Larval habitats, species composition and distribution of malaria vectors in regions with autochthonous and imported malaria in Roraima state, Brazil

Abstract

Background Malaria control requires local action. Assessing the vector diversity and abundance provides information on the local malariogenic potential or risk of transmission. This study aimed to determine the Anopheles species composition, habitats, seasonal occurrence, and distribution in areas with autochthonous and imported malaria cases in Roraima State. Methods A longitudinal study was conducted from January 2017 to October 2018, sampling larvae and adult mosquitoes in three municipalities of Roraima State: Boa Vista, Pacaraima and São João da Baliza. These areas have different risks of malaria importation. Four to six mosquito larval habitats were selected for larval sampling at each municipality, along with two additional sites for adult mosquito collection. All larval habitats were surveyed every two months using a standardized larval sampling methodology and MosqTent for adult mosquitoes. Results A total of 544 Anopheles larvae and 1488 adult mosquitoes were collected from the three municipalities studied. Although the species abundance differed between municipalities, the larvae of Anopheles albitarsis s.l., Anopheles nuneztovari s.l. and Anopheles triannulatus s.l. were collected from all larval habitats studied while Anopheles darlingi were collected only from Boa Vista and São João da Baliza. Adults of 11 species of the genus Anopheles were collected, and the predominant species in Boa Vista was An. albitarsis (88.2%) followed by An. darlingi (6.9%), while in São João da Baliza, An. darlingi (85.6%) was the most predominant species followed by An. albitarsis s.l. (9.2%). In contrast, the most abundant species in Pacaraima was Anopheles braziliensis (62%), followed by Anopheles peryassui (18%). Overall, the majority of anophelines exhibited greater extradomicile than peridomicile-biting preference. Anopheles darlingi was the only species found indoors. Variability in biting times was observed among species and municipalities. Conclusion This study revealed the composition of anopheline species and habitats in Boa Vista, Pacaraima and São João da Baliza. The species sampled differed in their behaviour with only An. darlingi being found indoors. Anopheles darlingi appeared to be the most important vector in São João da Baliza, an area of autochthonous malaria, and An. albitarsis s.l. and An. braziliensis in areas of low transmission, although there were increasing reports of imported malaria. Understanding the diversity of vector species and their ecology is essential for designing effective vector control strategies for these municipalities.

Little noticed, but very important: The role of breeding sites formed by bamboos in maintaining the diversity of mosquitoes (Diptera: Culicidae) in the Atlantic Forest biome

“…Culex pereyrai can also be found on riverbanks, where the current is slow [ 75 ]. Anopheles albitarsis is considered a generalist species in terms of breeding sites, which can even use transient breeding sites formed by the accumulation of rainwater, puddles, and permanent breeding sites such as lakes [ 76 , 77 ]. Meanwhile, Ps .…”

Malaria Resilience in South America: Epidemiology, Vector Biology, and Immunology Insights from the Amazonian International Center of Excellence in Malaria Research Network in Peru and Brazil

“…Likewise, at a different geographic scale, preliminary studies in the case of migrants in the North of Brazil support the notion that vectors modulate the effect of migrants on local transmission. 78 In particular, areas that receive a significant influx of migrants have many imported malaria cases, but that does not translate into a spike of local cases following the massive introduction of infected individuals simply because the local vector is not very efficient at breeding in proximity to those infected individuals. Thus, assessing the impact of human mobility on regional malaria resilience requires the novel integration of parasite, epidemiological, and entomological data.…”