Regular blood transfusions for patients with thalassemia have improved their overall survival although these transfusions carry a definite risk of the transmission of certain viruses. Infection with hepatitis B virus (HBV), hepatitis C virus (HCV), cytomegalovirus (CMV) and human immunodeficiency virus (HIV) leads to complications which contribute to the morbidity and mortality of patients with thalassemia. We analyzed the blood samples taken from 85 transfusion dependent thalassemics receiving treatment at the day care center in Hospital Universiti Kebangsaan Malaysia and found that the seroprevalence rates for HBV, HCV and CMV were 2.4%, 22.4% and 91.8% respectively. None of the patients tested positive for HIV. Those positive for HBV and HCV will require further tests and treatment if chronic hepatitis is confirmed.
An IgM dot-immunobinding assay (IgM-DIA) was developed for the diagnosis of scrub typhus infection. The whole cell antigens of Karp, Kato and Gilliam strains of Rickettsia tsutsugamushi were immobilized onto nitrocellulose paper and reacted with patients sera. The presence of IgM R. tsutsugamushi specific antibody in the patient sera could be detected by the observation of a visible brown dot on the nitrocellulose paper. The IgM-DIA has a sensitivity of 90.4% and specificity of 81.4% as compared to the indirect immunoperoxidase test. The IgM-DIA is rapid, simple, cost-effective, does not require microscope or incubator. It is recommended as a rapid screening test for the diagnosis of scrub typhus infection in the field or rural area within the hyperendemic region.
Pulsed field gel electrophoresis (PFGE) and antimicrobial susceptibility analysis were undertaken on twenty-three strains of Salmonella enterica serovar Tshiongwe, an unusual serovar, which recently emerged in Malaysia. Antimicrobial susceptibility analysis showed that all the strains were sensitive to ampicilin, chloramphenicol, cotrimoxazole, and kanamycin. Twenty (87%) and 8 (3.5%) strains had resistance to tetracycline and streptomycin respectively. PFGE analysis subtyped 23 strains into 10 profiles (Dice coefficient of similarity, F = 0.7-1.0). The predominant profile, X1 was found in both clinical and environmental isolates and was widely distributed in different parts of Malaysia during the study period. In addition, isolates recovered from food, a hand-towel, apron and the surface of a table-top in one particular location had unique, indistinguishable profiles (X4/4a) and identical antibiograms. Similarly, isolates from cooked meat and a chopping board had PFGE profiles similar to some human isolates. These probably indicated cross-contamination and poor hygiene in food practices, hence contributing to Salmonellosis. Factors causing the emergence of this rare Salmonella serovar being responsible for food poisoning episodes during the study period remained unclear. The study reiterated the usefulness and versatility of PFGE in the molecular subtyping of this rare Salmonella serovar in Malaysia.
Mycoplasma pneumoniae is increasingly recognized as an important cause of community acquired pneumonia (CAP) in children. We determined the importance of M. pneumoniae as a causative agent in 170 children aged 1 month to 15 years who were hospitalized with CAP over a 6-month period. The diagnosis of M. pneumoniae infection was based on serological evidence obtained by a particle agglutination test (SERODIA-MYCO II). A positive serological diagnosis was made if the acute phase serum titer was more than 1:160 or paired samples taken 2-4 weeks apart showed a four-fold or greater rise in the serum titer. M. pneumoniae was identified as the causative agent in 40 (23.5%) children. Children with M. pneumoniae infection were more likely to be older than 3 years (OR 4.0 95%CI 1.8-9.1, p<0.001), Chinese (OR 4.3 95%CI 2.0-8.9, p<0.001), have a duration of illness longer than 7 days prior to admission (OR 6.0 95%CI 2.7-13.5, p<0.001) and have perihilar interstitial changes on chest X-ray (OR 4.6 95%CI 2.2-9.9, p<0.001). A significant number of hospital admissions for CAP in Malaysian children can be attributed to M. pneumoniae. It is important to identify these children so as to administer the most appropriate antibiotic treatment.
A total of 736 sera collected from cord blood babies, children and adults of both sexes and of different age groups in Malaysia were tested using indirect fluorescent antibody technique for Toxoplasma antibodies. The RH strain of Toxoplasma gondii zoites were used as antigen. One hundred and twenty five sera which were reactive at 1:64 or high titres were tested with IgM specific conjugate. Results of the present studies showed that the prevalence of Toxoplasma antibody was highest among the Malays and lowest among children than among adults. The significance of Toxoplasma specific IgM was discussed.
