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Malaria coinfection reduced mortality during Ebola outbreak
Ebola patients coinfected with malaria appeared to have greater survival rates than those without detectable Plasmodium spp. parasites, according to a recently published analysis.
“Although we found a positive association between Plasmodium spp. parasitemia and survival of Ebola virus infection in our cohort, this effect was not affected by treatment with antimalarials,” Kyle Rosenke, PhD, molecular biologist at the NIH, and colleagues wrote. “Thus, our data currently do not warrant changing the guidelines for treatment of malaria in patients with suspected, probable and confirmed Ebola virus infection.”
With the infrastructure of West African’s public health damaged by the Ebola outbreak, malaria infection within this endemic region likely increased and resulted in a subset of coinfected patients, Rosenke and colleagues wrote. To understand coinfection and other patient-level factors of Ebola, the researchers 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.
Rosenke and colleagues examined 1,182 patient samples with molecularly confirmed Ebola virus infection. Forty-eight percent of these patients survived their infection, with greater survival rates reported among women (P = .007) and those aged 5 years to 39 years (P = .007). Higher cycle thresholds — which the researchers said may serve as a proxy for low viral load — was a predictor of survival in univariate analysis (P < .0001).
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).
Emmie de Wit, one of the study authors, is shown using a sealed glovebox to inactivate virus in patient blood samples prior to testing for Ebola.
Source: NIAID
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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