High Malaria Transmission Setting Research Articles

Access to quality-assured artemisinin-based combination therapy and associated factors among clients of selected private drug outlets in Uganda

BackgroundMalaria treatment in sub-Saharan Africa is faced with challenges including unreliable supply of efficacious agents, substandard medicines coupled with high price of artemisinin-based combinations. This affects access to effective treatment increasing risk of malaria parasite resistance development and adverse drug events. This study investigated access to quality-assured artemisinin-based combination therapy (QAACT) medicines among clients of selected private drug-outlets in Uganda.MethodsThis was a cross sectional study where exit interviews were conducted among clients of private drug outlets in low and high malaria transmission settings in Uganda. This study adapted the World Health Organization/Health Action International (WHO/HAI) standardized criteria. Data was collected using a validated questionnaire. Data entry screen with checks was created in Epi-data ver 4.2 software and data entered in duplicate. Data was transferred to STATA ver 14.0 and cleaned prior to analysis. The analysis was done at 95% level of significance.ResultsA total of 1114 exit interviews were conducted among systematically sampled drug outlet clients. Over half, 54.9% (611/1114) of the participants were males. Majority, 97.2% (1083/1114) purchased an artemisinin-based combination anti-malarial. Most, 55.5% (618/1114) of the participants had a laboratory diagnosis of malaria. Majority, 77.9% (868/1114) of the participants obtained anti-malarial agents without a prescription. Less than a third, 27.7% (309/1114) of the participants obtained a QAACT. Of the participants who obtained QAACT, more than half 56.9% (173/309) reported finding the medicine expensive. The predictors of accessing a QAACT anti-malarial among drug outlet clients include type of drug outlet visited (aPR = 0.74; 95%CI 0.6, 0.91), not obtaining full dose (3-day treatment) of ACT (aPR = 0.49; 95%CI 0.33, 0.73), not finding the ACT expensive (aPR = 1.24; 95%CI 1.03, 1.49), post-primary education (aPR = 1.29; 95%CI 1.07,1.56), business occupation (aPR = 1.24; 95%CI 1.02,1.50) and not having a prescription (aPR = 0.76; 95%CI 0.63, 0.92).ConclusionLess than a third of the private drug outlet clients obtained a QAACT for management of malaria symptoms. Individuals who did not find artemisinin-based combinations to be expensive were more likely to obtain a QAACT anti-malarial. The Ministry of Health needs to conduct regular surveillance to monitor accessibility of QAACT anti-malarial agents under the current private sector copayment mechanism.

Copayment mechanism in selected districts of Uganda: Availability, market share and price of quality assured artemisinin-based combination therapies in private drug outlets.

Malaria remains one of the leading causes of morbidity, and mortality in Uganda. A large proportion of malaria symptomatic patients seek healthcare in private sector. However, availability and affordability are major barriers to access to effective treatment. The private sector copayment mechanism in Uganda aims to increase availability and affordability of antimalarial agents. Our study assessed availability, price, and market share of quality assured artemisinin-based combination therapies (QAACTs) in private drug outlets in selected districts during the implementation of copayment mechanism. This was a cross-sectional survey of anti-malarial agents in private drug outlets in in selected moderate-to-high (Tororo, and Apac districts) and low (Kabale and Mbarara districts) malaria transmission settings. Following the World Health Organization/Health Action International (WHO/HAI) criteria, an audit of the antimalarial agents was done using a checklist to determine availability, price, and market share of QAACTs. Data were entered in Epi-data and analyzed in STATA ver 14.0 at 95% confidence level. A total of twenty-eight (28) private drug outlets (pharmacies and drug shops) were included in the survey. One in seven (20/144: 95%CI: 9.1, 20.6) of the antimalarial agents in private drug outlets were quality assured artemisinin-based combination therapies (QAACT). Artemether-lumefantrine (AL), 8.9% (11/124) and Artesunate-Amodiaquine (AQ), 7.3% (9/124) were the only QAACTs present in the drug outlets at the time of the survey. The majority, 86.1%% (124/144) of antimalarial agents present in stock in the drug outlets were artemisinin based. The most common, 38.9% (56/144) ACT in the drug outlets was Dihydroartemisinin-Piperaquine (DHP). Most, 69.4% (100/144) of the antimalarial agents were in high malaria transmission settings. The cost of ACT antimalarial agents is high in the country, USD 1.4 (Artemether-Lumefantrine, AL), USD 2.4 (Dihydroartemisinin-Piperaquine, DP), the first line and second-line agents respectively for treatment of uncomplicated malaria in Uganda. There was a statistically significant difference between the dispensing price of 'Green leaf' ACTs (QAACT) and the recommended price (p<0.001). Predictors of availability of QAACT in private drug outlets include pharmacy drug outlet (aPR:0.4; 95%CI: 0.2, 0.9) and dispensing price more than 3000UGX (USD 0.83) (aPR: 0.4, 95%CI: 0.1, 0.51). Quality assured artemisinin-based combination therapies (QAACTs) are not common in private drug outlets in selected districts in Uganda. All the drug outlets had at least one ACT antimalarial agent present on the day of the survey. The dispensing price of QAACTs was significantly higher than the recommended markup price. There is need for awareness creation, surveillance, and monitoring of the implementation of Copayment mechanism in the country.