Poliovirus kept on the cut surfaces of fully ripe papaya cubes placed in an ice box showed a sharp and significant reduction in the recovery of infectious virus about 15 minutes after exposure. Thereafter, a very gradual decrease ensued and infectious residual virus was detected up to the end of the 6-hour exposure period. Papaya cubes washed or kept overnight before virus inoculation, and from less ripe fruits produced a similar survival pattern. A very small proportion of the inoculum was recovered from the mashed content of the inoculated papaya cubes thus suggesting that most of the non-recovered virus particles were inactivated. The results suggest that the importance of poliovirus-contaminated cut papayas as a transmission vehicle for the virus is greatly reduced by the rapid decline in the infectivity of a large proportion of the virus soon after contamination. Nevertheless, the potential to transmit remains as a small residual pool of infectious poliovirus is able to survive for a relatively long period.
Mark-release-recapture experiments were undertaken in January 1989, in Pos Betau, Pahang, Malaysia, with the malaria vector Anopheles maculatus. On two consecutive nights, 121 and 175 blood-fed mosquitos were released. A mean recapture rate of 11.5% and survival rates of 0.699-0.705 with an estimated oviposition cycle period of 2.35 days were obtained from the releases. About 68% of all recaptures were taken within a distance of 0.5 km from their release points and the longest detected flight was 1.6 km. No heterogeneity was found between indoor and outdoor biters of An. maculatus.
Comparative laboratory bioassays of Tolypocladium cylindrosporum, California strain (Kal) was conducted against third instar larvae of four species of mosquito, viz. Aedes aegypti, Anopheles balabacensis, Culex quinquefasciatus and Mansonia uniformis in Malaysia. Of the four mosquito species tested, Ma. uniformis was found to be the most susceptible, followed by Cx. quinquefasciatus, An. balabacensis and Ae. aegypti, in a decreasing order. The LC50 values for Ma. uniformis, Cx. quinquefasciatus, An. balabacensis and Ae. aegypti after four days of exposure were 1.18 X 10(4), 2.02 X 10(5), 4.76 X 10(5) and 1.84 X 10(7) spores per ml test media, respectively. The high sensitivity of Ma. uniformis and its longer life cycle seems to indicate that T. cylindrosporum Kal has good potential as a biocontrol agent for this species of mosquito. But, for Ae. aegypti, this fungus appears to be less effective.
The pathogenicity of Bacillus sphaericus strain 1593 was tested against laboratory-reared larvae of four local species of mosquitoes of public health importance in Malaysia; Aedes aegypti, Anopheles balabacensis, Mansonia uniformis and Culex quinquefasciatus. The bacteria was shake-cultured at 28 +/- 1 degrees C for three days, using Glucose-Yeast Extract Salts medium. After which, the spores and vegetative cells were harvested and stored at 4 degrees C before use. Conditions for bioassays were mean temperature of 25 +/- 1 degrees C and relative humidity 65 +/- 5.0. Twenty third-instar larvae of each species were assayed in 90 ml of diluted spore solution. Each concentration and a control were replicated three times for each bioassay. Larval mortalities at 24 hours and 48 hours were taken and analyzed through Probit Analysis using a computer (IBM 370). LC50 values after 48 hours of exposure showed an increasing order of larval susceptibility as follows: Ae. aegypti (417.70 x 10(4)), An. balabacensis (45.84 x 10(4)), Ma. uniformis (18.23 x 10(4)) and Cx. quinquefasciatus (4.14 x 10(4) spores/ml). With the ability to kill 90% of the Cx. quinquefasciatus larvae tested with just a concentration of 10(5) spores/ml, B. sphaericus (strain 1593) has shown good potential as a biocontrol agent for this species of mosquito.
Susceptibility tests were carried between 1987-1989 on Anopheles maculatus female adults collected from twelve different localities in Peninsular Malaysia to DDT. Mosquitoes collected from all localities except those from Kuala Berang, Trengganu state were found to be susceptible to DDT when tested with 4% impregnated paper. Several factors contributing to the lack of development of resistance despite many years of residual spraying in Peninsular Malaysia include exophily, exophagic and excito-repellency behaviour of An. maculatus and the inadequate spraying coverage of houses.
