Extensive diversity in the allelic frequency of Plasmodium falciparum merozoite surface proteins and glutamate-rich protein in rural and urban settings of southwestern Nigeria

Modeling and investigating malaria P. Falciparum and P. Vivax infections: Application to Djibouti data

Malaria is an infectious and communicable disease, caused by one or more species of Plasmodium parasites. There are five species of parasites responsible for malaria in humans, of which two, Plasmodium Falciparum and Plasmodium Vivax, are the most dangerous. In Djibouti, the two species of Plasmodium are present in different proportions in the infected population: 77% of P. Falciparum and 33% of P. Vivax. In this study we present a new mathematical model describing the temporal dynamics of Plasmodium Falciparum and Plasmodium Vivax co-infection. We focus briefly on the well posedness of this model and on the calculation of the basic reproductive numbers for the infections with each Plasmodium species that help us understand the long-term dynamics of this model (i.e., existence and stability of various eqiuilibria). Then we use computational approaches to: (a) identify model parameters using real data on malaria infections in Djibouti; (b) illustrate the influence of different estimated parameters on the basic reproduction numbers; (c) perform global sensitivity and uncertainty analysis for the impact of various model parameters on the transient dynamics of infectious mosquitoes and infected humans, for infections with each of the Plasmodium species. The originality of this research stems from employing the FAST method and the LHS method to identify the key factors influencing the progression of the disease within the population of Djibouti. In addition, sensitivity analysis identified the most influential parameter for Falciparium and Vivax reproduction rates. Finally, the uncertainty analysis enabled us to understand the variability of certain parameters on the infected compartments.

Diverse role, structural trends, and applications of fluorinated sulphonamide compounds in agrochemical and pharmaceutical fields

Our knowledge of fluorine's unique and complex properties has significantly increased over the past 20 years. Consequently, more sophisticated and innovative techniques have emerged to incorporate this feature into the design of potential drug candidates. In recent years, researchers have become interested in synthesizing fluoro-sulphonamide compounds to discover new chemical entities with distinct and unexpected physical, chemical, and biological characteristics. The fluorinated sulphonamide molecules have shown significant biomedical importance. Their potential is not limited to biomedical applications but also includes crop protection. The discovery of novel fluorine and Sulfur compounds has highlighted their importance in the chemical sector, particularly in the agrochemical and medicinal fields. Recently, several fluorinated sulphonamide derivatives have been developed and frequently used by agriculturalists to produce food for the growing global population. These molecules have also exhibited their potential in health by inhibiting various human diseases. In today's world, it is crucial to have a steady supply of innovative pharmaceutical and agrochemical molecules that are highly effective, less harmful to the environment, and affordable. This review summarizes the available information on the activity of Fluorine and Sulphonamide compounds, which have proven active in pharmaceuticals and agrochemicals with excellent environmental and human health approaches. Moreover, it focuses on the current literature on the chemical structures, the application of fluorinated sulphonamide compounds against various pathological conditions, and their effectiveness in crop protection.

Malaria: biochemical, physiological, diagnostic, and therapeutic updates

Background

Malaria has been appraised as a significant vector-borne parasitic disease with grave morbidity and high-rate mortality. Several challenges have been confronting the efficient diagnosis and treatment of malaria.

Method

Google Scholar, PubMed, Web of Science, and the Egyptian Knowledge Bank (EKB) were all used to gather articles.

Results

Diverse biochemical and physiological indices can mirror complicated malaria e.g., hypoglycemia, dyslipidemia, elevated renal and hepatic functions in addition to the lower antioxidant capacity that does not only destroy the parasite but also induces endothelial damage. Multiple trials have been conducted to improve recent points of care in malaria involving biosensors, lap on-chip, and microdevices technology. Regarding recent therapeutic trials, chemical falcipain inhibitors and plant extracts with anti-plasmodial activities are presented. Moreover, antimalaria nano-medicine and the emergence of nanocarrier (either active or passive) in drug transportation are promising. The combination therapeutic trials e.g., amodiaquine + artemether + lumefantrine are presented to safely counterbalance the emerging drug resistance in addition to the Tafenoquine as a new anti-relapse therapy.

Conclusion

Recognizing the pathophysiology indices potentiate diagnosis of malaria. The new points of care can smartly manipulate the biochemical and hematological alterations for a more sensitive and specific diagnosis of malaria. Nano-medicine appeared promising. Chemical and plant extracts remain points of research.

A Case Series: A Mother and Daughter with a Critically Low Hemoglobin Level Resulting from Severe Anemia Secondary to Malaria

Background

Malaria can lead to anemia, a condition marked by a reduction in red blood cells or lower than typical levels of hemoglobin. This condition mainly affects women and children and, in severe cases, can hinder the cognitive and motor development of children. It also poses significant risks for pregnant women and their unborn children.

Case presentation

An 18-month-old girl and her mother, referred from conflict-affected West Wollega, Ethiopia due to severe malaria, were admitted to Assosa General Hospital, Ethiopia, with critical health indicators. The daughter (case 1) had a hemoglobin level of 0.8 g/dL, a red blood cell count of 0.44 × 10^6u/L, an oxygen saturation of 90%, a body temperature of 36.6 °C, a heartbeat of 132 beats per minute, and a respiratory rate of 48 breaths per minute. She displayed signs of pale conjunctivitis and severe palmar paleness, and weighed 7 kg. The mother(case 2), aged 35, also had a history of severe malaria and presented with a critically low hemoglobin level of 2.5g/dL and a red blood cell count of 0.75 × 10^6u/L, with an oxygen saturation of 89%. Blood transfusion and malaria treatment were administered, and by the end of their hospital stay, both cases' symptoms had resolved, and they returned to normal baseline vital signs, including their hemoglobin levels.

Conclusions

Severely low hemoglobin levels, worsened by severe malaria, present a significant danger in cases of anemia. As far as I am aware, this might be the lowest hemoglobin level recorded. Promoting awareness, economic empowerment initiatives, alongside routine provision of iron supplements and Prompt malaria diagnosis and treatment to create a comprehensive approach that addresses the multifaceted challenges posed by anemia, ultimately leading to improved health outcomes for vulnerable populations.

A Comparative Study of Genetic Diversity and Multiplicity of Infection in Uncomplicated Plasmodium falciparum Infections in Selected Regions of Pre-Elimination and High Transmission Settings Using MSP1 and MSP2 Genes

BACKGROUND

Understanding the genetic structure of P. falciparum population in different regions is pivotal to malaria elimination. Genetic diversity and the multiplicity of infection are indicators used for measuring malaria endemicity across different transmission settings. Therefore, this study characterized P. falciparum infections from selected areas constituting pre-elimination and high transmission settings in South Africa and Nigeria, respectively.

METHODS

Parasite genomic DNA was extracted from 129 participants with uncomplicated P. falciparum infections. Isolates were collected from 78 participants in South Africa (southern Africa) and 51 in Nigeria (western Africa). Allelic typing of the msp1 and msp2 genes was carried out using nested PCR.

RESULTS

In msp1, the K1 allele (39.7%) was the most common allele among the South African isolates, while the RO33 allele (90.2%) was the most common allele among the Nigerian isolates. In the msp2 gene, FC27 and IC3D7 showed almost the same percentage distribution (44.9% and 43.6%) in the South African isolates, whereas FC27 had the highest percentage distribution (60.8%) in the Nigerian isolates. The msp2 gene showed highly distinctive genotypes, indicating high genetic diversity in the South African isolates, whereas msp1 showed high genetic diversity in the Nigerian isolates. The RO33 allelic family displayed an inverse relationship with participants' age in the Nigerian isolates. The overall multiplicity of infection (MOI) was significantly higher in Nigeria (2.87) than in South Africa (2.44) (p < 0.000 *). In addition, heterozygosity was moderately higher in South Africa (1.46) than in Nigeria (1.13).

CONCLUSIONS

The high genetic diversity and MOI in P. falciparum that were observed in this study could provide surveillance data, on the basis of which appropriate control strategies should be adopted.

Asymptomatic malaria infection and its associated factors among pregnant women in Ethiopia; a systematic review and meta-analysis

Background

Asymptomatic malaria during pregnancy is a significant public health concern in malaria-endemic regions, which worsens the various effects of malaria on the mother and fetus and increases maternal and neonatal mortality. To date, no meta-analysis has been conducted on asymptomatic malaria in pregnant women in Ethiopia. Thus, we aimed to estimate the pooled prevalence of asymptomatic malaria and its associated factors in pregnant women in Ethiopia.

Methods

PubMed/Medline, Google Scholar, Web of Science, Cochrane, AJOL, and Ethiopian University repositories were systematically searched to identify studies reporting the prevalence of asymptomatic malaria infection among pregnant women in Ethiopia. A random effects model was used to perform the analysis. The heterogeneity of the studies was assessed with the I-squared tests, and subgroup analyses were performed to identify the sources of heterogeneity.

Results

Ten articles with 3277 study participants were included in this review. The pooled prevalence of asymptomatic malaria infection among pregnant women in Ethiopia was 7.03% (95% CI: 6.23-9.12); I2 = 81.2%). In the species-specific pooled prevalence estimate, Plasmodium falciparum prevalence was 5.34% (95%CI: 3.38-7.3; I2 = 87.8%), and Plasmodium vivax prevalence was 1.69% (95%CI: 1.2-5; I2 = 91.5%).Not using insecticide-treated bed nets [OR = 7.36, 95% CI (2.75, 19.73)], being primi-gravida [OR = 1.86, 95% CI (1.23, 2.82)]; lack of health education about malaria prevention [OR = 6.86, 95% CI (2.90, 11.44)] were predictors of asymptomatic malaria infection during pregnancy.

Conclusion

This study revealed that asymptomatic malaria was prevalent among pregnant women in Ethiopia. This suggests that relying merely on reported symptoms may result in missed malaria cases. Therefore, regular screening and treatment protocols for malaria are recommended in antenatal care. It is also crucial to ensure that pregnant women have access to insecticide-treated bed nets and other effective malaria prevention measures.

A fractional-order mathematical model for malaria and COVID-19 co-infection dynamics

This study proposes a fractional-order mathematical model for malaria and COVID-19 co-infection using the Atangana-Baleanu Derivative. We explain the various stages of the diseases together in humans and mosquitoes, and we also establish the existence and uniqueness of the fractional order co-infection model solution using the fixed point theorem. We conduct the qualitative analysis along with an epidemic indicator, the basic reproduction number R0 of this model. We investigate the global stability at the disease and endemic free equilibrium of the malaria-only, COVID-19-only, and co-infection models. We run different simulations of the fractional-order co-infection model using a two-step Lagrange interpolation polynomial approximate method with the aid of the Maple software package. The results reveal that reducing the risk of malaria and COVID-19 by taking preventive measures will reduce the risk factor for getting COVID-19 after contracting malaria and will also reduce the risk factor for getting malaria after contracting COVID-19 even to the point of extinction.

