Geometric Mean Parasite Density Research Articles

Association between malaria and undernutrition among pregnant women at presentation for antenatal care in health facilities in the Mount Cameroon region.

In resource limited settings, malaria and undernutrition are major public health problems in pregnancy. Therefore, this study assessed the association between malaria infection and undernutrition among pregnant women in the Mount Cameroon area. This cross-sectional study enrolled 1,014 pregnant women consecutively over a year. A structured questionnaire was used to collect socio-demographic information and clinical data. Maternal nutrition was assessed using dietary diversity (DD). Peripheral blood samples collected were used for the diagnosis of malaria parasitaemia by microscopy whereas haemoglobin (Hb) levels were determined using an Hb meter. Logistic regression was used to determine factors associated with malaria and dietary diversity. The prevalence of malaria infection and undernutrition was 17.8% and 89.6% respectively. In addition, of those infected with malaria, geometric mean parasite density was 301/μL of blood (range: 40-9280) while mean DD score was 3.57±0.82 (range: 1-7). The odds of being infected with malaria parasitaemia was highest among women enrolled in the rainy season (OR = 1.58, P = 0.043), who were farmers (OR = 2.3, P = 0.030), had a household size of < 4 individuals (OR = 1.48, P = 0.026) and who were febrile (OR = 1.87, P < 0.001). Also, attending clinic visits in Mutengene Medical Centre (OR = 2.0, P = 0.012) or Buea Integrated Health Centre (OR = 2.9, P = < 0.001), being < 25 years (OR = 2.4, P = 0.002) and a farmer (OR = 10.6, P = 0.024) as well as < 4 clinic visits (OR = 1.62, P = 0.039) were identified as predictors of undernutrition. Furthermore, the association between malaria and DD was statistically significant (P = 0.015). In this study, undernutrition was highly frequent than malaria infection. Thus, there is an urgent need to improve maternal awareness through nutritional counselling and health campaigns on the benefits of consuming at least five food groups. Besides, improved maternal dietary nutrient intake is likely to have impact on the burden of malaria parasite infection.

A Comparative Study of the Risk Factors of Malaria within Urban and Rural Settings in the Sahelian Region of Cameroon and the Role of Insecticide Resistance in Mosquitoes

Background: Cameroon is among the 11 countries that account for 92 % of malaria infection in sub-Saharan-Africa in 2018, and Maroua III Health District and her environs witnessed a malaria outbreak in 2013 with hundredths of deaths.&#x0D; Aim: To determine the risk factors of malaria in the urban and rural population and to investigate the level of mosquito’s resistance to Deltamethrin and Permethrin.&#x0D; Methods: It was a cross-sectional community-based study carried out in August, September and October 2019, in which questionnaires were administered to 500 participants, to obtain information on demographics, socioeconomics, behavioral, and environmental factors thought to be associated with malaria infection in both rural and urban settings. Blood samples were collected for diagnosis of malaria and bivariate and multivariate regression analysis were used to identify risk factors of malaria. Mosquito resistance to Deltamethrin and Permethrin were determined using the CDC Bottle Bioassay test. &#x0D; Results: Malaria prevalence was 52.2 % which was significantly higher (P = 0.016) in rural areas (57.6%) than urban areas (46.8%). The prevalence of asymptomatic malaria was 43.4% and the geometric mean parasite density was 6333.60 parasites/µL of blood. Malaria infection was significantly (P&lt;0.001) associated with children (64.1%) and teenagers (58.1%). Likewise, the infection was significantly associated with the presence of crops around homes (P=0.031), usage of old LLINs for more than three years and in urban settings, with primary education level (P=0.023). The overall mortality of Anopheles species was 93.57% (91.19% in rural and 95.83% in urban areas) for deltamethrin which was more sensitive than 83.85% (85.24% in rural and 82.46% in urban areas) for permethrin.&#x0D; Conclusion: Relevant data for malaria control in Maroua III health district, a typical Sahelian environment has been generated, and indicates that most of the burden of malaria is borne by children and teenagers.

Transmission efficiency of Plasmodium vivax at low parasitaemia

BackgroundPlasmodium vivax is responsible for much of malaria outside Africa. Although most P. vivax infections in endemic areas are asymptomatic and have low parasite densities, they are considered a potentially important source of transmission. Several studies have demonstrated that asymptomatic P. vivax carriers can transmit the parasite to mosquitoes, but the efficiency has not been well quantified. The aim of this study is to determine the relationship between parasite density and mosquito infectivity, particularly at low parasitaemia.MethodsMembrane feeding assays were performed using serial dilutions of P. vivax-infected blood to define the relationship between parasitaemia and mosquito infectivity.ResultsThe infection rate (oocyst prevalence) and intensity (oocyst load) were positively correlated with the parasite density in the blood. There was a broad case-to-case variation in parasite infectivity. The geometric mean parasite density yielding a 10% mosquito infection rate was 33 (CI 95 9–120) parasites/µl or 4 (CI 95 1–17) gametocytes/µl. The geometric mean parasite density yielding a 50% mosquito infection rate was 146 (CI 95 36–586) parasites/µl or 13 (CI 95 3–49) gametocytes/µl.ConclusionThis study quantified the ability of P. vivax to infect Anopheles dirus at over a broad range of parasite densities. It provides important information about parasite infectivity at low parasitaemia common among asymptomatic P. vivax carriers.

