Malaria in Nonimmune Travelers

Background: With the current increase of international travel to
tropical endemic areas, the incidence of malaria being imported
into nonendemic countries has increased significantly. Disagreement
concerning malaria chemoprophylaxis and inadequate knowledge of
malarious areas, morbidity, and pretravel advise has led to
confusion among both health professionals as well as travelers.
Therefore, this study was conducted to investigate malaria imported
into Germany by identifying the high-risk endemic areas, clinical
presentations, and chemoprophylactic and therapeutic regimens
related to reported cases. Methods: Between 1990 and 1993, the 160
nonimmune travelers, all German nationals or residents for more
than 10 years, presenting to our travel clinic with microscopically
confirmed malaria were investigated. For each, the travel history,
chemoprophylaxis used during travel, symptoms, pathological
diagnosis, and treatment efficacy were analyzed. Results: Africa
(73%), Asia (21%), and Central South America (6%) were the endemic
countries visited by our patients, of whom only 3% used the
chemoprophylaxis recommended for their destination. Plasmodium
falciparum was the most common pathogen, found in more than half of
our patients, and P. vivax (29%), P. ova le (6%), P. malariae(6%),
a mixed infection with P.falciparum and P vivax (3%) were also
detected. All patients presented with fever and headaches, a
majority with profuse night sweats, insomnia, arthralgias, and
myalgias, and diarrhea and abdominal cramps were experienced in 13%
and 8%, respectively. In falciparum malaria, a recrudescence was
observed in all patients who received chloroquine only, whereas
quinine, halofantrine, and mefloquine were highly effective. In
vivax malaria, a relapse rate of 14% was noted in the patients
treated with the currently recommended regimen of chloroquine and
primaquine. Conclusions: Visitors to endemic countries, especially
to Africa, are of significant risk. Given the low compliance rate
of chemoprophylaxis, a high percentage of malaria in our patients
could have been avoided by an appropriate prophylaxis regimen and
optimal pretravel counseling.