Giardia intestinalis in Thailand: Identification of Genotypes.

This study was undertaken to determine the genetic diversities of Giardia intestinalis isolated in Thailand. G. intestinalis cysts were collected from stool samples of 61 subjects residing in Bangkok or in rural communities of Thailand with and without gastrointestinal symptoms. All the cyst samples gave positive tpi amplicons (100% sensitivity), either of the 148- or the 81-bp tpi segments. Cyst assemblage identification of the 148- and 81-bp tpi gene segments by polymerase chain reaction showed that 8% of the cysts were assemblage A, 41% assemblage A and B combined, and 51% assemblage B. The prevalence of assemblage A was significantly lower than that of assemblage B and the mixed types. Restriction fragment length polymorphism (RFLP) of the 384-bp ß-giardin gene segment revealed that 12% and 88% of the assemblage A cysts were AI and AII respectively. RFLP, based on the 432-bp gdh gene segment, showed 45.5% of the assemblage B cysts to be BIII and 54.5% to be BIV. The AI sub-assemblage was less prevalent than the others. All subjects with AI and 50% of the subjects with BIII sub-assemblage cysts were symptomatic; 80% of symptomatic Bangkok residents were adults/elderly while 85% of the rural cases were children.

Blastocystis hominis infection in irritable bowel syndrome patients.

Irritable bowel syndrome (IBS) is a functional bowel disorder in which abdominal pain is associated with a defect or a change in bowel habits. Subtle inflammation, especially after infectious enteritis, has been sometimes suspected as one mechanism of pathogenesis. This research was performed (1) to evaluate the prevalence of parasitic infections and (2) the possible association of IBS and parasitic infections. Fifty-nine IBS patients were recruited using symptom-based criteria (Rome Criteria II) with an absence of intestinal parasitic infection by direct smear method. Stool samples of individual patients were examined using 7 methods, ie examination for stool occult blood, simple saline smear method, formalin-ether technique, culture for Blastocystis hominis, modified trichrome stain, modified Ziehl-Neelsen method, and trichrome stain for parasitic and bacterial infections. Of the 59 patients, stool samples of 13 patients (22.1%) were positive for parasites. These were B. hominis (13.6%), Strongyloides stercoralis larvae (1.7%), Giardia lamblia cysts (1.7%), and non-pathogenic protozoa, ie Endolimax nana cysts (5.1%). The prevalence rate of parasitic infections in the control group (20%) was not statistically different from the patients. There was no statistical difference between B. hominis infection in IBS patients and control was found in this study (p = 0.87). In the IBS group, B. hominis infection predominated (13.6%), while other parasitic infections were found in 8.5%. The culture method for B. hominis is more sensitive than the direct (simple) stool smear method, which is the routine diagnostic method in most laboratories. These results were also found in control group.

Intestinal microsporidiosis in HIV-infected children with diarrhea.

Intestinal microsporidiosis is a common opportunistic disease associated with diarrhea in adult AIDS patients in Thailand; the data regarding this infection in children are scarce. The present study was designed to investigate the prevalence and clinical features of intestinal microsporidiosis in hospitalized HIV-infected and uninfected (free of HIV) children with diarrhea. Of the 95 HIV-infected children and 87 uninfected children, 24 (25.3%) and 13 (14.9%) respectively were diagnosed with intestinal microsporidiosis. Species identification of microsporidia spores, by transmission electron microscopy, demonstrated Enterocytozoon bieneusi in 5 cases. Cryptosporidium parvum was a common coinfective parasite; pneumonia was the most frequent concurrent disease found in children with intestinal microsporidiosis. Malnutrition was commoner in the HIV-infected group (79.2% vs 23.1%; p = 0.003). This study indicates that intestinal microsporidiosis is an important disease in both HIV-infected and uninfected Thai children with diarrhea.