 6 months of age. To analyze how different predictors affected EBV viral load over time, we performed multilevel mixed modeling. This modeling revealed that residence in Kisumu and younger age at first EBV infection were significant predictors for having a higher EBV viral load throughout the period of observation.

CONCLUSIONS

Children from a region at high risk for eBL were infected very early in life with EBV, resulting in higher viral loads throughout infancy.

Hepatitis B infection is associated with asymptomatic malaria in the Brazilian Amazon

Background

Areas that are endemic for malaria are also highly endemic for hepatitis B virus (HBV) infection. Nevertheless, it is unknown whether HBV infection modifies the clinical presentation of malaria. This study aimed to address this question.

Methodology and Findings

An observational study of 636 individuals was performed in Rondônia, western Amazon, Brazil between 2006 and 2007. Active and passive case detections identified Plasmodium infection by field microscopy and nested Polymerase Chain Reaction (PCR). HBV infections were identified by serology and confirmed by real-time PCR. Epidemiological information and plasma cytokine profiles were studied. The data were analyzed using adjusted multinomial logistic regression. Plasmodium-infected individuals with active HBV infection were more likely to be asymptomatic (OR: 120.13, P<0.0001), present with lower levels of parasitemia and demonstrate a decreased inflammatory cytokine profile. Nevertheless, co-infected individuals presented higher HBV viremia. Plasmodium parasitemia inversely correlated with plasma HBV DNA levels (r = −0.6; P = 0.0003).

Conclusion

HBV infection diminishes the intensity of malaria infection in individuals from this endemic area. This effect seems related to cytokine balance and control of inflammatory responses. These findings add important insights to the understanding of the factors affecting the clinical outcomes of malaria in endemic regions.

Hepatitis C virus infection may lead to slower emergence of P. falciparum in blood

Background

Areas endemic for Plasmodium falciparum, hepatitis B virus (HBV) and hepatitis C virus (HCV) overlap in many parts of sub-Saharan Africa. HBV and HCV infections develop in the liver, where takes place the first development stage of P. falciparum before its further spread in blood. The complex mechanisms involved in the development of hepatitis may potentially influence the development of the liver stage of malaria parasites. Understanding the molecular mechanisms of these interactions could provide new pathophysiological insights for treatment strategies in Malaria.

Methodology

We studied a cohort of 319 individuals living in a village where the three infections are prevalent. The patients were initially given a curative antimalarial treatment and were then monitored for the emergence of asexual P. falciparum forms in blood, fortnightly for one year, by microscopy and polymerase chain reaction.

Principal Findings

At inclusion, 65 (20.4%) subjects had detectable malaria parasites in blood, 36 (11.3%) were HBV chronic carriers, and 61 (18.9%) were HCV chronic carriers. During follow-up, asexual P. falciparum forms were detected in the blood of 203 patients. The median time to P. falciparum emergence in blood was respectively 140 and 120 days in HBV- and HBV+ individuals, and 135 and 224 days in HCV- and HCV+ individuals. HCV carriage was associated with delayed emergence of asexual P. falciparum forms in blood relative to patients without HCV infection.

Conclusions

This pilot study represents first tentative evidence of a potential epidemiological interaction between HBV, HCV and P. falciparum infections. Age is an important confounding factor in this setting however multivariate analysis points to an interaction between P. falciparum and HCV at the hepatic level with a slower emergence of P. falciparum in HCV chronic carriers. More in depth analysis are necessary to unravel the basis of hepatic interactions between these two pathogens, which could help in identifying new therapeutic approaches against malaria.

