Collections of pupae and larvae of black flies (Diptera : Simuliidae) were carried out in 1992 and 1994 at 59 sites in four provinces of Sumatra, Indonesia. As a result, 22 simuliid species including 12 species newly recorded from Sumatra were identified, bringing the total number of simuliid species recorded from Sumatra to 26. All these species were assigned to the genus Simulium s. 1. and placed into three subgenera, i.e., Gomphostilbia (12 spp.), Nevermannia (3 spp.), and Simulium s. str. (11 spp.). Further groupings were made at the species-group level within each subgenus. The simuliid fauna of Sumatra is Oriental in character, being very closely related to those of Peninsular Malaysia and Java. Infections with mermithids, microsporidians and/or fungi due to Coelomycidium sp. were found in the larvae of 10 of the 22 black-fly species examined.

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Simulium (Gomphostilbia) chumpornense sp. nov. is described from reared adults, pupae and mature larvae collected from southern Thailand. This new species is assigned to the varicorne species-group within the subgenus Gomphostilbia by having the adult antennae composed of 2+8 segments in place of usual 2+9 segments. In addition, nine known simuliid species, most of which were described from Peninsular Malaysia, are recorded for the first time from Thailand, bringing the total number of simuliid species in this country to 40.

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Sibling species A of Anopheles subpictus (fresh water form) has been incriminated and established as a primary vector of malaria for the first time in an area (Tarakeswar, West Bengal) in Indian subcontinent with a natural sporozoite (Plasmodium vivax) rate of 0.32% (2/621). Moderate anthropophilic index (41.0) and high survival rate per gonotrophic cycle (0.58) indicate its efficiency as vector. Coincidence of higher malaria cases and higher density of An. subpictus in the study area is of high relevance. No natural sporozoite infection was detected in other anophelines available like An. vagus, An. annularis and An. barbirostris.

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The effect of repeated 4 monthly treatment of single dose of 400 mg albendazole on the prevalence and worm burden of Ascaris, Trichuris and hookworm was studied in an endemic area. Repeated 4 monthly treatment, had significant effect in reducing the worm burden of Ascaris and not the prevalence. As for hookworm infection repeated 4 monthly treatment had significant impact in reducing both prevalence and worm burden in the community. However, repeated 4 monthly treatments had no significant impact in reducing the prevalence and worm burden of Trichuris infection in the community. Trichuris infection should be considered as a continuing infection rather than reinfection because of poor cure rate of albendazole at the onset of the study. Significant and strong predisposition (p < 0.0001) were detected after single and repeated 4 monthly treatment in Ascaris and Trichuris infection but not in hookworm infection. Stratification of data indicated that significant and strong predisposition was also seen in gender. This study concludes that changes in mean egg count per gram (mean EPG) is a sensitive indicator in measuring effect of treatment in an endemic area, and repeated 4 monthly treatments has successfully reduced the worm burden of Ascaris and hookworm infection. Subjects remained predisposed to Ascaris infection over 2 reinfection periods, and for hookworm infection evidence of predisposition was seen only over 1 reinfection period.

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It was indicated that tachyzoites and bradyzoites of Toxoplasma gondii (T. gondii) defined by the susceptibility/resistance to acid treatment could be quantitatively analyzed by a quantitative competitive polymerase chain reaction method targeting SAG1 gene, specific for T. gondii. The tachyzoites were destroyed not only by pepsin-HCl but also by HCl or other acid solutions. The acid-induced destructions occurred under the pH conditions lower than pH 1.8. Tachyzoite DNA of T. gondii was easily destructed by acid treatment. These DNA destructions made it possible to differentiate between tachyzoites and bradyzoites by QC-PCR.

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