Sera from 243 donors belonging to the four main ethnic groups in West Malaysia (Orang Asli, Malays, Chinese and Indians) were tested, using the indirect fluorescent antibody technique for the prevalence of antibodies to Sarcocystis. Almost 20% reacted positively at dilutions of 1:64 or higher and eight among the Orang Asli and Malays gave the highest titres of 1:256. Prevalence was highest in the Orang Asli and lowest in Chinese. 22 sera also reacted positively to Toxoplasma, whether due to polyparasitism or cross-reaction is, as yet, unknown.
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.
A review of the various studies on toxoplasmosis in peninsular Malaysia is presented. The period of review spanned between 1973 and 1980 during which a number of serological surveys were carried out for the presence of Toxoplasma gondii antibody in Malaysians, using either the indirect hemagglutination (I.H.A.) or the indirect fluorescent antibody (I.F.A.) tests. The prevalence rates of Toxoplasma antibody were consistently foundhighest among Malays, followed by Indians, Orang Aslis (Aborigines) and lowest among Malays, followed by Indians, Orang Aslia (Aborigines) and lowest among Chinese, the 4 major ethnic groups living in Malaysia. Positive titres, present in all age groups, showed an increase with age but no difference due to sex. However, higher prevalence of positive cases was recorded among rural dwellers and the lower socioeconomic group than from urban dwellers. The possible routes of infection among the ethnic groups were discussed. Among animal populations, the presence of Toxoplasma antibody was detected in buffaloes, swine, goats, cattle, cats and dogs. The epidemiological importance of the findings are discussed and suggestions made for future studies.
Toxoplasmosis was found not to be an important cause of intrauterine infection in Malaysia as the rate of toxoplasma-specific IgM in 1,060 congenitally defective Malaysian children, 0 to 4 months old (0.4%) was lower than that in 405 normal children of the same age group (2.0%). A total of 8.2 intra-uterine toxoplasmic infections per 1,000 live births was detected of which one-third (2.7 per 1,000 live births) was overt, manifesting symptoms more of liver damage, than eye or brain damage. A comparison was made with the rates in U.S.A. and Europe. The role of toxoplasmosis in abortion needs to be studied.
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.
Thirty in vitro serial passages of Toxoplasman gondii cultures in Vero cell line performed once in every five days had a mean increase in parasite count of 74.4 +/- 14.8 times from that of initial counts. Long term cultures in Vero cell line did not alter the virulence of the parasite. The good correlation (r = 0.99) between the IFA titer and ELISA OD values using the parasite antigens from in vitro sources indicates that long term maintenance of T. gondii in culture does not affect significantly the ability to recognize antibodies to surface and soluble antigens. The results also show that soluble antigens containing host cells can be directly used for immunodiagnostic purposes without purification. The in vitro maintenance of T. gondii is safer and cheaper when compared to the in vivo method.
C57BL/6 mice were orally infected with different doses of cysts of ME49 strain of Toxoplasma gondii to produce groups of acutely and chronically infected mice. Sera were obtained at different periods post-infection. SDS-PAGE was ran with excretory/secretory antigens of ME49 and RH strains of T. gondii, followed by Western blot analyses using the above sera and anti- IgA, IgM, IgG as conjugates. The SDS-PAGE profiles of the two antigens were similar. However the antigenic bands showed variations in all blots, most evidently in IgA blots of chronic sera. IgG blots showed greatest similarities in reactive bands. In IgM blots, more common bands were shown in chronic sera than in acute sera. Variations and similarities in prominence of some bands and time of their appearance were also noted, especially in IgM and IgG blots of chronic sera. Thus antigenic variations and similarities are present in excretory/secretory products of different strains of T. gondii.
Mice were chronically infected with cysts of ME49 strain of Toxoplasma gondii. At different periods post-infection, their spleens were removed and single cell suspensions were made. Lymphocyte transformation experiments were performed on the lymphocyte suspensions using three different kinds of antigens of ME49 strain of T. gondii, namely soluble, excretory/secretory and cystic forms. The results showed that the pattern of lymphocyte responsiveness was dependent on the kind of antigen employed for induction of the blastogenesis. Using soluble and cystic forms of the antigen, different periods of lymphocyte suppression and lymphocyte proliferation were demonstrated. However, with the use of excretory/secretory antigen, no significant suppression of lymphocyte stimulation was noted throughout the course of infection. Thus excretory/secretory antigen may be the best form of antigen for stimulation of the cell-mediated immune response and hence it appears to be a good candidate for vaccine in toxoplasmosis.
The distribution of anti-toxoplasma antibodies among the aborigines in Malaysia and its association with other soil transmitted infections and eosinophilia were studied. A total of 415 serum samples were collected and tested by IFA test. Overall prevalence was 10.6%, lower than previously reported. The antibody titers showed a unimodal distribution peaking at 1:8 dilution. There was a higher proportion of high antibody titer (> 1:128) in the adult compared to the children with no significant difference in prevalence rate by sex. The pattern of infection does not differ from other soil transmitted infections and there was no association between raised Toxoplasma antibodies with eosinophilia.