A molecular link between malaria and Epstein-Barr virus reactivation

Although malaria and Epstein–Barr (EBV) infection are recognized cofactors in the genesis of endemic Burkitt lymphoma (BL), their relative contribution is not understood. BL, the most common paediatric cancer in equatorial Africa, is a high-grade B cell lymphoma characterized by c-myc translocation. EBV is a ubiquitous B lymphotropic virus that persists in a latent state after primary infection, and in Africa, most children have sero-converted by 3 y of age. Malaria infection profoundly affects the B cell compartment, inducing polyclonal activation and hyper-gammaglobulinemia. We recently identified the cystein-rich inter-domain region 1α (CIDR1α) of the Plasmodium falciparum membrane protein 1 as a polyclonal B cell activator that preferentially activates the memory compartment, where EBV is known to persist. Here, we have addressed the mechanisms of interaction between CIDR1α and EBV in the context of B cells. We show that CIDR1α binds to the EBV-positive B cell line Akata and increases the number of cells switching to the viral lytic cycle as measured by green fluorescent protein (GFP) expression driven by a lytic promoter. The virus production in CIDR1α-exposed cultures was directly proportional to the number of GFP-positive Akata cells (lytic EBV) and to the increased expression of the EBV lytic promoter BZLF1. Furthermore, CIDR1α stimulated the production of EBV in peripheral blood mononuclear cells derived from healthy donors and children with BL. Our results suggest that P. falciparum antigens such as CIDR1α can directly induce EBV reactivation during malaria infection that may increase the risk of BL development for children living in malaria-endemic areas. To our knowledge, this is the first report to show that a microbial protein can drive a latently infected B cell into EBV replication.

Malaria and Epstein–Barr virus (EBV) infections are recognized cofactors in the genesis of endemic Burkitt lymphoma, the most common paediatric cancer in equatorial Africa. EBV is a ubiquitous virus residing in B lymphocytes that establishes a lifelong persistence in the host after primary infection. EBV has two lifestyles: latent infection (non-productive), and lytic replication (productive). Children living in malaria-endemic areas exhibit an elevated viral load, and acute malaria infection increases the levels of circulating EBV. The mechanisms leading to viral reactivation during Plasmodium falciparum malaria infection are not well understood. Cystein-rich inter-domain region 1α (CIDR1α) is a domain of a large protein expressed at the surface of P. falciparum–infected red blood cells. Based on previous findings showing that CIDR1α activates and expands the B cells compartment where EBV persists, we assessed the impact of CIDR1α on viral reactivation. Here, we identify CIDR1α as the first microbial protein able to drive a latently EBV-infected B cell (no virus production) into lytic replication (virus production). Our results suggest that P. falciparum–derived proteins can lead to a direct reactivation of EBV during acute malaria infection, increasing the risk of Burkitt lymphoma development for children living in malaria-endemic areas.

Malaria treatment efficacy among people living with HIV: the role of host and parasite factors

Identification of an effect of HIV-associated immunosuppression on response to antimalarial therapy would help guide management of malaria infection in areas of high HIV prevalence. Therefore, we conducted an observational study of people living with HIV infection in Blantyre, Malawi. Participants who developed malaria were treated with sulfadoxine-pyrimethamine (SP) and followed for 28 days. Molecular markers for SP resistance were measured. One hundred seventy-eight episodes of malaria were assessed. The 28-day cumulative treatment failure rate was 29.1%. In univariate analysis, CD4 cell count was not associated with treatment failure (hazard ratio 0.6, 95% confidence interval 0.3-1.2). Among children, the risk of treatment failure increased with infection with SP-resistant parasites and anemia. Decreased CD4 cell count was not associated with impaired response to antimalarial therapy or diminished ability to clear SP-resistant parasites, suggesting that acquired immunity to malaria is retained in the face of HIV-associated immunosuppression.

Malaria and HIV: a silent alliance

HIV and malaria are leading causes of morbidity in sub-Saharan Africa. Recently, Abu-Raddad and colleagues explored the synergy between these diseases through a mathematical model that included all documented interactions. It emerges from the model parameter inputs that concomitant infection of both HIV and malaria fuels the spread of both diseases. For the first time, it is shown that, according to the model, transient but repeatedly elevated HIV viral loads due to recurrent co-infections, such as malaria, can also influence and increase HIV prevalence. Probably, these results are conservative and the true impact of the interaction could be even more important.

