Molecular identification of Plasmodium spp. and blood meal sources of anophelines in environmental reserves on São Luís Island, state of Maranhão, Brazil

Abstract

BackgroundConsidering the diversity of feeding habits that females of some species of anophelines present, it is important to understand which vertebrates are part of blood food sources and how important is the role of each in the ecoepidemiology of malaria. There are many vector species for Plasmodium spp. in the State of Maranhão, Brazil. In São Luís Island, Anopheles aquasalis is the main vector for human malaria; this species is abundant in areas with primates that are positive for Plasmodium. Anopheles aquasalis has natural exophilic and zoophilic feeding behavior, but in cases of high density and absence of animals, presents quite varied behavior, and feeds on human blood. In this context, the objective of the present study was to identify Plasmodium spp. and the blood meal sources of anophelines in two environmental reserves on São Luís Island, state of Maranhão, using molecular methods.MethodsBetween June and July 2013, female anophelines were collected in the Sítio Aguahy Private Reserve, in the municipality of São José de Ribamar, and in the Sítio Mangalho Reserve, located within the Maracanã Environmental Protection Area, in the municipality of São Luís. CDC-type light traps, Shannon traps and protected human bait were used during three consecutive hours in peridomestic and wooded areas. Pools of anophelines were formed using mosquitoes of the same species that had been caught at the same site on the same date. A genus-specific amplification protocol based on the 18S rRNA gene was used for qPCR and cPCR.ResultsA total of 416 anophelines were collected, of the following species: An. aquasalis (399), An. mediopunctatus (3), An. shannoni (1), An. nuneztovari (sensu lato) (1), An. goeldii (1), An. evansae (2) and An. (Nyssorhynchus) sp. (9), comprising 54 pools. Two pools were positive for Plasmodium (2/54) based on the 18S rRNA gene. In the phylogenetic analysis using the maximum likelihood method, based on a 240 bp fragment of the 18S rRNA gene, it was found that the sequences of Plasmodium sp. amplified from pools of An. aquasalis (pool 2) and An. nuneztovari (s.l.) (pool 10) were phylogenetically related to a clade of P. falciparum isolates from India, and to a clade of Plasmodium sp. isolates from psittacines in Brazil, respectively. Cat, dog and human DNA were identified in the blood meals of the anophelines sampled.ConclusionThe species An. aquasalis was the most abundant anopheline species in São Luís Island. Plasmodium spp. DNA was detected, thus confirming the importance of this species as the main vector on São Luís Island, Brazil. In addition, the presence of An. nuneztovari (s.l.) with DNA positive for Plasmodium spp. confirms its importance as a secondary vector.

Outbreak of autochthonous cases of malaria in coastal regions of Northeast Brazil: the diversity and spatial distribution of species of Anopheles

“…However, when it is present in large numbers in the absence of animals, the mosquito also uses human blood as a source of food. This is possibly what happened in Conde during this malaria outbreak, as the species also shows some degree of anthropophilia [ 14 , 31 ]. This peculiarity has been observed in other anopheline mosquitoes, including mosquitoes of the An.…”

“…However, the latter proved to be extremely effective in the present study. Targeted collection using the mouth aspirator in peri- and extradomicile areas was the only method that collected all species found in the locality, thereby demonstrating both the efficiency of this method of capture and the exophilic behavior of these mosquitoes [ 14 , 31 ]. Such behavior is reflected in the density and diversity of the species, showing that these species were found in greater abundance and diversity in the best-preserved areas located at some distance from urban agglomerations.…”

Identification of Plasmodium spp. in Neotropical primates of Maranhense Amazon in Northeast Brazil

“…Thus, malaria as a zoonotic disease should be seen not only as a public health problem, but also as one of environmental conservation, encompassing preservation of the wild environment, hosts and vectors, in order to preserve the balance in these areas. Through extinction or decreased populations of nonhuman primates, vector mosquitoes have the alternative of replace their primatophilic food source with an anthropophilic source, as has been reported with other hosts [ 65 , 66 ], and thus the disease may come to present epidemiological characteristics of greater severity.…”

Forêts tropicales, changements d’usage des sols et risques infectieux émergents

“…Dans la forêt atlantique brésilienne, P. simium avait été décrit chez les singes de la famille des Atelidés [24], puis chez les singes de deux autres familles, celles des Cébidés et des Callithricidés [34,35]. La proximité génétique démontrée de P. simium avec P. vivax [36] a remis en avant la possibilité d'infection de l'humain par le parasite simien, voire à suggérer que le complexe P. vivax/simium, comme le complexe P. malaria/brasilianum, devaient être bien considérés comme des zoonoses [37]. Ces éléments changent aujourd'hui la vision que l'on a du cycle du genre Plasmodium, et interrogent sur le rôle des modifications d'habitats et d'écosystèmes sur la transmission de ce type de parasite.…”