Pro- and anti-inflammatory cytokine profiles in Plasmodium Falciparum-infected individuals from Baiyeku, Ikorodu, Lagos, Nigeria

Available evidence indicates that the various stages of the malaria parasite life cycle elicit specific immune responses of which the relative levels of pro-inflammatory cytokines are key to disease progression, killing the parasite and mediating disease outcomes. This study investigated T-cell response in malaria. Four hundred and sixty-two participants were screened in a community survey of Plasmodium falciparum malaria in Baiyeku, Lagos, Nigeria. P. falciparum parasitaemia was determined by microscopy while the serum levels of IL-10, IFNγ and TNFα were determined by Enzyme-linked immunosorbent assay (ELISA). A total of 70 (15.2 %) participants were microscopically positive for P. falciparum of which 70% were females, 30% were males while children aged 1-17 years were 65.7%. The geometric mean parasite density (GMPD) was significantly (p=0.001) higher among females than males. The GMPD of participants &lt;5 years of age was also significantly (p=0.001) higher than other age groups. About 46.8% of the participants were underweight (Body Mass Index, BMI &lt; 18.5) and also had the highest parasite intensity. The TNFα, IFNγ and IL-10 levels were significantly (p&lt; 0.05) higher in the infected than the uninfected participants. IFN-γ values were significantly (p=0.014) elevated among the symptomatic than the asymptomatic participants while there was no significant difference (P&gt;0.053) in the levels of TNF-α and IL-10 (P&gt;0.093) between the symptomatic and asymptomatic participants. The prevalence of P. falciparum obtained in this study area which is endemic to malaria is 15.2% suggesting a significant reduction of the disease over time due to awareness of the disease in the community. The levels of pro-inflammatory cytokines (IFN-γ and TNF-α) in this study were lower due to the down-regulatory action of the anti-inflammatory cytokines (IL-10). These findings suggest that higher levels of anti-inflammatory cytokines, especially IL-10 levels may contribute to the pathogenesis of uncomplicated malaria.

Prevalence and risk factors of malaria among first antenatal care attendees in rural Burkina Faso

BackgroundThe WHO recommends continuous surveillance of malaria in endemic countries to identify areas and populations most in need for targeted interventions. The aim of this study was to assess the prevalence of malaria and its associated factors among first antenatal care (ANC) attendees in rural Burkina Faso.MethodsA cross-sectional survey was conducted between August 2019 and September 2020 at the Yako health district and included 1067 first ANC attendees. Sociodemographic, gyneco-obstetric, and medical characteristics were collected. Malaria was diagnosed by standard microscopy and hemoglobin level was measured by spectrophotometry. A multivariate logistic regression analysis was used to identify factors associated with malaria infection.ResultsOverall malaria infection prevalence was 16.1% (167/1039). Among malaria-positive women, the geometric mean parasite density was 1204 [95% confidence interval (CI) 934–1552] parasites/µL and the proportion of very low (1–199 parasites/µL), low (200–999 parasites/µL), medium (1000–9999 parasites/µL) and high (≥ 10,000 parasites/µL) parasite densities were 15.0%, 35.3%, 38.3% and 11.4%, respectively. Age < 20 years (adjusted odds ratio (aOR): 2.2; 95% CI 1.4–3.5), anemia (hemoglobin < 11 g/deciliter) (aOR: 3.4; 95% CI 2.2–5.5), the non-use of bed net (aOR: 1.8; 95% CI 1.1–2.8), and the absence of intermittent preventive treatment with sulfadoxine–pyrimethamine (aOR: 5.8; 95% CI 2.1–24.5) were positively associated with malaria infection.ConclusionsThe study showed that one out of six pregnant women had a microscopy-detected P. falciparum malaria infection at their first ANC visit. Strengthening malaria prevention strategies during the first ANC visit is needed to prevent unfavorable birth outcomes.

Diagnostic Performance of Loop-Mediated Isothermal Amplification and Ultrasensitive Rapid Diagnostic Tests for Malaria Screening Among Pregnant Women in Kenya.

Screen-and-treat strategies with sensitive diagnostic tests may reduce malaria-associated adverse pregnancy outcomes. We conducted a diagnostic accuracy study to evaluate new point-of-care tests to screen pregnant women for malaria at their first antenatal visit in western Kenya. Consecutively women were tested for Plasmodium infection by expert microscopy, conventional rapid diagnostic test (cRDT), ultra sensitive RDT (usRDT), and loop-mediated isothermal amplification (LAMP). Photoinduced electron-transfer polymerase chain reaction (PET-PCR) served as the reference standard. Diagnostic performance was calculated and modelled at low parasite densities. Between May and September 2018, 172 of 482 screened participants (35.7%) were PET-PCR positive. Relative to PET-PCR, expert microscopy was least sensitive (40.1%; 95% confidence interval [CI], 32.7%-47.9%), followed by cRDT (49.4%; 95% CI, 41.7%-57.1), usRDT (54.7%; 95% CI, 46.9%-62.2%), and LAMP (68.6%; 95% CI, 61.1%-75.5%). Test sensitivities were comparable in febrile women (n = 90). Among afebrile women (n = 392), the geometric-mean parasite density was 29 parasites/µL and LAMP (sensitivity = 61.9%) and usRDT (43.2%) detected 1.74 (95% CI, 1.31-2.30) and 1.21 (95% CI, 88-2.21) more infections than cRDT (35.6%). Per our model, tests performed similarly at densities >200 parasites/µL. At 50 parasites/µL, the sensitivities were 45%, 56%, 62%, and 74% with expert microscopy, cRDT, usRDT, and LAMP, respectively. This first-generation usRDT provided moderate improvement in detecting low-density infections in afebrile pregnant women compared to cRDTs.

