Imported malaria treated in Melbourne, Australia: Epidemiology and clinical features in 246 patients

Background: Imported malaria is increasing in nonendemic countries, includi ng Australia. The objective of this study was to describe the epidemiology and clinical features of travelers with imported malaria presenting to a sp ecialist infectious diseases hospital. Methods: A retrospective case series of 246 consecutively admitted inpatien ts with laboratory confirmed malaria. The main outcome measures were the pr oportion of patients infected with each malaria species, and relationship b etween species and country of birth, area of acquisition, adequacy of chemo prophylaxis, clinical features, laboratory investigations, and treatment. Results: Plasmodium vivax caused 182 (68.9%) episodes, Plasmodium falciparu m caused 71 (26.9%), Plasmodium ovale caused 5 (1.9%), and Plasmodium malar iae 1 (0.4%). Fifty-six percent of patients reported chemoprophylaxis use. People born in a country with endemic malaria (36.6%) were less likely to h ave used chemoprophylaxis. Malaria was most commonly acquired in Papua New Guinea and Southeast Asia, The median times to diagnosis after return to Au stralia for P. falciparum and P. vivax infections were 1 and 9 weeks respec tively. The longest interval between last arrival in Australia and presenta tion with P. falciparum malaria was 32 weeks. Fever (96%), headache (74%), and a tender or palpable spleen (40%), were the most common clinical featur es. Diarrhea was more common in P falciparum, and rigors in P. vivax infect ions. Thrombocytopenia (71%), abnormal liver function tests and an elevated C-reactive protein (85%) were common. Six patients had severe falciparum m alaria but no deaths occurred during the study period. Conclusions: Malaria remains a health threat for those traveling in endemic areas and is associated with failure to use chemoprophylaxis appropriately . Nonspecific clinical features may lead to delayed diagnosis and misdiagno sis. Malaria should be suspected in the febrile traveler, regardless of bir thplace, prophylaxis, symptomatology, or the time that has elapsed since le aving the malarious area.