Egg production capacity of one-pair worms of Schistosoma japonicum in albino mice.

In the present study, a series of procedures of egg count were carried out to determine the egg production capacity in 21 ICR mice each infected with one-pair of Schistosoma japonicum. The egg count began from the first day, they were detected in the feces, which was based on a stool collection over 24 hours, twice a week. Each female S. japonicum produced an average of 2,198 eggs/day during the study period of 99 days after infection (ranged 61-147 days). Fourty-seven percent of the eggs were in the feces and 53% in tissues (45% in large intestine, 31% in small intestine, 23% in liver, 0.4% in pancreas, 0.2% in lungs, 0.1% in spleen, 0.1% in lymph nodes, 0.06% in stomach and 0.05% in heart, kidney, diaphragm and brain).

Ultrastructural observations on cercaria of Schistosoma japonicum.

The present paper describes the ultrastructure of the surface topography, head organ, tegument, musculature, glandular system, primary alimentary tract and flame cells of the Chinese mainland strain of Schistosoma japonicum cercaria, as visualized with both scanning and transmission electron microscopes. The results not only illustrate the morphological features of the cercarial surface and its internal structure reflecting an adaptation to the aqueous habitat but also reveal the correlation between the morphological structure and physiological function.

Susceptibility of snail vectors to Oriental anthropophilic Schistosoma.

Laboratory experiments were carried out to study the susceptibility of snail vectors to Oriental anthropophilic Schistosoma. Oncomelania hupensis hupensis was readily infected with the local strain of Schistosoma japonicum (Chinese strain), and also infected with S. japonicum (Philippines strain). O.h. quadrasi was only susceptible to its S. japonicum (Philippines strain). The Oncomelania races were refractory to S. mekongi, S. japonicum-like species (Malaysian strain). Tricula aperta (beta race) was readily infected with S. mekongi, S. sinensium and S. japonicum-like species from Malaysia, but not S. japonicum. T. bollingi was susceptible to S. sinensium and S. mekongi. Robertsiella kaporensis was only susceptible to the local strain, S. japonicum-like species from Malaysia. Geographical isolation may be the cause of these differences in compatibility between the snail vectors and the schistosome parasites.

Studies on the susceptibility of new Taiwan foci of Oncomelania hupensis to Ilan and Japanese strains of Schistosoma japonicum.

Sixty snails from four new foci of O. hupensis in Taitung, Chiayi, Hualien and Nantou counties, and 4 known colonies of O. h. chiui in Alilao and Pali in Taipei as well as of O. h. formosana in Changhua and Ilan on Taiwan were exposed each to 5 miracidia of Ilan zoophilic strain and Japanese anthropophilic or human strain of S. japonicum. This is the first report to note that all four new foci of O. hupensis snails were highly susceptible to Ilan strain of S. japonicum (17-20%). Susceptibility to the Japanese strain was detected in Taitung (33%), but, very low to not susceptible for the Hualien (2%), Chiayi and Nantou snails. Susceptibility of new Taiwan foci to the geographic strains of S. japonicum has now been well established, widespread distribution of susceptible snails in Taiwan could possibly lead to public health problem in the event that S. japonicum were introduced to the island.

An epidemiological study on Schistosoma japonicum in domestic animals in Leyte, Philippines.

An epidemiological study of Schistosoma japonicum in domestic animals in two municipalities of the Eastern coastal plain of Leyte, Philippines, showed that pigs and dogs have the highest rates of prevalence. Dogs had the highest mean 24-hour egg output, and pigs the proportion of hatchable eggs. However, dogs serve an important role in maintaining the transmission of the parasite as indicated by a high transmission potential and the close habitual contact of the animals to human. Although necropsy of 49 dogs and 35 pigs which were coprologically and serologically negative revealed 10 dogs and 6 pigs with adult schistosomes in the mesenteric and portal veins, statistical analysis showed a positive correlation (p less than 0.05) between merthiolate iodine formalin concentration technique and circumoval precipitin test indicating the usefulness of the two tests in field diagnosis of schistosomiasis in domestic animals.