Evaluation of the performance of advantage P.f. malaria Card® and advantage malaria Pan + Pf Card®, two rapid diagnostic tests for parasitological confirmation of malaria cases in field situation in Togo

BACKGROUND

In Togo, malaria remains a major public health problem, and the management of suspected cases requires confirmation with appropriate biological methods. Malaria diagnosis has been improved by the introduction of rapid diagnostic tests (RDTs), recommended by the World Health Organization (WHO) for areas where microscopy is not available. To be used, these RDTs must meet performance criteria defined by the WHO. This study was conducted to evaluate the diagnostic performance of two RDTs: Advantage P.f. Malaria Card® detecting HRP2 antigen and Advantage Malaria Pan + Pf Card® detecting both HRP2 and pLDH antigens.

METHODS

This was a cross-sectional analytical study conducted from December 2019 to February 2020 on malaria-suspected cases received in three sentinel sites in Togo and from whom capillary blood was collected to perform the two RDTs according to the manufacturer's instructions. Sensitivity and specificity were estimated by comparing to thick/thin blood smear, the gold standard, and to PCR, which is a more sensitive.

RESULTS

A total of 390 participants (54.9% female) with a median age of 18 (± 0.8) years were included in the study. The sensitivity of both Advantage P.f. Malaria Card® and Advantage Malaria Pan + Pf Card® compared to thick/thin blood smear was 91.8% and 91.3%, respectively, and for both the specificity was 94.7%. Compared to PCR, the sensitivity was 84.2% and 83.8%, respectively, and the specificity 96.5%.

CONCLUSIONS

The performances of the Advantage P.f. Malaria Card® and Advantage Malaria PAN + Pf Card® compared to microscopy, considered the gold standard, were acceptable under the field conditions found in Togo. They can therefore be used for the biological diagnosis of malaria.

In vitro anticancer evaluation of Enceleamycin A and its underlying mechanism

It has become more crucial than ever to find novel anticancer compounds due to the rise in cancer mortality and resistance to the present chemotherapeutic drugs. Naphthoquinones are regarded as privileged structures for their ability to inhibit various cancers. The current study examined three novel furo-naphthoquinones (Enceleamycins A-C) previously isolated from Amycolatopsis sp. MCC 0218 for their anticancer potential. Enceleamycin A demonstrated considerable cytotoxicity for triple-negative breast cancer (TNBC) MDA-MB-231 cells with an IC50 value of 1.25 μg mL-1 (3.78 μM). It also showed the ability to inhibit MDA-MB-231 cell migration. Enceleamycin A raises intracellular ROS levels in TNBC cells, ultimately leading to apoptotic cell death, as demonstrated by Annexin V/PI staining. The molecular docking and simulation investigation revealed better binding affinity of Enceleamycin A with AKT2, which plays a vital role in breast cancer's invasiveness and chemo-resistance. Enceleamycin A inhibits the AKT2 enzyme in vitro with an IC50 value of 0.736 μg mL-1 (2.22 μM), further validating the docking study. The in silico physicochemical and pharmacokinetics characteristics of Enceleamycin A demonstrated its drug-likeness. Intriguingly, Enceleamycin A is non-hemolytic in nature. Taken together, Enceleamycin A could be a candidate molecule for treating TNBC cells by targeting the AKT2 signaling pathway.

Prevalence and Associated Factors of Anemia Among Hospital Admitted Patients in Eastern Ethiopia

Background

Anemia is one of the most common comorbidities frequently seen in admitted patients. However, there is a scarcity of evidence regarding anemia among hospital admitted patients in Ethiopia, particularly in the Harari Region. Therefore, this study aimed to assess the prevalence and associated factors of anemia among hospital admitted patients in Eastern Ethiopia.

Methods

A hospital-based cross-sectional study was conducted from October 25 to December 30, 2022. Four milliliters of venous blood were collected and complete blood count was done using the DxH 800 (Beckman Coulter, Inc, Miami, FL) hematology analyzer. The data were entered in Epi-data version 4 and exported to SPSS version 26 for statistical analysis. Bivariable and multivariable logistic regression models were fitted. The level of significance was declared at a p-value of < 0.05.

Results

Of the 381 hospital admitted patients, 64.8% (95% CI = 60.01, 69.65) of the participants were anemic. Admitted patients who drank standard alcohol daily (AOR = 3.78, 95% CI = 1.71, 8.30), underweight (AOR = 9.39, 95% CI = 2.90, 30.46), and undernourished patients (AOR = 2.59, 95% CI = 1.15, 5.84), patients admitted with chronic kidney disease (AOR = 11.16, 95% CI = 4.06, 30.64), chronic liver disease (AOR = 3.20, 95% CI = 1.21, 8.47), deep vein thrombosis (AOR = 6.22, 95% CI = 1.98, 19.52), infectious disease (AOR = 9.71, 95% CI = 2.77, 34.02), and chronic non-communicable disease (AOR = 7.01, 95% CI = 1.90, 25.99) were all significantly associated with anemia.

Conclusion

Anemia was common among hospital admitted patients and should prompt the focus on admission diagnoses that are likely to play leading roles in etiology. This information indicates a need for routine screening of anemia for all admitted patients to improve their health.

SD-Bioline malaria rapid diagnostic test performance and time to become negative after treatment of malaria infection in Southwest Nigerian Children

Context and Aim

Given the challenges of microscopy, we compared its performance with SD-Bioline malaria rapid diagnostic test (MRDT) and polymerase chain reaction (PCR) and evaluated the time it took for positive results to become negative after treatment of children with acute uncomplicated malaria.

Subjects and Methods

We present the report of 485 participants with complete MRDT, microscopy, and PCR data out of 511 febrile children aged 3-59 months who participated in a cohort study over a 12-month period in rural and urban areas of Ibadan, Nigeria. MRDT-positive children received antimalaria and tested at every visit over 28 days. Speciation was also carried out by PCR.

Results

With microscopy as the gold standard, SD-Bioline™ had 95.2% sensitivity, 66.4% specificity, 67.5% positive predictive value (PPV), and 94.9 negative predictive value (NPV), while with PCR the findings were 84.3% sensitivity, 66.5% specificity, 72.7% PPV, and 80.1% NPV. PCR speciation of malaria parasites revealed 91.6% Plasmodium falciparum, 18.9% Plasmodium malariae, and 4.4% Plasmodium ovale. Among the 47 children with P. malariae infections, 66.0% were coinfected with P. falciparum, while 54.6% cases of P. ovale occurred as coinfections with P. falciparum. The median time to a negative MRDT was 23.2 days, while the median time to a negative malaria microscopy was 3.8 days. The two survival curves were significantly different.

Conclusions

The SD-BiolineTM MRDT performed well, with remarkable persistence of rapid test-positive for an average of 23 days post treatment. The prevalence of P. malaria is somewhat greater than expected.

Severity of Schistosoma haematobium co-infection with malaria in school-children is potentially modulated by host CD14 gene variants

OBJECTIVE

Schistosomiasis remains a chronic disease of global importance, especially in many rural areas of the world where co-infection with Plasmodium falciparum is common. It is critical to decipher the role of single or co-infected disease scenarios on immune system regulation in such individuals and how such co-infections can either ameliorate or complicate immune response and the consequent disease outcome. First, 10 ml of urine samples, collected between 10:00 am and 2:00 pm, was filtered for diagnosis of schistosomiasis, while egg count, indicative of disease severity, was determined by microscopy. Furthermore, genomic DNA samples extracted from dried blood spots collected on filter paper from one hundred and forty-four Schistosoma haematobium-infected school-children was tested for P. falciparum parasite positivity by an allele-specific nested-PCR analysis of merozoite surface protein (msp)-1 and -2 genes and a real-time PCR assay. In addition, among P. falciparum parasite-positive individuals, we carried out a Taqman SNP genotyping assay to extrapolate the effect of host CD14 (-159 C/T; rs2569190) genetic variants on schistosome egg count.

RESULTS

Of the 144 individuals recruited, P. falciparum parasite positivity with msp-1 gene were 34%, 43% and 55% for MAD20, RO33 and K1 alleles respectively. Of the co-infected individuals, CD14 genetic variants ranged from 18.8% vs 21.5%, 33.3% vs 44.4%, 9.7% vs 11.8% for single versus schistosome co-infection for the wild type (CC), heterozygous (CT) and mutant (TT) variants respectively. Though the mean egg count for co-infected individuals with CD14 wild type (33.7 eggs per 10 ml of urine) and heterozygote variants (37.5 eggs per 10 ml of urine) were lower than that of schistosome infection alone (52.48 and 48.08 eggs/10 ml of urine respectively), it lacked statistical significance (p-value 0.12 and 0.29), possibly reflecting the benefit of the CD14 activation in schistosome plus malaria co-infection and not schistosome infection alone. In addition, the lower mean egg count in co-infected individuals reveal the benefit of downstream Th1 immune response mitigated by CD14 innate activation that is absent in schistosome infection alone.

Antimalarial and Antioxidant Activities of Ethanolic Stem Bark Extract of Terminalia macroptera in Swiss Albino Mice Infected with Plasmodium berghei

Background

Reduction of oxidative stress during malaria infection is considered as being of great benefit so long as treatment and drug development approaches are concerned. This study had the aim of evaluating the antimalarial and antioxidant activities of the ethanolic extract of Terminalia macroptera in Swiss albino mice infected with the Plasmodium berghei NK65 strain.

Methods

In vivo, the antiplasmodial activity of the plant ethanolic extract was tested in a four-day suppressive and curative assay using P. berghei in Swiss albino mice. The extract was administered to the mice at doses of 125, 250, and 500 mg/kg per day. Then, parameters, such as parasite suppression and survival time of the mice, were evaluated. Furthermore, the effect of plant extract on liver damage, oxidative stress indicators, and lipid profile changes in P. berghei-infected mice were studied.

Results

Administration of T. macroptera significantly suppressed P. berghei infection by 55.17%, 70.69%, and 71.10% at doses of 125, 250, and 500 mg/kg, respectively, whereas chloroquine had 84.64% suppression relative to the untreated group 1% Dimethyl sulfoxide (1% DMSO) at day 4 (post-infection) in the four-day suppressive test. This suppression activity rate was dose-dependent. The curative test also presented a significant reduction in parasitemia and an extension of the survival time of the treated groups. Treatment of infected parasitized mice with the extract of T. macroptera had a significant (p < 0.05) reduction in parameters, such as total protein, aspartate aminotransferase, and alanine aminotransferase. Infection may also lead to a significant increase in the enzymatic activity of liver catalase and superoxide dismutase compared with the normal control group. The non-enzymatic antioxidant activity in parasitized mice was significantly reduced in malondialdehyde and increased in glutathione and nitric oxide when compared with the normal control group.

