Chloroquine-resistant falciparum malaria among British service personnel in West Malaysia and Singapore

Plasmodium falciparum: increased proportion of severe resistance (RII and RIII) to chloroquine and high rate of resistance to sulfadoxine-pyrimethamine in Peninsular Malaysia after two decades

Uncomplicated falciparum malaria patients were randomly assigned to receive either 25 mg/kg chloroquine (CHL) over 3 d or a statim dose of 25 mg/kg sulfadoxine (SDX) plus 1.25 mg/kg pyrimethamine (PYR). Patients were followed up for 28 d and the parasite response graded according to World Health Organization criteria. Overall resistance to CHL was 63.3% and 47.4% to SDX/PYR. RI, RII and RIII rates were 9.1%, 42.4% and 12.1% for CHL and 10.5%, 21.1% and 15.8% for SDX/PYR, respectively. Degree and rates of resistance to CHL were significantly correlated with pre-treatment parasite density, but not those to SDX/PYR. Plasma CHL and SDX/PYR levels were within the reported ranges and were not significantly different in patients with sensitive and resistant responses.

Plasma Paludrine levels--some observations in Commonwealth troops in the Far East 1970

Some information on plasma Paludrine levels in troops on various dose-regimes and conditions of activity is recorded. Some observations on Paludrine dose-regimes are made. The use of Paludrine in the Army is very briefly reviewed and a preliminary report on recent experience included.

In vivo and in vitro studies of chloroquine-resistant malaria in Thailand

Fourteen patients infected with falciparum malaria admitted to the Hospital for Tropical Diseases in Bangkok, Faculty of Tropical Medicine, Mahidol University, were studied. In vivo and in vitro methods were used to compare the effects of chloroquine on Plasmodium falciparum. The results showed that RI in vivo corresponded to samples containing chloroquine base 2.5-3.5 millimicromoles per ml of blood in vitro and RII in vivo corresponded to samples with chloroquine base of 4.0 millimicromoles per ml of blood.

Studies on the resistance of malaria to chloroquine and to a combination of chloroquine and pyrimethamine in Peninsular Malaysia

In vivo chloroquine resistance surveys, which allowed for detection of late recrudescing RI resistance, were conducted in three regions of Peninsular Malaysia, which were previously not recognized as having appreciable drug resistance. Among the 485 Plasmodium falciparum infections tested resistance rates ranged locally from 20% to 67% in those with parasitaemias over 1,000 per mm3, and 5% to 59% in all parasitaemias. The region found to have the most serious resistance was western Pahang. In one study a combination of chloroquine and pyrimethamine proved no more efficacious than chloroquine alone. Most of the resistance encountered was the late recrudescing RI type. There was no apparent correlation between drug resistance and Anopheles balabacensis as this species was not found despite intensive collections in two of the three main regions. There was no evidence of resistance among the 222 P. vivax and 35 P. malariae infections also tested.

Thrombocytopenia in malaria with immunoglobulin (IgM) changes

Of 33 cases of naturally occurring human malaria 32 were found to have significant thrombocytopenia. Only one patient showed signs of bleeding. The lowest platelet levels were found between the day of diagnosis and the fourth day of treatment. Thereafter they returned to normal values. No other factors could be found to correlate with the presence or depth of thrombocytopenia, and no evidence of intravascular coagulation was found in any case. A rise in the immunoglobulin IgM was found in all 13 cases in which it was estimated. Since thrombocytopenia can occur independently of intravascular coagulation the latter should be diagnosed and heparin given only after clotting factors have been shown to be depleted.