Molecular Malaria Epidemiology: Mapping and Burden Estimates for the Democratic Republic of the Congo, 2007

BackgroundEpidemiologic data on malaria are scant in many high-burden countries including the Democratic Republic of the Congo (DRC), which suffers the second-highest global burden of malaria. Malaria control efforts in regions with challenging infrastructure require reproducible and efficient surveillance. We employed new high-throughput molecular testing to characterize the state of malaria control in the DRC and estimate childhood mortality attributable to excess malaria transmission.Methods and FindingsThe Demographic and Health Survey was a cross-sectional, population-based cluster household survey of adults aged 15–59 years in 2007 employing structured questionnaires and dried blood spot collection. Parasitemia was detected by real-time PCR, and survey responses measured adoption of malaria control measures and under-5 health indices. The response rate was 99% at the household level, and 8,886 households were surveyed in 300 clusters; from 8,838 respondents molecular results were available. The overall prevalence of parasitemia was 33.5% (95% confidence interval [C.I.] 32–34.9); P. falciparum was the most prevalent species, either as monoinfection (90.4%; 95% C.I. 88.8–92.1) or combined with P. malariae (4.9%; 95% C.I. 3.7–5.9) or P. ovale (0.6%; 95% C.I. 0.1–0.9). Only 7.7% (95% CI 6.8–8.6) of households with children under 5 owned an insecticide-treated bednet (ITN), and only 6.8% (95% CI 6.1–7.5) of under-fives slept under an ITN the preceding night. The overall under-5 mortality rate was 147 deaths per 1,000 live births (95% C.I. 141–153) and between clusters was associated with increased P. falciparum prevalence; based on the population attributable fraction, 26,488 yearly under-5 deaths were attributable to excess malaria transmission.ConclusionsAdult P. falciparum prevalence is substantial in the DRC and is associated with under-5 mortality. Molecular testing offers a new, generalizable, and efficient approach to characterizing malaria endemicity in underserved countries

Prevalence of Human African Trypanosomiasis in the Democratic Republic of the Congo

Human African Trypanosomiasis (HAT) is a major public health problem in the Democratic Republic of the Congo (DRC). Active and passive surveillance for HAT is conducted but may underestimate the true prevalence of the disease. We used ELISA to screen 7,769 leftover dried blood spots from a nationally representative population-based survey, the 2007 Demographic and Health Survey. 26 samples were positive by ELISA. Three of these were also positive by trypanolysis and/or PCR. From these data, we estimate that there were 18,592 people with HAT (95% confidence interval, 4,883–32,302) in the DRC in 2007, slightly more than twice as many as were reported

Spatial and socio-behavioral patterns of HIV prevalence in the Democratic Republic of Congo

This study uses a 2007 population-based household survey to examine the individual and community-level factors that increase an individual's risk for HIV infection in the Democratic Republic of Congo (DRC). Using the 2007 DRC Demographic Health Surveillance (DHS) Survey, we use spatial analytical methods to explore sub-regional patterns of HIV infection in the DRC. Geographic coordinates of survey communities are used to map prevalence of HIV infection and explore geographic variables related to HIV risk. Spatial cluster techniques are used to identify hotspots of infection. HIV prevalence is related to individual demographic characteristics and sexual behaviors and community-level factors. We found that the prevalence of HIV within 25 km of an individual's community is an important positive indicator of HIV infection. Distance from a city is negatively associated with HIV infection overall and for women in particular. This study highlights the importance of improved surveillance systems in the DRC and other African countries along with the use of spatial analytical methods to enhance understanding of the determinants of HIV infection and geographic patterns of prevalence, thereby contributing to improved allocation of public health resources in the future.HIV Congo Spatial analysis Sexual behaviors

Individual and cluster characteristics by malaria endemicity.

<p>Values are expressed as percentages unless otherwise indicated; those in parentheses are 95% confidence intervals. ITN, insecticide-treated bednet.</p>a<p>Quintiles of 1 (poorest) – 5 (wealthiest) based on household ownership of goods owned and lodging characteristics.</p>b<p>Includes mixed-species parasitemias.</p

Geographic clusters from which households were selected for sampling.

<p>Geographic clusters from which households were selected for sampling.</p

Malaria indices from household survey.

<p>Proportions weighted to account for sampling design. ITN, insecticide-treated bednet. HIV, human immunodeficiency virus. ACT, artemisinin-combination therapy.</p

Under-5 mortality and malaria endemicity.

<p>A. U5MR (deaths per 1000 live births) by survey cluster. B. Cluster U5MR by adult <i>P. falciparum</i> prevalence. Black dots represent actual U5MRs, weighted relative to the number of births in each cluster; black line represents trend line from an unadjusted linear regression model (R² = 0.0538; p<0.001) weighted for differences in numbers of births between clusters (gray area is 95% confidence interval). C. Cluster U5MR by malaria endemicity category. Boxes represent interquartile range, midline is median, individual dots are outliers. p = 0.001 for overall comparison of medians by Kruskal-Wallis analysis of variance.</p

Spatial epidemiology of <i>P. falciparum</i>, <i>ovale</i>, and <i>malariae</i> parasitemias.

<p>Parasite prevalence within 300 survey clusters. (note difference in visual scales). A. <i>P. Falciparum</i>. B. <i>P. ovale</i>. C. <i>P. malariae.</i></p

Results of a multilevel model of cluster-level indicators on under-5 deaths.

<p>C.I.: confidence interval. Odds ratios are adjusted for other covariates. 1^st quartile are clusters with the lowest proportion of the indicated variable, 4^th quartile with the highest proportion of the indicated variable. All children born to female respondents in or since 2003 were included (n = 8290).</p>a<p>Proportion of adults in each cluster who were parasitemic with <i>P. falciparum</i> by real-time PCR testing.</p>b<p>Proportion children under 5 in each cluster who had ever received any vaccination for any disease (as reported by the child's mother).</p>c<p>Proportion of children under 5 in each cluster who had diarrhea, fever, or cough in the preceding two weeks, (as reported by the child's mother).</p

Penetration of malaria control measures.

<p>(note difference in visual scales). A. Proportion of households with children under 5 years of age by cluster who reported owning an insecticide-treated net. B. Proportion of children under 5 years of age by cluster that were reported to have slept under an insecticide-treated net the night prior to the survey. C. Proportion of pregnant women by cluster who reported sleeping under an insecticide-treated net the night prior to the survey. D. Proportion of women by cluster who reported taking any antimalarial during their most recent pregnancy within the preceding 5 years.</p