Conclusions

These findings support the ethnobotanical use of T. macroptera stem bark as an antimalarial remedy coupled with antioxidant activity. However, further in vivo toxicity tests are required to ascertain its safety.

Efficacy and safety of pyronaridine-artesunate versus artemether-lumefantrine in the treatment of acute uncomplicated malaria in children in South-West Nigeria: an open-labelled randomized controlled trial

BACKGROUND

In Nigeria, declining responsiveness to artemether-lumefantrine (AL), the artemisinin-based combination therapy (ACT) of choice since 2005, has been reported. Pyronaridine-artesunate (PA) is a newer fixed-dose ACT recently prequalified by the WHO for the treatment of uncomplicated falciparum malaria. However, PA data from the Nigerian pediatric population is scarce. Therefore, the efficacy and safety of PA and AL using the WHO 28-day anti-malarial therapeutic efficacy study protocol in Ibadan, southwest Nigeria, were compared.

METHODS

In an open-labelled, randomized, controlled clinical trial, 172 children aged 3-144 months with a history of fever and microscopically confirmed uncomplicated Plasmodium falciparum malaria were enrolled in southwest Nigeria. Enrollees were randomly assigned to receive PA or AL at standard dosages according to body weight for 3 days. Venous blood was obtained for hematology, blood chemistry, and liver function tests on days 0, 3, 7, and 28 as part of the safety evaluation.

RESULTS

165 (95.9%) of the enrolled individuals completed the study. About half (52.3%; 90/172) of enrollees were male. Eighty-seven (50.6%) received AL, while 85 (49.4%) received PA. Day 28, adequate clinical and parasitological response for PA was 92.7% [(76/82) 95% CI 83.1, 95.9] and 71.1% [(59/83) 95% CI 60.4, 79.9] for AL (0.001). Fever and parasite clearance were similar in both groups. Two of six and eight of 24 parasite recurrences were observed among PA- and AL-treated children, respectively. PCR-corrected Day-28 cure rates for PA were 97.4% (76/78) and 88.1% (59/67) for AL (= 0.04) in the per-protocol population after new infections were censored. Hematological recovery at day 28 was significantly better among PA-treated patients (34.9% 2.8) compared to those treated with AL (33.1% 3.0) (0.002). Adverse events in both treatment arms were mild and similar to the symptoms of malaria infection. Blood chemistry and liver function tests were mostly within normal limits, with an occasional marginal rise.

CONCLUSION

PA and AL were well-tolerated. PA was significantly more efficacious than AL in both the PCR-uncorrected and PCR-corrected per-protocol populations during this study. The results of this study support the inclusion of PA in the anti-malarial treatment guidelines in Nigeria.

RETROSPECTIVE TRIAL REGISTRATION

Clinicaltrials.gov: NCT05192265.

Revisiting the role of mesenchymal stem cells in tuberculosis and other infectious diseases

Mesenchymal stem cells (MSCs) play diverse roles ranging from regeneration and wound healing to immune signaling. Recent investigations have indicated the crucial role of these multipotent stem cells in regulating various aspects of the immune system. MSCs express unique signaling molecules and secrete various soluble factors that play critical roles in modulating and shaping immune responses, and in some other cases, MSCs can also exert direct antimicrobial effects, thereby helping with the eradication of invading organisms. Recently, it has been demonstrated that MSCs are recruited at the periphery of the granuloma containing Mycobacterium tuberculosis and exert "Janus"-like functions by harboring pathogens and mediating host protective immune responses. This leads to the establishment of a dynamic balance between the host and the pathogen. MSCs function through various immunomodulatory factors such as nitric oxide (NO), IDO, and immunosuppressive cytokines. Recently, our group has shown that M.tb uses MSCs as a niche to evade host protective immune surveillance mechanisms and establish dormancy. MSCs also express a large number of ABC efflux pumps; therefore, dormant M.tb residing in MSCs are exposed to a suboptimal dose of drugs. Therefore, it is highly likely that drug resistance is coupled with dormancy and originates within MSCs. In this review, we discussed various immunomodulatory properties of MSCs, their interactions with important immune cells, and soluble factors. We also discussed the possible roles of MSCs in the outcome of multiple infections and in shaping the immune system, which may provide insight into therapeutic approaches using these cells in different infection models.

The synergistic effect of climatic factors on malaria transmission: a predictive approach for northeastern states of India

The northeast region of India is highlighted as the most vulnerable region for malaria. This study attempts to explore the epidemiological profile and quantify the climate-induced influence on malaria cases in the context of tropical states, taking Meghalaya and Tripura as study areas. Monthly malaria cases and meteorological data from 2011 to 2018 and 2013 to 2019 were collected from the states of Meghalaya and Tripura, respectively. The nonlinear associations between individual and synergistic effect of meteorological factors and malaria cases were assessed, and climate-based malaria prediction models were developed using the generalized additive model (GAM) with Gaussian distribution. During the study period, a total of 216,943 and 125,926 cases were recorded in Meghalaya and Tripura, respectively, and majority of the cases occurred due to the infection of Plasmodium falciparum in both the states. The temperature and relative humidity in Meghalaya and temperature, rainfall, relative humidity, and soil moisture in Tripura showed a significant nonlinear effect on malaria; moreover, the synergistic effects of temperature and relative humidity (SI=2.37, RERI=0.58, AP=0.29) and temperature and rainfall (SI=6.09, RERI=2.25, AP=0.61) were found to be the key determinants of malaria transmission in Meghalaya and Tripura, respectively. The developed climate-based malaria prediction models are able to predict the malaria cases accurately in both Meghalaya (RMSE: 0.0889; R²: 0.944) and Tripura (RMSE: 0.0451; R²: 0.884). The study found that not only the individual climatic factors can significantly increase the risk of malaria transmission but also the synergistic effects of climatic factors can drive the malaria transmission multifold. This reminds the policymakers to pay attention to the control of malaria in situations with high temperature and relative humidity and high temperature and rainfall in Meghalaya and Tripura, respectively.

Correlates of haemoglobin level in mothers of children under two years in Nanton district: A cross-sectional study from Ghana

Objectives

Anaemia, defined using haemoglobin level, is one of the most prevalent nutritional deficiency diseases among women of childbearing age. Whilst most studies of anaemia were conducted on pregnant women, data are lacking on the haemoglobin level and its correlates of mothers in Ghana. In this paper, we report data on the correlates of haemoglobin level among mothers in Nanton district, Northern Region, Ghana.

Method

A cross-sectional study design was used to study 420 mothers of children under 2 years selected randomly from the child welfare clinics (CWCs) of five health facilities in Nanton District, Ghana. Women were interviewed on their socio-demographic characteristics, dietary practices, reproductive history, and knowledge on anaemia using a structured questionnaire in health facilities. Haemoglobin values during pregnancy were retrieved from antenatal clinic files whilst finger-pricked blood test samples were obtained and used to determine haemoglobin levels during the survey. Multiple linear regression was used to identify the correlates of haemoglobin level of the mothers.

Results

The mean age (±SD) and parity of the subjects were 29.4 (±6.36) years, and 3.36 (±1.78) respectively. The mean haemoglobin (±SD) was 10.35 (±2.17) g/dl and 56.0% of the subjects had anaemia. Multivariable regression analysis identified 12 haemoglobin correlates, but based on standardized regression coefficients, the seven most important correlates of haemoglobin were: parity (β = -0.396), age (β = 0.352), having malaria infection postpartum (β = - 0.340), frequency of fruit consumption (once weekly, β = 0.322), frequency of vegetable consumption (twice weekly, β = 0.296), overall index of anaemia knowledge (richest tertile, β = 0.125), and CWC attendance (β = 0.110). It is recommended to strengthen family planning and malaria prevention programmes, and to intensify education on fruit and vegetable consumption, and anaemia.

Functionalized lipid-based drug delivery nanosystems for the treatment of human infectious diseases

Infectious diseases are still public health problems. Microorganisms such as fungi, bacteria, viruses, and parasites are the main causing agents related to these diseases. In this context, the search for new effective strategies in prevention and/or treatment is considered essential, since current drugs often have side effects or end up, causing microbial resistance, making it a serious health problem. As an alternative to these limitations, nanotechnology has been widely used. The use of lipid-based drug delivery nanosystems (DDNs) has some advantages, such as biocompatibility, low toxicity, controlled release, the ability to carry both hydrophilic and lipophilic drugs, in addition to be easel scalable. Besides, as an improvement, studies involving the conjugation of signalling molecules on the surfaces of these nanocarriers can allow the target of certain tissues or cells. Thus, this review summarizes the performance of functionalized lipid-based DDNs for the treatment of infectious diseases caused by viruses, including SARS-CoV-2, bacteria, fungi, and parasites.

Genetic diversity of Plasmodium falciparum among asymptomatic pregnant women on intermittent preventive treatment with sulfadoxine-pyrimethamine in Nigeria

This study investigated the genetic diversity of Plasmodium falciparum among asymptomatic pregnant women on intermittent preventive treatment with sulfadoxine-pyrimethamine (IPTp-Sp) in Osogbo, southwest Nigeria. Blood sample was obtained from consenting pregnant women attending antenatal clinics. Microscopy and Polymerase chain reaction (PCR) were employed to diagnose and analyse genetic diversity. Of the 301 samples, 53 (18%) and 83 (28%) were positive for P. falciparum by microscopy and PCR, respectively. Using the merozoite surface protein (msp)-1, msp-2, and glutamate-rich protein (glurp) genes of P. falciparum as polymorphic markers, the msp-1 gene showed nine alleles with R033 (66.7%) being predominant, followed by K1 (45.5%) and MAD20 (33.3%). The msp-2 gene had 16 alleles (eight each for FC27 and 3D7). The 3D7 alleles (82.1%) was significantly more than FC27 alleles (48.2%) (p = 0.0093). Nine alleles were detected with glurp gene, presenting with the highest monoclonal and the lowest polyclonal infection. The multiplicity of infection (MOI) of 1.5, 1.8, and 1.2 were obtained for msp-1, msp-2 and glurp genes. In light of the high P. falciparum genetic diversity among pregnant women on IPT-Sp in this study, additional strategies for preventing and controlling malaria in pregnancy might be required.

High prevalence of persistent residual parasitemia on days 3 and 14 after artemether-lumefantrine or pyronaridine-artesunate treatment of uncomplicated Plasmodium falciparum malaria in Nigeria

BACKGROUND

Microscopic evaluation of parasite clearance is the gold standard in antimalarial drug efficacy trials. However, the presence of sub-microscopic residual parasitemia after artemisinin-based combination therapy (ACT) needs to be investigated.

