Scientists researching malaria in western Kenya have gone back to the drawing board following a stagnation in malaria prevalence.

Data collected by the Kenya Medical Research Institute (Kemri) in collaboration with the Atlanta, Us-based Centre for Disease Control and Prevention (CDC) in 2013 shows that the number of people carrying parasites in their blood is still 35 per cent in children below five, 56 per cent in those aged five and 15 and 22 per cent in those above 15.

These results make western Kenya one of the regions with the highest burden of malaria in the country and also the biggest source of malaria nationally.

According to Simon Kariuki, a senior scientist at the Kisumu-based Centre for Global Health Research (CGHR), at Kemri, following the widespread introduction of long-lasting insecticide-treated nets, the burden of malaria has significantly reduced in many parts of the country, but transmission in western Kenya remains high. For over 30 years, Kemri and CDC have been conducting malaria research and surveillance in Siaya, Western Kenya.

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In this area, Dr Kariuki says the community prevalence of the malaria parasite P. falciparum parasitemia (the number of people with parasites in their blood) among children below five years declined from 70 per cent in 1997 to around 40 per cent in 2008. But since 2008, transmission intensity and malaria prevalence has stagnated.

Now the Kemri researchers contend that for malaria rates to drop further, scaling up control strategies and introduction of new strategies is needed. For this reason, the Malaria Elimination Consortium, Western Kenya (MEC-WK) has been established in partnership with the government.

Each partner brings a unique set of skills and expertise in malaria control and research. The idea behind the initiative is to optimise the existing interventions while introducing new strategies based on strong scientific evidence, creating ownership of malaria control in the community and the government and having a co-ordinated approach to malaria control in the area.

Activities planned in the next year include the provision of treated bed nets, uninterrupted access to malaria diagnostics and constant supply of effective medicine to prevent and treat malaria.

“An important part of this strategy will be to ensure malaria cases in the community are detected early and treated promptly by community health workers,” said Dr Kariuki.

“Information on these cases will be sent to the Ministry of Health using smartphones to allow experts to see where malaria ‘hotspots’ are so that additional help can be channelled to there.”

Western Kenya has a high number of people who are asymptomatic (carrying the malaria parasite but having no symptoms) and up to 50 per cent of parasitemic individuals in community-based cross-sectional surveys report not having fever anytime during the previous two weeks.

“Because these people do not have symptoms, they do not seek medical care or receive treatment to clear the parasites. They act as sources of parasites that are picked up by mosquitoes during feeding and therefore sustain the transmission of malaria” said Meghna Desai, Malaria Programme director at CDC-Kenya.

Removing mosquitoes that transmit malaria to humans is another strategy that will be important to reduce the burden of malaria.

“This is best done through indoor residual spraying (IRS). Traditionally, IRS has not been a malaria control strategy in this area,” noted Dr Desai.

However, based on available scientific evidence, experts believe that IRS represents an important additional way of controlling malaria in the region.