Wilai Saksirisampant

Intestinal parasitic infections: prevalences in HIV/AIDS patients in a Thai AIDS-care centre

Abstract During 2005, the intestinal parasitic infections in the adult HIV/AIDS patients in a combined AIDS-care centre and hospice in Thailand were identified in a cross-sectional study. Overall, 41 (45.6%) of the 90 stool samples investigated, by microscopy and/or PCR, were found parasite-positive. Cryptosporidium was the genus most commonly encountered, with 27 (30.0%) of the patients positive for Cr. hominis and four (4.4%) positive for Cr. meleagridis. Enterocytozoon bieneusi, always of genotype D, was detected in five (5.6%) of the patients while two patients (2.2%) were found infected with Blastocystis, just one patient (1.1%) was found infected with Cyclospora cayetanensis and one more (1.1%) was found positive for Isospora belli. The only helminth infection detected was opisthorchiosis and that was only seen in two (2.2%) of the subjects. Patients with stools of unusual consistency (categorized as mucous, loose–watery or watery) were more likely to be found infected with one or more species of protozoan parasite than the patients with stools of normal consistency (P=0.022). In a multivariate analysis, compared with the other subjects, the patients with stools of unusual consistency were 4.9-fold more likely to have (opportunistic) intestinal infection with parasitic protozoa (with a 95% confidence interval for the adjusted odds ratio of 1.370–17.350; P=0.014). Although there was also a trend for stools of unusual colour (red–brown, red–orange, green, black or grey) to be positively associated with intestinal parasitic infection, this was not statistically significant (P=0.658). The observation of the consistency of stools of HIV/AIDS patients could help in the presumptive diagnosis of opportunistic protozoan infections and allow parasitological investigation to be targeted at the cases most likely to be found positive.

Screening for Intestinal Parasitic Infections Among Myanmar Migrant Workers in Thai Food Industry: A High-Risk Transmission

The impact of intestinal parasitic infections on public health has been neglected. Millions of Myanmar natives have migrated to work in Thailand. We performed a study of intestinal parasitic infections in Myanmar-migrants working in the Thai food industry. A total of 338 Myanmar migrant workers in a food plant at Samut Sakhon Province, Thailand, were recruited for this study. 284 (84%) returned requested stool samples. Samples were examined for intestinal parasites by means of simple smear, formalin-ether concentration, Locke-Egg-Serum medium, and Harada-Mori culture methods. We found parasites in 177 (62.3%) migrants (29 of 46 males; 148 of 238 females). The majority (89.3%) were infected with parasites transmitted by fecal-oral route, including Blastocystis hominis (41.5%), Trichuris trichiura (22.2%), Giardia lamblia (14.1%), and Ascaris lumbricoides (1.8%). Mixed infections were common (40.7%). The highest prevalence (73.3%) was found among migrants from Kohsong city, Myanmar. This high parasite infection rate in Myanmar migrant workers is an obvious public health hazard.

Study of specific IgG subclass antibodies for diagnosis of Gnathostoma spinigerum

Gnathostoma spinigerum infection is endemic in Thailand and many Asian countries. Current diagnosis is the skin test and enzyme-linked immunosorbent assay (ELISA) for IgG antibody against the G. spinigerum third-stage larvae (L3), but cross-reactivity is common. We evaluated the sensitivity and specificity of anti-G. spinigerum L3 IgG subclass antibodies for diagnosis of 43 patients with gnathostomiasis. The majority of patients with gnathostomiasis (91%) had eosinophilia. While the anti-G. spinigerum L3 IgG1 antibody provided the highest sensitivity (98%), the anti-G. spinigerum L3 IgG2 antibody had the highest specificity (88%). The ELISA that detected anti-G. spinigerum L3 IgG1 antibody could be a reliable laboratory screening test, while anti-G. spinigerum L3 IgG2 antibody could be used to confirm the diagnosis.

Clonal diversity of the glutamate dehydrogenase gene in Giardia duodenalis from Thai Isolates: evidence of genetic exchange or Mixed Infections?

BackgroundThe glutamate dehydrogenase gene (gdh) is one of the most popular and useful genetic markers for the genotypic analysis of Giardia duodenalis (syn. G. lamblia, G. intestinalis), the protozoan that widely causes enteric disease in humans. To determine the distribution of genotypes of G. duodenalis in Thai populations and to investigate the extent of sequence variation at this locus, 42 fecal samples were collected from 3 regions of Thailand i.e., Central, Northern, and Eastern regions. All specimens were analyzed using PCR-based genotyping and recombinant subcloning methods.ResultsThe results showed that the prevalence of assemblages A and B among these populations was approximately equal, 20 (47.6%) and 22 (52.4%), respectively. Sequence analysis revealed that the nucleotide diversity of assemblage B was significantly greater than that in assemblage A. Among all assemblage B positive specimens, the allelic sequence divergence within isolates was detected. Nine isolates showed mixed alleles, ranged from three to nine distinct alleles per isolate. Statistical analysis demonstrated the occurrence of genetic recombination within subassemblages BIII and BIV was likely.ConclusionThis study supports increasing evidence that G. duodenalis has the potential for genetic exchange.

A survey of the infective larvae of Gnathostoma spinigerum in swamp eels bought in a local market in Bangkok, Thailand

Abstract The livers were separated from the viscera of 2738 swamp eels (Monopterus alba) purchased from Klong Toey market, the largest market in Bangkok, between June 1999 and May 2000. When these livers were digested in artificial gastric juice, 524 (19.1%) were found to be infected with the human-infective, third-stage larvae (L3) of Gnathostoma spp. All the identified larvae were confirmed morphologically to be G. spinigerum. Prevalence of the infection varied with season, from a high of 38.3% in September to a low of 7.0% in April, being generally high during the rainy season and winter (June-February). The mean (S.E.) number of L3 recovered/infected liver, which was 3.99 (0.52) overall, also varied with the season, peaking at 5.38 (1.89) in January, but the month-on-month variation was not statistically significant. Although the results of an earlier study had indicated that the prevalence of eel infection decreased in November, after the rainy season, the most abrupt decrease observed in the present study occurred at the beginning of summer (March). However, the period covered by the present study was unusually wet, and the prevalence of eel infection may depend on rainfall more than season.

Short CommunicationPlatelet parameters in subjects infected with hookworm

Hookworm is an important intestinal parasite infection with high prevalence in tropical countries. In addition to iron deficiency anaemia, the human hookworm appears to have evolved a number of complementary strategies to overcome the host’s haemostatic processes. These include the inhibition of blood coagulation, platelet aggregation and mediator release, and the secretion of fibrinogenolytic enzymes. In this work, we studied the platelets in the subjects with detection of hookworm infection from screening stool examination comparing to those without. One hundred subjects were included, studied for stool parasite and platelet parameters. Of our 100 subjects, hookworms were identified in stools of six cases, giving an infection rate equal to 6%. The platelet parameters of the subjects showed a statistically significant lowering of mean platelet volume (MPV) in the subjects with hookworm infection. Also, we detected a non-significant lower platelet count in subjects with hookworm infections. Of interest, the alteration in platelet size, identified by platelet parameters, has never been documented in the literature. This observation might be a pathological process or might be an accidental finding in our study.