METHODS

One hundred and twenty (AL: n = 60, PA: n = 60) days 3 and 14 dried blood spots, negative by microscopy were analysed for residual parasitemia using nested PCR. Isolates with residual parasitemia on days 3 and 14 were further genotyped with their corresponding day-0 isolates using merozoite surface proteins msp-1, msp-2, and glurp genes for allelic similarity.

RESULTS

Persistent PCR-determined sub-microscopic residual parasitemia at day 3 post ACT treatment was 83.3 (AL) and 88.3% (PA), respectively (ρ = 0.600), while 63.6 and 36.4% (ρ = 0.066) isolates were parasitemic at day 14 for AL and PA, respectively. Microscopy-confirmed gametocytemia persisted from days 0 to 7 and from days 0 to 21 for AL and PA. When the alleles of day 3 versus day 0 were compared according to base pair sizes, 59% of parasites shared identical alleles for glurp, 36% each for 3D7 and FC27, while K1 was 77%, RO33 64%, and MAD20 23%, respectively. Similarly, day 14 versus day 0 was 36% (glurp), 64% (3D7), and 32% (FC27), while 73% (K1), 77% (RO33), and 41% (MAD20), respectively.

CONCLUSION

The occurrence of residual parasitemia on days 3 and 14 following AL or PA treatment may be attributable to the presence of either viable asexual, gametocytes, or dead parasite DNAs, which requires further investigation.

Low genetic diversity of Plasmodium falciparum merozoite surface protein 1 and 2 and multiplicity of infections in western Ethiopia following effective malaria interventions

BACKGROUND

Genetic diversity of malaria parasites can inform the intensity of transmission and poses a major threat to malaria control and elimination interventions. Characterization of the genetic diversity would provide essential information about the ongoing control efforts. This study aimed to explore allelic polymorphism of merozoite surface protein 1 (msp1) and merozoite surface protein 2 (msp2) to determine the genetic diversity and multiplicity of Plasmodium falciparum infections circulating in high and low transmission sites in western Ethiopia.

METHODS

Parasite genomic DNA was extracted from a total of 225 dried blood spots collected from confirmed uncomplicated P. falciparum malaria-infected patients in western Ethiopia. Of these, 72.4% (163/225) and 27.6% (62/225) of the samples were collected in high and low transmission areas, respectively. Polymorphic msp1 and msp2 genes were used to explore the genetic diversity and multiplicity of falciparum malaria infections. Genotyping of msp1 was successful in 86.5% (141/163) and 88.7% (55/62) samples collected from high and low transmission areas, respectively. Genotyping of msp2 was carried out among 85.3% (139/163) and 96.8% (60/62) of the samples collected in high and low transmission sites, respectively. Plasmodium falciparum msp1 and msp2 genes were amplified by nested PCR and the PCR products were analysed by QIAxcel ScreenGel Software. A P-value of less or equal to 0.05 was considered significant.

RESULTS

High prevalence of falciparum malaria was identified in children less than 15 years as compared with those  ≥ 15 years old (AOR = 2.438, P = 0.005). The three allelic families of msp1 (K1, MAD20, and RO33) and the two allelic families of msp2 (FC27 and 3D7), were observed in samples collected in high and low transmission areas. However, MAD 20 and FC 27 alleles were the predominant allelic families in both settings. Plasmodium falciparum isolates circulating in western Ethiopia had low genetic diversity and mean MOI. No difference in mean MOI between high transmission sites (mean MOI 1.104) compared with low transmission area (mean MOI 1.08) (p > 0.05). The expected heterozygosity of msp1 was slightly higher in isolates collected from high transmission sites (He = 0.17) than in those isolates from low transmission (He = 0.12). However, the heterozygosity of msp2 was not different in both settings (Pfmsp2: 0.04 in high transmission; pfmsp2: 0.03 in low transmission).

CONCLUSION

Plasmodium falciparum from clinical malaria cases in western Ethiopia has low genetic diversity and multiplicity of infection irrespective of the intensity of transmission at the site of sampling. These may be signaling the effectiveness of malaria control strategies in Ethiopia; although further studies are required to determine how specific intervention strategies and other parameters that drive the pattern.

Genetics of cerebral malaria: pathogenesis, biomarkers and emerging therapeutic interventions

Background

Cerebral malaria (CM) is a preeminent cause of severe disease and premature deaths in Sub-Saharan Africa, where an estimated 90% of cases occur. The key features of CM are a deep, unarousable coma that persists for longer than 1 h in patients with peripheral Plasmodium falciparum and no other explanation for encephalopathy. Significant research efforts on CM in the last few decades have focused on unravelling the molecular underpinnings of the disease pathogenesis and the identification of potential targets for therapeutic or pharmacologic intervention. These efforts have been greatly aided by the generation and study of mouse models of CM, which have provided great insights into key events of CM pathogenesis, revealed an interesting interplay of host versus parasite factors that determine the progression of malaria to severe disease and exposed possible targets for therapeutic intervention in severe disease.

Main Body

This paper reviews our current understanding of the pathogenic and immunologic factors involved in CM. We present the current view of the roles of certain gene products e.g., the var gene, ABCA-1, ICAM-1, TNF-alpha, CD-36, PfEMP-1 and G6PD, in CM pathogenesis. We also present alterations in the blood–brain barrier as a consequence of disease proliferation as well as complicated host and parasite interactions, including the T-cell immune reaction, reduced deformation of erythrocytes and cytoadherence. We further looked at recent advances in cerebral malaria treatment interventions by emphasizing on biomarkers, new diagnostic tools and emerging therapeutic options.

Conclusion

Finally, we discuss how the current understanding of some of these pathogenic and immunologic factors could inform the development of novel therapeutic interventions to fight CM.

Escalating pyrethroid resistance in two major malaria vectors Anopheles funestus and Anopheles gambiae (s.l.) in Atatam, Southern Ghana

BACKGROUND

Aggravation of insecticide resistance in malaria vectors is threatening the efforts to control malaria by reducing the efficacy of insecticide-based interventions hence needs to be closely monitored. This study investigated the intensity of insecticide resistance of two major malaria vectors An. funestus sensu stricto (s.s.) and An. gambiae sensu lato (s.l.) collected in southern Ghana and assessed the bio-efficacy of several long-lasting insecticidal nets (LLINs) against these mosquito populations.

METHODS

The insecticide susceptibility profiles of Anopheles funestus s.s. and Anopheles gambiae s.l. populations from Obuasi region (Atatam), southern Ghana were characterized and the bio-efficacy of some LLINs was assessed to determine the impact of insecticide resistance on the effectiveness of these tools. Furthermore, molecular markers associated with insecticide resistance in both species were characterized in the F0 and F1 populations using PCR and qPCR methods.

RESULTS

Anopheles funestus s.s. was the predominant species and was resistant to pyrethroids, organochlorine and carbamate insecticides, but fully susceptible to organophosphates. An. gambiae s.l. was resistant to all four insecticide classes. High intensity of resistance to 5 × and 10 × the discriminating concentration (DC) of pyrethroids was observed in both species inducing a considerable loss of efficacy of long-lasting insecticidal nets (LLINs). Temporal expression analysis revealed a massive 12-fold increase in expression of the CYP6P4a cytochrome P450 gene in An. funestus s.s., initially from a fold change of 41 (2014) to 500 (2021). For both species, the expression of candidate genes did not vary according to discriminating doses. An. gambiae s.l. exhibited high frequencies of target-site resistance including Vgsc-1014F (90%) and Ace-1 (50%) while these mutations were absent in An. funestus s.s.

CONCLUSIONS

The multiple and high intensity of resistance observed in both malaria vectors highlights the need to implement resistance management strategies and the introduction of new insecticide chemistries.

Genetic diversity of Plasmodium falciparum isolates in Nigeria. A review

Background

The complexity of infection in malaria-endemic areas is exacerbated by the presence of genetically diverse Plasmodium falciparum strains. There is a risk that more virulent or drug-resistant versions of the disease may arise. Therefore, we reviewed most reported molecular markers that have been detailed to date in Nigeria.

Main body of the abstract

In this review, we have summarized the genetic diversity of P. falciparum in Nigeria using the two well-reported genes (msp1 and msp2) as genetic diversity biomarkers. The review includes the findings obtained from research conducted in all major geopolitical regions of the country. We found that MSP-2 infection complexity is generally moderate to high in the North-central region. However, in the South-West, there were several regions where the multiplicity of infection (MOI) was either low or extremely high.

Conclusion

Understanding how Nigeria's malaria situation fits into various reports on P. falciparum genetic variation can improve treatment and immunization options. This review will be helpful for future treatment strategies that would be tailored to the specific needs of Nigeria's malaria-endemic populations.

RDT- AND MICROSCOPIC-BASED TRENDS OF MALARIA AMONG LOCAL AND MIGRANT POPULATIONS IN THE PROVINCE OF CENTRAL KALIMANTAN, INDONESIA DURING 2017-2020

Background

Indonesia has demonstrated a significant progress in malaria elimination. Kapuas and Gunung Mas Districts in Central Kalimantan Province have not been freed from malaria and there is no information of malaria incidences in these areas. Palangka Raya city has been freed from malaria in 2018.

Materials and Methods

The total number of 140 samples consisting of 75 malaria Giemsa-stained blood smears and 65 RDT cartridges from both local and migrant populations. Both males and females aged15 years and above were included and their demographic data were recorded. The malaria trend in these areas was analyzed based on the number of cases, species of Plasmodium and the demographic characteristics of the enrolled subjects.

Results

The study findings disclosed a yearly decrement of malaria trend in both local and migrant populations of the studied areas. The highest number of P.vivax infection (8.76%)occurred in 2018 among migrant population in Gunung Mas district, while P.falciparum infection was found in 2017contributed by both population. The decreased number of cases was shown by very low number of cases among migrant population in almost every year. The observed significant decrease in malaria incidences indicated the success and effective implementation of the malaria control programs at the sub-district level.

Conclusion

To minimize malaria cases among gold miners, mosquito repellent, prophylactic administration of antimalarial drugs and enough enlightenment should be considered before and during their activities. From that standpoint, the effective collaboration between health officers and environmental authorities is recommended to control, prevent and eliminate malaria in these areas.

