Urban lymphatic filariasis in the metropolis of Dar es Salaam, Tanzania

Abstract

BackgroundThe last decades have seen a considerable increase in urbanization in Sub-Saharan Africa, and it is estimated that over 50% of the population will live in urban areas by 2040. Rapid growth of cities combined with limited economic resources often result in informal settlements and slums with favorable conditions for proliferation of vectors of lymphatic filariasis (LF). In Dar es Salaam, which has grown more than 30 times in population during the past 55 years (4.4 million inhabitants in 2012), previous surveys have indicated high prevalences of LF. This study investigated epidemiological aspects of LF in Dar es Salaam, as a background for planning and implementation of control.MethodsSix sites with varying distance from the city center (3–30 km) and covering different population densities, socioeconomic characteristics, and water, sewerage and sanitary facilities were selected for the study. Pupils from one public primary school at each site were screened for circulating filarial antigen (CFA; marker of adult worm infection) and antibodies to Bm14 (marker of exposure to transmission). Community members were examined for CFA, microfilariae and chronic manifestations. Structured questionnaires were administered to pupils and heads of community households, and vector surveys were carried out in selected households.ResultsThe study indicated that a tremendous decrease in the burden of LF infection had occurred, despite haphazard urbanisation. Contributing factors may be urban malaria control targeting Anopheles vectors, short survival time of the numerous Culex quinquefasciatus vectors in the urban environment, widespread use of bed nets and other mosquito proofing measures, and mass drug administration (MDA) in 2006 and 2007. Although the level of ongoing transmission was low, the burden of chronic LF disease was still high.ConclusionsThe development has so far been promising, but continued efforts are necessary to ensure elimination of LF as a public health problem. These will include improving the awareness of people about the role of mosquitoes in transmission of LF, more thorough implementation of environmental sanitation to reduce Cx. quinquefasciatus breeding, continued MDA to high-risk areas, and set-up of programmes for management of chronic LF disease.

Current Epidemiological Assessment of Bancroftian Filariasis in Tanga Region, Northeastern Tanzania

“…In Figure 4, young age groups (18–31 years) have increasing acute and chronic infections. A similar observation has been shown in Fiji [14]. These are the productive segment in the communities indicating a shifting trend of the clinical disease into the lower age groups because low-level transmission continues in those communities.…”

“…This could be possibly due to some existing hotspots in the communities whereby mosquito vectors pick infection from humans and maintain the local transmission [15]. It is also likely that the postponement of the MDA distribution within the timely scheduled period could have halted reaching the desired coverage of at least 65% according to the WHO, hence leading to LF resurgence [14]. It is vital to expand the frequency of drug administration to a maximum of three doses per year, expand the age range of the target population, and improve health education to the community with the aim of increasing coverage within the targeted areas.…”

Prevalence of Wuchereria bancrofti Infection in Mosquitoes from Pangani District, Northeastern Tanzania

“…quinquefasciatus was the most abundant vector species caught during the study. These observations concur with a study carried out in Dar es Salaam, 22 which reported that out of 12,096 vector mosquitoes caught using light traps, the great majority (99.0%) were Cx. quinquefasciatus, followed by a few Anopheles gambiae (0.9%) and Anopheles funestus (0.1%).…”

Knowledge, attitudes and perceptions regarding lymphatic filariasis: study on systematic noncompliance with mass drug administration

“…However, despite their knowledge of LF, this did not seem to affect their low compliance with MDA. Studies conducted on populations in endemic areas in India 29 , Tanzania 30 and Malaysia 31 revealed that there were individuals with little or no awareness of LF, even though the areas were considered endemic.…”