A 32 year old HIV positive intravenous drug user (IVDU) with a promiscuous lifestyle in the past presented with altered behaviour and was diagnosed to have pulmonary tuberculosis, tuberculous meningitis and tuberculous osteomyelitis. After initial response to anti-tuberculous therapy, his symptoms recurred with the appearance of cerebral mass lesions. A presumptive diagnosis of toxoplasma encephalitis was made based on clinical, serological and radiological evidence. He showed clinical improGement with anti-toxoplasmic therapy.
From November 1996 to December 1997, 24 infants with neonatal cholestasis were referred to the Department of Paediatrics, University of Malaya Medical Center, Kuala Lumpur for further investigations. Nineteen had neonatal hepatitis. There was considerable delay in referral of infants with cholestasis; the mean age of referral was 63.7 days. None had a positive family history of neonatal hepatitis. All infant had hepatomegaly and ten had splenomegaly. The stools were slightly pale in thirteen, persistently acholic in three and normally pigmented in three infants. Liver synthetic functions were normal in most of the infants. Cytomegalovirus (CMV) IgM antibodies were positive in seven but none were positive for toxoplasma or rubella. al - antitrypsin deficiency, hypothyroidism, and galactosaemia were excluded in all infants. DISIDA scans were performed in seventeen infants, being non-excretory in eight. Liver biopsies were performed in fifteen infants, showing neonatal hepatitis in fourteen, while histological features of large duct obstruction was seen in one. In majority of infants (eight out of ten) the jaundice disappeared by six months. Two infants had progressive jaundice and liver function impairment.
We describe the results of serology for parasitic infection of 250 foreign workers who were seen at the University of Malaya Medical Centre, UMMC during 7-months period. The 250 foreign workers participated included 114 from Indonesia, 142 from Bangladesh, two from Myanmar and two from Pakistan. Blood samples were taken from these workers and eight tests (amoebiasis, echinococcosis, filariasis, leishmaniasis, malaria, schistosomiasis, toxoplasmosis, and trypanosomiasis) were performed on serum. Among the 250 sera tested, 92 (36.8%) were found to be positive for at least one parasitic infection. There was one case where the serum was found positive for 5 tests. The most common antibody detected in those positive sera was antibody for toxoplasma (80.%), followed by filaria (32.8%) and amoeba (30%). Other tests showed low percentage of infection with schistosomiasias, 10%; echinococcosis, 6% and malaria, 3.6%. None of the foreign workers were found positive for leishmaniasis or trypanosomiasias.
In vitro lymphocyte proliferative response of peripheral blood leucocytes (PBL) to purified Toxoplasma gondii antigen were evaluated by 3[H] methyl thymidine incorporation in patients acutely and chronically infected with Toxoplama gondii. PBL from three patients with acute sylnptonlatic toxoplaslnosis showed no response to T. gondii antigen during the emergence of anti-Toxoplasma 1gM antibodies and the response returned as the infection became chronic. Lymphocytes of twelve chronically-infected patients responded positively to the antigen. In all patients the lymphocyte proliferative response to the mitogen, Concanavalill A (Con A) was normal. Analysis of Toxoplasma proliferative response of PBL from a patient with acute toxoplasrnosis showed that CD8+ cells were responsible for induction of suppression while the response during the chronic infection was lnediated by CD4+ cells. In human toxoplasmosis there was antigen-specific lymphocyte unresponsiveness during the acute phase of the infection and it appears that the initnunesuppression was mediated by CD8+ cells. KEYWORDS: Toxoplasmosis-lymphocyte blastogenesis-antigen specific-CD4+, CD8+
During the period 1996-1998, 134 patients suspected of having ocular toxoplasmosis were seen in the Ophthalmology Clinic of the University Hospital, Kuala Lumpur. Clinical presentations in these patients ranged from poor vision to severe retinal detachment. Of these patients, 72% were confirmed positive for Toxoplasma gondii infection by serological methods. Chorioretinjtis and vitritis were found to be the most apparent symptoms, both having 100%correlation with serological positivity, This was followed by uveitis, floaters, and retinal detachment with correlation at 78%, 75%and 75%, respectively. However, there was no correlation between level of serotitre and ocular presentations. KEYWORDS: Toxoplasmosis, serology, chorioretinitis, uveitis
A total of 200 pregnant women were recruited in this cross-sectional study. The overall seroprevalence of toxoplasmosis in pregnant women was found to be 49%, in which 39%, 4% and 6% for anti-Toxoplasma IgG, IgM and both anti-Toxoplasma IgG and IgM antibodies, respectively. We found the differences in Toxoplasma seroprevalence rates among the races were significant: the highest rate was in the Malays (55.7%), followed by the Indian (55.3%) and the Chinese (19.4%) (P<0.05) populations. An increase in Toxoplasma seroprevalence with increasing parity was detected (P<0.05). Women with no children had a prevalence of 39.7%, while women with one or more than two children had a prevalence of 44.2% and 62.9%, respectively. In this study, there was no significant association between Toxoplasma seroprevalence and various possible risk factors in pregnant women (P>0.05). When multivariate analysis was performed, no significant association between Toxoplasma seroprevalence and history of contact with cats, consumption of undercooked meat and blood transfusion was found (P>0.05). We did not find any newly diagnosed cases of acute acquired toxoplasmosis in pregnancy during the study period.