Spatial variation and risk factors of malaria and anaemia among children aged 0 to 59 months: a cross-sectional study of 2010 and 2015 datasets

Malaria and anaemia are common diseases that affect children, particularly in Africa. Studies on the risk associated with these diseases and their synergy are scanty. This work aims to study the spatial pattern of malaria and anaemia in Nigeria and adjust for their risk factors using separate models for malaria and anaemia. This study used Bayesian spatial models within the Integrated Nested Laplace Approach (INLA) to establish the relationship between malaria and anaemia. We also adjust for risk factors of malaria and anaemia and map the estimated relative risks of these diseases to identify regions with a relatively high risk of the diseases under consideration. We used data obtained from the Nigeria malaria indicator survey (NMIS) of 2010 and 2015. The spatial variability distribution of both diseases was investigated using the convolution model, Conditional Auto-Regressive (CAR) model, generalized linear mixed model (GLMM) and generalized linear model (GLM) for each year. The convolution and generalized linear mixed models (GLMM) showed the least Deviance Information Criteria (DIC) in 2010 for malaria and anaemia, respectively. The Conditional Auto-Regressive (CAR) and convolution models had the least DIC in 2015 for malaria and anaemia, respectively. This study revealed that children in rural areas had strong and significant odds of malaria and anaemia infection [2010; malaria: AOR = 1.348, 95% CI = (1.117, 1.627), anaemia: AOR = 1.455, 95% CI = (1.201, 1.7623). 2015; malaria: AOR = 1.889, 95% CI = (1.568, 2.277), anaemia: AOR = 1.440, 95% CI = (1.205, 1.719)]. Controlling the prevalence of malaria and anaemia in Nigeria requires the identification of a child’s location and proper confrontation of some socio-economic factors which may lead to the reduction of childhood malaria and anaemia infection.

Stratification at the health district level for targeting malaria control interventions in Mali

Malaria is the leading cause of morbidity and mortality in Mali. Between 2017 and 2020, the number of cases increased in the country, with 2,884,827 confirmed cases and 1454 reported deaths in 2020. We performed a malaria risk stratification at the health district level in Mali with a view to proposing targeted control interventions. Data on confirmed malaria cases were obtained from the District Health Information Software 2, data on malaria prevalence and mortality in children aged 6-59 months from the 2018 Demographic and Health Survey, entomological data from Malian research institutions working on malaria in the sentinel sites of the National Malaria Control Program (NMCP), and environmental data from the National Aeronautics and Space Administration. A stratification of malaria risk was performed. Targeted malaria control interventions were selected based on spatial heterogeneity of malaria incidence, malaria prevalence in children, vector resistance distribution, health facility usage, child mortality, and seasonality of transmission. These interventions were discussed with the NMCP and the different funding partners. In 2017-2019, median incidence across the 75 health districts was 129.34 cases per 1000 person-years (standard deviation = 86.48). Risk stratification identified 12 health districts in very low transmission areas, 19 in low transmission areas, 20 in moderate transmission areas, and 24 in high transmission areas. Low health facility usage and increased vector resistance were observed in high transmission areas. Eight intervention combinations were selected for implementation. Our work provides an updated risk stratification using advanced statistical methods to inform the targeting of malaria control interventions in Mali. This stratification can serve as a template for continuous malaria risk stratifications in Mali and other countries.

Plasmodium knowlesi: the game changer for malaria eradication

Plasmodium knowlesi is a zoonotic malaria parasite that has gained increasing medical interest over the past two decades. This zoonotic parasitic infection is prevalent in Southeast Asia and causes many cases with fulminant pathology. Despite several biogeographical restrictions that limit its distribution, knowlesi malaria cases have been reported in different parts of the world due to travelling and tourism activities. Here, breakthroughs and key information generated from recent (over the past five years, but not limited to) studies conducted on P. knowlesi were reviewed, and the knowledge gap in various research aspects that need to be filled was discussed. Besides, challenges and strategies required to control and eradicate human malaria with this emerging and potentially fatal zoonosis were described.

Community health workers and health equity in low- and middle-income countries: systematic review and recommendations for policy and practice

Background

The deployment of Community Health Workers (CHWs) is widely promoted as a strategy for reducing health inequities in low- and middle-income countries (LMIC). Yet there is limited evidence on whether and how CHW programmes achieve this. This systematic review aimed to synthesise research findings on the following questions: (1) How effective are CHW interventions at reaching the most disadvantaged groups in LMIC contexts? and (2) What evidence exists on whether and how these programmes reduce health inequities in the populations they serve?

Methods

We searched six academic databases for recent (2014–2020) studies reporting on CHW programme access, utilisation, quality, and effects on health outcomes/behaviours in relation to potential stratifiers of health opportunities and outcomes (e.g., gender, socioeconomic status, place of residence). Quantitative data were extracted, tabulated, and subjected to meta-analysis where appropriate. Qualitative findings were synthesised using thematic analysis.

Results

One hundred sixty-seven studies met the search criteria, reporting on CHW interventions in 33 LMIC. Quantitative synthesis showed that CHW programmes successfully reach many (although not all) marginalized groups, but that health inequalities often persist in the populations they serve. Qualitative findings suggest that disadvantaged groups experienced barriers to taking up CHW health advice and referrals and point to a range of strategies for improving the reach and impact of CHW programmes in these groups. Ensuring fair working conditions for CHWs and expanding opportunities for advocacy were also revealed as being important for bridging health equity gaps.

Conclusion

In order to optimise the equity impacts of CHW programmes, we need to move beyond seeing CHWs as a temporary sticking plaster, and instead build meaningful partnerships between CHWs, communities and policy-makers to confront and address the underlying structures of inequity.

Trial registration

PROSPERO registration number CRD42020177333.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12939-021-01615-y.

Tafenoquine for the treatment of Plasmodium vivax malaria

INTRODUCTION

Plasmodium vivax malaria causes significant disease burden worldwide, especially in Latin America, Southeast Asia, and Oceania. P. vivax is characterized by the production of liver hypnozoites that cause clinical relapses upon periodic activation. Primaquine, an 8-aminoquinoline drug, has been the standard of care for decades to treat liver-stage P. vivax malaria; however, it requires long treatment regimens (one to two weeks) that lead to poor adherence and thus clinical relapses. Tafenoquine (TFQ), a newly available and efficacious single-dose 8-aminoquinoline, aims to address this challenge. Safe administration is possible when paired with the use of glucose-6-phosphate dehydrogenase (G6PD) diagnostics to prevent 8-aminoquinoline-induced hemolysis in patients with underlying G6PD deficiency (G6PDd).

AREAS COVERED

In this review, the authors present the recent literature regarding the pharmacology, efficacy, safety, and tolerability of TFQ and highlight regional differences in these areas. The authors also discuss the potential for TFQ, complemented with primaquine PQ and effective screening for G6PDd, to improve P. vivax clinical management and facilitate targeted mass drug administration in communities to decrease transmission.

EXPERT OPINION

Clinical studies show therapeutic efficacy of TFQ as well as a good performance in terms of safety and tolerability. Additional research regarding the effectiveness and safety TFQ in malaria elimination strategies such as targeted or mass drug administration are needed.

Plasmodium falciparum multiplicity of infection and pregnancy outcomes in Congolese women from southern Brazzaville, Republic of Congo

Background

Investigating whether the multiplicity of Plasmodium falciparum infection (MOI) is related to pregnancy outcomes, is of interest in sub-Saharan area where malaria is highly endemic. The present study aimed to characterize the genetic diversity of P. falciparum in women at delivery from Southern Brazzaville, and investigate whether the MOI is associated with maternal anaemia, preterm delivery, or low birth weight.

Methods

This was a cross sectional study carried out with samples collected between March 2014 and April 2015 from 371 women recruited at delivery at a Health Centre in southern Brazzaville, Republic of Congo. Matched peripheral, placental, and cord blood collected from each of the women at delivery were used for the detection of P. falciparum microscopic and submicroscopic parasitaemia, and parasite DNA genotyping by nested PCR.

Results

From 371 recruited women, 27 were positive to microscopic malaria parasitaemia while 223 women harboured submicroscopic parasitaemia. All msp-1 block 2 family allelic types (K1, MAD20 and RO33) were observed in all the three compartments of blood, with K1 being most abundant. K1 (with 12, 10, and 08 alleles in the peripheral, placental, and cord blood respectively) and MAD20 (with 10, 09, and 06 alleles in the respective blood compartments) were more diverse compared to RO33 (with 06, 06, and 05 alleles in the respective blood compartments). From the 250 women with microscopic and/or submicroscopic parasitaemia, 38.5%, 30.5%, and 18.4% of peripheral, placental and cord blood sample, respectively, harboured more than one parasite clone, and polyclonal infection was more prevalent in the peripheral blood of women with microscopic parasitaemia (54.5%) compared to those with submicroscopic parasitaemia (36.7%) (p = 0.02). The mean multiplicity of genotypes per microscopic and submicroscopic infection in peripheral blood was higher in anemic women (2.00 ± 0.23 and 1.66 ± 0.11, respectively) than in non-anaemic women (1.36 ± 0.15 and 1.45 ± 0.06, respectively) (p = 0.03 and 0.06). In logistic regression, women infected with four or more clones of the parasite were 9.4 times more likely to be anaemic than women harbouring one clone. This association, however, was only observed with the peripheral blood infection. No significant association was found between the MOI and low birth weight or preterm delivery.

Conclusions

These results indicate that the genetic diversity of P. falciparum is high in pregnant women from southern Brazzaville in the Republic of Congo, and the multiplicity of the infection might represent a risk for maternal anaemia.

Association of toll-like receptors in malaria susceptibility and immunopathogenesis: A meta-analysis

Toll-like receptors (TLRs) play a key role in the induced immune response in malaria. Although the potential roles of TLRs have been described, it is necessary to elucidate which of these receptors may actually have an impact on the immunopathogenesis of the disease. This article performed a meta-analysis adhered to the PRISMA statement on TLRs studied in malaria by Plasmodium falciparum and Plasmodium vivax and its impact on susceptibility and pathogenesis during malaria. A search of the literature was undertaken in PubMed, LILACS and SciELO published until June 30th, 2020. The risk of bias was calculated using the Joanna Briggs Institute's Critical Review Checklist. Later, based on the inclusion and/or exclusion criteria, 17 out of 296 articles were harvested for this systematic review, the meta-analysis included studies incorporating 6,747 cases and 8,983 controls. The results showed that only TLR1, TLR9 and TLR4 receptors were associated with parasitemia, TLR2 and TLR6 were related with severity and none TLR was correlated with susceptibility. The data described here should be taken with caution, since the current evidence is limited and inconsistent. More studies are needed given that the results may change depending on the region and genetic background of the populations.

Mixed effect analysis of factors influencing the use of insecticides treated bed nets among pregnant women in Ghana: evidence from the 2019 Malaria Indicator Survey

Background

Malaria during pregnancy is a major cause of maternal morbidity globally and leads to poor birth outcomes. The World Health Organization has recommended the use of insecticide treated bed nets (ITN) as one of the effective malaria preventive strategies among pregnant women in malaria endemic areas. This study, therefore, seeks to examine the individual and household factors associated with the use of ITNs among pregnant women in Ghana.

