Abstract
BackgroundBlood-feeding patterns of mosquitoes are crucial for incriminating malaria vectors. However, little information is available on the host preferences of Anopheles mosquitoes in Bangladesh. Therefore, the objective of the present study was to determine the hematophagic tendencies of the anophelines inhabiting a malaria-endemic area of Bangladesh.MethodsAdult Anopheles mosquitoes were collected using light traps (LTs), pyrethrum spray (PS), and human bait (HB) from a malaria-endemic village (Kumari, Bandarban, Bangladesh) during the peak months of malaria transmission (August-September). Enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR) were performed to identify the host blood meals of Anopheles mosquitoes.ResultsIn total, 2456 female anopheline mosquitoes representing 21 species were collected from the study area. Anopheles vagus Doenitz (35.71%) was the dominant species followed by An. philippinensis Ludlow (26.67%) and An. minimus s.l. Theobald (5.78%). All species were collected by LTs set indoors (n = 1094), 19 species were from outdoors (n = 784), whereas, six by PS (n = 549) and four species by HB (n = 29). Anopheline species composition significantly differed between every possible combination of the three collection methods (χ2 test, P < 0.001). Host blood meals were successfully detected from 1318 (53.66%) Anopheles samples belonging to 17 species. Values of the human blood index (HBI) of anophelines collected from indoors and outdoors were 6.96% and 11.73%, respectively. The highest values of HBI were found in An. baimai Baimaii (80%), followed by An. minimus s.l. (43.64%) and An. annularis Van den Wulp (37.50%). Anopheles baimai (Bi = 0.63) and An. minimus s.l. (Bi = 0.24) showed strong relative preferences (Bi) for humans among all hosts (human, bovine, goats/sheep, and others). Anopheles annularis, An. maculatus s.l. Theobald, and An. pallidus Theobald exhibited opportunistic blood-feeding behavior, in that they fed on either humans or animals, depending on whichever was accessible. The remaining 12 species preferred bovines as hosts.ConclusionsThe observed high anthropophilic nature of An. baimai, An. minimus s.l., and An. annularis revealed these species to be important malaria vectors in hilly areas of Bangladesh. Higher values of HBI in outdoor-resting mosquitoes indicated that indoor collection alone is not adequate for evaluating malaria transmission in the area.
Highlights
Blood-feeding patterns of mosquitoes are crucial for incriminating malaria vectors
2456 female anopheline mosquitoes belonging to 21 species were collected using light traps (LTs), pyrethrum spray (PS), and human bait (HB) (Table 1)
Comparisons between LTs and HB indicated that An. philippinensis and An. minimus s.l. were collected more often in HB (c2 test, P < 0.05), whereas five species (An. vagus, An. peditaeniatus, An. barbirostris, An. karwari and An. umbrosus) were collected more frequently with LTs (c2 test, P < 0.05); catches of two species did not significantly differ between the two methods
Summary
Blood-feeding patterns of mosquitoes are crucial for incriminating malaria vectors. little information is available on the host preferences of Anopheles mosquitoes in Bangladesh. Thirteen of 64 districts bordering India and Myanmar are severely affected by malaria [1]. The districts of Chittagong, Rangamati, Khagrachari, Bandarban, and Cox’s Bazar are hyperendemic, whereas the districts of Kurigram, Sherpur, Mymensingh, Netrakona, Sylhet, Sunamgonj, Moulvibazar, and Hobiganj are prone to low-level epidemics. Most infections are caused by Plasmodium falciparum in all districts except for Kurigram, where P. vivax (75.07%) is dominant [3]. The highest incidence of P. falciparum (93.16%) in Bangladesh has been reported from the three hilly districts (Bandarban, Khagrachari, and Rangamati) [4]. The average malaria prevalence in these three districts is 11.7% (Figure 1) [1], and these areas remain highly conducive to malaria due to uncontrolled immigration, political unrest, and hilly terrain
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