Comparative morphometry, morphology of egg and adult surface topography under light and scanning electron microscopies, and metaphase karyotype among three size-races of Fasciola gigantica in Thailand.

Comparative morphometry of eggs and adults under light microscope, and morphology of adults under scanning electron microscope (SEM) were undertaken in the three size-races (< 25 mm, 25-35 mm, > 35 mm) of Fasciola gigantica (Thailand strain). Morphometric examination revealed intraspecific variation with respects to the dimensions of eggs and adults, whereas surface topography of the three size-race adults under SEM was morphologically similar. The observations on mitotic metaphase chromosomes of spermatogonial cells from testes of the three size-races revealed 2n=20 (diploid type), and no karyotypic difference was observed among them. The meiotic metaphase chromosome was 10 bivalents in primary spermatocyte in diplotene to diakinesis, and many mature spermatozoa were seen in the testicular preparations.

Bancroftian filariasis in Tambol Na-Sai, Amphoe Li, Lamphun Province: a preliminary survey for microfilaraemia.

A preliminary survey for Bancroftian filariasis in villagers of Ban Prabat Heuy Tom, Tambol Na-Sai, Amphoe Li, Lamphun Province was performed between July 12, 1986 and March 19, 1987. A total of 1,435 villagers comprising 668 females and 767 males were examined for microfilaraemia in peripheral blood. Microfilariae were found in five males of which two cases were found to have developed hydrocele at a lesser degree and all of them had formerly resided in an endemic area of Tak Province. Microfilarial periodicity was studied in two cases, and it was shown to be nocturnally subperiodic.

Studies on the Japanese encephalitis vectors in Amphoe Muang, Chiang Mai, Northern Thailand.

From February 1987 to January 1988, biological and ecological studies were made to obtain the basic knowledge of Japanese encephalitis vectors, Culex tritaeniorhynchus, Cx. gelidus, and Cx. fuscocephala, in Amphoe Muang, Chiang Mai, northern Thailand. The following results were found. Peaks in the population densities of the vectors as measured four times a month, by UV-light trap and human-baited trap collections, occurred during rainy season. The JE vectors in rural areas showed a sharp rise in the population in July when most of the rice fields were ploughed and a marked decline in mosquito population densities occurred after transplanting in August when the fields were flooded. The average number of larvae plus pupae per m2 in rice fields was highest in July when the fields were ploughed, but in the period from transplanting to harvesting (August to November), the densities were very low. Daily survival rates of the adult females, as estimated from parous rates, were mostly as high as 0.7 throughout the year.

Filariasis in Tak Province, northwest Thailand: the presence of subperiodic variant Wuchereria bancrofti.

The microfilariae found in carriers at Tak Province, Northwestern Thailand were morphologically and morphometrically studied. It was found that the parasites conformed to that of W. bancrofti microfilaria. The microfilarial periodicity as determined from four carriers was found to be nocturnally (early evening) subperiodic type showing a distinct peak at 1800 hours.