Prevalence of Malaria Parasite Infections among U.S.-Bound Congolese Refugees with and without Splenomegaly

All U.S.-bound refugees from sub-Saharan Africa receive presumptive antimalarial treatment before departing for the United States. Among U.S.-bound Congolese refugees, breakthrough malaria cases and persistent splenomegaly have been reported. In response, an enhanced malaria diagnostic program was instituted. Here, we report the prevalence of plasmodial infection among 803 U.S.-bound Congolese refugees who received enhanced diagnostics. Infections by either rapid diagnostic test (RDT) or PCR were detected in 187 (23%) refugees, with 78 (10%) by RDT only, 35 (4%) by PCR only, and 74 (9%) by both. Infections identified by PCR included 103 monoinfections (87 Plasmodium falciparum, eight Plasmodium ovale, seven Plasmodium vivax, and one Plasmodium malariae) and six mixed infections. Splenomegaly was associated with malaria detectable by RDT (odds ratio: 1.8, 95% CI: 1.0-3.0), but not by PCR. Splenomegaly was not strongly associated with parasitemia, indicating that active malaria parasitemia is not necessary for splenomegaly.

Clinical Sequelae Associated with Unresolved Tropical Splenomegaly in a Cohort of Recently Resettled Congolese Refugees in the United States-Multiple States, 2015-2018

Tropical splenomegaly is often associated with malaria and schistosomiasis. In 2014 and 2015, 145 Congolese refugees in western Uganda diagnosed with splenomegaly during predeparture medical examinations underwent enhanced screening for various etiologies. After anecdotal reports of unresolved splenomegaly and complications after U.S. arrival, patients were reassessed to describe long-term clinical progression after arrival in the United States. Post-arrival medical information was obtained through medical chart abstraction in collaboration with state health partners in nine participating states. We evaluated observed splenomegaly duration and associated clinical sequelae between 130 case patients from eastern Congo and 102 controls through adjusted hierarchical Poisson models, accounting for familial clustering. Of the 130 case patients, 95 (73.1%) had detectable splenomegaly after arrival. Of the 85 patients with records beyond 6 months, 45 (52.9%) had persistent splenomegaly, with a median persistence of 14.7 months (range 6.0-27.9 months). Of the 112 patients with available results, 65 (58.0%) patients had evidence of malaria infection, and the mean splenomegaly duration did not differ by Plasmodium species. Refugees with splenomegaly on arrival were 43% more likely to have anemia (adjusted relative risk [aRR]: 1.43, 95% CI: 1.04-1.97). Those with persistent splenomegaly were 60% more likely (adjusted relative risk [aRR]: 1.60, 95% CI: 1.15-2.23) to have a hematologic abnormality, particularly thrombocytopenia (aRR: 5.53, 95% CI: 1.73-17.62), and elevated alkaline phosphatase (aRR: 1.57, 95% CI: 1.03-2.40). Many patients experienced persistent splenomegaly, contradicting literature describing resolution after treatment and removal from an endemic setting. Other possible etiologies should be investigated and effective treatment, beyond treatment for malaria and schistosomiasis, explored.