Validity of malaria diagnosis in nonimmune travelers in endemic areas.
BACKGROUND
Malaria has to be considered in all febrile travelers during or after a stay in endemic areas. However, malaria diagnosis in endemic countries may be inaccurate due to limited capacity and lack of resources of local health services. To assess the validity of malaria diagnosis in travelers in endemic areas, we investigated the retrospective confirmation of malaria by detection of specific antibodies.


METHODS
Sera of 105 nonimmune travelers who presented between 2003 and 2005 with a history of diagnosis and treatment of malaria during a stay in malaria-endemic countries within the previous 6 months were analyzed for antibodies against Plasmodium falciparum and Plasmodium vivax blood forms by an indirect immunofluorescence test. About 241 follow-up sera from 176 nonimmune patients with microscopically confirmed malaria served as a control group.


RESULTS
Antibodies against plasmodia were detectable within 180 days after reported date of diagnosis and treatment in 16 of 105 travelers (15.2%) only. In the control group, 71.6% of analyzed sera (151 of 211) showed positive results within this interval. Within 8 to 60 days after diagnosis of malaria, the seropositivity rates were 17.9% for travelers (n = 56) and 92.4% for controls (n = 92).


CONCLUSIONS
Although the sensitivity of malaria serology for retrospective confirmation of malaria is limited, the results of this analysis strongly suggest that the majority of travelers with a recent history of malaria diagnosed and treated in endemic countries did not have malaria and that diagnosis of malaria during travel in endemic areas is frequently incorrect.
Miranda
Isabel Barreto
IB
Department of Infectious Diseases and Tropical Medicine, Ludwig Maximilians University, Munich, Germany. barretomiranda@lrz.uni-muenchen.de
Weber
Christine
C
Fleischmann
Erna
E
Bretzel
Gisela
G
Löscher
Thomas
T
D000293:Adolescent; D000328:Adult; D000368:Aged; D000818:Animals; D000953:Antigens, Protozoan / Q000097:blood*; D002648:Child; D002675:Child, Preschool; D019353:Endemic Diseases; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D016778:Malaria, Falciparum / Q000175:diagnosis* / Q000453:epidemiology; D016780:Malaria, Vivax / Q000175:diagnosis* / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D010963:Plasmodium falciparum / Q000276:immunology*; D010966:Plasmodium vivax / Q000276:immunology*; D012680:Sensitivity and Specificity; D014195:Travel; D055815:Young Adult
D000953:Antigens, Protozoan