A Cluster of Plasmodium ovale Infections in Belgian Military Personnel after Deployment in Kindu, Democratic Republic of Congo: A Retrospective Study

Plasmodium ovale malaria is often neglected due to its less severe course compared to Plasmodium falciparum. In 2011–2012, Belgian Armed Forces identified a cluster of P. ovale cases among military personnel after deployment in the Democratic Republic of Congo (DRC). In this retrospective, monocentric, observational study, clinical and biological features of soldiers diagnosed with P. ovale after deployment in DRC were reviewed. Species diagnosis was based on polymerase chain reaction (PCR) and/or thick blood smear. Medical records of 149 soldiers screened at the Queen Astrid Military Hospital after deployment were reviewed. Eight cases (seven P. ovale infections and one P. ovale—falciparum coinfection) were identified. All had positive thick smears, and seven were confirmed by PCR. Chemoprophylaxis was mefloquine in all subjects. Median time of disease onset was 101 days after return from the endemic region. Median delay between return and diagnosis was 103 days. All P. ovale bouts were uncomplicated. None had relapses after primaquine treatment. This military cohort highlights a hotspot of P. ovale in Eastern DRC. Non-specific symptoms, the less severe presentation, the lack of sensitive parasitological tools in the field and long delays between infection and symptoms probably lead to underestimation of P. ovale cases.