Dataset Information

Community-wide Prevalence of Malaria Parasitemia in HIV-Infected and Uninfected Populations in a High-Transmission Setting in Uganda.

ABSTRACT: Malaria control strategies depend on identifying individuals with parasitemia, who may be asymptomatic but retain the ability to transmit disease. Population-level survey data on parasitemia are limited and traditionally exclude adults and human immunodeficiency virus (HIV)-infected individuals.We performed a cross-sectional survey of residents aged 18 months to 94 years in Nankoma, Uganda. Blood specimens were collected using the dried blood spot technique from 9629 residents (87.6%), and samples from a subset of 4131 were tested for malaria parasites, using loop-mediated isothermal amplification. Population-level prevalence was estimated using a weighted proportion, and predictors of parasitemia were identified using a multivariate Poisson regression model.The community prevalence of parasitemia was 83.8% (95% confidence interval [CI], 82.9%-84.6%). Parasite prevalence was highest among children aged 5-14 years (94.7%) and lowest among adults (61.9%). In analysis that controlled for age, HIV-infected individuals with an undetectable viral load had a lower risk of parasitemia, compared with HIV-uninfected individuals (adjusted relative risk, 0.16; 95% CI, .10-.27; P < .001).In a rural Ugandan community, 2 years after distribution of long-lasting insecticide-treated bed nets, the prevalence of malaria parasitemia was high across all ages, peaking in school-aged children. Persons with well-controlled HIV infection had a lower risk of parasitemia, presumably reflecting access to HIV care.

SUBMITTER: Katrak S

PROVIDER: S-EPMC4878723 | biostudies-literature | 2016 Jun

REPOSITORIES: biostudies-literature

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Community-wide Prevalence of Malaria Parasitemia in HIV-Infected and Uninfected Populations in a High-Transmission Setting in Uganda.

Katrak Shereen S Day Nathan N Ssemmondo Emmanuel E Kwarisiima Dalsone D Midekisa Alemayehu A Greenhouse Bryan B Kamya Moses M Havlir Diane D Dorsey Grant G

The Journal of infectious diseases 20160210 12

<h4>Background</h4>Malaria control strategies depend on identifying individuals with parasitemia, who may be asymptomatic but retain the ability to transmit disease. Population-level survey data on parasitemia are limited and traditionally exclude adults and human immunodeficiency virus (HIV)-infected individuals.<h4>Methods</h4>We performed a cross-sectional survey of residents aged 18 months to 94 years in Nankoma, Uganda. Blood specimens were collected using the dried blood spot technique fro ...[more]

PMID: 26908725

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Project description:HIV-exposed, uninfected (HEU) infants suffer high morbidity and mortality in the first year of life compared to HIV-unexposed, uninfected (HUU) infants, but accurate data on the contribution of malaria are limited.The incidence of febrile illnesses and malaria were evaluated in a birth cohort of HEU infants. Infants were prescribed daily trimethoprim-sulfamethoxazole (TS) prophylaxis from 6 weeks of age until exclusion of HIV-infection after cessation of breastfeeding. Infants were followed for all illnesses using passive surveillance and routine blood smears were done monthly. Malaria was diagnosed as a positive blood smear plus fever. Placental malaria was determined by histopathology, placental blood smear and PCR. Risk factors for time to first episode of malaria were assessed using a Cox proportional hazards model. Malaria incidence among HEU infants aged 6-12 months was compared to that in other cohorts of HEU and HUU infants from the same region.Among 361 HEU infants enrolled, 248 completed 12 months of follow-up resulting in 1562 episodes of febrile illness and 253 episodes of malaria after 305 person-years of follow-up. The incidence of febrile illness was 5.12 episodes per person-year (PPY), ranging from 4.13 episodes PPY in the first 4 months of life to 5.71 episodes PPY between 5 and 12 months of age. The overall malaria incidence was 0.83 episodes per person-year (PPY), increasing from 0.03 episodes PPY in the first 2 months of life to 2.00 episodes PPY between 11 and 12 months of age. There were no episodes of complicated malaria. The prevalence of asymptomatic parasitaemia was 1.2 % (19 of 1568 routine smears positive). Infants born to mothers with parasites detected from placental blood smears were at higher risk of malaria (hazard ratio = 4.51, P < 0.001). HEU infants in this study had a 2.4- to 3.5-fold lower incidence of malaria compared to HUU infants in other cohort studies from the same area.The burden of malaria in this birth cohort of HEU infants living in a high-transmission setting and taking daily TS prophylaxis was relatively low. Alternative etiologies of fever should be considered in HEU-infants taking daily TS prophylaxis who present with fever. Trial Registration NCT00993031, registered 8 October, 2009.