CTLA-4 blockade differentially influences the outcome of non-lethal and lethal Plasmodium yoelii infections

An immune response against malaria has to be tightly controlled. The production of pro-inflammatory cytokines is required to control parasites but the same cytokines are also involved in severe malaria. We have shown that CTLA-4 expression during Plasmodium berghei malaria dampens the immune response. This strain provokes a pro-inflammatory immune response that is associated with the pathology of cerebral malaria. Accordingly a blockade of CTLA-4 during the blood-stage of P. berghei malaria leads to an exacerbation of disease. To analyze the effects of a CTLA-4 blockade in a malaria model which is not prone to immune pathology we employed P. yoelii infection. Blood-stage infection led to a rapid induction of CTLA-4 on T cells. Using the non-lethal P. yoelii strain Py17NL we found that a blockade of CTLA-4 resulted in an increased T cell activation and IFN-gamma production, which was accompanied by a lower peak parasitemia and earlier parasite clearance. In contrast, blockade of CTLA-4 during infection with a P. yoelii strain exhibiting a higher parasitemia induced markedly increased serum-levels of TNF-alpha, which was associated with severe inflammation and reduced survival.

How did the ancestral HIV-1 group M retrovirus get to Leopoldville from southeastern Cameroon?

In previous papers in this journal, I have described and elaborated a hypothesis for the origin and evolution of a strain of HIV that has produced a lethal pandemic. Here I address the provocative question of how the ancestral HIV-1 group M retrovirus got to Leopoldville (Kinshasa, where the pandemic clearly spawned) from southeastern Cameroon (where the HIV-1 strains all seemed to originate from transfer of SIV(cpz) to humans). Consistent with the phylogenetic history of HIV-1 group M (e.g., by Korber et al.), I place the critical relocation of the ancestral HIV-1 in the timeframe 1920-1927. However, unlike other hypotheses, I believe that the ancestral retrovirus was already well adapted to humans and can be identified as HIV-1 Group M subtype A(pre)-1927. Based on documents from that time period (1920-1928), it can be shown that it was not unusual for native Africans to be brought as far as 500 miles for treatment at the Leopoldville clinic (national borders were no issue because health agencies had mandate to work throughout Cameroon and Congo-Brazzaville). Specifically, sleeping sickness (trypanosomiasis) was one of the diseases of most concern at the Leopoldville clinic; in the period 1926-1928 there was an outbreak of sleeping sickness in Cameroon; and one of the native African children in the pamaquine (plasmoquineTM) study that I believe selected for the major HIV-1 group M subgroups had trypanosomiasis. Thus, this child (or other patients/relatives from Cameroon) could have brought the ancestral HIV-1 group M retrovirus to the Leopoldville laboratory and spread it among the group of children who were undergoing treatment for malaria between February and August 1927. The diagnosis and monitoring of these protozoan diseases (trypanosomiasis and malaria) involved repetitive sampling of blood, which provides many opportunities for spreading the ancestral HIV-1 infection.

Co-infection of malaria with HIV: an immunological perspective

Human immunodeficiency virus (HIV) and Plasmodium parasites are pathogens that induce significant perturbation and activation of the immune system. Due to their geographical overlap, there have been concerns that co-infection with the two pathogens may be a factor in the modification of their development, and in the severity and rate of disease progression that they induce. In this article, we have reviewed some of the studies that have addressed this topic and we have tried to provide immunological mechanisms to explain these potential interactions.

Observational cohort study of HIV-infected African children

BACKGROUND

Most information about children living with HIV is based on follow up from children identified through mother-to-child transmission studies. Children identified through voluntary counseling and testing (VCT) represent a unique cohort that has not been previously described in the literature.

METHODS

Children who were found to have HIV infection through VCT were offered enrollment in this study. They were evaluated monthly and encouraged to return to the clinic any time they were ill. Thorough evaluation was performed for every illness.

RESULTS

Forty-five children were enrolled in the study. Many of the participants (33%) had a serious acute disease at the time of enrollment. The most common diagnoses were symptomatic malaria and pneumonia. The children were more ill than adults who were enrolled in a simultaneous study and had a higher death rate (37 versus 15 deaths per 100 person-years of observation). The mortality rate was 22%. Undernutrition and low CD4 cell count were independently associated with increased risk of death.

