Background: The 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.
Methods: Six 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.
Results: The 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.
Conclusions: The 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.