Two vivax-like parasites, believed to be true P. vivax but in abnormal form, are described. The deviation from normal appearances was probably due, it is suggested, to growth in an abnormal environment.
Chloroquine resistance is a well established entity in South East Asia, and presents a problem of increasing importance. Strains of P. falciparum resistant to chloroquine have also been found to be resistant to amodiaquine and a combination of pyrimethamine and sulphadoxine. Knowledge of the drug sensitivity of the strains of malaria parasite in a given locality is important so that the right choice of drugs can be made in treatment of the disease. The treatment of chloroquine resistant malaria in West Malaysia is a subject of another paper but suffice it to say that increased doses of chloroquine have still been found to be effective in treating many cases of falciparum malaria from areas of chloroquine resistance.
A trial of suppression of malaria by administration of combined sulphadoxine-pyrimethamine tablets every 28 days was undertaken in West Malaysia during 1972. One thousand subjects were followed over a 10-month period, including control groups on placebo and on weekly chloroquine. Subjects were examined monthly for parasitaemia, drug reactions, leucopenia, teratogenicity and haemolysis among the subjects deficient in glucose-6-phosphate dehydrogenase. Rates of new infections in the placebo group were 8.0% with Plasmodium falciparum and 6.2% with P. vivax; in the group receiving weekly chloroquine, 5.1% P. falciparum and 0.3% P. vivax; and in the group receiving monthly sulphadoxine-pyrimethamine, 0.3% P. Falciparum and 1.0% P. vivax. The effective rate of cure of new infections with P. falciparum by a single suppressive dose of combined sulphadoxine-pyrimethamine given the following month was 88.7%. No serious side effects were observed.
In the context of this study the ethnic origin of the patients revealed no noteworthy difference in the clinical reaction to the parasite; neither did age or sex of the patients. Any minor differences whcih appeared in length of history before seeking treatment and frequency of repeat attacks were more a reflection of the cultural pattern of response to illness (i.e. resort to traditional medicines) and the distance between the patient's home and the doctor rather than any altered response on the part of the host to the parasite. However, the fact that about 35 per cent of all the episodes had a history of eight or more days (about 10 per cent more than 30 days) suggest that more "malaria consciousness" is called for in what is after all an endemic malaria area. The value (and necessity) of repeated examination of the blood to detect the parasite is confirmed but it is also encouraging to note that in 84% of cases a single careful examination of the blood revealed the parasite. Since in 49% of our malaria episodes the patient was afebrile when the parasite was discovered, it is obvious that in outpatient practice especially blood should be examined when the patient presents for treatment, irrespective of the presence or absence of pyrexia. As always, a prerequisite to the diagnosis of malaria is an awareness of its possible presence.
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.
The 1980 malaria notifications in Malaysian soldiers are analysed. The number of new cases notified was 964, giving an annual incidence of11.81/1000 soldiers. Sixty-three percent were falciparum and 36 percent were vivax infections. There were 48 relapses and recrudescences. Twenty-three carriers were detected on mass screening. The yield from mass screening was very low - 5.09/1000 screened. The current practice of chemotherapy, though generally acceptable, was unsuitable for a number of patients. Recommended regimens are not being adhered to. There were two cases ofcerebral malaria, one of whom died.
A seroepidemiological study was carried out on Orang Asli (Aborigines) children who lead a semi-nomadic life in the deep jungles of Ulu Kelantan, Malaysia. Out of a total of about 190 children below 14 years, 143 were studied. Blood was collected from finger pricks on standard "strip type" filter papers for indirect fluorescent antibody (IFA) tests with Plasmodium falciparum antigen. A positive reaction at 1:10 dilution in infants and young children was considered positive and the reasons are given. The P. falciparum antibody prevalence rate was 84.6% compared to 81.8% spleen and 43.4% parasite rates. Both P. Falciparum and P. vivax were present in children. The age-specific patterns of antibody, spleen and parasite rates were those of a hyperendemic community. There was a positive correlation between antibody and spleen rates up to the age of 9 years. In older children, the antibody rates increased while the spleen and the parasite rates dropped.
The indirect hemagglutination test was used to measure malaria antibody levels in residents of an endemic area of Malaysia. Blood specimens were collected at 4-week intervals for a year. Seropositivity rates increased with age and number of episodes of malaria in young children. Although antibody levels were variable, titers tended to rise with parasitemia and fall in the absence of detected parasites. In general, the serologic indices tended to reflect the parasitologic findings.