Strong positive selection biases identity-by-descent-based inferences of recent demography and population structure in Plasmodium falciparum

Malaria genomic surveillance often estimates parasite genetic relatedness using metrics such as Identity-By-Decent (IBD), yet strong positive selection stemming from antimalarial drug resistance or other interventions may bias IBD-based estimates. In this study, we use simulations, a true IBD inference algorithm, and empirical data sets from different malaria transmission settings to investigate the extent of this bias and explore potential correction strategies. We analyze whole genome sequence data generated from 640 new and 3089 publicly available Plasmodium falciparum clinical isolates. We demonstrate that positive selection distorts IBD distributions, leading to underestimated effective population size and blurred population structure. Additionally, we discover that the removal of IBD peak regions partially restores the accuracy of IBD-based inferences, with this effect contingent on the population’s background genetic relatedness and extent of inbreeding. Consequently, we advocate for selection correction for parasite populations undergoing strong, recent positive selection, particularly in high malaria transmission settings.

Prevalence and determinants of anaemia among pregnant women in a high malaria transmission setting: a cross-sectional study in rural Burkina Faso.

anemia, the commonest nutritional deficiency disorder among pregnant women in sub-Saharan Africa, is associated with severe peripartum complications. Its regular monitoring is necessary to timely inform clinical and preventive decision-making. The aim of this study was to assess the prevalence and determinants of anemia among pregnant women in rural areas of Burkina Faso. between August 2019 and March 2020, a cross-sectional study was conducted to collect maternal sociodemographic, gynaeco-obstetric, and medical characteristics by face-to-face interview or by review of antenatal care books. In addition, maternal malaria was diagnosed by standard microscopy and the hemoglobin levels (Hb) measured by spectrophotometry. The proportion of anaemia (Hb<11.0 g/dL), moderate (7.0<Hb<9.9 g/dL) and severe (Hb<7.0 g/dL) anaemia were determined. The maternal factors associated with anaemia were identified using regression models with likelihood ratio tests. A p-value < 0.05 was considered statistically significant. of 594 pregnant women assessed, the mean hemoglobin level (± standard deviation) was 10.7 (±0.1) g/dL, and the prevalence of anemia was 54.4% (323/594). The proportion of moderate, and severe anemia among pregnant women was 49.2% (95% CI: 45.1%-53.2%), and 5.2% (95% CI: 3.7%-7.3%) respectively. Multivariate analysis showed that the young maternal age (<20 years old) (adjusted OR (aOR): 1.5, 95% CI: 1.1-2.3) and the presence of malaria (aOR: 2.0, 95% CI: 1.3-3.2) were independently associated with the presence of maternal anemia. anemia remains common in the study setting and interventions to strengthen malaria prevention in pregnancy, particularly among young adolescent pregnant women, are required to prevent maternal anemia.

Experiences of healthcare personnel on the efficacy of artemisinin-based combination therapy and malaria diagnosis in hospitals in Uganda

BackgroundThe risk of widespread resistance to artemisinin-based combination therapy (ACT) remains high in Uganda following detection of Plasmodium falciparum parasites with delayed artemisinin clearance genotype and phenotype. Establishment of context specific interventions to mitigate emergence and spread of artemisinin resistance is thus key in the fight against malaria in the country. The aim of this study was to explore the experiences of healthcare personnel on malaria diagnosis and self-reported efficacy of ACT in the management of malaria symptomatic patients in hospitals in low and high malaria transmission settings in Uganda.MethodsThis was a qualitative study in which data was collected from healthcare personnel in hospitals using key informant interviews. The key informant interview guide was developed, pre-tested prior to use and covered the following areas, (i) sociodemographic characteristics, (ii) malaria diagnosis (clinical and parasite based), (iii) quality-assured artemisinin-based combination therapy, (iv) malaria patient follow-up, (v) artemisinin resistance, (vi) anti-malarial self-medication. Data was entered in Atlas.ti ver 9.0 and analysis done following a framework criterion.ResultsA total of 22 respondents were interviewed of which 16 (72.7%) were clinicians. Majority, 81.8% (18/22) of the respondents were male. The following themes were developed from the analysis, malaria diagnosis (procedures and challenges), use of malaria laboratory test results, malaria treatment in hospitals, use of quality assured ACT (QAACT) in malaria treatment, and efficacy of ACT in malaria treatment.ConclusionMost healthcare personnel-initiated malaria treatment after a positive laboratory test. Cases of malaria patients who report remaining symptomatic after prior use of ACT exist especially in high malaria transmission settings in Uganda. There is need for regular monitoring of artemisinin resistance emergence and spread in the country.