Intestinal helminths as predictors of some malaria clinical outcomes and IL-1β levels in outpatients attending two public hospitals in Bamenda, North West Cameroon.

This study aimed at determining the impact of intestinal helminths on malaria parasitaemia, anaemia and pyrexia considering the levels of IL-1β among outpatients in Bamenda. A cohort of 358 consented participants aged three (3) years and above, both males and females on malaria consultation were recruited in the study. At enrolment, patients’ axillary body temperatures were measured and recorded. Venous blood was collected for haemoglobin concentration and malaria parasitaemia determination. Blood plasma was used to measure human IL-1β levels using Human ELISA Kit. The Kato-Katz technique was used to process stool samples. Five species of intestinal helminths Ascaris lumbricoides (6.4%), Enterobius vermicularis (5.0%), Taenia species (4.2%), Trichuris trichiura (1.1%) and hookworms (0.8%) were identified. The overall prevalence of Plasmodium falciparum and intestinal helminths was 30.4% (109/358) and 17.6% (63/358) respectively. The prevalence of intestinal helminths in malaria patients was 17.4% (19/109). Higher Geometric mean parasite density (GMPD ±SD) (malaria parasitaemia) was significantly observed in patients co-infected with Enterobius vermicularis (5548 ± 2829/μL, p = 0.041) and with Taenia species (6799 ± 4584/μL, p = 0.020) than in Plasmodium falciparum infected patients alone (651 ± 6076/ μL). Higher parasitaemia of (1393 ± 3031/μL) and (3464 ± 2828/μL) were recorded in patients co-infected with Ascaris lumbricoides and with hookworms respectively but the differences were not significant (p > 0.05). Anaemia and pyrexia prevalence was 27.1% (97/358) and 33.5% (120/358) respectively. Malaria patients co-infected with Enterobius vermicularis and Ascaris lumbricoides had increased risk of anaemia (OR = 13.712, p = 0.002 and OR = 16.969, p = 0.014) respectively and pyrexia (OR = 18.07, p = 0.001 and OR = 22.560, p = 0.007) respectively than their counterparts. Increased levels of IL-1β were significantly observed in anaemic (148.884 ± 36.073 pg/mL, t = 7.411, p = 0.000) and pyretic (127.737 ± 50.322 pg/mL, t = 5.028, p = 0.000) patients than in non-anaemic (64.335 ± 38.995pg/mL) and apyretic patients (58.479 ± 36.194pg/mL). Malaria patients co-infected with each species of intestinal helminths recorded higher IL-1β levels (IL-1β > 121.68 ± 58.86 pg/mL) and the overall mean (139.63 ± 38.33pg/mL) was higher compared with levels in malaria (121.68 ± 58.86 pg/mL) and helminth (61.78 ± 31.69pg/mL) infected patients alone. Intestinal helminths exacerbated the clinical outcomes of malaria in the patients and increased levels of IL-1β were observed in co-infected patients with anaemia, pyrexia and higher parasitaemia.

Effect of Asymptomatic Plasmodium falciparum Parasitaemia on Platelets Thrombogenicity in Blood Donors

Currently, blood donors in Ghana are not screened for malaria parasites. Therefore, this study assessed platelet thrombogenicity in blood donors infected asymptomatically with Plasmodium falciparum and the relationship between tumour necrosis factor alpha (TNF-α), 8-iso-prostaglandin F2α oxidative stress biomarker (8-iso-PG2α), C-reactive protein (hs-CRP) and D-dimer, and platelet thrombogenes levels. Haematology analyser was used to enumerate platelet count and platelet indices in 80 P. falciparum infected blood donors and 160 matched non-infected controls. Replicate serum levels of von Willebrand Factor (vWF), platelet factor 4 (PF4), P-selectin thrombogenic factors as well as TNF-α and 8-iso-PG2α were determined using enzyme immuno-assay while high sensitive hs-CRP and D-dimer concentrations were determined by fluorescent immunoassay. The geometric mean of parasite density in malaria infected donors was 1784 parasites/µL (505-2478 parasites/µL). This led to significant increase in the mean levels of 8-iso-PG2α, hs-CRP, TNF-α and D-dimer. However, PF4, P-selectin were significantly lower in infected donors while vWF levels did not differ significantly among the groups even though lower levels were observed in the infected donors. Significant direct relationship existed between both P-selectin and PF4 and platelet count, and plateletcrit and platelet large cell ratio whereas these thrombogenic factors varied inversely to 8-iso-PG2α, TNF-α and hs-CRP. Relative thrombocytopaenia was associated with significant reduction in P-selectin and platelet factor 4 levels together with increased 8-iso-PG2α, hs-CRP, TNF-α and D-dimer levels. Taken together, it is recommended that all P. falciparum infected blood donors should be deferred.