Methods

Data for this study was obtained from the 2019 Ghana Malaria Indicator Survey (GMIS) conducted between September 25 and November 24, 2019. The weighted sample comprised 353 pregnant women aged 15–49 years. Data was analyzed with SPSS version 22 using both descriptive and multilevel logistics regression modelling. Statistically significant level was set at p < 0.05.

Results

The study found that 49.2% of pregnant women in Ghana use ITN to prevent malaria. Pregnant women aged 35–49 years (AOR = 3.403, CI: 1.191–9.725), those with no formal education (AOR = 5.585, CI = 1.315–23.716), and those who had secondary education (AOR = 3.509, CI = 1.076–11.440) had higher odds of using ITN. Similarly, higher odds of ITN usage was found among who belonged to the Akan ethnic group (AOR = 7.234, CI = 1.497–34.955), dwell in male-headed households (AOR = 2.232, CI = 1.105–4.508) and those whose household heads are aged 60–69 years (AOR = 4.303, CI = 1.160–15.966). However, pregnant women who resided in urban areas (AOR = 0.355, CI = 0.216–0.582), those whose household heads aged 40–49 years (AOR = 0.175, CI = 0.066–0.467) and those who belonged to richer (AOR =0.184, CI = 0.050–0.679) and richest (AOR = 0.107, CI = 0.021–0.552) households had lower odds of using ITN for malaria prevention.

Conclusions

Individual socio-demographic and household factors such as pregnant women’s age, educational level, place of residence, ethnicity, sex and age of household head, and household wealth quintile are associated with the use of ITN for malaria prevention among pregnant women. These factors ought to be considered in strengthening malaria prevention campaigns and develop new interventions to help increase ITN utilization among vulnerable population living in malaria- endemic areas.

Plasmodium falciparum Clinical Isolates Reveal Analogous Circulation of 3D7 and FC27 Allelic Variants and Multiplicity of Infection in Urban and Rural Settings: The Case of Adama and Its Surroundings, Oromia, Ethiopia

Background

Despite significant progress achieved globally in reducing malaria burden, still it is one of the major public health and economic problems in Ethiopia. Investigation of the local genetic polymorphism of P. falciparum, the most virulent and predominant malaria parasite primarily targeted in malaria control and elimination program, is paramount to assess intensity of parasite transmission. Analysis of the block 3 region of the msp-2 gene of P. falciparum provides strong molecular evidence to evaluate the real picture of malaria epidemiology to fine-tune the ongoing control and elimination programs in the region. Thus, this study was aimed at examining the status of such polymorphic gene and its implications in Adama and its surroundings.

Methods

148 isolates from patients with uncomplicated falciparum malaria were collected in the study from September 2019 to August 2020. Tween® 20 and the Chelex method were employed for parasite DNA extraction. msp-2 allelic families were genotyped by using nested polymerase chain reaction targeting its 3D7 and FC27 allelic variants followed by gel electrophoresis for fragment analysis.

Results

Seventeen different polymorphic forms of msp-2 allelic fragments were detected in the study area. Moreover, 47 (31.8%) and 41(27.7%) were detected for 3D7 and FC27 allelic families, respectively. Furthermore, the multiclonal allele type accounted for 60 (40.5%). The mean MOI was 1.4, and the heterogeneity index (He) is 0.49 indicating nearly intermediate malaria transmission in the study area.

Conclusions

The study revealed nearly intermediate genetic diversity and mean MOI of P. falciparum in the study area, demanding further scale up of the ongoing control and elimination efforts.

Genomic miscellany and allelic frequencies of Plasmodium falciparum msp-1, msp-2 and glurp in parasite isolates

Introduction

The genomic miscellany of malaria parasites can help inform the intensity of malaria transmission and identify potential deficiencies in malaria control programs. This study was aimed at investigating the genomic miscellany, allele frequencies, and MOI of P. falciparum infection.

Methods

A total of 85 P. falciparum confirmed isolates out of 100 were included in this study that were collected from P. falciparum patients aged 4 months to 60 years in nine districts of Khyber Pakhtunkhwa Province. Parasite DNA was extracted from 200µL whole blood samples using the Qiagen DNA extraction kit following the manufacturer’s instructions. The polymorphic regions of msp-1, msp-2 and glurp loci were genotyped using nested PCR followed by gel electrophoresis for amplified fragments identification and subsequent data analysis.

Results

Out of 85 P. falciparum infections detected, 30 were msp-1 and 32 were msp-2 alleles specific. Successful amplification occurred in 88.23% (75/85) isolates for msp-1, 78.9% (67/85) for msp-2 and 70% (60/85) for glurp gene. In msp-1, the K1 allelic family was predominantly prevalent as 66.66% (50/75), followed by RO33 and MAD20. The frequency of samples with single infection having only K1, MAD20 and RO33 were 21.34% (16/75), 8% (6/75), and 10.67% (8/75), respectively. In msp-2, both the FC27 and 3D7 allelic families revealed almost the same frequencies as 70.14% (47/67) and 67.16% (45/67), respectively. Nine glurp RII region alleles were identified in 60 isolates. The overall mean multiplicity of infection for msp genes was 1.6 with 1.8 for msp-1 and 1.4 for msp-2, while for glurp the MOI was 1.03. There was no significant association between multiplicity of infection and age groups (Spearman’s rank coefficient = 0.050; P = 0.6) while MOI and parasite density correlated for only msp-2 allelic marker.

Conclusions

The study showed high genetic diversity and allelic frequency with multiple clones of msp-1, msp-2 and glurp in P. falciparum isolates in Khyber Pakhtunkhwa, Pakistan. In the present study the genotype data may provide valuable information essential for monitoring the impact of malaria eradication efforts in this region.

Scientific achievements and reflections after 20 years of vector biology and control research at the Pu Teuy mosquito field research station, Thailand

Additional vector control tools are needed to supplement current strategies to achieve malaria elimination and control of Aedes-borne diseases in many settings in Thailand and the Greater Mekong Sub-region. Within the next decade, the vector control community, Kasetsart University (KU), and the Ministry of Higher Education, Science, Research and Innovation must take full advantage of these tools that combine different active ingredients with different modes of action. Pu Teuy Mosquito Field Research Station (MFRS), Department of Entomology, Faculty of Agriculture, Kasetsart University (KU), Thailand was established in 2001 and has grown into a leading facility for performing high-quality vector biology and control studies and evaluation of public health insecticides that are operationally relevant. Several onsite mosquito research platforms have been established including experimental huts, a 40-m long semi-field screening enclosure, mosquito insectary, field-laboratory, and living quarters for students and researchers. Field research and assessments ranged from 'basic' investigations on mosquito biology, taxonomy and genetics to more 'applied' studies on responses of mosquitoes to insecticides including repellency, behavioural avoidance and toxicity. In the course of two decades, 51 peer-reviewed articles have been published, and 7 masters and 16 doctoral degrees in Entomology have been awarded to national and international students. Continued support of key national stakeholders will sustain MFRS as a Greater Mekong Subregion centre of excellence and a resource for both insecticide trials and entomological research.

Barcoded Asaia bacteria enable mosquito in vivo screens and identify novel systemic insecticides and inhibitors of malaria transmission

This work addresses the need for new chemical matter in product development for control of pest insects and vector-borne diseases. We present a barcoding strategy that enables phenotypic screens of blood-feeding insects against small molecules in microtiter plate-based arrays and apply this to discovery of novel systemic insecticides and compounds that block malaria parasite development in the mosquito vector. Encoding of the blood meals was achieved through recombinant DNA-tagged Asaia bacteria that successfully colonised Aedes and Anopheles mosquitoes. An arrayed screen of a collection of pesticides showed that chemical classes of avermectins, phenylpyrazoles, and neonicotinoids were enriched for compounds with systemic adulticide activity against Anopheles. Using a luminescent Plasmodium falciparum reporter strain, barcoded screens identified 48 drug-like transmission-blocking compounds from a 400-compound antimicrobial library. The approach significantly increases the throughput in phenotypic screening campaigns using adult insects and identifies novel candidate small molecules for disease control.

This study presents a barcoding strategy that enables high-throughput phenotypic screens of blood-feeding insects against small molecules in microtiter plate-based arrays and applies this to the discovery of novel systemic insecticides and compounds that block malaria parasite development in the mosquito vector.

Bayesian spatio-temporal distributed lag modeling for delayed climatic effects on sparse malaria incidence data

Background

In many areas of the Greater Mekong Subregion (GMS), malaria endemic regions have shrunk to patches of predominantly low-transmission. With a regional goal of elimination by 2030, it is important to use appropriate methods to analyze and predict trends in incidence in these remaining transmission foci to inform planning efforts. Climatic variables have been associated with malaria incidence to varying degrees across the globe but the relationship is less clear in the GMS and standard methodologies may not be appropriate to account for the lag between climate and incidence and for locations with low numbers of cases.

Methods

In this study, a methodology was developed to estimate the spatio-temporal lag effect of climatic factors on malaria incidence in Thailand within a Bayesian framework. A simulation was conducted based on ground truth of lagged effect curves representing the delayed relation with sparse malaria cases as seen in our study population. A case study to estimate the delayed effect of environmental variables was used with malaria incidence at a fine geographic scale of sub-districts in a western province of Thailand.

Results

From the simulation study, the model assumptions which accommodated both delayed effects and excessive zeros appeared to have the best overall performance across evaluation metrics and scenarios. The case study demonstrated lagged climatic effect estimation of the proposed modeling with real data. The models appeared to be useful to estimate the shape of association with malaria incidence.

Conclusions

A new method to estimate the spatiotemporal effect of climate on malaria trends in low transmission settings is presented. The developed methodology has potential to improve understanding and estimation of past and future trends in malaria incidence. With further development, this could assist policy makers with decisions on how to more effectively distribute resources and plan strategies for malaria elimination.

Distribution of clones among hosts for the lizard malaria parasite Plasmodium mexicanum

Background

Malaria parasites reproduce asexually, leading to the production of large numbers of genetically identical parasites, here termed a clonal line or clone. Infected hosts may harbor one or more clones, and the number of clones in a host is termed multiplicity of infection (MOI). Understanding the distribution of parasite clones among hosts can shed light on the processes shaping this distribution and is important for modeling MOI. Here, I determine whether the distribution of clones of the lizard malaria parasite Plasmodium mexicanum differ significantly from statistical distributions commonly used to model MOI and logical extensions of these models.

Methods

The number of clones per infection was assessed using four microsatellite loci with the maximum number of alleles at any one locus used as a simple estimate of MOI for each infection. I fit statistical models (Poisson, negative binomial, zero-inflated models) to data from four individual sites to determine a best fit model. I also simulated the number of alleles per locus using an unbiased estimate of MOI to determine whether the simple (but potentially biased) method I used to estimate MOI influenced model fit.

