Difficulties in the prevention, diagnosis, and treatment of imported malaria

Background: Imported malaria is quite common in the United States. Increasi ng antimalarial drug resistance and changes in travel patterns may have imp ortant implications for the prevention, clinical presentation, and manageme nt of this disease. Methods: Medical records were reviewed for 121 patients with microscopicall y confirmed malaria diagnosed at 2 university-affiliated hospitals in San F rancisco, Calif, between 1988 and 1997. Results: Among 57 travelers from the United States, only 13 (23%) had been compliant with an appropriate chemoprophylactic regimen. No patients develo ped falciparum malaria after consistent chemoprophylactic therapy with mefl oquine hydrochloride. However, 12 (19%) of US residents with imported malar ia developed Plasmodium vivax or Plasmodium ovale infections despite an app ropriate chemoprophylactic regimen, generally with a late onset suggestive of relapsing disease. Clinical presentations were similar between foreign r esidents and American travelers and between patients with falciparum and no nfalciparum infections; 98% of patients had a history of fever. Sixteen per cent of patients had received previous evaluations during which the diagnos is of malaria was not considered. In 9% of patients, there were errors in t reatment. Only I patient developed severe malaria. Conclusions: Our results suggest that a standard chemoprophylactic regimen is highly effective in preventing falciparum malaria, but that many America n travelers do not receive it. Also, relapsing P vivax or P ovale infection despite appropriate chemoprophylactic therapy was not uncommon among our c ases. The presentation of imported malaria is nonspecific, highlighting the need to consider the diagnosis in any febrile patient who has been in a ma laria-endemic area. Although errors in diagnosis and treatment were quite c ommon in our study population, patient outcomes were good once the appropri ate therapy was initiated.