Field performance of ultrasensitive and conventional malaria rapid diagnostic tests in southern Mozambique

BackgroundAn ultrasensitive malaria rapid diagnostic test (RDT) was recently developed for the improved detection of low-density Plasmodium falciparum infections. This study aimed to compare the diagnostic performance of the PfHRP2-based Abbott Malaria Ag P. falciparum ultrasensitive RDT (uRDT) to that of the conventional SD-Bioline Malaria Ag P. falciparum RDT (cRDT) when performed under field conditions.MethodsFinger-prick blood samples were collected from adults and children in two cross-sectional surveys in May of 2017 in southern Mozambique. Using real-time quantitative PCR (RT-qPCR) as the reference method, the age-specific diagnostic performance indicators of the cRDT and uRDT were compared. The presence of histidine-rich protein 2 (HRP2) and Plasmodium lactate dehydrogenase (pLDH) antigens was evaluated in a subset from dried blood spots by a quantitative antigen assay. pfhrp2 and pfhrp3 gene deletions were assessed in samples positive by RT-qPCR and negative by both RDTs.ResultsAmong the 4,396 participants with complete test results, the sensitivity of uRDTs (68.2; 95% CI 60.8 to 74.9) was marginally better than that of cRDTs (61.5; 95% CI 53.9 to 68.6) (p-value = 0.004), while the specificities were similar (uRDT: 99.0 [95% CI 98.6 to 99.2], cRDT: 99.2 [95% CI 98.9 to 99.4], p-value = 0.02). While the performance of both RDTs was lowest in ≥ 15-year-olds, driven by the higher prevalence of low parasite density infections in this group, the sensitivity of uRDTs was significantly higher in this age group (54.9, 95% CI 40.3 to 68.9) compared to the sensitivity of cRDTs (39.2, 95% CI 25.8 to 53.9) (p-value = 0.008). Both RDTs detected P. falciparum infections at similar geometric mean parasite densities (112.9 parasites/μL for uRDTs and 145.5 parasites/μL for cRDTs). The presence of HRP2 antigen was similar among false positive (FP) samples of both tests (80.5% among uRDT-FPs and 84.4% among cRDT-FPs). Only one false negative sample was detected with a partial pfhrp2 deletion.ConclusionThis study showed that the uRDTs developed by Abbott do not substantially outperform SD-Bioline Pf malaria RDTs in the community and are still not comparable to molecular methods to detect P. falciparum infections in this study setting.

Epidemiology of malaria among pregnant women during their first antenatal clinic visit in the middle belt of Ghana: a cross sectional study

BackgroundMalaria during pregnancy may result in unfavourable outcomes in both mothers and their foetuses. This study sought to document the current burden and factors associated with malaria and anaemia among pregnant women attending their first antenatal clinic visit in an area of Ghana with perennial malaria transmission.MethodsA total of 1655 pregnant women aged 18 years and above with a gestational age of 13–22 weeks, who attended an antenatal care (ANC) clinic for the first time, were consented and enrolled into the study. A structured questionnaire was used to collect socio-demographic and obstetric data and information on use of malaria preventive measures. Venous blood (2 mL) was collected before sulfadoxine-pyrimethamine administration. Malaria parasitaemia and haemoglobin concentration were determined using microscopy and an automated haematology analyser, respectively. Data analysis was carried out using Stata 14.ResultsMean age (SD) and gestational age (SD) of women at enrolment were 27.4 (6.2) years and 16.7 (4.3) weeks, respectively. Overall malaria parasite prevalence was 20.4% (95% CI 18.5–22.4%). Geometric mean parasite density was 442 parasites/µL (95% CI 380–515). Among women with parasitaemia, the proportion of very low (1–199 parasites/µL), low (200–999 parasites/µL), medium (1000–9999 parasites/µL) and high (≥ 10,000 parasites/µL) parasite density were 31.1, 47.0, 18.9, and 3.0%, respectively. Age ≥ 25 years (OR 0.57, 95% CI 0.41–0.79), multigravid (OR 0.50, 95% CI 0.33–0.74), educated to high school level or above (OR 0.53, 95% CI 0.33–0.83) and in household with higher socio-economic status (OR 0.34, 95% CI 0.21–0.54) were associated with a lower risk of malaria parasitaemia. The prevalence of anaemia (< 11.0 g/dL) was 56.0%, and the mean haemoglobin concentration in women with or without parasitaemia was 9.9 g/dL or 10.9 g/dL, respectively.ConclusionOne out of five pregnant women attending their first ANC clinic visit in an area of perennial malaria transmission in the middle belt of Ghana had Plasmodium falciparum infection. Majority of the infections were below 1000 parasites/µL and with associated anaemia. There is a need to strengthen existing malaria prevention strategies to prevent unfavourable maternal and fetal birth outcomes in this population.

