Co-occurrence of swine cysticercosis due to Taenia solium and Taenia hydatigena in ethnic minority villages at the Thai-Myanmar border.

As part of the international joint projects working towards the control of taeniosis/cysticercosis in Asia Pacific, epidemiological studies on Taenia solium cysticercosis have been carried out in high-incidence populations, such as minority groups in Thailand. To assess the epidemiology of cysticercotic infections in pigs in the hill-tribe minority villages (Karen) in Tak province, Thailand, we conducted serological screening and necropsies. The patterns of antibody response to T. solium antigens were then investigated using immunoblot assays. Of the 188 pig serum samples tested for antibody responses to partially purified low-molecular-weight antigens of T. solium cyst fluid, positive responses were detected in 37 samples (19.7%). Based on these results, 16 pigs (10 seropositive and 6 seronegative) were necropsied for investigation of cysticerci and intestinal parasites. All seropositive pigs were coinfected with both T. solium and Taenia hydatigena cysticerci, except one, which was infected with T. hydatigena alone. Three of the six seronegative pigs were confirmed to be infected with T. hydatigena. Pigs infected with T. solium showed much stronger antibody responses than those infected with T. hydatigena. Our results demonstrate the co-occurrence of two swine cysticercoses due to T. solium and T. hydatigena in the studied areas. This study also reveals the importance of direct confirmation of the presence of cysticerci by necropsy after serological screening. In addition to the prevalence of swine cysticercosis in these endemic areas, our findings also reveal potential implications for the development of serological diagnostic assays for swine cysticercosis.

Parasitic infections in relation to practices and knowledge in a rural village in Northern Thailand with emphasis on fish-borne trematode infection.

The present study integrates several aspects of a parasitological survey in a rural community village combining community knowledge of parasites, their potential transmission routes and health risk factors. A rural community located in Northern Thailand was surveyed for intestinal parasites, and an overall prevalence of 45.2% for helminths and 4.8% for protozoan infections was identified. Socio-demographic characteristics, customs and perceptions were compiled using individual questionnaires and interviews for participants surveyed for parasitic screening. The results allowed us to determine the knowledge and perception of local people concerning helminthic infection and transmission. Despite the fact that the participants in this community were aware of parasitic transmission routes, their widespread custom of eating raw fish and meat render the reduction of helminthiasis difficult. A detailed study on the infection of fish-borne parasitic trematodes, the most prevalent helminth, allowed us to determine that the distance from a given household to the river is a determinant of infection intensity. Health education activities organised in the local community resulted in a change in perception of risks associated with parasite transmission.

Gastrointestinal helminths and Taenia spp. in parenteral tissues of free-roaming pigs (Sus scrofa indicus) from hilltribe village at the western border of Thailand.

A serological survey of pig cysticercosis was conducted in a hill-tribe village at Thai-Myanmar border, Tak province of Thailand in 2012. Sixteen backyard pigs were examined for pig cysticercosis and gastrointestinal helminth infection. In addition to cysticerci of Taenia solium and Taenia hydatigena found outside the gut, nine other helminth species were found in guts: Echinostoma malayanum, Pseudanoplocephala crawfordi, Ascarops dentata, Physocephalus sexalatus, Gnathostoma doloresi, Ascaris suum, Globocephalus sp., Oesophagostomum dentatum and Bourgelatia diducta. The study presents a report for the first time of adult tapeworm, P. crawfordi infection in pigs from Thailand. For medical importance, E. malayanum, P. crawfordi, G. doloresi and A. suum have been confirmed as potentially zoonotic helminths and pigs may act as one of the reservoir hosts for human helminthiases. Pigs of both gender and all ages appeared to be exposed to the parasites equally and did not show any significant difference to these helminth species in richness and total intensity.

Patterns of trematode infections of Opisthorchis viverrini (Opisthorchiidae) and Haplorchis taichui (Heterophyidae) in human populations from two villages in Savannakhet Province, Lao PDR.

