Changing epidemiological and clinical aspects of imported malaria in Belgium

Background: In the early nineties the increase of imported malaria in some European countries was temporarily halted, but it resumed in 1994. More Afr icans, more European travelers, and fewer long-term residents were counted amongst patients. A shift towards more subacute disease has been noted. Thi s study intends to assess whether the same trends were observed in Belgium. Methods: Clinical and epidemiological data of 128 patients treated for mala ria in 1997 at the Institute of Tropical Medicine and the University Hospit al of Antwerp were compared with 209 malaria patients treated in 1988/1989. Risk factors for clinical presentation and parasitemia were analysed. Results: In Belgium the number of reported imported malaria cases remained almost stable between 1988 and 1997. In 1997, there were more African patie nts, less infections from Central Africa, and 50% less residents. Less pati ents reported prophylaxis use. The causative agent shifted from Plasmodium falciparum to other species. Subacute and atypical malaria became less freq uent. In both years, there were no deaths, and severe malaria did not incre ase significantly. Mefloquine disappeared almost as a curative treatment, a nd was replaced by quinine, with or without a long acting agent, or by halo fantrine. The ethnic origin, nor the use of chemoprophylaxis, influenced disease char acteristics. In 1988, malaria attacks in the previous months predisposed to subacute disease; longer residence, and attacks in the previous months, pr otected against high parasitemia; longer symptom duration correlated with a bsence of fever, and with splenomegaly. None of these risk factors was corr elated with severe malaria. Conclusion:The incidence of subacute malaria dropped significantly in the l ast decade. Although this presentation is almost limited to residents, the decline in malaria can not be explained by an overall shorter duration of s tay, since the decline in this particular clinical presentation of malaria was also spectacular in residents. Apparently, insufficient treatment of ma laria attacks in the previous months is the only independent risk factor.