Background malaria incidence and parasitemia during the three-dose RTS,S/AS01 vaccination series do not reduce magnitude of antibody response nor efficacy against the first case of malaria

BackgroundRTS,S/AS01 has been recommended by WHO for widespread implementation in medium to high malaria transmission settings. Previous analyses have noted lower vaccine efficacies in higher transmission settings, possibly due to the more rapid development of naturally acquired immunity in the control group.MethodsTo investigate a reduced immune response to vaccination as a potential mechanism behind lower efficacy in high transmission areas, we examine initial vaccine antibody (anti-CSP IgG) response and vaccine efficacy against the first case of malaria (to exclude the effect of naturally acquired immunity) using data from three study areas (Kintampo, Ghana; Lilongwe, Malawi; Lambaréné, Gabon) from the 2009–2014 phase III trial (NCT00866619). Our key exposures are parasitemia during the vaccination series and background malaria incidence. We calculate vaccine efficacy (one minus hazard ratio) using a cox-proportional hazards model and allowing for the time-varying effect of RTS,S/AS01.ResultsWe find that antibody responses to the primary three-dose vaccination series were higher in Ghana than in Malawi and Gabon, but that neither antibody levels nor vaccine efficacy against the first case of malaria varied by background incidence or parasitemia during the primary vaccination series.ConclusionsWe find that vaccine efficacy is unrelated to infections during vaccination. Contributing to a conflicting literature, our results suggest that vaccine efficacy is also unrelated to infections before vaccination, meaning that control-group immunity is likely a major reason for lower efficacy in high transmission settings, not reduced immune responses to RTS,S/AS01. This may be reassuring for implementation in high transmission settings, though further studies are needed.

The Impact of Household and Community Indoor Residual Spray Coverage with Fludora Fusion in a High Malaria Transmission Setting in Northern Zambia.

Zambia's National Malaria Elimination Program transitioned to Fludora Fusion in 2019 for annual indoor residual spraying (IRS) in Nchelenge District, an area with holoendemic malaria transmission. Previously, IRS was associated with reductions in parasite prevalence during the rainy season only, presumably because of insufficient residual insecticide longevity. This study assessed the impact of transitioning from Actellic 300CS to long-acting Fludora Fusion using active surveillance data from 2014 through 2021. A difference-in-differences analysis estimated changes in rainy season parasite prevalence associated with living in a sprayed house, comparing insecticides. The change in the 2020 to 2021 dry season parasite prevalence associated with living in a house sprayed with Fludora Fusion was also estimated. Indoor residual spraying with Fludora Fusion was not associated with decreased rainy season parasite prevalence compared with IRS with Actellic 300CS (ratio of prevalence ratios [PRs], 1.09; 95% CI, 0.89-1.33). Moreover, living in a house sprayed with either insecticide was not associated with decreased malaria risk (Actellic 300CS: PR, 0.97; 95% CI, 0.86-1.10; Fludora Fusion: rainy season PR, 1.06; 95% CI, 0.89-1.25; dry season PR, 1.21; 95% CI, 0.99-1.48). In contrast, each 10% increase in community IRS coverage was associated with a 4% to 5% reduction in parasite prevalence (rainy season: PR, 0.95; 95% CI, 0.92-0.97; dry season: PR, 0.96; 95% CI, 0.94-0.99), suggesting a community-level protective effect, and corroborating the importance of high-intervention coverage.

Pharmacopeial quality of artemether–lumefantrine anti-malarial agents in Uganda

BackgroundSubstandard anti-malarial agents pose a significant challenge to effective malaria control and elimination efforts especially in sub-Saharan Africa. The quality of anti-malarials in most low-and-middle income countries (LMICs) is affected by several factors including inadequate regulation and limited resources. In this study, the pharmacopeial quality of artemether–lumefantrine (AL) in low and high malaria transmission settings in Uganda was assessed.MethodsThis was a cross-sectional study conducted among randomly selected private drug outlets. The AL anti-malarials available in drug outlets were purchased using overt method. The samples were screened for quality using visual inspection, weight uniformity, content assay and dissolution tests. The assay test was done using liquid chromatography–mass spectrometry (LC–MS). The samples were considered substandard if the active pharmaceutical ingredient (API) content was outside 90–110% range of the label claim. Dissolution test was conducted following United States Pharmacopoeia (USP) method. Data was analysed using descriptive statistics and presented as means with standard deviations, frequencies, and proportions. Correlation between medicine quality and independent variables was determined using Fisher’s exact test of independence at 95% level of significance.ResultsA total of 74 AL anti-malarial samples were purchased from high (49/74; 66.2%) and low (25/74; 33.8%) malaria transmission settings. The most common batch of AL was LONART, 32.4% (24/74), with 33.8% (25/74) being ‘Green leaf’. Overall prevalence of substandard quality artemether–lumefantrine was 18.9% (14/74; 95% CI: 11.4–29.7). Substandard quality AL was significantly associated with setting (p = 0.002). A total of 10 samples (13.5%) failed artemether content assay test while, 4 samples (5.4%, 4/74) failed the lumefantrine assay test. One sample from a high malaria transmission setting failed both artemether and lumefantrine assay content test. Of the samples that failed artemether assay test, 90% had low (< 90%) artemether content. All the samples passed visual inspection and dissolution tests.ConclusionArtemether–lumefantrine agents, the recommended first-line treatment for uncomplicated malaria with APIs outside the recommended pharmacopeial content assay limit is common especially in high malaria transmission settings. There is need for continuous surveillance and monitoring of the quality of artemisinin-based anti-malarials across the country by the drug regulatory agency.