Comparative laboratory bioassays of three formulations of Bacillus thuringiensis H-14 (IPS-78, San 402-I and Bactimos) were conducted against late 3rd/early 4th instar larvae of four species of mosquito, viz., Aedes aegypti, Culex quinquefasciatus, Anopheles balabacensis and Mansonia (Mansonioides) indiana, in Malaysia. From the average response of the mosquito larvae to the three formulations of B. thuringiensis H-14, Ae. aegypti was found to be most susceptible, followed by Cx. quinquefasciatus, An. balabacensis and M. (M.) indiana in decreasing order. The LC50 values for Ae. aegypti, Cx. quinquefasciatus, An. balabacensis and M. (M.) indiana after a 48-hour exposure to IPS-78 formulation were 50.9, 129.3, 117.8 and 169.6 International Toxic Unit (ITU) Ae. ae./l; to San 402-I formulation were 54.6, 223.1, 405.1 and 177.6 ITU Ae. ae/l and to Bactimos formulation were 57.2, 175.7, 35.6 and 514.5 ITU Ae. ae./l respectively. The efficacy of the bacterial product was also found to be determined by its formulation in relation to the feeding and resting habits of the mosquito larvae. No delayed pupation or emergence was observed on the larvae exposed to B. thuringiensis H-14 at sub-lethal concentrations.
An ovitrap survey was carried out in April and May of 1975 at twenty-one locations scattered throughout Penang Island excluding the City of Georgetown. The results showed the ubiquitous presence of Ae. albopictus. Ae. aegypti was recorded only in Tanjung Tokong Lama, an area adjacent to the City of Georgetown. In the survey, Ae. albopictus females were found to prefer the outdoor ovitraps than indoor ones. The effectiveness of ovitrap in Aedes survey was discussed.
A cross-sectional study of the nutritional status of schoolchildren aged 7-10 years from the Kuala Betis Resettlement Scheme in Gua Musang, Kelantan was done. A total of 291 schoolchildren were examined but only 183 (62.9%) fecal samples were returned for geo-helminth infection analysis. The prevalence of stunting was 40.4% and underweight was 28.4%. A total of 127 schoolchildren (69.4%) were positive for at least one of the 3 geo-helminth infections. The most common geo-helminth was Ascaris lumbricoides (62.8%), followed by Trichuris trichiura (38.9%), and hookworm infection was relatively low (12.6%). All the anthropometric indices measured were lower in the geo-helminth infected children compared to the uninfected childen, except for the weight-for-height z-score. However the differences were insignificant Geo-helminth infections may not be a significant factor in malnutrition of these schoolchildren. However, with the availability of safe, efficacious and cheap broad spectrum anthelmintics, regular mass treatment should be given in selected areas where the prevalence of geo-helminth infections is still high, so that these schoolchildren will be able to achieve their growth potential during their school years.
Various studies on toxoplasmosis in Malaysia have shown that specific antibodies to Toxoplasma gondii are common among Malaysians. Among the ethnic groups, the Malays have the highest prevalence rate followed by Indians, Orang Aslis (aborigines) and Chinese. Antibody is acquired early in life and increases with age. There is no significant difference in the prevalence rate between males and females. The disease is apparently more prevalent among rural dwellers and those in the lower socioeconomic group. It appears that the prevalence rate is also influenced by environmental conditions, occupation, diet and cultural habits. Studies with animals have shown the presence of antibody to T. gondii, but this does not seem to be the source of infection since Malaysians normally cook their meat well.
Serum IgG levels and complement C3 levels were assayed on Day 0, 1, 3-4, 7 and 56-70 post-treatment with diethylcarbamizine citrate (DEC) in a series to 26 patients with Brugia malayi infection and 6 volunteers without infection. On treatment, the microfilariae were cleared from the blood within 24 hours. The eosinophils decreased dramatically on Day 1 post-treatment but increased rapidly by Day 4 to 7 and then dropped to normal levels in 45 days. The serum IgG mean levels decreased briefly following treatment with DEC but then returned to original levels. However, the complement C3 levels gradually increased over the 2 months period of study reaching statistical significance levels (p less than 0.01) in patients with initial high blood microfilariae. The observation suggests that Brugia malayi infection probably induces a high rate of synthesis of complement C3 and this process continued in the post-treatment phase. Since, DEC treatment did not cause a decrease in complement C3 with the elimination of blood microfilariae, it would appear that the complement C3 is consumed following antibody attachment to the microfilariae as they enter the blood circulation.
Serum tumor necrosis factor alpha (TNF) concentration was assayed in 105 patients with nasopharyngeal carcinoma using a sensitive ELISA technique with detection level of 10 pg/ml. The TNF levels were detectable in 45 of 63 (71.4%) patients newly diagnosed for the malignancy and 29 of 42 (69%) patients in remission following treatment with radiotherapy. In 25 normal controls the TNF were less than 10 pg/ml. While TNF may be present in the majority of the patients with the malignant disease, the TNF concentration appeared to have no clinical significance in diagnosis or prognosis of the patients.