The Toxoplasma gondii number was evaluated by quantitative competitive polymerase chain reaction (QC-PCR) assay with or without sulfamethoxazole treatment in the heart, blood, brain, and small intestine of IFN-γ knockout (GKO) BALB/c (B/c) mice after peroral infection with the cyst-forming Fukaya strain. T. gondii infection was observed in the heart, blood, and brain, but not in the small intestine, of mice treated with sulfamethoxazole for 4 weeks. No correlation between T. gondii loads and sulfamethoxazole concentrations in tissues and blood was observed. T gondii was not detected in the heart and blood after continuous sulfamethoxazole treatment for two months, but a small number of parasites was demonstrated in the brain. Thus, we successfully established an animal model for evaluating chemotherapy regimens in immunocompromised hosts by using GKO B/c mice infected with T. gondii.

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The contamination of tap water by microorganisms was surveyed at Surabaya and Jakarta, Indonesia, and at Hat Yai, Thailand. Water samples were directly collected from house faucets and filtered through membranes. The membranes were examined for protozoan parasites by immunomagnetic separation. Coliform and Escherichia coli were examined at each sample collection site using commercially available kits. A total of 115 water samples were examined and 37 (32%) were positive for any of four microorganisms which were two species of protozoa (Giardia intestinalis and Cryptosporidium parvum) and two kinds of bacteria (coliform and Escherichia coli). G. intestinalis and C. parvum were found in 9% and 1% of total samples, respectively. Of those detected, coliform was the most common and was found in all three areas with a mean detection rate of 30% (15-52%). The water samples that were positive for any of the four types of microorganisms showed a tendency to have lower residual chlorine concentrations and higher turbidities compared with negative samples. It is important to supply safe water in order to maintain people's health because most of the people surveyed (4-88%) ordinarily drank tap water without treating it. Continued efforts are needed to maintain and improve drinking water quality. (193 words)

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The single-step screening method (SSS) is a qualitative rapid screening test for glucose-6-phosphate dehydrogenase (G6PD) deficiency based on blue formazan formation on anion-exchanger.The reaction mixture contains equal volumes of anion exchanger, substrate mixture, coloring mixture (MTT-PMS mix) and distilled water. We assessed the stability of the reaction mixture and evaluated its reliability with two anion exchangers, DEAE-Sephadex A50™ and DEAE-Sephacel™, for applications in tests under field conditions. The reaction mixture was sufficiently stable under conditions of incubation at 70°C for 6 hours or vigorous shaking for 24 hours at room temperature. The reaction mixture could be kept at 30-35°C for 14 days under indoor conditions without shielding if it contained no MTT-PMS mix. The coloring was detectable even in diluted blood with hemoglobin concentration as low as 1.6 g/dl. Under laboratory conditions, the proportion of the samples with 10% of the normal level of activity that were diagnosed as 'low activity' was higher with DEAE-Sephacel (92%) than with DEAE-Sephadex A-50 (81%) (p=0.023). The proportion of the samples with normal activity that were diagnosed as 'normal' was 98% with DEAE-Sephacel and 100% with DEAE-Sephadex A-50. In field samples obtained in Myanmar and Indonesia, the sensitivity was lower (P=0.03 using DEAE-Sephadex and p< 0.001using DEAE-Sephacel) when we used the blue formazan spot test (BFST) as the standard. Twenty-three of 27 G6PD-deficient individuals subjected to genetic analysis were found to have mutations. All individuals who had concordant results between the SSS and the blue formazan spot test (BFST) carried molecular mutations. One case of G6PD mutation was detected among four cases diagnosed as G6PD-deficient by SSS with DEAE-Sephacel™, but diagnosed as 'normal' by BFST. The costs of one test with the DEAE-Sephadex A-50™ and the DEAE-Sephacel™ system were 0.15 US dollar and 0.30 US dollar, respectively. (297 words)

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To find out the natural infection with filarial larvae, female adult black flies were collected on a human attractant in December, 2001 at Tambol Ban Laung (altitude 750 m), Doi Inthanon National Park, in northern Thailand. The total number of females collected was 823 : of which 557 (67.7%) were identified as Simulium asakoae Takaoka et Davies, 144 (17.5%) as S. nigrogilvum Summers, 97 (11.8%) as S. nakhonense Takaoka et Suzuki and 25 (3%) as other six simuliid species. By dissections, eight third-and one second-stage larvae of unidentified filarial species were found in one of 138 S. nigrogilvum and one of 484 S. asakoae, respectively. Non-filarial nematodes were found in 1.03% (5/484) of S. asakoae. This is the first report of natural infections of two black-fly species, S. nigrogilvum and S. asakoae, with a filarial larva.

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