Imported Malaria in Travelers Presenting to a Tertiary Urban Hospital, 2000–2016

Abstract

Background. Due to increasing global travel and evolving epidemiologic factors, the number of incident cases of malaria imported into the United States has been growing in recent years. Methods. We conducted a retrospective review of 90 cases of malaria seen at a single urban university hospital during 2000-2016. Results. Of the 90 cases, 77% were Plasmodium falciparum, 14% were either P. ovale or P. vivax, 1% was P. malariae, and the rest were mixed or unknown. Eighty-one patients had traveled to Africa, four to Asia, four to more than one continent, and one to Haiti. Mean age was 41, and 59% were male. The main presenting symptoms were fever (92%), chills (78%), and headache (66%); 10% presented with cerebral malaria. Thirteen cases were managed as outpatients, 59 on a medical ward, and 18 in the ICU. Fourteen (16%) had severe malaria; these were more likely to present with hypotension, non-segmented neutrophilia, hyponatremia, metabolic acidosis, and acute kidney injury (all P < 0.01). Thrombocytopenia was more severe in patients with severe malaria (54,000 vs. 113,000, P < 0.01). Treatment included quinine-based therapy (38%), atovaquone/ proguanil (31%), artemether/lumefantrine (19%), and chloroquine/primaquine (11%). Twenty (22%) required change of treatment regimen due to inadequate clinical response or adverse effects. The most common in-hospital complications were ARDS (8%), QT prolongation (7%), and nosocomial infection (4%). Two patients were pregnant at the time of presentation; one suffered severe malaria and fetal loss. Only 3% of patients reported being prescribed a prophylactic regimen and completing it; 20% reported taking an incomplete course, and the majority took no prophylaxis at all. Of 27 patients who had presented to another United States-based medical provider prior to hospitalization, 11 were initially misdiagnosed and treated for conditions other than malaria, including two who underwent extensive hematologic investigations. Inadequate experience and resources in treating malaria were the primary reasons cited for transfer to the tertiary hospital from community-based providers. Conclusion. Malaria poses a substantial health risk to US travelers, particularly in light of under-utilization of prophylaxis, lack of familiarity with the disease by local providers, and delays to diagnosis.