Integrated Mapping of Neglected Tropical Diseases: Epidemiological Findings and Control Implications for Northern Bahr-el-Ghazal State, Southern Sudan

Abstract

BackgroundThere are few detailed data on the geographic distribution of most neglected tropical diseases (NTDs) in post-conflict Southern Sudan. To guide intervention by the recently established national programme for integrated NTD control, we conducted an integrated prevalence survey for schistosomiasis, soil-transmitted helminth (STH) infection, lymphatic filariasis (LF), and loiasis in Northern Bahr-el-Ghazal State. Our aim was to establish which communities require mass drug administration (MDA) with preventive chemotherapy (PCT), rather than to provide precise estimates of infection prevalence.Methods and FindingsThe integrated survey design used anecdotal reports of LF and proximity to water bodies (for schistosomiasis) to guide selection of survey sites. In total, 86 communities were surveyed for schistosomiasis and STH; 43 of these were also surveyed for LF and loiasis. From these, 4834 urine samples were tested for blood in urine using Hemastix reagent strips, 4438 stool samples were analyzed using the Kato-Katz technique, and 5254 blood samples were tested for circulating Wuchereria bancrofti antigen using immunochromatographic card tests (ICT). 4461 individuals were interviewed regarding a history of ‘eye worm’ (a proxy measure for loiasis) and 31 village chiefs were interviewed regarding the presence of clinical manifestations of LF in their community. At the village level, prevalence of Schistosoma haematobium and S. mansoni ranged from 0 to 65.6% and from 0 to 9.3%, respectively. The main STH species was hookworm, ranging from 0 to 70% by village. Infection with LF and loiasis was extremely rare, with only four individuals testing positive or reporting symptoms, respectively. Questionnaire data on clinical signs of LF did not provide a reliable indication of endemicity. MDA intervention thresholds recommended by the World Health Organization were only exceeded for urinary schistosomiasis and hookworm in a few, yet distinct, communities.ConclusionThis was the first attempt to use an integrated survey design for this group of infections and to generate detailed results to guide their control over a large area of Southern Sudan. The approach proved practical, but could be further simplified to reduce field work and costs. The results show that only a few areas need to be targeted with MDA of PCT, thus confirming the importance of detailed mapping for cost-effective control.

Prevalence and risk factors of Schistosoma haematobium infections among primary school children in Igbokuta Village, Ikorodu North Local Government, Lagos State.

“…In addition, mean age of infected pupils ranges from 7.5 ± 1.89 to 8.4 ± 2.02 and heavier among pupils of 7.5 ± 1.89 to 8.7 ± 2.05 years ( Table 2). As reported by other scholars 28,29 , the prevalence of urinary schistosomiasis is highest among primary school pupils in age groups 8-11 years and lowest among pupils of age range 12-15. This may be due to improved habits, low level of exposure and the development of naturally acquired anti-S. haematobium antibodies as age progresses 36 .…”

Soil-transmitted helminthiasis in Latin America and the Caribbean: modelling the determinants, prevalence, population at risk and costs of control at sub-national level

“…There is a need for statistical and geospatial tools that can accurately characterise the size and spatial distribution of the population-at-risk of STH infection, including stratification of areas by infection risk, in order to implement cost-effective control measures on a large scale (Brooker and Michael, 2000;Brooker et al, 2006). Increasingly, geographical information systems (GIS) are being employed to understand, model and predict the distribution and trends of infectious diseases in general and helminthiases in particular, to serve as inputs for programmatic decision-making Brooker, 2007;Sturrock et al, 2009;Zhou et al, 2009). Furthermore, several attempts have been made to quantify the burden 2 , the population in need of MDA 3 and the resource needs for the control 4 of STH at the global, regional, national and sub-national levels.…”

Climate Change and Health Research in the Eastern Mediterranean Region

“…Lymphatic filariasis, also transmitted by mosquitoes, affects approximately 0.4 million people in Egypt, Sudan, and the Republic of Yemen combined (El Setouhy and Ramzy, 2003;Sturrock et al, 2009). Similar to malaria, temperature plays an important role in the density of vector populations and transmission patterns for lymphatic filariasis (Lindsay and Thomas, 2000), dengue fever, and RVF (IPCC, 2007).…”

“…The geographic distribution of Leishmaniasis vectors have changed during the past two decades (Klaus et al, 1999;IPCC, 2007) and the disease is reemerging in Afghanistan, Iran, Saudi Arabia, Sudan, the Syrian Arab Republic, and Tunisia (Rathor, 2000;Sturrock et al, 2009). A recent study conducted in northwest Iran reported a strong association between rising temperatures and rising populations of carrier-sandflies that cause leishmaniasis (Oshaghi et al, 2009).…”