Project description:BackgroundSymptomatic malaria cases reflect only a small proportion of all Plasmodium spp infections. Many infected individuals are asymptomatic, and persistent asymptomatic Plasmodium falciparum infections are common in endemic settings. We aimed to quantify the contribution of symptomatic and asymptomatic infections to P falciparum transmission in Tororo, Uganda.MethodsWe did a longitudinal, observational cohort study in Tororo district, Uganda. We recruited participants of all ages from randomly selected households within this district. Participants were eligible if the selected household had no more than nine permanent residents and at least two members younger than 10 years, and the household was their primary residence, and they agreed to come to the study clinic for any fever episode and avoid antimalarial medications outside the study. Participants were followed-up by continuous passive surveillance for the incidence of symptomatic infections; routine assessments (ie, standardised clinical evaluation and blood samples) were done at baseline and at routine visits every 4 weeks for 2 years. P falciparum parasite density, gametocyte density, and genetic composition were determined molecularly using quantitative PCR (qPCR), quantitative reverse transcriptase PCR (qRT-PCR), and amplicon deep sequencing, respectively. Membrane feeding assays were also done to assess infectivity to mosquitoes. The contribution of different populations to the infectious reservoir was estimated for symptomatic infections, asymptomatic but microscopically detected infections, and asymptomatic but qPCR-detected infections; and for age groups younger than 5 years, 5-15 years, and 16 years or older.FindingsBetween Oct 4, 2017, and Oct 31, 2019, 531 individuals were enrolled from 80 randomly selected households and were followed-up for 2 years. At baseline, P falciparum was detected in 28 (5·3%) of 531 participants by microscopy and an additional 64 (12·1%) by qPCR and declined thereafter. In 538 mosquito feeding experiments on 107 individuals, 446 (1·2%) of 37 404 mosquitoes became infected, with mosquito infection rates being strongly associated with gametocyte densities (β=2·11, 95% CI 1·62-2·67; p<0·0001). Considering both transmissibility of infections and their relative frequency, the estimated human infectious reservoir consisted primarily of asymptomatic microscopy-detected infections (83·8%), followed by asymptomatic submicroscopic infections (15·6%), and symptomatic infections (0·6%). Children aged 5-15 years accounted for more than half of the infectious reservoir (58·7%); individuals younger than 5 years (25·8%) and those 16 years or older (15·6%) contributed less. Samples from four children contribued to 279 (62·6%) of 446 infected mosquitoes after multiple mosquito-feeding assays.InterpretationIndividuals with asymptomatic infections were important drivers of malaria transmission. School-aged children contributed to more than half of all mosquito infections, with a small minority of asymptomatic children being highly infectious. Demographically targeted interventions, aimed at school-aged children, could further reduce transmission in areas under effective vector control.FundingUS National Institutes of Health, Bill & Melinda Gates Foundation, and the European Research Council.

Dataset Information

Community-wide Prevalence of Malaria Parasitemia in HIV-Infected and Uninfected Populations in a High-Transmission Setting in Uganda.

Publications

Community-wide Prevalence of Malaria Parasitemia in HIV-Infected and Uninfected Populations in a High-Transmission Setting in Uganda.

Similar Datasets

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