Results

The distribution of clones among hosts at individual sites differed significantly from traditional Poisson and negative binomial distributions, but not from zero-inflated modifications of these distributions. A consistent excess of two-clone infections and shortage of one-clone infections relative to all fit distributions was also observed. Any bias introduced by the simple method for estimating of MOI did not appear to qualitatively alter the results.

Conclusions

The statistical distributions used to model MOI are typically zero-truncated; truncating the Poisson or zero-inflated Poisson yield the same distribution, so the reasonable fit of the zero-inflated Poisson to the data suggests that the use of the zero-truncated Poisson in modeling is adequate. The improved fit of zero-inflated distributions relative to standard distributions may suggest that only a portion of the host population is located in areas suitable for transmission even at small sites (<1 ha). Collective transmission of clones and premunition may also contribute to deviations from standard distributions.

Association between intimate partner violence and the use of maternal health care services among married Malawian women

Background

Maternal and child health care (MCH) services aim at improving the overall health outcomes of both the mother and newborn. Intimate partner violence (IPV) has been linked with poor health outcomes and under usage of MCH services. In Malawi, IPV is a persistent problem, while MCH services’ uptake remains a constant challenge. However, there is limited information on the association between IPV and MCH services in Malawi. The study examined the association between IPV and the use of MCH services among married Malawian women.

Methods

The 2015–16 Malawi demographic and health survey was used to analyze the association of IPV and the use of MCH services among 2712 married Malawian women. Multivariable logistic regression models were used to estimate the strength of association.

Results

Approximately 41.4% of the women reported experiencing IPV. Specifically, 27.8%, 19.3%, and 23.6% reported experiencing physical, sexual, and emotional violence, respectively. Women who reported experiencing any form of IPV had a 34% reduced likelihood of delivering at a health facility [adjusted odds ratio (aOR): 0.66; 95% confidence interval (CI) 0.46–0.96] or were 36% less likely [aOR: 0.64; 95% CI 0.46–0.90] to have had skilled assistance during delivery compared to those who never experienced IPV.

Conclusion

IPV was associated with MCH services use, specifically delivery at a health facility and skilled birth attendants. The high prevalence of IPV underscores the need to design effective programs to raise awareness regarding IPV and reduce IPV. Reducing IPV may be a promising means to support a more integrated and sustainable approach to improve the use of MCH services.

The effect of brimonidine and proparacaine on metabolic enzymes: Glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, and glutathione reductase

Oxidative stress is to upregulate the pentose phosphate pathway (PPP). The PPP consists of two functional branches, glucose-6-phosphate dehydrogenase (G6PD) and 6-phosphogluconaste dehydrogenase (6PGD). Glutathione reductase (GR) has a significant role in catalyzing an oxidized glutathione form into a reduced form. The purpose of this study is to investigate the effects of brimonidine and proparacaine on the activity of 6PGD, G6PD, and GR enzymes purified from human erythrocytes. Brimonidine displayed considerable inhibition profile against G6PD with IC₅₀ value and K_I constant of 29.93 ± 3.56 and 48.46 ± 0.66 μM, respectively. On the other hand, proparacaine had no inhibitory effect against G6PD. K_I values were found to be 66.06 ± 0.78 and 811.50 ± 11.13 μM for brimonidine and proparacaine, respectively, for 6PGD. K_I values were found to be 144.10 ± 2.01 and 1,654.00 ± 26.29 μM for brimonidine and proparacaine, respectively, for GR. Herein, also in silico molecular docking studies were performed between drugs and enzymes.

Association of information, education, and communication with enrolment in health insurance: a case of Nepal

BACKGROUND

Many studies indicate that various health programmes have been failed because of the lack of appropriate information, education, and communication [IEC] for the target audiences. It is still unanswered which methods/means of communication could be the most powerful for changing behaviour or decision-making capacity. The paper aims to assess the effects of IEC on family enrolment in health insurance programme [HIP] in Nepal.

METHODS

We employed a household-based observational study with a control group. Altogether 810 household interviews were conducted in Baglung and Kailali districts of Nepal in 2018. The study used a validated structured interview schedule. Background characteristics of the family and respondents and their exposure to the means of communication were the independent variables while enrolment in health insurance [HI] was the dependent variable.

RESULTS

Data showed that 72% of the respondents heard about the HI and 66% knew the contribution amount for enrolment in HI. In the total enrolled households, 53% were household heads, 59% belonged to the age group 41-60 and 68% were above 60 years. More than half (56%) of rich compared to 46 and 49% of middle and poor (p < 0.05); 60% of the family member suffering from the chronic disease were enrolled in the HI. Similarly, 68% of those who heard about HI compared to 4 % who did not hear were enrolled (p < 0.001). A vast majority (69%) of those knowing contribution amount, 73% who interact with peer neighbour compared to 39% who did not, and 62% of those who listened to the radio and 63% of those who watched TV were enrolled in HI (p < 0.001). However, heard about HI (aOR = 21.18, 95%CI: 10.17-44.13, p < 0.001), knowledge about contribution amount (aOR = 5.13, 95%CI: 3.09-8.52, p < 0.001), having HI related books or guidelines (aOR = 4.84, 95%CI: 2.61-8.98, p < 0.001), and interact with peer or neighbours (aOR = 1.74, 95%CI: 1.34-2.65, p < 0.01) were appeared to be positive and significant predictors for enrolment in HI.

CONCLUSION

Knowledge about HI and interaction with peers and neighbours about the HI scheme of the government could lead to higher participation in the HIP. It would be better to incorporate this strategy while planning interventions for increasing enrolment in the HIP.

Genetic diversity and complexity of Plasmodium falciparum infections in the microenvironment among siblings of the same household in North-Central Nigeria

Background

Plasmodium falciparum parasites are known to exhibit extensive genetic diversity in areas of high transmission intensity and infected individuals in such communities often harbour several complex mixtures of parasite clones with different genetic characteristics. However, in the micro-environment, the extent of genetic diversity of P. falciparum parasites remain largely unknown. In this study therefore, the complexity of P. falciparum infections in households was investigated among symptomatic siblings, living under the same roof in north-central Nigeria.

Methods

Children were enrolled into the study if they were at least two from a household and presented with symptoms of uncomplicated malaria. Clinical malaria was confirmed by light microscopy of Giemsa-stained thick and thin blood films. Genomic DNA was isolated from blood spots on filter paper. Molecular characterization of P. falciparum isolates was done by allele-specific nested PCR of the highly polymorphic merozoite surface protein-2 (msp-2) gene.

Results

Ninety-three children from 43 households were enrolled into this study. A total of 26 different msp-2 alleles were identified from 215 fragments (range: 180–480 bp). Majority of the isolates [65.6% (n = 61)] were polyclonal infections consisting of 2–6 clones and were significantly more common with the FC27 allelic family (p = 0.036). The multiplicity of infection (MOI) per household ranged from 1.0 to 4.5 while the overall MOI in the study population was 2.31. The pattern of distribution of msp-2 allele types among the households fell into two categories: households where both msp-2 allele types (FC27 and 3D7) were present; households where only one msp-2 allele type (FC27 or 3D7) was present. Majority of the households [88.4% (n = 38)], had both msp-2 allele types but they were disproportionately distributed among the children while in a few households [11.6% (n = 5)], all the children were infected with only one type of msp-2 allele.

Conclusion

These findings showed that P. falciparum isolates exhibit remarkable degree of genetic diversity in the micro-environment and are composed mainly of multiclonal infections, which is an indication of a high ongoing parasite transmission. This suggests that the micro-environment is an important area of focus for malaria control interventions and for evaluating intervention programmes.

Fine scale spatial investigation of multiple insecticide resistance and underlying target-site and metabolic mechanisms in Anopheles gambiae in central Côte d'Ivoire

Routine monitoring of occurrence, levels and mechanisms of insecticide resistance informs effective management strategies, and should be used to assess the effect of new tools on resistance. As part of a cluster randomised controlled trial evaluating a novel insecticide-based intervention in central Côte d’Ivoire, we assessed resistance and its underlying mechanisms in Anopheles gambiae populations from a subset of trial villages. Resistance to multiple insecticides in An. gambiae s.s. and An. coluzzii was detected across villages, with dose–response assays demonstrating extremely high resistance intensity to the pyrethroid deltamethrin (> 1,500-fold), and mortality following exposure to pyrethroid-treated bednets was low (< 30% mortality in cone bioassays). The 1014F kdr mutation was almost fixed (≥ 90%) in all villages but the 1575Y kdr-amplifying mutation was relatively rare (< 15%). The carbamate and organophosphate resistance-associated Ace-1 G119S mutation was also detected at moderate frequencies (22–43%). Transcriptome analysis identified overexpression of P450 genes known to confer pyrethroid resistance (Cyp9K1, Cyp6P3, and Cyp6M2), and also a carboxylesterase (COEAE1F) as major candidates. Cyp6P3 expression was high but variable (up to 33-fold) and correlated positively with deltamethrin resistance intensity across villages (r² = 0.78, P = 0.02). Tools and strategies to mitigate the extreme and multiple resistance provided by these mechanisms are required in this area to avoid future control failures.

Geographic and host distribution of haemosporidian parasite lineages from birds of the family Turdidae

Background

Haemosporidians (Apicomplexa, Protista) are obligate heteroxenous parasites of vertebrates and blood-sucking dipteran insects. Avian haemosporidians comprise more than 250 species traditionally classified into four genera, Plasmodium, Haemoproteus, Leucocytozoon, and Fallisia. However, analyses of the mitochondrial CytB gene revealed a vast variety of lineages not yet linked to morphospecies. This study aimed to analyse and discuss the data of haemosporidian lineages isolated from birds of the family Turdidae, to visualise host and geographic distribution using DNA haplotype networks and to suggest directions for taxonomy research on parasite species.

Methods

Haemosporidian CytB sequence data from 350 thrushes were analysed for the present study and complemented with CytB data of avian haemosporidians gathered from Genbank and MalAvi database. Maximum Likelihood trees were calculated to identify clades featuring lineages isolated from Turdidae species. For each clade, DNA haplotype networks were calculated and provided with information on host and geographic distribution.

Results

In species of the Turdidae, this study identified 82 Plasmodium, 37 Haemoproteus, and 119 Leucocytozoon lineages, 68, 28, and 112 of which are mainly found in this host group. Most of these lineages cluster in the clades, which are shown as DNA haplotype networks. The lineages of the Leucocytozoon clades were almost exclusively isolated from thrushes and usually were restricted to one host genus, whereas the Plasmodium and Haemoproteus networks featured multiple lineages also recovered from other passeriform and non-passeriform birds.

