Hyperreactive malaria in expatriates returning from sub-Saharan Africa

The extreme presentation of hyperreactive malaria is hyperreactive malarial splenomegaly syndrome (HMS). Some patients present with a less pronounced syndrome. To investigate whether the degree of splenomegaly correlates with the degree of immune stimulation, whether prophylaxis or recent treatment play a role, and whether short therapy alone is effective, we examined retr ospectively the medical records of expatriates with exposure to P. falcipar um who attended our outpatient department from 1986 to 1997, particularly s ubacute symptoms or signs, strongly elevated malarial antibodies and elevat ed total serum IgM. We analysed duration of stay, prophlyaxis intake, splee n size, serum IgM levels and response to antimalarial treatment. Serum IgM levels were significantly higher in patients with larger splenomegaly. The use of chloroquine alone as treatment for presumptive or proved malaria att acks was correlated with larger spleen size. Short adequate antimalarial th erapy resulted in marked improvement or complete recovery In nine patients the hyperreactive response reappeared after re-exposure, in four of them tw ice. We conclude that patients with subacute symptoms but without gross spl enomegaly may have very high levels of IgM and malarial antibodies, and rel apse on re-exposure, suggesting the existence of a variant of the hyperreac tive malarial splenomegaly syndrome without gross splenomegaly.