Sharing bedroom with chicken will keep mosquitoes at bay, study says

The smell of chicken by your bedside could be an effective control measure to keep away mosquitoes.

In a study carried out in East Wollega Zone of western Ethiopia and findings released on Thursday, scientists found out that one of the main species that transmits malaria in sub-Saharan Africa known as Anopheles Arabiensis avoided chicken when looking for hosts.

They discovered that there were repelling chemicals in chicken that mosquitoes avoid, a principle that could be used as an additional malaria prevention strategy.

Titled, Chicken Volatiles Repel Host-seeking Malaria Mosquitoes, the study published in the Malaria Journal investigated ways to prevent mosquitoes from reaching the host where they would transmit malaria.

“Anopheles mosquitoes primarily use their sense of smell to locate suitable hosts. Qualitative differences in the detected volatile profiles associated with the various hosts provide a chemical signature on which female host selection relies,” read excerpts of the study that explain how the mosquito chooses a host to bite.

The scientists noted that by studying the kind of hosts mosquitoes chose to bite from humans to chicken, cattle and other domestic animals were used to develop bait technologies for control of the Anopheles mosquito.

Control strategies

Whereas the scientists noted that the widespread use of indoor residual spraying (IRS) and insecticide-treated bed nets (ITNs) have led to a significant reduction in the main vector of malaria, they were looking for additional new vector control strategies based on sustained modification of mosquito behaviour.

Kenya Medical Research Unit Chief Research Officer Andrew Githeko welcomed the findings of the study, adding that the principles of repulsion of mosquitoes by chicken smell by chemicals known as volatiles could be used to keep mosquitoes at bay.

“It is not wise to keep chicken by your bedside but the same knowledge can be translated to come up with chemicals that can be sprayed in houses or smeared on walls to keep the nuisance mosquitoes away from man,” Dr Githeko said in an interview with The Standard on Saturday.

Dr Githeko defined volatiles as odours or chemicals released by animals or plants that are detected by insects as a signal that the host is unfriendly and thus can be used to create a repellent.

“When this smell gets to the mosquito, it communicates that the animal or chicken is unsuitable for biting, thus it moves to the next most preferred host who is man,” Dr Githeko said.

Dr Githeko also attributed the unsuitability of the chicken as a probable host for the malaria parasite due to its physiological and behavioural factors.

“Birds like chicken also have an interesting way of keeping away mosquitoes by vigorously flapping their wings when attacked, thus creating a hostile environment for the mosquito to transmit the malaria-causing parasite,” Dr Githeko added.

The findings in Ethiopia come with ongoing research to develop a malaria vaccine candidate known as RTSS, which is designed to prevent the malaria parasite from infecting, maturing and multiplying in the liver, after which the parasite would normally re-enter the bloodstream and infect red blood cells, leading to disease symptoms.

Cause of illness

The RTSS vaccine candidate is intended to complement existing measures to fight malaria, such as bed nets and indoor residual insecticide spraying. The final results of a pivotal, large-scale Phase 3 efficacy and safety trial were published in The Lancet in April 2015; they showed that if used correctly, the vaccine candidate “has the potential to prevent millions of cases of malaria”. Though preventable, malaria is a curable and life-threatening disease caused by parasites that are mostly transmitted through the infected female Anopheles Gambie mosquito species.

Anopheles mosquitoes lay their eggs in water, which then hatch into larvae, eventually emerging as adult mosquitoes. The female mosquitoes seek a blood meal to nurture their eggs.

Malaria is a leading cause of illness and death in Kenya, with Nyanza, Western Kenya and Coast regions cited as having a high burden especially in children, non-immune pregnant women, people with HIV/AIDS and international travellers from non-endemic areas.

Those who live in the highlands have also been known to get a type of the disease known as highland malaria because they have low immunity.