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MDA reduces malaria incidence during Ebola outbreak
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A mass drug administration initiative conducted in Monrovia, Liberia, during the Ebola outbreak appeared to reduce the incidence of malaria throughout the city, according to recent study findings.
“While the number of confirmed Ebola cases in Monrovia began to decline in October 2014, malaria transmission continued and health care for non-Ebola illnesses including malaria remained limited,” Anna Kuehne, DrMed, MPH, epidemiologist at the Robert Koch Institute, Berlin, and colleagues wrote. “Thus, Médecins Sans Frontières initiated mass administrations of antimalarial drugs in cooperation with the Liberian [National Malaria Control Program] in four administrative zones of Monrovia, to decrease malaria-associated morbidity and mortality in order to mitigate the reduced access to general health care and reduce admissions to [Ebola treatment units] for malaria-associated fever.”
MDA effective despite low initiation rates
Médecins Sans Frontières conducted two rounds of mass drug administration (MDA), which involved raising community awareness and rapidly distributing prepared artesunate/amodiaquine treatments. To gauge the impact of this campaign, Kuehne and colleagues systematically surveyed a sample of households that participated in the intervention. The researchers asked respondents to report their adherence to the treatment, attitude toward household distribution, side effects and symptoms. Using these responses and distribution data, Kuehne and colleagues estimated the overall incidence of malaria and population compliance with the treatments.
Within the targeted distribution zones, Médecins Sans Frontières distributed more than 1.2 million courses within an estimated population of 558,483. There were 90,411 household vouchers redeemed for medication packs in the first round of treatment, and 89,546 exchanged in the second.
The researchers contacted and included 222 households consisting of 1,643 residents in the survey analysis. The median age of residents who could be re-identified during both distribution rounds was 16 years; 54% were female.
All of the households attended the first round of distribution, and 96% attended the second. Ninety percent of household members received sufficient medication during the first round, as opposed to 99% during round two. Initiation among household members who attended the MDA was 52% in the first round and 22% in the second, with 29% and 47% of household members, respectively, in the two rounds reporting that they did not initiate treatment because they wished to save it for later. Forty-eight percent of household members who received the treatment adhered to the full course in round one, while 21% did so in round two. Side effects among household members during round one did not affect initiation during the second round, after adjustment.
Incidence of self-reported fever episodes — the primary indicator of malaria prevention — decreased from 4.2% in the month before the first round to 1.5% afterward (P < .0001). This decline in self-reported fever occurred among those who did and did not take a full course of treatment, but was greater among the household members who did so (P < .001).
This MDA was among the largest conducted, the researchers wrote, and the first conducted using artesunate/amodiaquine. Although these data indicate its success despite the ongoing Ebola outbreak, they noted how complications related to the emerging disease may have complicated prevention efforts.
“Despite high acceptance and coverage of the MDA and the small impact of side effects, initiation of malaria chemoprevention was low, possibly due to health messaging and behavior in the pre-Ebola outbreak period and the ongoing lack of health care services,” Kuehne and colleagues wrote. “Stronger community involvement by dedicated local staff prior to the intervention and improved coordination with other actors in the target area may have been helpful in identifying relevant sensitization messages and hidden communities earlier, and could have possibly addressed misconceptions, fears and rumors more effectively.”
Malaria coinfection reduced Ebola mortality
While this MDA and other preventive efforts looked to reduce the impact of malaria during the Ebola outbreak, recently published data suggest there may be an unexpected survival benefit for coinfected patients.
In their study, Emmie de Wit, PhD, of the National Institute of Allergy and Infectious Diseases’ Laboratory of Virology, and colleagues reviewed laboratory data collected from patients at a Médecins Sans Frontières Ebola treatment unit. They analyzed molecular diagnostic results against demographic data to identify any factors significantly associated with the clinical outcome of these patients.
Analysis of 956 samples for Plasmodium spp. revealed a 19% rate of coinfection. These patients were frequently younger (P = .0001) and demonstrated a greater rate of survival than those who were monoinfected (58% vs. 46%; P = .007). Further, patients with higher levels of parasitemia, as determined by cycle threshold, appeared to have even greater rates of survival. The effect of coinfection on survival held up in a multivariate analysis controlling for patient age and Ebola cycle threshold (adjusted RR = 1.2; 95% CI, 1.1-1.4).
All patients at the Ebola treatment unit were treated with antimalarial drugs regardless of coinfection, and the researchers observed no evidence of malaria drug-related survival benefits in an accompanying mouse model. According to the researchers, this could indicate that the increase in survival rates is likely due to interactions with the parasites themselves, as opposed to malaria care.
“The link between Plasmodium spp. coinfection and survival of Ebola virus infection clearly warrants further investigation into the mechanism(s) underlying this phenomenon,” they wrote. “If increased survival is indeed due to an immunomodulatory effect of Plasmodium spp. coinfection, immunomodulatory drugs could be investigated as potential options for supportive therapy to alleviate Ebola virus infection once the mechanism is better understood.” – by Dave Muoio
Disclosure: The researchers report no relevant financial disclosures.
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