Early control of new malaria vector critical, expert warns

Prof Richard Mukabana, a senior researcher at African Institute for Development Policy (Afidep).

Households and government agencies should take a proactive role to prevent the spread of a new invasive species of mosquitoes discovered in Kenya, a top malaria expert has warned.

Prof Richard Mukabana, a senior researcher at African Institute for Development Policy (Afidep) told the Nation that the threat posed by the Anopheles stephensi is real and steps taken at the earliest opportunity could prove effective in the long run.

On February 10, Kenya Medical Research Institute (Kemri) announced the presence of the highly invasive malaria vector that thrives in both urban and rural areas. Research conducted in all counties in December last year found the new species in Laisami and Saku, Marsabit County.

 “Following its detection in Kenya, there is a likelihood of malaria transmission occurring in urban and peri-urban set-ups in the country. The new mosquito poses a serious threat and could reverse the gains made in the fight against malaria,” Kemri warned.

 Prof Mukabana now says the possibility of urban infections from this mosquito overrunning the healthcare systems should worry everybody. The mosquito species that transmit malaria in Kenya—Anopheles gambiae and Anopheles funestus— are mainly found in rural areas.

“Existing tools may work as well, but it’s important to fight larvae control more; that is to kill mosquitoes before they start flying around. We will also need to borrow a lot more from control strategies of their points of origin,” Prof Mukabana said.

 According to Kemri, the mosquito mainly breeds in containers such as jerry cans, tyres, open tanks, sewers, cisterns, overhead tanks and underground tanks. This is in contrast to the known malaria mosquitoes in Kenya that breed in water pools, rice paddies, streams, surface run-offs, tyre tracks and hoof prints.

 “In rural areas, it will take a lot of mosquitoes to reach humans who are spread far and in between. In urban areas, their effort is far much less, and this would mean you could easily have a large number of people affected,” said Prof Mukabana.

Dr Edna Ototo, a parasitologist who has done a number of studies on mosquitoes, said that existing interventions should be expanded even to non-endemic regions like urban areas.

“In as much as vector surveillance needs to be increased, we have to continue working on control and prevention of malaria. If you have stagnant water at home, ensure that you drain it. If you live near swamps, plant vegetation around it. Our water tanks at home should be covered, they are breeding areas for mosquitoes,” she explained.

 Prof Mukabana explained that in as much as it is not yet fully confirmed which of the various malaria-causing plasmodium parasites the new species carries, it is clear from their bionomics that they are adapted for disease transmission.

 “The urban type is undoubtedly much better in transmission than their rural form. Its arrival in an urban setting like Nairobi for instance, could be quite the game-changer,” he warned.

Earlier genetic analysis of the breed in other countries indicated two offshoots of the same species, one in India and another in Pakistan which later spread to Djibouti. It is the India-Pakistani species that has found its way into Kenya.

Prof Mukabana said countries would do well to adopt cross-border vector control measures to avoid the spread of the breed.

 “Mosquitos truly do not know borders. It is therefore necessary that governments talk, and enhance policy dialogue among their research institutions to ensure informed decisions,” he said.