CONCLUSIONS

Malawian children found to be HIV-infected through VCT had a high morbidity and mortality rate, highlighting the potential benefit of trimethoprim-sulfamethizole prophylaxis and available antiretroviral therapy.

Exposure to holoendemic malaria results in elevated Epstein-Barr virus loads in children

Perennial and intense malaria transmission (holoendemic malaria) and Epstein-Barr virus (EBV) infection are 2 cofactors in the pathogenesis of endemic Burkitt lymphoma (eBL). In the present study, we compared EBV loads in children living in 2 regions of Kenya with differing malaria transmission intensities: Kisumu District, where malaria transmission is holoendemic, and Nandi District, where malaria transmission is sporadic. For comparison, blood samples were also obtained from US adults, Kenyan adults, and patients with eBL. Extraction of DNA from blood and quantification by polymerase chain reaction give an EBV load estimate that reflects the number of EBV-infected B cells. We observed a significant linear trend in mean EBV load, with the lowest EBV load detected in US adults and increasing EBV loads detected in Kenyan adults, Nandi children, Kisumu children, and patients with eBL, respectively. In addition, EBV loads were significantly higher in Kisumu children 1-4 years of age than in Nandi children of the same age. Our results support the hypothesis that repeated malaria infections in very young children modulate the persistence of EBV and increase the risk for the development of eBL.

Hepatic pathology in AIDS: a pathological study from Mumbai, India

OBJECTIVES

To assess the spectrum of hepatic disorders in AIDS, liver specimens from 171 patients (155 autopsies and 16 biopsies) were reviewed.

METHODS

A retrospective and prospective study of 171 autopsy and biopsy specimens was carried out at a tertiary level hospital in Mumbai, India.

RESULTS

Of the patients included in the study, 127 (74%) were male and 44 (26%) were female. The heterosexual route was the predominant mode of HIV transmission, identified in 163 (95%) patients. A total of 99 of 171 patients (58%) showed significant pathological lesions, and the most common pathological processes involving the liver appeared to be secondary to infections. None of our patients showed isolated infectious diseases of the liver. The spectrum of liver diseases identified was as follows: tuberculosis in 70 patients (41%), cryptococcosis in eight (5%), cytomegalovirus infection in six (3%), hepatitis B infection in five (3%), candidiasis in one (0.5%), malaria in one (0.5%), cirrhosis in six (3%), amyloidosis in one (0.5%) and primary hepatic lymphoma in one (0.5%).

CONCLUSIONS

AIDS patients were found to have a high prevalence of underlying hepatic abnormalities. The spectrum of disease among patients with AIDS in India differs from that in developed countries. Our results suggest that hepatic tuberculosis is more common in AIDS than previously recognized, and that liver specimens should be examined routinely for the presence of acid-fast bacilli.

Maternal malaria and perinatal HIV transmission, western Kenya

To determine whether maternal placental malaria is associated with an increased risk for perinatal mother-to-child HIV transmission (MTCT), we studied HIV-positive women in western Kenya. We enrolled 512 mother-infant pairs; 128 (25.0%) women had placental malaria, and 102 (19.9%) infants acquired HIV perinatally. Log10 HIV viral load and episiotomy or perineal tear were associated with increased perinatal HIV transmission, whereas low-density placental malaria (<10,000 parasites/mL) was associated with reduced risk (adjusted relative risk [ARR] 0.4). Among women dually infected with malaria and HIV, high-density placental malaria (>10,000 parasites/mL) was associated with increased risk for perinatal MTCT (ARR 2.0), compared to low-density malaria. The interaction between placental malaria and MTCT appears to be variable and complex: placental malaria that is controlled at low density may cause an increase in broad-based immune responses that protect against MTCT; uncontrolled, high-density malaria may simultaneously disrupt placental architecture and generate substantial antigen stimulus to HIV replication and increase risk for MTCT.

