title: Evidence for undetected malaria infection in non-immune Australian travellers not taking chemoprophylaxis.
abstract: To determine whether travellers from malaria-free countries can develop unrecognised or asymptomatic malaria after visiting endemic areas, we analysed data from 751 prospective blood donors who had visited or resided in malaria-risk areas in the previous 3 years. Malarial antibodies were measured using an established commercial enzyme-linked immunoassay incorporating four recombinant blood-stage plasmodial antigens and with published sensitivity > or =83% and specificity 100%. Details of countries visited and antimalarial chemoprophylaxis used were obtained by questionnaire. Among the 606 subjects resident in malaria-free countries and with no past history of malaria, 176 had visited high-risk countries as categorised by the World Health Organisation (WHO). Of these, 89 took no chemoprophylaxis including 6 (6.7%) who were antibody-positive; there were no antibody-positive subjects in the 87 who took chemoprophylaxis (P=0.029), which was that recommended by WHO in 84% of cases. These data underscore the value of effective antimalarial prophylaxis in non-immune travellers visiting high malaria-risk areas but also suggest that unrecognised infections can occur in those unprotected by chemoprophylaxis.
authors.affiliation: Australian Red Cross Blood Service, 97 Great Eastern Highway Rivervale, Western Australia 6103, Australia. cseed@arcbs.redcross.org.au
authors.forename: Clive R
authors.initials: CR
authors.lastname: Seed
authors.forename: Juliana
authors.initials: J
authors.lastname: Hamzah
authors.forename: Timothy M E
authors.initials: TM
authors.lastname: Davis
mesh_terms: D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood; D001782:Blood Donors; D018890:Chemoprevention; D019353:Endemic Diseases; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D008288:Malaria / Q000097:blood / Q000175:diagnosis* / Q000453:epidemiology / Q000517:prevention & control; D010961:Plasmodium / Q000302:isolation & purification*; D016036:Seroepidemiologic Studies; D014195:Travel; D014904:Western Australia / Q000453:epidemiology
chemical_list: D000913:Antibodies, Protozoan