The liver fluke, Opisthorchis viverrini, and the minute intestinal fluke, Haplorchis taichui, are prevalent in many Asian countries. This study analysed the patterns of infections of O. viverrini and H. taichui in Lahanam and Thakhamlien villages (Savannakhet Province, Lao PDR), in two cross-sectional investigations. Out of a total of 207 human participants, post-anthelmintic treatment positivity rates for expelled worms were 170 (82.1%) for H. taichui and 65 (31.4%) for O. viverrini. Both these species co-exist in the study villages. When each parasite was analysed separately, H. taichui infections reached a plateau among people aged >20 years. Opisthorchis viverrini infection rates were highest in the age group 21-30 years, with decreasing infection rates after the age of 30. Our findings indicated that fish-borne trematode infections were more prevalent among adults. Fish, common intermediate hosts, were acquired in the study area for analysis. The examination of 35 species of fish as intermediate hosts found O. viverrini metacercariae in only six species, and these were found mostly during the month of November. Many farmers who live on the rice fields obtain their food from their immediate environment, including these intermediate-host fish, potentially putting them at greater risk of O. viverrini infection. By contrast, H. taichui metacercariae were found in three species of fish obtained from the market, meaning that anyone could consume them and become infected. If people who work in rice fields limit the species of fish they consume, or avoid consuming raw fish during the month of November, they may reduce their risk of O. viverrini infection.

Strongyloides stercoralis infection and chronological changes of other soil-transmitted helminthiases in an endemic area of southern Thailand.

A field survey was conducted in 4 primary schools in Nakhon Si Thammarat Province, southern Thailand. By Sasa modified Harada-Mori cultivation method, 1.8% of the schoolchildren were found to be infected with Strongyloides stercoralis, and 25.1% had hookworm infection. By Kato's thick smear method, the overall prevalence of soil-transmitted helminths was 46.8%, being Trichuris trichiura 28.5%, hookworm 18.0%, and Ascaris lumbricoides 5.7%. Fecal examination, performed by Kato's thick smear and culture method, indicated that the prevalence of hookworm infection was 26.9%. The prevalence in the present study was very much lower than many previous reports in the past decade. This may indicate the partial success of the parasite control project in Thailand by mass treatment, improving the sanitation and personal hygiene of the people in the endemic area. In light infection with Trichuris, albendazole administered at a dosage of 200 mg daily for 3 days showed a 48.7% cure rate. When mebendazole was given at 100 mg twice daily for 3 days, its effectiveness was 88.5%. A lower cure rate was obtained (70.0%) in moderate to heavy infection.

Vitamin B1, B2 and B6 deficiency in primary school children infected with hookworm.

One thousand and seven hundred thirty-six school children from two districts in Nakhon Si Thammarat Province were screened for hookworm infection using the Kato-Katz stool examination technic. Two hundred students who have at least 2,000 eggs per g of stool were recruited into the program. The students were divided into six groups: groups 1, 2 and 3 were from Tha Sala district while groups 4, 5 and 6 were from Ronpibul district. Three milliliter blood samples were obtained from the cubital vein of each subject and were evaluated for erythrocyte transketolase activity (ETK) for vitamin B1, erythrocyte glutathione oxidoreductase activity (EGR) for vitamin B2, and erythrocyte aspartate aminotransferase activity (EAST) for vitamin B6. The school children were divided into three groups: those infected only with hookworm, those with both hookworm and Trichuris trichiura, and those whose stools show no parasite eggs. The results show that 10-20% of the school children are vitamin B1 deficient, about 40% to 80% are vitamin B2 deficient, and about 14% to 23% are vitamin B6 deficient. No correlation could be made between vitamin deficiencies and parasitic infection.

Effect of single-dose albendazole and single-dose mebendazole on Necator americanus.

One hundred two children (43 males and 59 females) aged 6 to 14 years with positive stool examination by Kato-Katz and/or Harada-Mori culture techniques for N. americanus, were randomly divided into two groups. Group I with 48 children were treated with a single dose albendazole, 400 mg. Group II, 54 children, received a single dose mebendazole, 600 mg. After treatment, repeated stool examination was performed on Day 14, Day 21 and Day 28. The children were considered cured when stool examination was negative on all three occasions by both methods. The cure rate was 64% in Group I and 11% in Group II. The difference was statistically significant (p less than 0.05). The eggs reduction rate was 98% in Group I and 95% in Group II. Mild and transient side effects such as nausea, dizziness and headache were observed in both groups. Albendazole, 400 mg, as a single dose treatment was shown to be superior to mebendazole, 600 mg, single dose for the mass treatment of hookworm infection, especially that of Necator americanus, in an endemic area.