Thrombocytopenia is frequently observed in vivax malaria but the exact mechanism has not been elucidated. 27 cases of acute vivax malaria were studied, out of which 24 cases had thrombocytopenia. This was the most common hematological finding. None had bleeding from any site. Anaemia and splenomegaly were not present in any of the cases. Platelet counts reverted to normal on treatment. Other causes of thrombocytopenia were ruled out by complete history and physical examination, dengue serology and blood culture. DIC was ruled out by peripheral smear examination and measurement of FDP levels. This study stresses the importance of thrombocytopenia as an early indicator for acute malaria; a finding that is frequent and present even before anemia and splenomegaly set in. The possible mechanisms leading to thrombocytopenia in malaria have been discussed which include immune mechanisms, oxidative stress, alterations in splenic functions and a direct interaction between plasmodium and platelets.

The Chloroquine (CQ) and primaquine (PQ) are used in Colombia for treatment of uncomplicated vivax malaria but there are few efficacy studies of this scheme. The objective of the study were: (a) to investigate the clinical picture of vivax malaria in adult patients; (b) to evaluate the antimalarial treatment response to the standard scheme CQ-PQ; (c) to compare the efficacy of the standard scheme and two alternative schemes with equal dose of CQ and different PQ dose; (d) to identify the adverse effects of CQ-PQ treatment. Randomized, nonblind design; three groups, defined according to total dose of PQ: 45, 105 and 210 mg. All patients received CQ (1500 mg, in 48 hours), which was followed by PQ. Patients were recruited in Turbo and El Bagre. The follow-up period was 28 days. Antimalarial treatment response was classified according to the WHO-2001 protocol (early failure, late failure, adequate response). In total 228 patients were recruited, 18 were lost between days 4 and 27; the antimalarial treatment response was evaluated in 210. The clinical findings were similar to those described by other authors. Parasitaemia clearance was confirmed during the first 24 hours of CQ treatment in 11% of patients. At 48 hours 66% and at 72 hours 97% of patients were negative. All patients (210) displayed adequate treatment response to the CQ-PQ treatment. The different doses of PQ did not affect this response.

CQ-PQ should be conserved as the first treatment choice and should be evaluated in other areas. Simultaneous administration of CQ and PQ is proposed.