A newly developed agglutination test using gelatin particles as an antigen carrier (GPAT) was compared with a conventional enzyme-linked immunosorbent assay (ELISA) for the detection of Parastrongylus cantonensis antibodies in sera from patients. A total of 70 sera was used in the study. Of these, 10 each were from patients with parastrongyliasis, gnathostomiasis, paragonimiasis, cysticercosis, toxocariasis, filariasis and malaria. The control group consisted of 50 serum samples from normal healthy individuals. The mean reciprocal titer of the parastrongyliasis patients group was significantly higher than that of the normal group as well as those of other parasitic infections. The sensitivity and specificity of the GPAT were 100% and 92.4%, respectively. The results of GPAT in detecting P. cantonensis antibodies appeared to be closely correlated with those obtained with ELISA. The GPAT, however, is more easy, rapid and cheap; it may also be a test of choice for routine immunodiagnosis of human parastrongyliasis.

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The sporozoite penetration process of a rodent malaria parasite, Plasmodium berghei, into the salivary glands of the vector mosquito, Anopheles stephensi and sporozoite distribution in the cytoplasm and secretory cavity in the distal region of salivary glands were observed with a scanning electron microscope and a transmission electron microscope. In noninfected mosquitoes, many swellings were observed on the outer surface of the median lobes of salivary glands, whereas many shallow depressions were observed on the lateral lobes. In infected mosquitoes, sporozoites were concentrated on the distal region of median and lateral lobes of salivary glands and penetration occurred from the anterior end into both lobes. Sporozoites were about 10 μm long with one end flat and the other round. Small holes through which sporozoites might have passed were observed on the surface of both median and lateral lobes. A white powder like substance, which might come from the holes, covered the surface of both lobes. Sporozoites invading the cytoplasm of the salivary gland cells were surrounded with vacuoles. These sporozoites invaded the secretory cavity and lodged to form bundles.

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A total of 1, 889 voluntarily donated blood from five provinces in northern Thailand were investigated for the prevalences of hepatitis B virus (HBV), hepatitis C virus (HCV) and human immunodeficiency virus (HIV) infection. The average positive rates of HBs-Ag, anti-HBs, IgM anti-HBc, anti-HCV and anti-HIV were 8.7, 42.6, 0.5, 1.6 and 1.7%, respectively. The highest positive rates of HBs-Ag, anti-HBs, IgM anti-HCV and anti-HIV were found in the age group under 19 years (13.3%), 40-49 year old group (47.6%), 20-29 year old group (0.6%), 30-39 year old group (2.6%) and 20-29 year old group (2.9%), respectively. We found only two cases that were anti-HIV and HBs-Ag positive. There are no cases that were anti-HIV and IgM anti-HBc positive, and that were anti-HIV and anti-HCV positive. These results suggest that in northern Thailand, most of the HBV infections are due to vertical transmission from mother to child, although HBV infection is a major cause of viral hepatitis, HCV infection will become an important public health problem in the near future and that the prevalence of HIV infection is quite high among sexually active generations. Therefore, there is a need for more medical attention to these blood-borne virus diseases, and we strongly recommend routine blood screening for HCV in every medical institutions in northern Thailand.

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