Comparison of the fluorescence microscopy Cyscope\xae with light microscopy for malaria diagnosis in a small and active surveillance in Cameroon

BackgroundMalaria has a negative impact on the activities of companies in endemic countries especially in Cameroon. In this regard, an increasingly growing number of companies have started to include management of malarious patients in their health policies. In the present study, we will evaluate the diagnostic performances of a fluorescence microscopy (FM), Cyscope® microscope, in the detection of malaria parasites.MethodsA cross-sectional study was conducted among employees of two companies of the town of Douala on 21 and 22 March 2017. Sociodemographic information of employees was collected using a questionnaire form. Blood samples of ~ 10 μL were collected by venipuncture for the diagnosis of malaria using FM and light microscopy (LM). Performances of FM with respect to sensitivity (Se), specificity (Sp), positive and negative predictive values (PPV and NPV), positive and negative likelihood rates (PLR and NLR), accuracy, reliability, and Kappa index were calculated using LM as gold standard.ResultsIn total, 442 employees, aged 37.8 ± 9.7 years old on average, were included in the study. Prevalence of malaria using FM and LM was 39.2% and 17%, respectively (p < 0.01). Plasmodium falciparum and P. vivax were the two species involved in malaria infection cases. In terms of developmental stages, 68%, 45.3%, and 1.3% of employees carried gametocytes, trophozoites, and schizonts, respectively. Findings on diagnostic performances of FM were as follows: Se = 84%, Sp = 69.95%, PPV = 63.58%, NPV = 95.5%, accuracy = 89.36%, and reliability = 53.95%. Sensitivity of Cyscope® microscope increased as a function of parasitemia with values ranging from 76.92% at parasitemia between 1 and 500 parasites/μL to 91.11% at parasitemia between 501 and 5000 parasites/μL. The geometric mean parasite density was1850 parasites per μL of blood (range 1600–40,000), and most of employees (60.8%) had moderate parasitemia. The performances of FM were similar between febrile and afebrile patients.ConclusionsThis study showed good performances of Cyscope® microscope and outlines that this diagnostic tool could be used in management of malaria at workplace.

Prevalence of asymptomatic malaria infections in selected military camps in Tanzania

Background: Despite a decrease in malaria burden reported between 2000 and 2015, an increasing trend of malaria transmission has been recently reported in some endemic countries including Tanzania. Periodic monitoring to identify pocket areas for asymptomatic Plasmodium falciparum infection is vital for malaria elimination efforts. The objective of this study was to determine prevalence of asymptomatic malaria infections among military recruits in selected camps in Tanzania.&#x0D; Methods: A cross-sectional study was conducted in 2015 at four military camps (Bulombora, Mgambo, Ruvu, and Rwamkoma) of National Service located in regions with varying malaria endemicity in Tanzania. Finger prick blood samples collected from asymptomatic military recruits who had been at the camps for over two months were simultaneously tested using microscopy and malaria rapid diagnostic tests (mRDTs) to detect malaria parasite infections.&#x0D; Results: Malaria parasite prevalence among asymptomatic recruits was 20.3% and 19.4% by microscopy and mRDT respectively. There was moderate agreement (Kappa=0.724) between microscopy and mRDT test results. A significant difference (p&lt;0.001) of malaria parasite prevalence among the four study camps was observed; ranging from 1.9% in Bulombora to 39.4% in Rwamkoma. The geometric mean parasite density was 11,053 asexual parasites/µl and most recruits (56.8%) had 200 to 1999 asexual parasites/µl. P. falciparum was the predominant (99.2%) malaria parasite species.&#x0D; Conclusion: Our study found high prevalence of asymptomatic malaria infections among military recruits in the selected camps, and this varied from one camp to another. The study has highlighted that public residence institutions such as military camps can be potential hotspots for malaria infection and therefore should not be skipped in routine national malaria surveillance system for monitoring trends of infections

Variation of prevalence of malaria, parasite density and the multiplicity of Plasmodium falciparum infection throughout the year at three different health centers in Brazzaville, Republic of Congo

BackgroundIn the Republic of Congo, hot temperature and seasons distortions observed may impact the development of malaria parasites. We investigate the variation of malaria cases, parasite density and the multiplicity of Plasmodium falciparum infection throughout the year in Brazzaville.MethodsFrom May 2015 to May 2016, suspected patients with uncomplicated malaria were enrolled at the Hôpital de Mfilou, CSI « Maman Mboualé», and the Laboratoire National de Santé Publique. For each patient, thick blood was examined and parasite density was calculated. After DNA isolation, MSP1 and MSP2 genes were genotyped.ResultsA total of 416, 259 and 131 patients with suspected malaria were enrolled at the CSI «Maman Mboualé», Hôpital de Mfilou and the Laboratoire National de Santé Publique respectively. Proportion of malaria cases and geometric mean parasite density were higher at the CSI «Maman Mboualé» compared to over sites (P-value <0.001). However the multiplicity of infection was higher at the Hôpital de Mfilou (P-value <0.001).At the Laboratoire National de Santé Publique, malaria cases and multiplicity of infection were not influenced by different seasons. However, variation of the mean parasite density was statistically significant (P-value <0.01).Higher proportions of malaria cases were found at the end of main rainy season either the beginning of the main dry season at the Hôpital de Mfilou and the CSI «Maman Mboualé»; while, lowest proportions were observed in September and January and in September and March respectively. Higher mean parasite densities were found at the end of rainy seasons with persistence at the beginning of dry seasons. The lowest mean parasite densities were found during dry seasons, with persistence at the beginning of rainy seasons. Fluctuation of the multiplicity of infection throughout the year was observed without significance between seasons.ConclusionThe current study suggests that malaria transmission is still variable between the north and south parts of Brazzaville. Seasonal fluctuations of malaria cases and mean parasite densities were observed with some extension to different seasons. Thus, both meteorological and entomological studies are needed to update the season’s periods as well as malaria transmission intensity in Brazzaville.