Performance of PfHRP2-RDT for malaria diagnosis during the first year of life in a high malaria transmission area in Burkina Faso.

In this study, we evaluated the performance of a P. falciparum Histidine Rich Protein 2 (PfHRP2)-based rapid diagnostic test (RDT) used for malaria case detection (SD-Bioline malaria RDT P.f®) along with light microscopy (LM) against qPCR among children during the first year of life in a high and seasonal malaria transmission area in Burkina Faso. A total of 723 suspected malaria cases (including multiple episodes) that occurred among 414 children participating in a birth-cohort study were included in the present analysis. Factors including age at the time of malaria screening, transmission season and parasite densities were investigated for their potential influence in the performance of the RDT. Clinical malaria cases as detected by RDT, LM and qPCR were 63.8%, 41.5% and 49.8%, respectively. Compared with qPCR, RDT had a false-positive results rate of 26.7%, resulting in an overall accuracy of 79.9% with a sensitivity of 93%, a specificity of 66.1%, a Positive Predictive Value of 73.3% and a Negative Predictive Value of 91.6%. Its specificity differed significantly between high and low transmission seasons (53.7% vs 79.8%; P < 0.001) and decreased with increasing age (80.6-62%; P for trend = 0.024). The overall accuracy of LM was 91.1% and its performance was not significantly influenced by transmission season or age. These findings highlight the need to adapt malaria diagnostic tools recommendations to face the challenge of adequate malaria detection in this population group living in high burden and seasonal malaria transmission settings.

Prevalence and factors associated with anaemia in children aged 6-24 months living a high malaria transmission setting in Burundi.

In very young children, anaemia has been linked to increased morbidity, mortality and poor cognitive development. Although Burundi has a high burden of anaemia, which may be worsened by the high burden of malaria, little is known about the extent of the problem in very young children who are most at risk of severe disease. We estimated the prevalence, and assessed the factors associated with anaemia in children aged 6-24 months using baseline data collected as part of an on-going study evaluating the effect of Micronutrient supplementation on anaemia and cognition among children in high malaria transmission settings in Burundi. Between February and March 2020, surveys were conducted in 498 households within the catchment area of Mukenke Health Center. One child aged 6-24 months was selected per household to participate in the survey. Following written informed consent, we administered a questionnaire to the child's primary caregiver to capture information on child's demographics, nutritional status, food intake, health (status, and morbidity and treatment-seeking practices), as well as the household markers of wealth. A physical exam was conducted, and a blood sample was collected to: 1) assess for presence of plasmodium infection using a rapid diagnosis test; 2) estimate the haemoglobin levels using a portable haemocue machine. A stool sample was also collected to examine for the presence of helminth infections. The prevalence of anaemia was 74.3% (95% confidence interval [CI] 61.5%-84.0%), with most of the anaemic study participants classified as having moderate anaemia (59.2%). A total of 62 (12.5%) participants had positive malaria rapid diagnosis tests. Factors significantly associated with higher odds of developing anaemia included not receiving deworming medication (adjusted Odd ratio [aOR] = 3.54, 95% CI 1.79-6.99, p<0.001), the child's home location (Mukenke II: aOR = 2.22, 95% CI 1.89-2.62, p<0.001; Mukenke: aOR = 2.76, 95% CI 2.46-3.10, p<0.001 and Budahunga: aOR = 3.12, 95% CI 2. 94-3.31, p<0.001) and the child's age group (Children aged 6-11 months: aOR = 2.27, 95% CI 1.32-3.91, p<0.001). Education level was inversely associated with less odds of anaemia: child's primary care giver with a secondary (aOR = 0.67; 95% CI: 0.47-0.95, p = 0,024) and tertiary education level (aOR = 0.48; 95% CI: 0.38-0.61, p<0.001). Anaemia is highly prevalent among young children in high malaria transmission setting. Anaemia is more prevalent among children who not dewormed and those with malaria. To prevent the long-term adverse outcomes of the anaemia in children, policy makers should focus on improving uptake of the deworming and malaria prevention programs, promote preventive interventions and improve the education of women especially in families with very young children.

Associations between environmental covariates and temporal changes in malaria incidence in high transmission settings of Uganda: a distributed lag nonlinear analysis

