Echinostomiasis--a snail-borne intestinal trematode zoonosis.

Numerous echinostome trematodes are found in the intestines of birds and mammals throughout the world, and echinostomiasis in humans has been attributed to approximately 16 different species. In humans it is usually regarded as a rare intestinal parasite of little clinical importance except in heavy infections. Diagnosis of echinostomiasis is made by identification of eggs during fecal examination; however, speciation of echinostomes requires morphological study of adult worms following anthelminthic treatment. The complex life cycles of echinostomes are all linked to freshwater habitats. A mammalian or avian definitive host, one or two molluscan hosts, and one or two freshwater stages are usually required to complete the life cycle. In addition, amphibians and fish have been implicated in the transmission of some species. Prevention of human cases is dependent on eating habits, since raw or insufficiently cooked molluses, and to a lesser extent fish and amphibians, are sources of infection for humans. Human cases have been effectively, albeit accidentally, controlled by the introduction of fish which prey on the larval stages of the essential molluscan hosts.

Application of biotechnology methods to the study of trematodes.

Advances in biotechnology over the past decade offer renewed hope for solutions to trematode parasitoses in Thailand. Trematode diseases have remained the same, but the tools (1) to exploit the innate ability of cells to replicate and produce biological products upon demand, (2) to manipulate the genetic makeup of an organism, (3) and to biologically or synthetically manufacture peptides have provided scientists with new reagents for diagnosing, treating, preventing and controlling trematode diseases. Although recent applications have been focused on schistosomiasis, they have potential application to other trematode diseases (paragonimiasis, clonorchiasis, opisthorchiasis, fasciolopsiasis, and fascioliasis) endemic to Thailand. The optimism which new technology has generated must be tempered with realism and continued support for basic parasitology. Progress is dependent on a combination of approaches involving techniques at the molecular, cellular, organism and population levels. The new tools must be used in conjunction with old knowledge. Most of all there must be a rational strategy for the use of products of new technology. Defined vaccines alone will not be the answer, even if they become a reality. They must be applied in a manner that optimizes their effectiveness. The silver bullets may be out there, but they are still in a roughly molded stage. They must be finished, loaded in an appropriate epidemiological gun, and fired by an expert at specific targets.

Intestinal parasites of man in Oriental Mindoro, Philippines, with emphasis on schistosomiasis.

An intestinal parasite survey was conducted in the town of Victoria, Oriental Mindoro, Philippines in 1978 in order to estimate the current schistosomiasis situation in this area of the Philippines and Schistosoma japonicum eggs were detected in 20% of 1058 fecal specimens examined. The prevalence was more than twice as high as had been previously estimated. Infection rates were higher in males than in females, 26 versus 15% and age-wise were infrequent in young children (8%) and moderately common in other age groups (20-32%). Other intestinal helminths and protozoan parasites of man in Oriental Mindoro were: Ascaris lumbricoides, Trichuris trichiura, Necator americanus, Enterobius vermicularis, Strongyloides stercoralis, Capillaria sp, taenid tapeworm, echinostome, dicrocoelid and opisthorchiid trematode, Entamoeba histolytica, Entamoeba coli, Endolimax nana, Giardia lamblia, Iodamoeba bütschlii, Trichomonas hominis and Chilomastix mesnili.

Intestinal parasites of man in Bukidnon, Philippines, with emphasis on schistosomiasis.

A total of 831 fecal specimens from Malay-balay, Mindanao, Philippines were examined for schistosomiasis and common intestinal parasites. Schistosoma japonicum eggs were found in 16% of the samples. Infections were more common in males (20%) than in females (12%). Age-wise, infections were infrequently diagnosed in children less than 10 years and infections in older age groups varied from 12-27%. Hookworm, chiefly Necator americanus, was the most common parasite found (44%) followed by Ascaris lumbricoides (32%) Trichuris trichiura was found in only 12%. Enterobius vermicularis and eggs of Taenia sp., echinostome, heterophyid and dicrocoelid trematodes were identified in less than 1% of the samples. Entamoeba histolytica, Entamoeba coli, Entamoeba hartmanni, Endolimax nana, Giardia lamblia, Iodamoeba butschlii, Trichomonas hominis and Chilomastix mesnili were also found to parasitize man in this region of Mindanao.

Intestinal parasites of man in Northern Bohol, Philippines, with emphasis on schistosomiasis.

