[Plasmodium falciparum malaria attacks with low or negative parasitemia on returning from areas of endemic resistance to 4-aminoquinolines]. / Accès palustres à Plasmodium falciparum à parasitémie faible ou nulle au retour de régions d'endémie de résistance aux amino-4-quinoléines.

Twelve recent cases of Plasmodium falciparum malaria presented with unusual clinical and laboratory features. All patients had regularly been taking adequate doses of amino-4-quinolines as prophylaxis. In most cases the symptoms were mild as compared with those in a group of 20 control patients with typical malaria. More surprisingly, parasitaemia was either negative or very weakly positive (less than 1000 infested erythrocytes per mm3). All cases occurred in people returning from areas in which resistance of P. falciparum to these drugs is endemic. Diagnostic problems could be solved in most patients by new immunological techniques relying on the detection of parasitized erythrocytes and plasmodium antigens using a battery of monoclonal antibodies. A physiopathological model explaining why parasitaemia is negative in such cases is suggested.