Behavioral patterns, parity rate and natural infection analysis in anopheline species involved in the transmission of malaria in the northeastern Brazilian Amazon region

Abstract

The characterization of behavioral patterns allows a better understanding of the transmission dynamics and the design of more effective malaria vector control strategies. This study analyzed the behavioral patterns of the Anopheles species of the Coração district situated in the northeast of the Brazilian Amazon region. The behavioral patterns of the anopheline species were measured based on the 36 collection sites of this district from December 2010 to November 2011. Collections of four hours for three consecutive nights each month and four 12-h collections, comprising two in the rainy season and two in the dry season, were performed. Furthermore, to infer the anthropophily and zoophily indexes, four additional four-hour collections were performed. The samples were also evaluated for parity rate and natural infectivity for Plasmodium spp. A total of 1689 anophelines were captured, comprising of nine species and two subgenera (Nyssorhynchus - six species, and Anopheles - three species). Anopheles darlingi was the most abundant and widely distributed species in the area, followed by A. braziliensis and A.marajoara. Anopheles darlingi and A. marajoara were the only species present in the four collections of 12-h, but only A. darlingi showed activity throughout night. Anopheles darlingi was the most anthropophilic species (AI=0.40), but the zoophily index was higher (ZI=0.60), revealing an eclectic and opportunistic behavior. Of the six most frequent species, A. nuneztovari s.l. was the most zoophilic species (ZI=1.00). All captured species showed predominance towards biting in outdoor environments. Anopheles darlingi and A. braziliensis showed multimodal biting peaks, whereas A. marajoara revealed a stable pattern, with the biting peak after sunset. Using the PCR technique, no anopheline was found infected with the malaria parasite. Since A. darlingi and A. marajoara are recognized as important vectors in this region, the district of Coração may be considered as a highly potent area for transmission of malaria, therefore, the prevention and surveillance measures should be taken constantly to prevent the same. The role of A. braziliensis as malaria vector needs to be urgently investigated.

An insight into the sialotranscriptome and virome of Amazonian anophelines

“…However, studies conducted in peri-urban areas of the city of Macapá, in the state of Amapá, Brazil, demonstrated that it can be a significant regional vector [9][10][11] as well as in Boa Vista, in the state of Roraima [12]. Supporting these findings, in the District of Coração, state of Amapá, A. marajoara was the most frequent species, together with A. darlingi and A. braziliensis, showing anthropophilic behavior and being captured in both indoor and outdoor environments [13,14].…”

“…Curiously, in the District of Coração, state of Amapá, A. braziliensis was one of the three most abundant and anthropophilic species. It was captured in both indoor and outdoor environments, although it was more abundant outdoors [14]. Thus, A. braziliensis may play some role in malaria transmission when at high density.…”

Exploring malaria vector diversity on the Amazon Frontier

“…Insufficient sampling meant that we could not attribute any significance to this structure. The local abundance of this species in the Amazon River basin varies considerably [ 37 , 67 , 70 ] but it appears to be common in human-modified environments [ 71 ]. The species is highly anthropophilic [ 37 ] and it has been found naturally infected with P .…”

“…A great variety of potential vectors have been recorded in the deforested areas of the Amazon [ 30 – 32 ], but the frequent occurrence of morphologically indistinguishable sibling species, which form species complexes [ 33 ], means that vectors are often misidentified or cryptic species boundaries go undetected [ 34 – 36 ]. Some vectors, such as Nyssorhynchus triannulatus and Anopheles peryassui , inhabit the forest edge, away from domestic environments and conventional vector control activities, but may be associated with human activity such as deforestation [ 37 ]. Failure to properly elucidate the diversity present in vector species complexes at locations where forest gives way to frontier settlements will likely obstruct the understanding of vector ecology and the Plasmodium transmission cycle associated with deforestation in the Amazon and impede efforts to develop strategies to control frontier malaria [ 10 , 38 ].…”

Genetic heterogeneity in Anopheles darlingi related to biting behavior in western Amazon

“…darlingi was considered essentially exophagic/endophagic or both. It also has presented resting behavior indoors (endophily) or outdoors (exophily) and a wide range of peak of biting times and patterns [23][24][25][26].…”