In Malysia, the proportion of children fully immunized againest diphtheria is generally low (20%). On the other hand, the Schick conversion rate rises with age and reaches 90% by 11 years of age. It is noted that asymptomatic carriers are an important epidemiological factor in diphtheria and that carrier rates for school children are high (prevalence of 7.5% while the rate of coloization with C. diphtheriae over a period of one year was 30%). Although immunization protects against clinical diphtheria, it does not prevent the carrier state. Thus, for the control of diphtheria, one should aim for 100% compliance. Some suggestions as to how higher levels of immunity may be achieved are described.
Salmonella weltevreden has been found to be one of the commonest Salmonella serotypes isolated from diverse sources in India and has also been isolated in a number of other countries. A phage typing scheme was developed for this serotype using a set of six typing phages. These phages had been selected out of 146 phage strains isolated and purified from stool samples of man, laboratory animals and other animals, sewage and surface water sources, and the lytic mutants of temperate phages form S. weltevreden. The phage typing scheme was applied systematically to type the 946 strains from India isolated during 1958-1974 and 148 strains originating from Australia, Burma, England, Gan Island, Holland, Hong Kong, Malaysia, New Zealand, Papua New Guinea, The Philippines, Thailand, The United States and Vietnam during 1953-1971. The scheme was particularly studied to evaluate its utility in mapping the epidemiologically related strains from various sources. The S. weltevreden strains could be classified into ten phage types. Phage types 2 and 7 were found exclusively amongst Indian strains, type 6 from Vietnam and type 8 from Burma, Thailand and Vietnam. Phage types were found to be stable and consistent with the independent epidemiological data available.
The findings of a cholera epidemic in Krian district is reported. There were 77 cases and 92 carriers in the epidemic. Although the three main ethnic groups of Malays, Chinese and Indians were involved in the epidemic, the Malays constituted majority of the cases and carriers. The overall infection rate and case attack rate was higher among the younger population. The case: carrier ratio was also higher among the younger population especially among Indians. Various reasons and probable causes of the epidemic have been described briefly.
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.
HBeAg and anti-HBe were determined in the blood of 189 male blood donors. The incidence of HBsAg was 6.9% while that for HBeAg and anti-HBe was 1.6 and 18%, respectively. Of the 13 samples positive for HBsAg, two (15.4%) were positive for HBe while six (46.2%) were positive for anti-HBe. One specimen was negative for HBsAg but was positive for HBeAg and anti-HBe. The observations are discussed.
House shrews (Suncus murinus) and rats (Rattus rattus diardii), trapped during a survey period from July 1978 to December 1979 and thereafter on a random basis, from residences within and outside the Veterinary Research Institute, Ipoh, Malaysia campus, were bacteriologically examined for the presence of salmonellae. Of the 55 shrews and 8 rats examined, 39 (71%) shrews and 2 (25%) rats were found positive. There were 46 Salmonella isolates which included 5 dual infections. These were serotyped as S. weltevreden, S. bareilly, S. stanley, S. augustenborg, S. hvittingfoss, S. emek, S. paratyphi B, S. ohio and S. matopeni in order of frequency of isolation. The significance of these findings especially with regard to salmonellosis in man and animals is discussed.
Pharyngeal carriage of group A streptococcus was determined in 432 primary school children between the ages of 6 and 8 years. Beta-haemolytic streptococci were isolated from throat swab culture of 71 pupils, with a carrier rate of 16.4% (71/432) of which 9.4% (39/432) belonged to Lancefield's group A. Serogrouping of the isolates was determined by the coagglutination method and Lancefield's hot acid extraction method. 54.9% (39/71) of the total beta-hemolytic streptococci isolated belonged to group A , 25.3% (18/71) to group G, 15.4% (11/71) to group C and 1.4%(1/71) to group F. T typing pattern of group A streptococcus was determined by the standard agglutination method. Sensitivity to antibiotics was determined by the disc diffusion technique (comparative method). All group A streptococcal isolates were sensitive to penicillin and erythromycin, 6 strains (15.4%) were resistant to tetracycline and 1 strain (2.5%) was resistant to cephaloridine.
A total of 2,153 high vaginal swabs were processed for the presence of yeasts. The specimens were obtained from pregnant and non-pregnant Malaysian women with and without vaginitis. The yeast species most commonly isolated were Candida albicans, C. glabrata, C. famata and C. parapsilosis. C. albicans was isolated from 27% of pregnant women with vaginitis, 14% of pregnant women with no overt vaginitis, 15% of non-pregnant women with vaginitis, and 3% of non-pregnant women with no vaginitis. The significant difference of the isolation rates from women with and without vaginitis indicates that C. albicans is likely to be a vaginal pathogen.
Blood samples from 1,600 persons who sought immunisation against hepatitis B in private clinics in Singapore in 1988-1989 were screened for two viral markers. Of that total, 4.81% were positive for HBsAg and 17.31% had anti-HBs levels greater than 10 mIU/ml, indicating that about 22.12% of the general population would not benefit from immunisation. Preimmunisation screening will identify persons not requiring the hepatitis B vaccine and thus, avoid wastage. When immunisation has already been performed without screening, recall for post-immunisation screening should be considered in order to detect the infectious hepatitis B carriers. Data in this study indicates that at this point in time, it is important to immunise adolescents and adults, in addition to neonates and children.
Two episodes of El Tor cholera outbreak occurred in Tumpat, Kelantan between the 13th of January and the 16th of May 1990. Every case and carrier reported were investigated to determine the source and mode of transmission and to identify specific preventive measures to break the chain of transmission. There were 109 cases and 85 carriers involved in this study. The first episode of one case only was of Inaba serotype while the second episode was caused by the imported Ogawa serotype. Two foci of spread were identified from cluster occurrence but the majority of infection had no discernible link between them. The outbreak became both explosive and protracted indicating poor basic sanitation and personal hygiene. Person-to-person transmission via food and water was the main mode of spread. The Kelantan river water and river clams were confirmed sources of reservoir during the outbreak. Recommendations for prevention are intensified surveillance throughout the year,urgent upgrading of potable water supply and concerted effort in public health education especially against the use of river water and the consumption of raw food.