A survey for intestinal parasites with emphasis on Oriental schistosomiasis was conducted in the townships of Trinidad and Talibon, Bohol Province, Philippines and approximately 1,700 stool samples were examined. Schistosoma japonicum is still endemic to these areas of northern Bohol but infection rates were much lower than expected, 5% rather than 30%. Soil-transmitted helminths were the most common parasitic infections. Hookworms were found in 71% of the samples tested, most infections were due to Necator americanus 97% and Ancylostoma duodenale accounted for only 3%. Trichuris trichiura and Ascaris lumbricoides eggs were diagnosed in 58% and 45% respectively of the fecal samples examined. Other helminths and protozoan parasites detected were Enterobius vermicularis, Stronglyoides stercoralis, Entamoeba histolytica, Entamoeba hartmanni, Entamoeba coli, Endolimax nana, Iodamoeba bütschlii, Giardia lamblia and Chilomastix mesnili.

Angiostrongyliasis in Indonesia: additional geographic and host occurrence records.

Geographical and host occurrence records for Angiostrongylus cantonensis throughout the Indonesian archipelago a;e reported. A. cantonensis was found in the following provinces: West Sumatra, South Sumatra, Lampung, West Java, Central Java, North Sulawesi and East Nusa Tenggara. Infections were diagnosed in the following rodents: Rattus rattus diardii, Rattus exulans, Rattus tiomanicus jaloriensis, Rattus lepturus, Rattus norvegicus and Bandicota indica setifera and in the giant African land snail, Achatina fulica. Infection rates varied considerably.

Serological study of amoebiasis and toxoplasmosis in the Malili area, South Sulawesi, Indonesia.

Results of a serology survey in September 1972 for Entamoeba histolytica and Toxoplasma gondii antibodies among 915 volunteers from the Malili area of South Sulawesi (Celebes), Indonesia are presented. Indirect hemagglutination antibody titers for amoebiasis were found in 22.7% of the sampled population while 9.5% demonstrated antibody titers greater than or equal to 1:128. The frequency distribution of antibody titers were similar by sex and age. There was no significant correlation between stool positivity and seropositivity. Indirect hemagglutination antibody titers for T. gondii were detected in 62% of the population sampled, and titers greater than or equal to 1:32 were demonstrated in 29% of the samples tested. The distribution of antibody titers was similar in males and females. In both sexes the prevalence of IHA antibody titer against T. gondii increased with age. There was no consistent association between altitude and prevalence of seropositive samples.

Human parasitoses of the Malili area, South Sulawesi (Celebes) province, Indonesia.

A biomedical survey was conducted in 9 villages in the Malili area of South Sulawesi, Indonesia. Blood specimens were examined for malaria and microfilariae; stool specimens were examined for intestinal parasites. Malaria parasitemias were rare; Plasmodium falciparum was detected in 10 and P. vivax in 11 of 985 blood smears. Malayan filariasis was endemic to all villages surveyed. The overall prevalence of detectable microfilaremias was 15%, varying from 34% in Kawata to 1% in Nuha. Microfilarial densities, expressed as MfD50 averaged 8.0 and varied from 1.1 in Timampu to 16.0 in Karabbe. Intestinal parasites were common. Although Schistosoma japonicum was not found, 97% of the examined had one or more intestinal parasites as follows: Ascaris lumbricoides (74%), Trichuris trichiura (65%), hookworm (62%), Entamoeba coli (38%), Endolimax nana (10%), Entamoeba histolytica (6%), Iodamoeba bütschlii (4%), Entamoeba hartmanni (3%), Giardia lamblia (2%) Chilomastix mesnili (1%) and Enterobius vermicularis (1%). Strongyloides stercoralis larvae and Hymenolepis nana eggs were detected once each and heterophyid-like eggs were detected twice.

Malayan filariasis in Central Sulawesi (Celebes), Indonesia.

Seven villages in Central Sulawesi were surveyed in September 1971 and finger blood samples from 3,658 persons examined for microfilariae. Periodic, nocturnal Brugia malayi was endemic in all seven villages with microfilarial rates (Mf-rate) of 10-42% (av. 25%). The median microfilarial density (MfD50) averaged 5.4 and varied from 0.8 to 9.4 microfilariae per 20 microliter of blood. Males had higher Mf-rate and MfD50 value than females and in males Mf-rates and MfD50 values increased with age. In the female population, however, neither Mf-rates or MfD50 values varied significantly with age. Clinical manifestations of filariasis were found in 12% of 2,412 persons examined and only 2% had elephantiasis. Clinical signs of disease with the exception of elephantiasis, showed good correlations with Mf-rates but not with MfD50 values. Transmigrants experienced clinical manifestations of filariasis earlier and more often than the indigenous population.

