Geographic information system of Opisthorchis viverrini in northeast Thailand.

Background: Opisthorchiasis caused by Opisthorchis viverrini remains a major public health problem in many parts of Southeast Asia including Thailand, Lao PDR, Vietnam, and Cambodia. The epicenter of this disease is located in northeast Thailand, where high a prevalence of opisthorchiasis coexists with a high incidence of cholangiocarcinoma (CHCA), a major primary carcinoma of the liver with a very poor prognosis. Objective: Determine the surveillance characteristics of O. viverrini infections in northeast Thailand. Methods: Four thousand one hundred eighteen stool samples from 19 provinces were used in this study. All age groups were included, from below four years to more than 60 years. The geographic information system (GIS) was deployed to overlay the prevalence of disease on urban and agricultural areas as well as manmade land uses. Results: Results showed a rate of Opisthorchiasis of 20.39% (840/4,118). Farmland and forests (loam soil) were highly associated with infection. Conclusion: The rate of Opisthorchiasis is high in farmland and forests and lower in residential areas. Mass treatment targeted at high-risk areas may be a cost-effective control strategy and warrants further study.

A study of ectoparasites of Canis lupus familiaris in Mueang district, Khon Kaen, Thailand.

We studied ectoparasites found on Canis lupus familiaris sampled in five areas in Mueang district, Khon Kaen Province, Thailand. The prevalence of fleas and ticks as well as their density were determined in 100 dogs that did not receive treatments. A total number of 458 ectoparasites was found corresponding to two species: 25.8% Ctenocephalides canis and 74.2% Rhipicephalus sanguineus. R. sanguineus was the most abundant species, and Ct. canis was the only flea species found. The stages of R. sanguineus were larvae (5.3%), nymphs (29.1%) and adults (39.1% in male and 26.5% in female). The stages of Ct. canis were larvae (41.5%) and adults (58.5%). Both species were commonly found on domestic dogs in all areas of the study. Ct. canis was not present on domestic dogs in one sub-district. The prevalence rates of tick-harboring domestic dogs was 80% (R. sanguineus), and flea-haboring domestic dogs was 26% (Ct. canis).

Malaria and enterobiasis among Karen Long-neck tribe in Mae Hong Son Province.

In Thailand, Mae Hong Son Province is highly endemic for malaria. Knowing this, the local Health Department has introduced a program to educate local residents about the risk factors, in particular the dangers and symptoms of malaria. This study was conducted to evaluate these efforts, by determining the number of malaria infections in a segment of the population, and also by testing for enterobiasis among a group of its children. Two villages in Mae Hong Son Province were chosen for this purpose with a combined population of about 300. Of these, 195 were screened for malaria. Two subjects were diagnosed positive for malaria by microscopy. One of these two villages was chosen to screen for Enterobius vermicularis infection in children as well. Out of 69 stool samples, five (7%) showed infection with E. vermicularis: three with a low number of eggs (1-50), and two with a high number of eggs (>100). Compared with infection rates in similar studies, the results of this study indicate that the Health Department's efforts are meeting with relative success. The low prevalence of infection indicates that the villagers are using the information they have received to help combat infection.

Parasitic infections among Karen in Kanchanaburi Province, western Thailand.

The purpose of this study was to determine the rate of intestinal parasitic and malarial infections during a period of low infection among the residents of remote Karen villages in Thailand. Fifty-five males and 64 females, aged 6 months to 70 years, were examined for malaria by thick blood smears using the Giemsa staining technique. Of the 119 subjects, 4 (3.36%) showed positive for malaria with vivax gametocytes. Results suggested that mass screening was not an effective way for diagnosing malaria. Stool samples were examined under a light microscope. The overall intestinal parasitic infection rates were 38.24% in 34 males, and 36.11% in 36 females. These were hookworm (17.14%), Ascaris lumbricoides (7.14%), Trichuris trichiura (1.43%), Strongyloides stercoralis (7.14%), Taenia spp (1.43%), Entamoeba histolytica (1.43%), Entamaeba coli (10.00%) and Giatdia lamblia (1.43%). The highest (55.55%) and lowest (16.66%) rates of infection were observed in age groups 0-5 and over 45, years respectively. In addition, A. lumbricoides and T. trichiura were found more frequently in children, while hookworms was found similarly in every age group. Results showed that the Karen living along the western border of Thailand possessed high rates of intestinal parasitic infections. Strict monitoring and control programs for these parasites should be implemented.