A study by Jaleta et al. in the Malaria Journal suggests that chickens may be helpful in the fight against malaria. Unlike humans who in the United States last year consumed 90 pounds of chicken each, mosquitos are a bit fussier. Who knew?
When dining indoors, the Anopheles species tested preferred humans, while for their al fresco dining, cattle was the main entrée. Very few, if any, choose chicken.
“Anopheles arabiensis is a selective blood feeder when host-seeking indoors, which prefers human blood and avoids cattle blood. In contrast, when found outdoors, An. arabiensis is an opportunistic blood feeder, randomly feeding on cattle, goats and sheep and avoiding humans. … While An. arabiensis feeds on many abundant vertebrate species, this study shows that it avoids chickens despite their relatively high abundance.”
Mosquitoes select their meal using their sense of smell, so that the “detected volatile profiles associated with the various hosts provide a chemical signature” to indicate excellent dining — evidently, the chicken does not qualify. In their testing, they found that eight bioactive compounds reduced mosquitoes caught in traps – as did suspending a caged chicken next to the traps.
Because of the effectiveness of anti-malarial programs, mosquitoes have shifted vectors from indoors to outdoors and from one species to another. Reminds us of our experience in the antimicrobial wars.
From their conclusions:
“Volatile compounds identified in the headspace extracts of chicken feathers appear to play a pivotal role in the observed non-host avoidance. Compounds that were able to disrupt the host-seeking behaviour of An. arabiensis included both chicken-specific and generic volatiles. This suggests that these volatiles function as medium- to long-range repellents.”
They did caution that the physical barrier of feathers, as well as the chicken's active interest in eating mosquitoes, could contribute to their findings. But the work strongly suggests that “Non-host volatiles, acting either as repellents or masking agents, can be developed to be used in concert with established integrated vector management programs.”
The lessons of escalation in the war against microbes – increasingly resistant organisms and increasingly toxic antibiotic “cures” is equally valid for mosquitoes as disease vectors. While the image of us walking around with chickens seems farcical, perhaps there is an avenue to pursue. Zika is carried by the Aedes aegypti mosquito who, like Anopheles, is not so fond of chicken.