Hideo Hasegawa

Prevalence of intestinal parasitic infection in five farms in Holambra, São Paulo, Brazil

A parasitological survey was carried out on 222 inhabitants of five farms in Holambra, located 30 km north of Campinas, São Paulo, Brazil, on October 1992. Approximately 70% of the inhabitants were found to be infected with at least one species of intestinal parasite. The positive rates of 6 helminths and 7 protozoan species detected are as follows: 5.4% Ascaris lumbricoides; 8.6% Trichuris trichiura; 19.8% Necator americanus; 10.4% Strongyloides stercoralis; 1.4% Enterobius vermicularis; 0.9% Hymenolepis nana; 3.2% Entamoeba histolytica; 2.7% E. hartmanni; 9.9% E. coli; 14.0% Endolimax nana; 2.3% Iodamoeba butschlii; 10.4% Giardia lamblia; 37.8% Blastocystis hominis. The positive rates of helminth infection were generaly higher in the younger-group under 16 years-old than those in the elder group aged 16 or more, whereas the infection rates of protozoan species were higher in the elder group. The infection rate of Strongyloides was found to be 10.4% by a newly developed sensitive method (an agarplate culture methods).

A parasitological survey on the feces of pygmy chimpanzees,Pan paniscus, at Wamba, Zaïre

A parasitological examination was carried out on the feces of pygmy chimpanzees,Pan paniscus, in Zaïre, Africa. Of a total of 390 feces, 99.0% containedTroglodytella sp. trophozoites, 45.1% dicrocoeliid trematode eggs, 21.0%Capillaria sp. eggs, 3.3%Trichuris sp. eggs, 52.9%Strongyloides sp. eggs, 17.9%Oesophagostomum sp. eggs, 21.0% hookworm-like nematode eggs and 6.2% oxyurid eggs. No zoonotic protozoan was found. This is the first survey on the parasites of the pygmy chimpanzees in their natural habitat.

Studies on prevalence of Strongyloides infection in Holambra and Maceió, Brazil, by the agar plate faecal culture method

Prevalence of Strongyloides stercoralis infection in three areas of Brazil was surveyed by a recently developed faecal culture method (an agar plate culture). The Strongyloides infection was confirmed in 11.3% of 432 subjects examined. The diagnostic efficacy of the agar plate culture was as high as 93.9% compared to only 28.5% and 26.5% by the Harada-Mori filter paper culture and faecal concentration methods, when faecal samples were examined simultaneously by these three methods. Among the 49 positive samples, about 60% were confirmed to be positive only by the agar plate culture. These results indicate that the agar plate culture is a sensitive new tool for the correct diagnosis of chronic Strongyloides infection.

Epidemiological and Ecological Studies of Japanese Encephalitis in Okinawa, Subtropical Area in Japan. I. Investigations on Antibody Levels to Japanese Encephalitis Virus in Swine Sera and Vector Mosquito in Okinawa, Miyako and Ishigaki Islands

From 1985 to 1989, serum specimens of swine raised in the northern, central and southern areas in Okinawa island were examined for Japanese encephalitis (JE) virus antibody by ELISA and hemagglutination‐inhibition test. The antibody positive rate was found to be higher in the north and central than in the south. The 2‐mercaptoethanol sensitive antibody to JE was detected mostly in June and July, and occasionally in other months except February and March. There was no month when all specimens from three areas turned antibody‐negative simultaneously, indicating that JE virus transmission to swine lasted longer in Okinawa island than in other temperate areas in Japan. From 1986 to 1991, the vector mosquitoes (Culex tritaeniorhynchus) were collected in a pig farm in the south of Okinawa island. A total of 153 strains of JE virus was isolated from the vector mosquitoes mainly in June. In Miyako and Ishigaki islands, the antibody positive rate in swine sera was found to be extremely low, compared with that in Okinawa island. In Miyako island, where no paddy rice field is cultivated, a few adults as well as larvae of the vector mosquito were collected, while in Ishigaki island, where there are many watered rice fields, a lot of adults as well as larvae were collected. Although the environmental situation is quite different between the two islands, JE virus transmission appeared to be very low in both islands.

Syphacia (Syphacia) ohtaorum n. sp. (Nematoda: Oxyuridae) from Mus caroli on Okinawa Island, Japan

Syphacia (Syphacia) ohtaorum n. sp. is described from Mus caroli on Okinawa Island, Japan. It is closest to Syphacia (Syphacia) megaloon Quentin, 1966 from Mus minutoides and M. setulosus of Africa, but is distinguished in having a slimmer body, distinct lateral alae in the male, many eggs in the female and a smaller egg-size.