Placental Malaria and Perinatal Transmission of Human Immunodeficiency Virus Type 1

Prevalence of placental malaria in human immunodeficiency virus (HIV) type 1-infected and -uninfected women and the effect of placental malaria on genital shedding and perinatal transmission of HIV-1 were examined. Genital samples for HIV-1 DNA RNA were collected during labor. Infants were tested for HIV-1 at 1 day and 6 weeks postpartum. Placental malaria was diagnosed by histopathological examination: 372 placentas of HIV-1-infected women and 277 of HIV-1-uninfected women were processed. A higher prevalence of placental malaria was seen in HIV-1-infected women. No association was found between placental malaria and either maternal virus load, genital HIV-1 DNA, or HIV-1 RNA. Placental malaria did not correlate with in utero or peripartal transmission of HIV-1.

Immune activation and induction of HIV-1 replication within CD14 macrophages during acute Plasmodium falciparum malaria coinfection

OBJECTIVES

To determine the impact of Plasmodium falciparum malaria coinfection and its treatment on cellular reservoirs of viral replication in HIV-1-infected persons and to relate this to changes in systemic immune activation.

METHODS

Plasma samples were obtained from HIV-1-infected individuals (n = 10) at diagnosis of acute malaria, 4 weeks after parasite clearance and from HIV-infected aparasitemic controls (n = 10). Immunomagnetic HIV-1 capture analysis was used to determine the cellular origin of cell-free virus particles present in all 30 plasma samples and indices of immune activation were measured using enzyme-linked immunosorbent assays.

RESULTS

Compared with controls, the detectable proportion of HIV-1 particles derived from CD14 macrophages and CD26 lymphocytes was increased in persons with acute malaria coinfection and correlated with markedly increased plasma concentrations of both proinflammatory cytokines and soluble markers of macrophage and lymphocyte activation. Parasite clearance following treatment with antimalarial drugs resulted in decreased detection of HIV-1 particles derived from the CD14 macrophage cell subset and correlated with a marked diminution in systemic immune activation.

CONCLUSIONS

Acute P. falciparum malaria coinfection impacts virus-host dynamics in HIV-1-infected persons at the cellular level, notably showing a reversible induction of HIV-1 replication in CD14 macrophages that is associated with changes in immune activation.

Malaria infection induces virus expression in human immunodeficiency virus transgenic mice by CD4 T cell-dependent immune activation

To test the capacity of malaria parasites to trigger virus expression in vivo, human immunodeficiency virus (HIV) transgenic mice were infected with Plasmodium chabaudi chabaudi clone AS. Splenocytes recovered during peak parasitemia showed a dramatic elevation in viral p24 production that returned to baseline by day 15 and failed to rebound at recrudescence or after reinfection. The major sources of virus expression were antigen-presenting cells (APCs) rather than T lymphocytes. Nevertheless, T cells from infected mice stimulated with plasmodial antigen triggered 5-10-fold increases in p24 production from dendritic cells in vitro, which suggests that viral induction stems from interaction of malaria-specific T lymphocytes with HIV-expressing APCs. Indeed, depletion of CD4 T cells resulted in a 70% reduction in the p24 response stimulated by malaria in vivo. These findings demonstrate the ability of Plasmodium species to immunologically activate latently integrated HIV in vivo but suggest that this process may be restricted to acute infection.

B-lymphotropic viruses in a novel tropical splenic lymphoma

Peripheral blood from patients with a novel tropical splenic lymphoma, characterized by splenomegaly and circulating naïve CD5-negative villous B lymphocytes, has been screened for evidence of an association with the B-lymphotropic viruses, Epstein--Barr virus (EBV), hepatitis C virus (HCV) and human herpesvirus 8 (HHV8). No increased prevalence of EBV, HCV and HHV8 was demonstrated using serological and molecular techniques, compared with a geographical, age-matched control group. However, lymphoma patients had markedly raised EBV antibody levels without a concomitant increase in the rate of detection of viral genomes in the peripheral blood. This phenomenon also occurred in patients with hyper-reactive malarial splenomegaly, a condition that occurs in the same geographical area and that is clinically indistinguishable from tropical splenic lymphoma, adding further weight to the suggestion that there may be an aetiological association between these two disorders.