BackgroundEnvironmental factors such as temperature, rainfall, and vegetation cover play a critical role in malaria transmission. However, quantifying the relationships between environmental factors and measures of disease burden relevant for public health can be complex as effects are often non-linear and subject to temporal lags between when changes in environmental factors lead to changes in malaria incidence. The study investigated the effect of environmental covariates on malaria incidence in high transmission settings of Uganda.MethodsThis study leveraged data from seven malaria reference centres (MRCs) located in high transmission settings of Uganda over a 24-month period. Estimates of monthly malaria incidence (MI) were derived from MRCs’ catchment areas. Environmental data including monthly temperature, rainfall, and normalized difference vegetation index (NDVI) were obtained from remote sensing sources. A distributed lag nonlinear model was used to investigate the effect of environmental covariates on malaria incidence.ResultsOverall, the median (range) monthly temperature was 30 °C (26–47), rainfall 133.0 mm (3.0–247), NDVI 0.66 (0.24–0.80) and MI was 790 per 1000 person-years (73–3973). Temperature of 35 °C was significantly associated with malaria incidence compared to the median observed temperature (30 °C) at month lag 2 (IRR: 2.00, 95% CI: 1.42–2.83) and the increased cumulative IRR of malaria at month lags 1–4, with the highest cumulative IRR of 8.16 (95% CI: 3.41–20.26) at lag-month 4. Rainfall of 200 mm significantly increased IRR of malaria compared to the median observed rainfall (133 mm) at lag-month 0 (IRR: 1.24, 95% CI: 1.01–1.52) and the increased cumulative IRR of malaria at month lags 1–4, with the highest cumulative IRR of 1.99(95% CI: 1.22–2.27) at lag-month 4. Average NVDI of 0.72 significantly increased the cumulative IRR of malaria compared to the median observed NDVI (0.66) at month lags 2–4, with the highest cumulative IRR of 1.57(95% CI: 1.09–2.25) at lag-month 4.ConclusionsIn high-malaria transmission settings, high values of environmental covariates were associated with increased cumulative IRR of malaria, with IRR peaks at variable lag times. The complex associations identified are valuable for designing strategies for early warning, prevention, and control of seasonal malaria surges and epidemics.

Current malaria infection, previous malaria exposure, and clinical profiles and outcomes of COVID-19 in a setting of high malaria transmission: an exploratory cohort study in Uganda

BackgroundThe potential effects of SARS-CoV-2 and Plasmodium falciparum co-infection on host susceptibility and pathogenesis remain unknown. We aimed to establish the prevalence of malaria and describe the clinical characteristics of SARS-CoV-2 and P falciparum co-infection in a high-burden malaria setting.MethodsThis was an exploratory prospective, cohort study of patients with COVID-19 who were admitted to hospital in Uganda. Patients of all ages with a PCR-confirmed diagnosis of SARS-CoV-2 infection who had provided informed consent or assent were consecutively enrolled from treatment centres in eight hospitals across the country and followed up until discharge or death. Clinical assessments and blood sampling were done at admission for all patients. Malaria diagnosis in all patients was done by rapid diagnostic tests, microscopy, and molecular methods. Previous P falciparum exposure was determined with serological responses to a panel of P falciparum antigens assessed using a multiplex bead assay. Additional evaluations included complete blood count, markers of inflammation, and serum biochemistries. The main outcome was overall prevalence of malaria infection and malaria prevalence by age (including age categories of 0–20 years, 21–40 years, 41–60 years, and >60 years). The frequency of symptoms was compared between patients with COVID-19 with P falciparum infection versus those without P falciparum infection. The frequency of comorbidities and COVID-19 clinical severity and outcomes was compared between patients with low previous exposure to P falciparum versus those with high previous exposure to P falciparum. The effect of previous exposure to P falciparum on COVID-19 clinical severity and outcomes was also assessed among patients with and those without comorbidities.FindingsOf 600 people with PCR-confirmed SARS-CoV-2 infection enrolled from April 15, to Oct 30, 2020, 597 (>99%) had complete information and were included in our analyses. The majority (502 [84%] of 597) were male individuals with a median age of 36 years (IQR 28–47). Overall prevalence of P falciparum infection was 12% (95% CI 9·4–14·6; 70 of 597 participants), with highest prevalence in the age groups of 0–20 years (22%, 8·7–44·8; five of 23 patients) and older than 60 years (20%, 10·2–34·1; nine of 46 patients). Confusion (four [6%] of 70 patients vs eight [2%] of 527 patients; p=0·040) and vomiting (four [6%] of 70 patients vs five [1%] of 527 patients; p=0·014] were more frequent among patients with P falciparum infection than those without. Patients with low versus those with high previous P falciparum exposure had a increased frequency of severe or critical COVID-19 clinical presentation (16 [30%] of 53 patients vs three [5%] of 56 patients; p=0·0010) and a higher burden of comorbidities, including diabetes (12 [23%] of 53 patients vs two [4%] of 56 patients; p=0·0010) and heart disease (seven [13%] of 53 patients vs zero [0%] of 56 patients; p=0·0030). Among patients with no comorbidities, those with low previous P falciparum exposure still had a higher proportion of cases of severe or critical COVID-19 than did those with high P falciparum exposure (six [18%] of 33 patients vs one [2%] of 49 patients; p=0·015). Multivariate analysis showed higher odds of unfavourable outcomes in patients who were older than 60 years (adjusted OR 8·7, 95% CI 1·0–75·5; p=0·049).InterpretationAlthough patients with COVID-19 with P falciparum co-infection had a higher frequency of confusion and vomiting, co-infection did not seem deleterious. The association between low previous malaria exposure and severe or critical COVID-19 and other adverse outcomes will require further study. These preliminary descriptive observations highlight the importance of understanding the potential clinical and therapeutic implications of overlapping co-infections.FundingMalaria Consortium (USA).

