ABSTRACT
Background: The blood-feeding patterns are crucial in incriminating disease vectors as well as facilitating the design and consolidation of effective vector control interventions in an area. Objective: This study aimed to establish if prolonged use of insecticide-treated bed nets (ITNs) caused a shift in the preferred hosts of the common malaria vectors as the hosts were under the bed net. Such a shift would render ITNs less effective and would probably explain the continued morbidity and mortality due to malaria in the highly endemic Kamuli district. Methods: A total of 3,519 indoor and outdoor human biting female Anopheles gambiae sensu latoand An. funestusmosquitoes were collected from 48 householdsusing human-baited bed net traps. All 187 indoor resting blood-fed anophelines collected were tested by direct enzyme-linked immunosorbent assay (ELISA) for blood meal host identification. Of these, 73 mid guts came from 24 households in villages with a 69% ITNs coverage, while 114 mid guts were from 24 households in non-ITN villages. Results: Blood meal hosts were identified in only 10.96% (n = 8) and 14.91% (n = 17) of the Anophelesblood meals from the intervention and non-intervention zones, respectively. Other blood meals could not be clearly identified. Eight (100%) blood meals in the intervention zone were from humans, while in the non-intervention zone, 15 (88.24%), one (5.88%) and one (5.88%) came from humans, cattle and goat, respectively. These findings demonstrated that the malaria vectors in Kamuli district are anthropophilic, with nearly all the mosquitoes collected from both zones feeding on humans during every blood meal (p = 0.82). This indicated high vector-human contacts, and thus implicating these species as important in the transmission of Plasmodiumspecies and probably other infections. Conclusion: The use of insecticide-treated bed nets is effective for controlling malaria vectors inside houses, evoking universal coverage of houses in the area.
ABSTRACT
Sixty used Long Lasting Insecticidal Nets (LLINs) from six malaria endemicareas of States and Regions of Myanmar were assessed for their bio-efficacy againstAnopheles mosquitoes. Total ten nets were collected from the randomly selectedhousehold of each area. Insecticide susceptibility and bio-efficacy test were doneaccording to WHO testing method. Results revealed that a total of 4470 mosquitoes of 12Anopheles species including main vector and secondary vectors were collected in highdensity in Beelin, Taungoo, Pyin Oo Lwin, Kamamaung and Hpa-an. All collectedmosquitoes were found susceptible to insecticides as recommended by the WHO. Bioefficacy of PermaNet 2.0, DAWA TANA, Yorkool, BASF, Net protect and Yahe LLINs netswere 12(100%), 11/12(91.67%), 4(100%), 8(100%), 5(100%) and 19(100%)respectively. The DAWA TANA net had 20% sensitivity after repetitive washing. Thesensitivity of LLINs nets was higher for all selected areas of States and Regions inMyanmar. The study suggested that there is need to distribute a large number of effectiveLLINs nets in malaria endemic areas as well as the replacement of expired, less effectiveand very old LLINs nets with a new one is also necessary. LLINs nets are very effectiveAnopheles mosquitoes control tools and it can reduce the human-vector contact effectively.Moreover, research on bio-efficacy evaluations of the LLINs nets is required regularly tomaintain and control the transmission of malaria through Anopheles mosquitoes.
ABSTRACT
Background: Malaria still remains a life-threatening disease worldwide causing between 190 and 311 million cases of malaria in 2008. Due to the ever increasing resistance to malaria drugs, source reduction has been recognized as a complementary approach to further reduce malaria transmission. Given that the availability of suitable habitats for the oviposition of anopheline mosquitoes increases their breeding and possibly malaria transmission. We proposed that characterizing the breeding site of Anopheles is of major importance for the transition from malaria control to elimination in our study area. However, information on the oviposition sites, characteristics and influencing factors of breeding sites of Anopheles mosquitoes is lacking. This study aimed to determine the preferential oviposition sites, breeding site characteristics and related environmental parameters. Methods: A study was undertaken in Abraka, Delta State to determine the preferential oviposition sites of Anopheles mosquito and characterize such sites. Potential larval habitats that might harbor anopheline immatures were sampled between August and September. The larval sampling was done by the standard dipping method. The habitats were characterized based on substrate type, turbidity, habitat type, algal coverage, canopy coverage, surrounding vegetation, surface debris and distance to the nearest house. A two way analysis of variance (ANOVA) was employed to test for significant difference in the occurrence of anopheline and culicine larvae in the different aquatic habitats sampled. Correlation analysis was used to assess the relationship between the environmental variables and the occurrence of the anopheline larvae in the habitats sampled and also to assess the relationship among the environmental variables examined. Results: A total of 80 aquatic habitats in 8 sites were sampled and 1117 anopheline and 370 culicine larvae were collected. Microscopic identification of the adult Anopheles mosquitoes yielded only Anopheles gambiae. There was no significant difference (P>0.05) in the occurrence of anopheline and culicine larvae in the different habitats sampled, but there was significant difference (P<0.05) for habitat type distribution for anophelines only and culicines only. Correlation analysis revealed that the occurrence of anopheline larvae was correlated with some of the environmental variables examined. Conclusion: The results obtained indicate that Anopheles gambiae prefers open, sunlit and undisturbed habitats for oviposition and that abiotic factors play a vital role in larvae’s habitat preference. Thus such factors should be considered when designing an integrated vector control programs.