Parasites of man in remote areas of Central and South Sulawesi, Indonesia.

A biomedical survey was conducted in 10 villages in remote, high mountain valleys of Central and South Sulawesi, Indonesia to learn whether Oriental schistosomiasis was endemic and to determine the prevalences of other intestinal parasites, malaria and filariasis in those areas. Although persons with Oriental schistosomiasis were found in three villages of South Sulawesi, follow-up inquiries revealed that these had recently migrated from a known schistosomiasis area in Central Sulawesi. Other intestinal parasites diagnosed were Ascaris lumbricoides (14%), Trichuris trichiura (7%), hookworm (68%), Entamoeba histolytica (3%), Entamoeba coli (17%), and Giardia lamblia (5%). Enterobius vermicularis, Strongyloides stercoralis, Trichostrongylus sp., Physaloptera sp., Diphyllobothrium sp. heterophyid, echinostome and dicrocoelid-like termatodes, Endolimax nana and Chilomastix mesnili were detected infrequently. Malaria parasitemias due to Plasmodium falciparum, P. vivax and P. malariae were detected in 4% of the sampled populations, Malayan filariasis was diagnosed in 21% of the subjects examined.

Intestinal and blood parasites in the Banggai Kabupaten, Central Sulawesi, Indonesia.

A survey for blood and intestinal parasites was carried out in the Banggai Kabupaten Central Sulawesi, Indonesia. A total of 336, stool specimens were obtained from 182 males and 154 females ranging in age from 2 to 90 years. Hookworm, Trichuris trichiura and Ascaris lumbricoides were the most common helminths encountered. Schistosoma japonicum was noticeably absent in the population sampled. The following intestingl protozoa were detected: Entamoeba coli, E.histolytica, Iodamoeba bütschlii, Giardia lamblia, Chilomostix mesnili and Endolimax nana. A total of 650 blood smears were examined and both Plasmodium falciparum and P. vivax were found in 5 % of the populations sampled. In addition, Brugia malayi microfilariae were detected in 3% of the blood smears examined.

Intestinal and blood parasites in the North Lore District, Central Sulawesi, Indonesia.

Over 1,000 stool specimens from residents of the Napu and Besoa Valleys, Central Sulawesi, Indonesia were examined. Schistosoma japonicum was detected in 31% of Napu Valley residents while in only 2% of the Besoa Valley residents. Hookworm infections were the most frequently encountered helminth parasitisms in both valleys. Other helminth parasites encountered were: Ascaris lumbricoides, Trichuris trichiura, Enterobius vermicularis, Strongyloides stercoralis, Physaloptera sp., Diphyllobothrium sp., echinostome and heterophyid trematodes. Intestinal protozoa endemic to the area were: Entamoeba histolytica, E. coli, E. hartmanni, Iodamoebe bütschlii, Giardia lamblia, Chilomastix mesnili and Trichomonas hominis. Plasmodium falciparum was responsible for malaria parasitaemias in 5% of 1353 specimens examined and Brugia malayi microfilaraemias were detected in 10% of 972 specimens examined.

Parasitology survey in the Palu Valley, central Sulawesi (Celebes), Indonesia.

A survey was undertaken in the Palu Valley, Central Sulasesi to determine whether schisto somiasis japonica was endemic in the area and to determine the prevalences rates of intestinal and blood parasites. Seven villages along the Palu River drainage system with an estimated popualtion of 18,700 were surveyed and 2,433 stools, 3,651 blood smears and 1,167 sera were collected and examined.

Distribution of Oncomelania hupensis in the Napu Valley of Central Sulawesi, Indonesia.

Fifteen colonies of Oncomelania hupensis were found near trails transecting the North Lore District, Napu Valley, Central Sulawesi. Habitats were in abandoned rice fields, uncultivated grazing areas for livestock, roadside ditches and, in one case, an actively worked rice field. Marsh grasses, Ischaemum barbatum and Laersia hexandra, were the most common plants in oncomelanid habitats. Other mollusks found in association with O. hupensis were Radix sp., Melanoides sp., Gyraulus sp., Idiopoma sp., Thiara sp., Opeas sp. and Indopyrgus sp. in that order of frequency. Schistosoma japonicum cercariae, as determined by mouse exposures, were shed from snails collected at four foci. In Sulawesi, O. hupensis and S. japonicum were found in high mountain valleys near, or above, 1,000 meters in elevation. Oncomelania hupensis, however, were not found in what appeared to be suitable habitats at lower elevations in the same drainage systems.