Molecular methods for tracking residual Plasmodium falciparum transmission in a close-to-elimination setting in Zanzibar

BackgroundMolecular detection of low-density Plasmodium falciparum infections is essential for surveillance studies conducted to inform malaria control strategies in close-to-elimination settings. Molecular monitoring of residual malaria infections usually requires a large study size, therefore sampling and diagnostic processes need to be economical and optimized for high-throughput. A method comparison was undertaken to identify the most efficient diagnostic procedure for processing large collections of community samples with optimal test sensitivity, simplicity, and minimal costs.MethodsIn a reactive case detection study conducted on Zanzibar, parasitaemia of 4590 individuals of all ages was investigated by a highly sensitive quantitative (q) PCR that targets multiple var gene copies per parasite genome. To reduce cost, a first round of positivity screening was performed on pools of dried blood spots from five individuals. Ten cycles of a pre-PCR were performed directly on the filter paper punches, followed by qPCR. In a second round, samples of positive pools were individually analysed by pre-PCR and qPCR.ResultsPrevalence in household members and neighbors of index cases was 1.7% (78/4590) with a geometric mean parasite density of 58 parasites/µl blood. Using qPCR as gold standard, diagnostic sensitivity of rapid diagnostic tests (RDTs) was 37% (29/78). Infections positive by qPCR but negative by RDT had mean densities of 15 parasites/µl blood.ConclusionThe approach of pre-screening reactive case detection samples in pools of five was ideal for a low prevalence setting such as in Zanzibar. Performing direct PCR on filter paper punches saves substantial time and justifies the higher cost for a polymerase suitable for amplifying DNA directly from whole blood. Molecular monitoring in community samples provided a more accurate picture of infection prevalence, as it identified a potential reservoir of infection that was largely missed by RDT. The developed qPCR-based methodology for screening large sample sets represents primarily a research tool that should inform the design of malaria elimination strategies. It may also prove beneficial for diagnostic tasks in surveillance-response activities.

Direct Estimation of Sensitivity of Plasmodium falciparum Rapid Diagnostic Test for Active Case Detection in a High-Transmission Community Setting.

Community-based active case detection of malaria parasites with conventional rapid diagnostic tests (cRDTs) is a strategy used most commonly in low-transmission settings. We estimated the sensitivity of this approach in a high-transmission setting in Western Kenya. We tested 3,547 members of 912 households identified in 2013-2014 by index children with (case) and without (control) cRDT-positive malaria. All were tested for Plasmodium falciparum with both a cRDT targeting histidine-rich protein 2 and with an ultrasensitive real-time polymerase chain reaction (PCR). We computed cRDT sensitivity against PCR as the referent, compared prevalence between participant types, and estimated cRDT detectability as a function of PCR-estimated parasite density. Parasite prevalence was 22.9% by cRDTs and 61.5% by PCR. Compared with children aged < 5 years or adults aged > 15 years, geometric mean parasite densities (95% CI) were highest in school-age children aged 5-15 years (8.4 p/uL; 6.6-10.6). The overall sensitivity of cRDT was 36%; among asymptomatic household members, cRDT sensitivity was 25.5% and lowest in adults aged > 15 years (15.8%). When modeled as a function of parasite density, relative to school-age children, the probability of cRDT positivity was reduced in both children aged < 5 years (odds ratio [OR] 0.48; 95% CI: 0.34-0.69) and in adults aged > 15 years (OR: 0.35; 95% CI: 0.27-0.47). An HRP2-detecting cRDT had poor sensitivity for active P. falciparum case detection in asymptomatic community members, and sensitivity was lowest in highly prevalent low-density infections and in adults. Future studies can model the incremental effects of high-sensitivity rapid diagnostic tests and the impacts on transmission.