Recombinant attenuated Toxoplasma gondii expressing the Plasmodium yoelii circumsporozoite protein provides highly effective priming for CD8+ T cell-dependent protective immunity against malaria

The protozoan parasite Toxoplasma gondii elicits strong cell-mediated immunity against itself as well as nonspecific resistance against other pathogens and tumors. For this reason, we asked whether recombinant Toxoplasma could be utilized as an effective vaccine vehicle for inducing immunity against heterologous microbial infections. The circumsporozoite protein (PyCSP) of Plasmodium yoelii was engineered into a T. gondii temperature-sensitive strain (ts-4), a mutant that induces complete protection against virulent Toxoplasma challenge. When administered to mice in a single dose, a recombinant ts-4 (CSC3) that both secretes and expresses surface PyCSP induced strong anti-CSP Ab responses, with an isotype distribution pattern similar to that stimulated by the T. gondii carrier. When challenged with P. yoelii sporozoites during the first month after CSC3 vaccination, these animals displayed substantial levels of nonspecific resistance attributable entirely to the T. gondii carrier. Nevertheless, after the nonspecific protection had waned, high levels (up to 79%) of specific immunity against sporozoite challenge were achieved by boosting the animals with recombinant vaccinia virus expressing PyCSP. These CSC3-primed PyCSP-vaccinia-boosted mice displayed high frequencies of splenic PyCSP-specific IFN-gamma-producing cells, as well as CD8+ T cell-dependent cytolytic activity. In vivo depletion of CD8+ lymphocytes at the time of challenge completely ablated protective immunity in the T. gondii-primed/vaccinia-boosted animals, while neutralization of IFN-gamma or IL-12 caused a partial but significant reduction in resistance. Together these findings establish the efficacy of recombinant attenuated Toxoplasma as a vaccine vehicle for priming CD8+-dependent cell-mediated immunity.

A study of maternal mortality at the University Teaching Hospital, Lusaka, Zambia: the emergence of tuberculosis as a major non-obstetric cause of maternal death

SETTING

The Department of Obstetrics and Gynaecology, University Teaching Hospital, Lusaka, Zambia.

OBJECTIVES

To ascertain 1) the non-obstetric causes of maternal mortality, 2) the importance of tuberculosis as a cause of maternal deaths, and 3) the trends in the aetiology of non-obstetric causes of maternal deaths during the past decade in the light of the human immunodeficiency virus epidemic.

DESIGN

A 2-year retrospective study of the aetiology of all maternal deaths occurring at the University Teaching Hospital (UTH), Lusaka, Zambia between 1 January 1996 and 31 December 1997. Comparison of these data with available data published between 1974 and 1989.

RESULTS

There were 251 maternal deaths recorded during the study period. Of these, 106 (42%) were due to direct (obstetric) causes and 145 (58%) were due to indirect (non-obstetric) causes. Malaria (30%), tuberculosis (25%) and unspecified chronic respiratory tract infections (22%) accounted for 77% of non-obstetric causes of maternal deaths and 44% of all causes of maternal deaths. The diagnosis of AIDS was closely linked with that of tuberculosis (92% of cases), and unspecified chronic respiratory illnesses (97%), but not with malaria (37%). The maternal mortality ratio for UTH was calculated at 921 per 100,000 live births, a significant increase from the 118 noted in 1982 and 667 in 1989.

CONCLUSIONS

Despite improved obstetric services, the maternal mortality ratios at UTH, Lusaka, have increased eight-fold over the past two decades. This dramatic increase is mainly due to non-obstetric causes of death. Malaria and AIDS-associated tuberculosis and unspecified 'chronic respiratory illnesses' are now major causes of maternal death in Zambia. Greater emphasis is urgently required on early detection, accurate diagnosis, treatment and prevention of malaria and tuberculosis in pregnancy. Further definition of chronic 'unspecified' respiratory illnesses is also required.