Mosquito species abundance and diversity in Malindi, Kenya and their potential implication in pathogen transmission

Abstract

Mosquitoes (Diptera: Culicidae) are important vectors of human disease-causing pathogens. Mosquitoes are found both in rural and urban areas. Deteriorating infrastructure, poor access to health, water and sanitation services, increasing population density, and widespread poverty contribute to conditions that modify the environment, which directly influences the risk of disease within the urban and peri-urban ecosystem. The objective of this study was to evaluate the mosquito vector abundance and diversity in urban, peri-urban, and rural strata in Malindi along the Kenya coast. The study was conducted in the coastal district of Malindi between January and December 2005. Three strata were selected which were described as urban, peri-urban, and rural. Sampling was done during the wet and dry seasons. Sampling in the wet season was done in the months of April and June to cover the long rainy season and in November and December to cover the short rainy season, while the dry season was between January and March and September and October. Adult mosquito collection was done using Pyrethrum Spray Collection (PSC) and Centers for Disease Control and Prevention (CDC) light traps inside houses and specimens were identified morphologically. In the three strata (urban, peri-urban, and rural), 78.5% of the total mosquito (n = 7,775) were collected using PSC while 18.1% (n = 1,795) were collected using the CDC light traps. Using oviposition traps, mosquito eggs were collected and reared in the insectary which yielded 329 adults of which 83.8% (n = 276) were Aedes aegypti and 16.2% (n = 53) were Culex quinquefasciatus. The mosquito distribution in the three sites varied significantly in each collection site. Anopheles gambiae, Anopheles funestus and Anopheles coustani were predominant in the rural stratum while C. quinquefasciatus was mostly found in urban and peri-urban strata. However, using PSC and CDC light trap collection techniques, A. aegypti was only found in urban strata. In the three strata, mosquitoes were mainly found in high numbers during the wet season. Further, A. gambiae, C. quinquefasciatus, and A. aegypti mosquitoes were found occurring together inside the houses. This in turn exposes the inhabitants to an array of mosquito-borne diseases including malaria, bancroftian filariasis, and arboviruses (dengue fever, Yellow fever, Rift Valley fever, Chikungunya fever, and West Nile Virus). In conclusion, our findings provide useful information for the design of integrated mosquito and disease control programs in East African environments.

Mosquito Vector Diversity across Habitats in Central Thailand Endemic for Dengue and Other Arthropod-Borne Diseases

“…Other studies that have compared mosquito communities across human-modified landscapes focused on urban, semi-urban, and rural environments also showed that urban environments are the least diverse [39], [45], [46], [47]. The mechanisms underlying this pattern are not well understood, but some have suggested the positive effect of habitat diversity on mosquito species diversity [48], [49], or that increased stress and pollution in urban habitats favor certain invasive genera such as Culex , which is more adaptable to a variety of habitats and may competitively exclude other species [50], [51], [52].…”

Shifts in malaria vector species composition and transmission dynamics along the Kenyan coast over the past 20 years

“…The data collected during these periods was standardized to show mean indoor-resting mosquito densities over different periods. The study areas have been described in detail elsewhere [15,19-22,24-27,29-34]. Briefly, the coastal plain is made up of dense forest, savannah type vegetation, seasonal swamps, dry thorn bush, and a number of plantations interspersed with uncultivated land.…”

“…Mean annual precipitation ranges from 750 to 1,200 mm [34]. Over the past 20 years, people living in near proximity to the Sabaki and Jaribuni rivers have started small-scale irrigated agriculture.…”

Factors Contributing to Urban Malaria Transmission in Sub-Saharan Africa: A Systematic Review

“…Furthermore, areas of low socioeconomic status, often at the periphery of cities, are at particular risk. Here, poor-quality housing, unpaved roads, and reduced access to healthcare provide little protection against the disease [9]. …”