Diagnostic performance of CareStart\u2122 malaria HRP2/pLDH test in comparison with standard microscopy for detection of uncomplicated malaria infection among symptomatic patients, Eastern Coast of Tanzania

BackgroundCareStart™ malaria HRP2/pLDH (Pf/pan) combo test is one of the several rapid diagnostic tests (RDT) approved for diagnosis of malaria at the point of care in Tanzania. However, there are limited studies on the diagnostic performance of RDT after wide scale use in primary health care facilities in Tanzania. Therefore, this study was carried out to determine the diagnostic performance of RDT when compared with blood smear (BS) microscopy as a reference standard.MethodsA cross-sectional study was conducted between March and August 2019 at Kibiti Health Centre, Pwani region, Tanzania. Blood samples for malaria tests were collected from patients with malaria symptoms. Diagnostic performance parameters of RDT, i.e. sensitivity, specificity, positive and negative likelihood ratios (LR+/−), diagnostic accuracy and predictive values were determined using contingency table. An agreement between RDT and microscopy was statistically determined by Cohen’s kappa test.ResultsOf 980 patients screened, 567 (57.9%) were found to be malaria positive by RDT, whereas 510 patients (52%) were positive by microscopy. Of the 510 microscopy-positive patients, 487 (95.5%) were infected with Plasmodium falciparum. The geometric mean parasite density was 2921parasites/µl, whereas majority (68.6%) of patients had parasite density greater than 10,000/µl. The sensitivity, specificity, positive and negative predictive values of CareStart™ were 99.8%, 87.6%, 89.8%, and 99.8%, respectively. The LR+ and LR− were 8.0 and 0.002, respectively. The diagnostic accuracy was 0.5. There was a strong agreement between the results obtained using CareStart™ and BS microscopy (kappa = 0.863, P < 0.0001).ConclusionCareStart™ malaria HRP2/pLDH (Pf/pan) had high sensitivity and strong agreement with microscopy results. However, moderate specificity of RDT resulted in a substantial number of patients with false positive malaria test. Wherever available, microscopy should be used to confirm RDT test results.

Efficacy and safety of dihydroartemisinin\u2013piperaquine for treatment of Plasmodium falciparum uncomplicated malaria in adult patients on antiretroviral therapy in Malawi and Mozambique: an open label non-randomized interventional trial

BackgroundHIV-infected individuals on antiretroviral therapy (ART) require treatment with artemisinin-based combination therapy (ACT) when infected with malaria. Dihydroartemisinin–piperaquine (DPQ) is recommended for treatment of Plasmodium falciparum malaria, but its efficacy and safety has not been evaluated in HIV-infected individuals on ART, among whom drug–drug interactions are expected. Day-42 adequate clinical and parasitological response (ACPR) and incidence of adverse events were assessed in HIV-infected individuals on non-nucleoside reverse transcriptase inhibitor-based ART (efavirenz and nevirapine) with uncomplicated P. falciparum malaria treated with dihydroartemisinin–piperaquine.MethodsAn open label single arm clinical trial was conducted in Malawi (Blantyre and Chikhwawa districts) and Mozambique (Manhiça district) involving patients aged 15–65 years with uncomplicated P. falciparum malaria who were on efavirenz-based or nevirapine-based ART. They received a directly-observed 3-day standard treatment of DPQ and were followed up until day 63 for malaria infection and adverse events. Day-42 PCR-corrected-ACPRs (95% confidence interval [CI]) were calculated for the intention-to-treat (ITT) population.ResultsThe study enrolled 160 and 61 patients on efavirenz and nevirapine-based ART, with a baseline geometric mean (95% CI) parasite density of 2681 (1964–3661) and 9819 (6606–14,593) parasites/µL, respectively. The day-42 PCR-corrected ACPR (95% CI) was 99.4% (95.6–99.9%) in the efavirenz group and 100% in the nevirapine group. Serious adverse events occurred in 5.0% (8/160) and 3.3% (2/61) of the participants in the efavirenz and nevirapine group, respectively, but none were definitively attributable to DPQ. Cases of prolonged QT interval (> 60 ms from baseline) occurred in 31.2% (48/154) and 13.3% (8/60) of the patients on the efavirenz and nevirapine ART groups, respectively. These were not clinically significant and resolved spontaneously over time. As this study was not designed to compare the efficacy and safety of DPQ in the two ART groups, no formal statistical comparisons were made between the two ART groups.ConclusionsDPQ was highly efficacious and safe for the treatment of malaria in HIV-infected patients concurrently taking efavirenz- or nevirapine-based ART, despite known pharmacokinetic interactions between dihydroartemisinin–piperaquine and efavirenz- or nevirapine-based ART regimens.Trial registration Pan African Clinical Trials Registry (PACTR): PACTR201311000659400. Registered on 4 October 2013, https://pactr.samrc.ac.za/Search.aspx

Seasonal Depiction of Malariometric Indices in Children under Five Years in a Sudanese Semi-urban Area of Burkina Faso

Aims: Malariometric indices are essential for the assessment of both new therapies and control strategies. As part of the characterization of a new malaria clinical trial site, this study was carried out to assess malariometric indices during the two seasons of a Sudanese area of Burkina Faso, in children aged under five years.&#x0D; Study Design: Two community-based cross-sectional surveys were conducted as follow: the first during the rainy season of 2009 and the second during the following dry season. Socio-demographic and clinical data were recorded. A finger prick blood sample was collected to perform malaria blood films and to measure the hemoglobin level.&#x0D; Results: Malaria parasitemia prevalence was 55.2% (N = 677) in the rainy season with a geometric mean of parasite density (GMPD) of 3439 trophozoites/µl against 23.3% (N = 720) in the dry season with a GMPD of 1368 trophozoites/µl. Gametocytemia prevalence was 21.7% and 6.5% respectively in rainy and dry season while splenomegaly prevalence was 11.2% (N = 689) in rainy season against 4.2% (N = 752) in dry season. The prevalence of anemia (hemoglobin &lt; 11.0 g/dl) was 90.0% in rainy season and 70.6% in dry season. All indices in rainy season were statistically higher than those in dry season (p-value &lt; 0.0001). The odds of parasite carriage were 3 to 5 times higher in rainy season compared to dry season (95% CI for OR = [3.1, 5.0]).&#x0D; Conclusion: The site is located in a seasonal hyper-endemic malaria area and seems appropriate for the conduct of malaria drugs or vaccines studies. Though the gap between seasons is considerable, the residual level of parasite carriage during low transmission period is not negligible and may command the development of strategies targeting this specific period, to break the chain of transmission of the disease.

