There are increasing reports of severe clinical cases exclusively associated with P. vivax infections, involving severe anaemia, renal failure, jaundice, cerebral malaria, seizures, respiratory failure, multi-organ failure, and death [2, 3] ; all these complications are generally believed to be exclusively associated with severe forms of falciparum malaria. Although these same clinical severity criteria are being used for P. vivax, it would be desirable to conduct prospective studies to establish a precise definition of clinical severity in P. vivax.