Impact of Current Malaria Infection and Previous Malaria Exposure on the Clinical Profiles and Outcome of COVID-19 in a High Malaria Transmission Setting: A Prospective Cohort Study

Background: Our understanding of the potential impact of SARS-CoV-2 and malaria co-infection on host susceptibility and pathogenesis remains unclear. We determined the prevalence of malaria and describe the consequences of SARS-CoV-2 and malaria co-infection in a high burden malaria setting.Methods: This was a prospective cohort study of hospitalized Covid-19 patients in Uganda. Malaria diagnosis was done using rapid diagnostic tests, microcopy and molecular methods. Previous P. falciparum exposure was assessed using serologic responses to a panel of P. falciparum antigens using a multiplex bead assay. Additional evaluations included complete blood count, markers of inflammation and serum biochemistries.Findings: Of 597 PCR confirmed Covid-19 cases enrolled between 16th April and 30th October 2020, 500 (84.1%) were male and median age (1QR) was 36 (28-47) years. Overall prevalence of P. falciparum infection was 11.7% (70/597, 95% CI 9.4 to 14.6), with highest prevalence in the 0- 20 years (21.7%, 5/23, 95% CI 8.7-44.8) and > 60 years (19.6%, 9/46, 95% CI 10.2-34.1) age groups. Confusion [5.7% (4/70) vs. 1.5%, (8/527), p=0.04] and vomiting [5.7% (5/70) vs.1.0%, 5/527), p=0.007] were more frequent among patients with P. falciparum infection. Patients with low previous P. falciparum exposure had a higher frequency of severe/critical Covid-19 cases (30.2%, 16/53, p=0.001), a higher burden of comorbidities [hypertension (30.2%, 16/53, p=0.02) and diabetes (22.6%, 12/53, p=0.003)] and more deaths (3.8%, 2/53, p=0.01). Among patients with no comorbidities, those with low previous exposure still had a higher proportion of severe/critical Covid-19 cases (18.2%, 6/53 vs. 2.0%, 1/56, p=0.01) compared to those with high exposure.Interpretation: Prevalence of P. falciparum infection among Covid-19 patients was relatively high. Though Covid-19 patients with P. falciparum infection had a higher frequency of confusion and vomiting, co-infection with malaria did not seem deleterious. Low previous malaria exposure was associated with severe/critical Covid-19 and adverse outcomes.Funding: Funding: Grant from Malaria Consortium, USDeclaration of Interest: HA and FN are members of the Mulago Hospital Research and Ethics but did not participate in decisions pertaining this study. All other authors declare no competing interests.Ethical Approval: The study was approved by the Mulago National Referral Hospital Research and Ethics committee and the Uganda National Council for Science and Technology.

Prevalence and factors associated with carriage of Pfmdr1 polymorphisms among pregnant women receiving intermittent preventive treatment with sulfadoxine-pyrimethamine (IPTp-SP) and artemether-lumefantrine for malaria treatment in Burkina Faso

BackgroundSingle nucleotide polymorphisms occurring in the Plasmodium falciparum multidrug resistant gene 1 (pfmdr1) are known to be associated with aminoquinoline resistance and, therefore, represent key P. falciparum markers for monitoring resistance both in susceptible groups (children under 5 years old and pregnant women) and in the general population. This study aimed to determine prevalence and factors associated with the carriage of pfmdr1 N86Y, Y184F and D1246Y polymorphisms among pregnant women in a setting of high malaria transmission in Burkina Faso.MethodsPlasmodium falciparum isolates were collected at the first antenatal care visit (ANC-1) as well as at delivery from pregnant women participating in the COSMIC trial (NTC01941264), which assessed malaria preventive interventions during pregnancy in the Nanoro Health District. Here, pregnant women received intermittent preventive treatment with sulfadoxine-pyrimethamine (IPTp-SP) and malaria infections and/or diseases were treated using artemether-lumefantrine (AL) during the trial. Parasite DNA was extracted from dried blood spots and the presence of pfmdr1 mutations at positions 86, 184 and 1246 was determined using nested PCR, followed by restriction fragment length polymorphism (RFLP) analysis.ResultsA prevalence of 13.2% (20/151) and 12.1% (14/116) of the pfmdr1 86Y mutant allele was found at ANC-1 and at delivery, respectively, while no mutant allele was observed for Y184F and D1246Y codons at both ANC-1 and at delivery. There were no significant factors associated with pfmdr1 86Y mutant allele carriage at ANC-1. However, malaria infections at delivery with a parasite density above the median (2237.2 (IQR: 613.5–11,425.7) parasites/µl) was associated with an increase risk of pfmdr1 86Y mutant allele carriage (AOR = 5.5 (95% CI 1.07–28.0); P = 0.04). In contrast, both three or more IPTp-SP doses (AOR = 0.25 (95% CI 0.07–0.92); P = 0.04) and one or more AL treatment (AOR = 0.25 (95% CI 0.07–0.89); P = 0.03) during pregnancy were associated with a significant reduce risk of pfmdr1 86Y mutant allele carriage at delivery.ConclusionThese findings suggest that both high coverage of IPTp-SP and the use of AL for the treatment of malaria infection/disease during pregnancy select for pfmdr1 N86 wild-type allele at delivery.