Severe oxidative stress in sickle cell disease patients with uncomplicated Plasmodium falciparum malaria in Kampala, Uganda

BackgroundOxidative stress plays a vital role in the pathogenesis of both Sickle Cell Disease (SCD) and Plasmodium falciparum malaria. However, there are limited studies on the effect of P. falciparum malaria infection on oxidative stress in SCD patients.MethodsA cross-sectional study was undertaken to compare levels of biomarkers of oxidative stress in isolates from SCD patients with uncomplicated P.falciparum malaria. The biomarkers namely: malondialdehyde (MDA), reduced glutathione (GSH), catalase (CAT) and glutathione peroxidase (GPx) were determined in plasma samples from SCD malaria positive, malaria positive, SCD malaria negative and healthy control participants. The genetic diversity of P.falciparum was determined by nested polymerase chain reaction of merozoite surface protein-2 (MSP-2) gene.ResultsOut of 207 participants, 54 (26%) were SCD malaria positive, 51 (24%) malaria positive, 51 (24%) SCD controls and 51 (24%) healthy control individuals. The mean concentration of MDA was significantly higher in SCD malaria positive than SCD controls (P < 0.0001). In contrast, the mean concentration of GSH (P < 0.0001) and GPx (P < 0.0001) were significantly lower in SCD malaria than SCD controls. Although not significantly different, the mean concentration of MDA was higher (P = 0.0478), but the geometric mean parasite density (P = 0.2430) and multiplicity of infection (P = 0.3478) were lower in SCD malaria samples than in malaria samples. The most prevalent MSP2 allelic family was IC3D7 in SCD malaria (72%) and Malaria (76%) samples. The biomarkers of oxidative stress were not significantly different between IC3D7 and FC27 allelic families of MSP2.ConclusionWe identified severe oxidative stress in Sickle cell disease patients with uncomplicated P.falciparum malaria.

Efficacy and safety of artemether\u2013lumefantrine as treatment for Plasmodium falciparum uncomplicated malaria in adult patients on efavirenz-based antiretroviral therapy in Zambia: an open label non-randomized interventional trial

BackgroundHIV-infected individuals on antiretroviral therapy (ART) require treatment with artemisinin-based combination therapy (ACT) when infected with malaria. Artemether–lumefantrine (AL) is the most commonly used ACT for treatment of falciparum malaria in Africa but there is limited evidence on the safety and efficacy of AL in HIV-infected individuals on ART, among whom drug–drug interactions are expected. Day-42 adequate clinical and parasitological response (ACPR) and incidence of adverse events was assessed in HIV-infected individuals on efavirenz-based ART with uncomplicated falciparum malaria treated with AL.MethodsA prospective, open label, non-randomized, interventional clinical trial was conducted at St Paul’s Hospital in northern Zambia, involving 152 patients aged 15–65 years with uncomplicated falciparum malaria, who were on efavirenz-based ART. They received a 3-day directly observed standard treatment of AL and were followed up until day 63. Day-42 polymerase chain reaction (PCR)-corrected ACPRs (95% confidence interval [CI]) were calculated for the intention-to-treat population.ResultsEnrolled patients had a baseline geometric mean (95% CI) parasite density of 1108 (841–1463) parasites/µL; 16.4% (25/152) of the participants had a recurrent malaria episode by day 42. However, PCR data was available for 17 out of the 25 patients who had malaria recurrence. Among all the 17 patients, PCR findings demonstrated malaria re-infection, making the PCR-adjusted day-42 ACPR 100% in the 144 patients who could be evaluated. Even when eight patients with missing PCR data were considered very conservatively as failures, the day-42 ACPR was over 94%. None of the participants, disease or treatment characteristics, including day-7 lumefantrine concentrations, predicted the risk of malaria recurrence by day 42. AL was well tolerated following administration. There were only two cases of grade 3 neutropaenia and one serious adverse event of lobar pneumonia, none of which was judged as probably related to intake of AL.ConclusionsAL was well tolerated and efficacious in treating uncomplicated falciparum malaria in HIV co-infected adults on efavirenz-based ART. However, a higher than anticipated proportion of participants experienced malaria re-infection, which highlights the need for additional malaria prevention measures in this sub-population after treatment with AL.Trial registration Pan African Clinical Trials Registry (PACTR): PACTR201311000659400. Registered on 4 October 2013. https://pactr.samrc.ac.za/Search.aspx