Kenya is experimenting with unconventional methods to tackle high malaria rates through the piloting of mass drug administration (MDA) - treating entire communities with anti-malarial drugs, regardless of whether they have the parasite.
The project is an initiative of the newly created Malaria Elimination Consortium of Western Kenya, founded in 2013 by the US Centers for Disease Control (CDC), Kenya Medical Research Institute (KEMRI), and other partners, and is set to be rolled out at the beginning of next year.
MDA has been considered a malaria control mechanism for over a century, with studies on MDA usage dating back to 1914. But more recently, with the availability of transmission-reducing antimalarials, scientists are beginning to refocus on the possibility of using mass treatment to eradicate the disease in areas where other methods have been unable to have a large impact.
In Siaya County in western Kenya, where MDA will be introduced, a large percentage of the population who are healthy nevertheless harbour the malaria parasite and can be transmitters to others, especially children, who have no immunity to malaria.
Siaya has by far the highest malaria burden in the country, with approximately 33 percent of under-5 children, 56 percent of those aged 5-15, and 22 percent of those above 15 carrying the malaria parasite in their blood, according to KEMRI research.
“Though not officially endorsed by WHO [World Health Organization], MDA is being considered and tested as a strategy to reduce the burden of malaria with the goal of elimination,” noted the CDC.
“We want to evaluate whether MDA can be an additional tool in tackling the disease. MDA will clear parasites from people so that mosquitoes will have no parasites to pick from people who have been treated when they bite. When these mosquitoes bite other people, they will have no parasites to transfer, thus reducing transmission,” Simon Kariuki, a senior scientist with KEMRI’s Centre for Global Health Research (CGHR), told IRIN by email.
MDA will be used as part of a holistic effort to introduce new treatments to curb malaria rates, and will be implemented alongside other approaches such as using long-lasting insecticide-treated nets, indoor residual spraying, and treating people with a drug called ivermectin. Mosquitos that bite someone who has invermectin in their blood system will weaken and die more rapidly, reducing the spread of malaria.
Coverage needs to be high
But, for the MDA initiative to succeed, Kariuki says, as many people need to be treated as possible, and compliance levels need to be high.
“If coverage is low, then transmission will not be interrupted, since there will be many people walking around with the parasites in their blood,” he said. “If people do not complete the full treatment course, the parasites will not be cleared in their blood and they will continue acting as a reservoir of parasites for mosquitoes to pick when they bite them.”
While WHO has in the past advocated MDA in situations where more conventional control measures have failed to end residual transmission, concern that there is insufficient evidence to indicate an overall benefit, and fears of acceleration of drug resistance among populations have led the organization to be cautious about the approach.
A 2013 meta-review of MDA studies by the Cochrane Collaboration found that while “MDA of antimalarials using therapeutic doses have an immediate and short-term impact on parasitaemia prevalence… optimum transmission scenarios and drug intervention regimens for producing a sustained impact with MDA remain largely unknown.”
But MDA can be useful, the researchers argue, especially in areas like western Kenya, where there are high numbers of people who do not show any signs of malaria.
“Because these people do not have symptoms, they do not seek medical care or receive treatment to clear parasites. These people act as sources [reservoirs] of parasites that are picked by mosquitoes during blood feeding and therefore sustain the transmission of malaria,” said Meghna Desai, malaria program director, CDC-Kenya. In Siaya County, up to 50 percent of individuals carrying the malaria parasite report not having had a fever any time in the past two weeks, according to community based surveys, KEMRI notes.
Therefore, the researchers believe that if MDA works in western Kenya, it can be a model for other countries with large proportions of populations that are asymptomatic. “If malaria can be tackled in Siaya County, experts think there is a chance that malaria can be tackled not only in Kenya, but also around the world, and can eventually be eliminated,” said Kariuku in a press statement.
The project is supported by the US Agency for International Development (USAID), the President’s Malaria Initiative, and the Bill and Melinda Gates Foundation.
Similar pilot programmes have worked well in Zambia, Senegal and Ethiopia, but there are also a number of logistical challenges to implementing it in Kenya. The initiative is costly, labour intensive, and difficult to implement among certain populations.
“Health workers will have [a] hard time finding mobile groups like fishermen, commercial cyclists [boda boda], business people and school-going children. If such groups represent large populations which are not treated, the impact of MDA could be minimal,” said Kariuki. “Poor transport networks too will be a challenge.”
“Even in settings with highly efficacious drugs, the overall field effectiveness of MDA will be greatly compromised if high coverage of the target population is not achieved,” noted the authors of the Cochrane study.
“Educating the community in the planning and execution of the programme, having specific groups of the treatment teams visiting schools and churches or working over the weekends or visiting houses early in the morning or late in the evening to cover the hard-to-reach groups is critical,” Kariuki added.