English

The selection of resistance is inevitable whenever chemotherapy is necessary for pathogen control. Notably, Plasmodium falciparum has developed multifaceted means to overcome the toxicity of nearly all antimalarial medicines. To bypass this challenge, not only should novel drugs be developed, but the resistance mechanisms to new and existing drugs need should be fully explored. Pyronaridine is a companion drug in Pyramax®, a blend of artesunate (ASN)-pyronaridine (PRD) which is the WHO prequalified alternative for malaria treatment in the African setting. However, half-life mismatch predisposes the PRD to swift emergence of resistance especially in high malaria transmission settings. However, there are no well-characterized PRD-resistant parasite lines. Previously, stable PRD- resistant P. berghei ANKA lines were selected by in vivo drug pressure and preliminary results showed cross-resistance with quinolines, therefore, hypothetically the activity of PRD and chloroquine or other quinolines may be comparable, hence, the resistance mechanisms may be parallel. Consequently, genetic polymorphisms and expression profiles of PbMDR-1 that could be associated with pyronaridine resistance were examined by PCR amplification, sequencing and transcript quantification by RT-qPCR. The transcripts level increased during resistance selection while translated PbMDR-1 sequence alignment of PRD-sensitive and PRD-resistant was the same, the expression may be linked to PRD resistance but not mutations. Key words: Quinolines, malaria, Pyronaridine, Pyramax®, resistance, expression, MDR-1 gene.

Seroprevalence and Parasite Rates of Plasmodium malariae in a High Malaria Transmission Setting of Southern Nigeria.

.Although Plasmodium falciparum continues to be the main target for malaria elimination, other Plasmodium species persist in Africa. Their clinical diagnosis is uncommon, whereas rapid diagnostic tests (RDTs), the most widely used malaria diagnostic tools, are only able to distinguish between P. falciparum and non-falciparum species, the latter as “pan-species.” Blood samples from health facilities were collected in southern Nigeria (Lagos and Calabar) in 2017 (October–December) and Calabar only in 2018 (October–November), and analyzed by several methods, namely, microscopy, quantitative real-time PCR (qPCR), and peptide serology targeting candidate antigens (Plasmodium malariae apical membrane antigen, P. malariae lactose dehydrogenase, and P. malariae circumsporozoite surface protein). Both microscopy and qPCR diagnostic approaches detected comparable proportions (∼80%) of all RDT-positive samples infected with the dominant P. falciparum malaria parasite. However, higher proportions of non-falciparum species were detected by qPCR than microscopy, 10% against 3% infections for P. malariae and 3% against 0% for Plasmodium ovale, respectively. No Plasmodium vivax infection was detected. Infection rates for P. malariae varied between age-groups, with the highest rates in individuals aged > 5 years. Plasmodium malariae–specific seroprevalence rates fluctuated in those aged < 10 years but generally reached the peak around 20 years of age for all peptides. The heterogeneity and rates of these non-falciparum species call for increased specific diagnosis and targeting by elimination strategies.

Estimating the optimal interval between rounds of indoor residual spraying of insecticide using malaria incidence data from cohort studies.

Indoor residual spraying (IRS) reduces vector densities and malaria transmission, however, the most effective spraying intervals for IRS have not been well established. We estimated the optimal timing interval for IRS using a statistical approach. Six rounds of IRS were implemented in Tororo District, a historically high malaria transmission setting in Uganda, during the study period (3 rounds with bendiocarb active ingredient (Ficam®): December 2014 to December 2015, and 3 rounds with pirimiphos methyl active ingredient (Actellic 300®CS): June 2016 to July 2018). A generalized additive model was used to estimate the optimal timing interval for IRS based on the predicted malaria incidence. The model was fitted to clinical incidence data from a cohort of children aged 0.5-10 years from selected households observed throughout the study period. 494 children, 67% aged less than 5 years at enrolment were analysed. Six-months period incidence of malaria decreased from 2.96 per person-years at the baseline to 1.74 following the first round of IRS and then to 0.02 after 6 rounds of IRS. The optimal time interval for IRS differed between bendiocarb and pirimiphos methyl and by IRS round. To retain an optimum impact, bendiocarb would require respraying 17 (95% CI: 14.2-21.0) weeks after application whereas pirimiphos methyl could remain impactful for 40 (95% CI: 37.0-42.8) weeks, although in the final year this estimates 36 (95% CI: 32.7-37.7) weeks. However, we could not estimate from the data the optimal time after the second and third rounds of bendiocarb and after the second round of pirimiphos methyl. Neither the amount of rainfall nor the EIR nor the distribution of nets were found to be statistically significant for determining the time period between spray rounds. In our setting, the effect of the two IRS products was distinct. Statistically, pirimiphos methyl provided a longer window of protection than bendiocarb, although impact varied between different spray rounds and years which was not explained by rainfall or EIR or distribution of nets in our statistical approach. Understanding the effectiveness of IRS and how long it lasts can help for planning campaigns, but one should consider the financial cost and insecticide resistance. Monitoring the timing of spray campaigns using clinical incidence could be repeated in future programs to help determine the average period of protectivity of these products.

Antibodies to full-length and the DBL5 domain of VAR2CSA in pregnant women after long-term implementation of intermittent preventive treatment in Etoudi, Cameroon.

