The Importance of Drains for the Larval Development of Lymphatic Filariasis and Malaria Vectors in Dar es Salaam, United Republic of Tanzania

Abstract

BackgroundDar es Salaam has an extensive drain network, mostly with inadequate water flow, blocked by waste, causing flooding after rainfall. The presence of Anopheles and Culex larvae is common, which is likely to impact the transmission of lymphatic filariasis and malaria by the resulting adult mosquito populations. However, the importance of drains as larval habitats remains unknown.MethodologyData on mosquito larval habitats routinely collected by the Urban Malaria Control Program (UMCP) and a special drain survey conducted in 2006 were used to obtain a typology of habitats. Focusing on drains, logistic regression was used to evaluate potential factors impacting the presence of mosquito larvae. Spatial variation in the proportion of habitats that contained larvae was assessed through the local Moran's I indicator of spatial association.Principal FindingsMore than 70% of larval habitats in Dar es Salaam were human-made. Aquatic habitats associated with agriculture had the highest proportion of Anopheles larvae presence and the second highest of Culex larvae presence. However, the majority of aquatic habitats were drains (42%), and therefore, 43% (1,364/3,149) of all culicine and 33% (320/976) of all anopheline positive habitats were drains. Compared with drains where water was flowing at normal velocity, the odds of finding Anopheles and Culex larvae were 8.8 and 6.3 (p<0.001) times larger, respectively, in drains with stagnant water. There was a positive association between vegetation and the presence of mosquito larvae (p<0.001). The proportion of habitats with mosquito larvae was spatially correlated.ConclusionRestoring and maintaining drains in Dar es Salaam has the potential to eliminate more than 40% of all potential mosquito larval habitats that are currently treated with larvicides by the UMCP. The importance of human-made larval habitats for both lymphatic filariasis and malaria vectors underscores the need for a synergy between on-going control efforts of those diseases.

Prevalence of mosquitoes (diptera: culicidae) in and around Bangladesh Agricultural University campus of Mymensingh in Bangladesh

“…jayporiensis (0.8%) were very low. The similar abundance of these species also observed in different studies by Castro et al (2010) in Dar Es Salaasm, Tanzania and Bashar et al (2005) in rural areas around Jahangirnagar University, Bangladesh.…”

Impact of Community-Based Larviciding on the Prevalence of Malaria Infection in Dar es Salaam, Tanzania

“…Other strategies included in an IVM approach could facilitate the use of larviciding. For example, in Dar es Salaam 33% of Anopheles breeding habitats are found in clogged drains [66]. In this context, the use of environmental management to restore the functionality of drains would result in fewer breeding habitats [43], and therefore reduce the area to be covered with larviciding.…”

The cross-cutting contribution of the end of neglected tropical diseases to the sustainable development goals

“…These can come from the faeces and urine of human and reservoir hosts, such as cows and buffalos, making it important to protect freshwater from animals and their waste. Poorly-constructed latrines facilitate the breeding of Culex mosquitoes, causing great nuisance as well as being efficient vectors of lymphatic filariasis and some viruses [91]. Replacement of pit latrines with modern toilets would contribute to a reduction in nuisance biting and transmission reduction [92].…”