Conclusion

This study represents the first attempt to summarise information on the haemosporidian parasite lineages of a whole bird family. The analyses allowed the identification of numerous groups of related lineages, which have not been linked to morphologically defined species yet, and they revealed several cases in which CytB lineages were probably assigned to the wrong morphospecies. These taxonomic issues are addressed by comparing distributional patterns of the CytB lineages with data from the original species descriptions and further literature. The authors also discuss the availability of sequence data and emphasise that MalAvi database should be considered an extremely valuable addition to GenBank, but not a replacement.

Genetic diversity of Plasmodium falciparum in Grande Comore Island

Background

Despite several control interventions resulting in a considerable decrease in malaria prevalence in the Union of the Comoros, the disease remains a public health problem with high transmission in Grande Comore compared to neighbouring islands. In this country, only a few studies investigating the genetic diversity of Plasmodium falciparum have been performed so far. For this reason, this study aims to examine the genetic diversity of P. falciparum by studying samples collected in Grande Comore in 2012 and 2013, using merozoite surface protein 1 (msp1), merozoite surface protein 2 (msp2) and single nucleotide polymorphism (SNP) genetic markers.

Methods

A total of 162 positive rapid diagnostic test (RDT) samples from Grande Comore were used to extract parasite DNA. Allelic families K1, Mad20 and RO33 of the msp1 gene as well as allelic families IC3D7 and FC37 of the msp2 gene were determined by using nested PCR. Additionally, 50 out of 151 samples were genotyped to study 24 SNPs by using high resolution melting (HRM).

Results

Two allelic families were predominant, the K1 family of msp1 gene (55%) and the FC27 family of msp2 gene (47.4%). Among 50 samples genotyped for 24 SNPs, 42 (84%) yielded interpretable results. Out of these isolates, 36 (85%) were genetically unique and 6 (15%) grouped into two clusters. The genetic diversity of P. falciparum calculated from msp1 and msp2 genes and SNPs was 0.82 and 0.61, respectively.

Conclusion

In summary, a large genetic diversity of P. falciparum was observed in Grande Comore. This may favour persistence of malaria and might be one of the reasons for the high malaria transmission compared to neighbouring islands. Further surveillance of P. falciparum isolates, mainly through environmental management and vector control, is warranted until complete elimination is attained.

Analysis of sulphadoxine-pyrimethamine resistance-associated mutations in Plasmodium falciparum isolates obtained from asymptomatic pregnant women in Ogun State, Southwest Nigeria

Intermittent preventive treatment in pregnancy with sulphadoxine-pyrimethamine (IPTp-SP) is one of the main strategies for protecting pregnant women, fetus, and their new-born against adverse effects of P. falciparum infection. The development of the drug resistance linked to mutations in P. falciparum dihydrofolate reductase gene (pfdhfr) and P. falciparum dihydropteroate synthase gene (pfdhps), is currently threatening the IPTp-SP approach. This study determined the prevalence of pfdhfr and pfdhps mutations in isolates obtained from pregnant women with asymptomatic P. falciparum infection in Nigerian. Additionally, P. falciparum genetic diversity and multiplicity of infection (MOI) was assessed by genotyping the P. falciparum merozoite surface Protein 1 and 2 (pfmsp-1 and pfmsp-2) genes. The pfdhfr and pfdhps were genotyped by direct sequencing, and the pfmsp-1 and pfmsp-2 fragment analysis by polymerase chain reaction was used to determine P. falciparum genetic diversity. Of the 406 pregnant women recruited, 123 had P. falciparum infection by PCR, and of these, 52 were successfully genotyped for pfdhfr and 42 for pfdhps genes. The pfdhfr triple-mutant parasites (N51I, C59R, and S108N) or the IRN haplotype were predominant (98%), whereas pfdhfr mutations C50R and I164L did not occur. For pfdhps gene, the prevalence of A437G, A581G, A436A, and A613S mutations were 98, 71, 55, and 36%, respectively. Nineteen (44%) isolates with quintuple mutations (CIRNI- SGKGA) had the highest combined pfdhfr-pfdhps haplotype. Isolates with sextuple mutants; CIRNI- AGKAS and CIRNI- AGKGA had a prevalence of 29 and 14%, respectively. High genetic diversity (7 pfmsp-1 alleles and 10 pfmsp-2 alleles) and monoclonal infection rate (76%) was observed. This study demonstrated a continuous high prevalence of pfdhfr mutation and an increase in pfdhps mutations associated with SP-resistance in southwest Nigeria. Continuous surveillance of IPTp-SP effectiveness and consideration of alternative IPTp strategies is recommended.

The Anopheles coluzzii microbiome and its interaction with the intracellular parasite Wolbachia

Wolbachia, an endosymbiotic alpha-proteobacterium commonly found in insects, can inhibit the transmission of human pathogens by mosquitoes. Biocontrol programs are underway using Aedes aegypti mosquitoes trans-infected with a non-natural Wolbachia strain to reduce dengue virus transmission. Less is known about the impact of Wolbachia on the biology and vectorial capacity of Anopheles mosquitoes, the vectors of malaria parasites. A naturally occurring strain of Wolbachia, wAnga, infects populations of the major malaria vectors Anopheles gambiae and Anopheles coluzzii in Burkina Faso. Previous studies found wAnga infection was negatively correlated with Plasmodium infection in the mosquito and wAnga influenced mosquito egg-laying behavior. Here, we investigate wAnga in natural populations of An. coluzzii and its interactions with other resident microbiota using targeted 16S sequencing. Though we find no major differences in microbiota composition associated with wAnga infection, we do find several taxa that correlate with the presence or absence of wAnga in female mosquitoes following oviposition, with the caveat that we could not rule out batch effects due to the unanticipated impact of wAnga on oviposition timing. These data suggest wAnga may influence or interact with the Anopheles microbiota, which may contribute to the impact of wAnga on Anopheles biology and vectorial capacity.

Parasite clearance, cure rate, post-treatment prophylaxis and safety of standard 3-day versus an extended 6-day treatment of artemether-lumefantrine and a single low-dose primaquine for uncomplicated Plasmodium falciparum malaria in Bagamoyo district, Tanzania: a randomized controlled trial

Background

Artemisinin-based combination therapy (ACT) resistant Plasmodium falciparum represents an increasing threat to Africa. Extended ACT regimens from standard 3 to 6 days may represent a means to prevent its development and potential spread in Africa.

Methods

Standard 3-day treatment with artemether–lumefantrine (control) was compared to extended 6-day treatment and single low-dose primaquine (intervention); in a randomized controlled, parallel group, superiority clinical trial of patients aged 1–65 years with microscopy confirmed uncomplicated P. falciparum malaria, enrolled in Bagamoyo district, Tanzania. The study evaluated parasite clearance, including proportion of PCR detectable P. falciparum on days 5 and 7 (primary endpoint), cure rate, post-treatment prophylaxis, safety and tolerability. Clinical, and laboratory assessments, including ECG were conducted during 42 days of follow-up. Blood samples were collected for parasite detection (by microscopy and PCR), molecular genotyping and pharmacokinetic analyses. Kaplan–Meier survival analyses were done for both parasite clearance and recurrence.

Results

A total of 280 patients were enrolled, 141 and 139 in the control and intervention arm, respectively, of whom 121 completed 42 days follow-up in each arm. There was no difference in proportion of PCR positivity across the arms at day 5 (80/130 (61.5%) vs 89/134 (66.4%), p = 0.44), or day 7 (71/129 (55.0%) vs 70/134 (52.2%), p = 0.71). Day 42 microscopy determined cure rates (PCR adjusted) were 97.4% (100/103) and 98.3% (110/112), p = 0.65, in the control and intervention arm, respectively. Microscopy determined crude recurrent parasitaemia during follow-up was 21/121 (17.4%) in the control and 14/121 (11.6%) in the intervention arm, p = 0.20, and it took 34 days and 42 days in the respective arms for 90% of the patients to remain without recurrent parasitaemia. Lumefantrine exposure was significantly higher in intervention arm from D3 to D42, but cardiac, biochemical and haematological safety was high and similar in both arms.

Conclusion

Extended 6-day artemether–lumefantrine treatment and a single low-dose of primaquine was not superior to standard 3-day treatment for ACT sensitive P. falciparum infections but, importantly, equally efficacious and safe. Thus, extended artemether–lumefantrine treatment may be considered as a future treatment regimen for ACT resistant P. falciparum, to prolong the therapeutic lifespan of ACT in Africa.

Trial registration ClinicalTrials.gov, NCT03241901. Registered July 27, 2017 https://clinicaltrials.gov/show/NCT03241901

Penguins are competent hosts of Haemoproteus parasites: the first detection of gametocytes, with molecular characterization of Haemoproteus larae

Background

The majority of penguins (Sphenisciformes) have evolved in areas with weak or absent transmission of haemosporidian parasites and are usually naïve to avian haemosporidian infections. Plasmodium parasites are transmitted by mosquitoes, and lethal avian malaria has been often reported in captive penguins in many countries. The related haemosporidian parasites belonging to Haemoproteus and Leucocytozoon have also been detected in penguins but less often than Plasmodium infections. The majority of Haemoproteus infection reports in penguins are based solely on PCR-based diagnostics. It remains unclear if haemoproteids can complete their life-cycle and produce infective stages (gametocytes) in penguins or whether these infections are abortive in penguins, and thus dead ends for transmission. In other words, it remains unknown if penguins are competent hosts for Haemoproteus parasites, which cause disease in non-adapted birds.

Methods

Two captive African penguins (Spheniscus demersus) and two Magellanic penguins (S. magellanicus) were found to be positive for Haemoproteus infection in two open-air aquariums in Japan, and the parasites were investigated using both PCR-based testing and microscopical examination of blood films. Samples from a black-tailed gull (Larus crassirostris) and previously tested gulls were used for comparison.

Results

The lineage hSPMAG12 was detected, and gametocytes of Haemoproteus sp. were seen in the examined penguins and gull. Observed gametocytes were indistinguishable from those of Haemoproteus larae, which naturally parasitize birds of the genus Larus (Laridae). The detected sequence information and Bayesian phylogenetic analysis supported this conclusion. Additionally, morphologically similar gametocytes and closely related DNA sequences were also found in other gull species in Japan. Phylogenetic analysis based on partial cytb sequences placed the lineage hSPMAG12 of H. larae within the clade of avian haemoproteids which belong to the subgenus Parahaemoproteus, indicating that Culicoides biting midges likely transmit the parasites between penguins and gulls.

Conclusions

This study shows that some species of Haemoproteus parasites complete their development and produce gametocytes in penguins, which may be source of infection for biting midges transmitting haemoproteosis. To prevent haemosporidiosis in zoos, we call for control not only of mosquitoes, but also biting midges.