In high malaria transmission settings, the use of sulfadoxine-pyrimethamine-based intermittent preventive treatment during pregnancy (IPTp-SP) has resulted in decreased antibody (Ab) levels to VAR2CSA. However, information of Ab levels in areas of low or intermediate malaria transmission after long-term implementation of IPTp-SP is still lacking. The present study sought to evaluate antibody prevalence and levels in women at delivery in Etoudi, a peri-urban area in the capital of Yaoundé, Cameroon, that is a relatively low-malaria transmission area. Peripheral plasma samples from 130 pregnant women were collected at delivery and tested for IgG to the full-length recombinant VAR2CSA (FV2) and its most immunogenic subdomain, DBL5. The study was conducted between 2013 and 2015, approximately ten years after implementation of IPTp-SP in Cameroon. About 8.6% of the women attending the clinic had placental malaria (PM). One, two or 3 doses of SP did not impact significantly on either the percentage of women with Ab to FV2 and DBL5 or Ab levels in Ab-positive women compared to women not taking SP. The prevalence of Ab to FV2 and DBL5 was only 36.9% and 36.1%, respectively. Surprisingly, among women who had PM at delivery, only 61.5% and 57.7% had Ab to FV2 and DBL5, respectively, with only 52.9% and 47.1% in PM-positive paucigravidae and 77.7% of multigravidae having Ab to both antigens. These results suggest that long-term implementation of IPTp-SP in a low-malaria transmission area results in few women having Ab to VAR2CSA.

Stage-specific Plasmodium falciparum immune responses in afebrile adults and children living in the Greater Accra Region of Ghana

BackgroundAsymptomatic carriage of Plasmodium falciparum is widespread in adults and children living in malaria-endemic countries. This study identified the prevalence of malaria parasites and the corresponding levels of naturally acquired anti-parasite antibody levels in afebrile adults living in two communities in the Greater Accra Region of Ghana.MethodsTwo cross-sectional studies conducted in January and February 2016 and repeated in July and August 2016 recruited subjects aged between 6 and 75 years from high parasite prevalence (Obom) and low parasite prevalence (Asutsuare) communities. Whole blood (5 ml) was collected from each volunteer, plasma was aliquoted and frozen until needed. An aliquot (10 µl) of the blood was used to prepare thick and thin blood smears, 100 µl was preserved in Trizol and the rest was separated into plasma and blood cells and each stored at − 20 °C until needed. Anti-MSP3 and Pfs230 antibody levels were measured using ELISA.ResultsAsexual parasite and gametocyte prevalence were higher in Obom than Asutsuare. Antibody (IgG, IgG1, IgG3, IgM) responses against the asexual parasite antigen MSP3 and gametocyte antigen Pfs230 were higher in Obom during the course of the study except for IgM responses against Pfs230, which was higher in Asutsuare than in Obom during the rainy season. Antibody responses in Asutsuare were more significantly associated with age than the responses measured in Obom.ConclusionThe pattern of antibody responses measured in people living in the high and low malaria transmission setting was similar. All antibody responses measured against the asexual antigen MSP3 increased, however, IgG and IgG1 responses against gametocyte antigen Pfs230 decreased in moving from the dry to the peak season in both sites. Whilst asexual and gametocyte prevalence was similar between the seasons in the low transmission setting, in the high transmission setting asexual parasite prevalence increased but gametocyte prevalence decreased in the rainy season relative to the dry season.

Risk factors for placental malaria and associated low birth weight in a rural high malaria transmission setting of Cote d'Ivoire.

Background:Placental malaria (PM) is associated with increased risk of both maternal and neonatal adverse outcomes. The objective of this study was to assess risks factors associated with PM including intermittent preventive treatment with sulfadoxine-pyrimethamine (IPTp-SP).Methods:A cross-sectional study was conducted at Ayame hospital in the southern region of Cote d'Ivoire between August 2016 and March 2017. Sociodemographic baseline characteristic and antenatal data were obtained from the mother's antenatal card and included timing and number of IPTp-SP doses. Newborn characteristics were recorded.Peripheral blood as well as placental and cord blood were used to prepare thick and thin blood films. In addition, pieces of placental tissues were used to prepare impression smears. Regression logistics were used to study factors associated with PM and low birth weight (LBW) (<2.500 g).Results:Three hundred delivered women were enrolled in the study. The mean age of the participants was 25 ± 6.5 years and most participants were multigravida (52.8%). The coverage rate of IPTp-SP with the full three doses recommended was 27.8%. Overall, 7.3% (22/300) of women examined had PM detected by microscopy using impression smear (22/300). Multivariate analysis showed that significant risks factors of PM were maternal peripheral parasitemia at delivery (P < 0.0001), residence (P = 0.03), and not sleeping under long-lasting insecticide treated nets (LLINs) (P = 0.006). LBW infants were born to 22.7% (5/22) of women with PM and 13.3% (37/278) of women without PM (P = 0.47). Only primiparous was associated with LBW in the multivariable analysis (P = 0.04).Conclusion:The prevalence of PM was 7.3%. Low parity, residence and not using LLINs and maternal peripheral parasitemia were identified as risks factors. PM was associated with LBW. Implementation of IPTp-SP should be improved by the National Malaria Control Program in rural settings.