Current Status of Gnathostoma Infection in Thailand

Abstract

Abstract

At least five species of Gnathostoma: G. spinigerum, G. hispidum, G. doloresi, G. vietnamicum and G. malaysiae have been documented in Thailand, but only G. spinigerum is known to cause human infection. From 1961 to 1963, about 900 patients were clinically diagnosed each year as having gnathostomosis, and about 10 deaths were reported between 1967-1981. Each year, from 1985 to 1988, between 300-600 suspected gnathostomosis patients came to the gnathostomosis clinic at the Hospital for Tropical Diseases, Faculty of Tropical Medicine, Mahidol University. From 1989 until now, about 100-400 new cases of suspected gnathostomosis have been seen each year at this hospital. In Nakhon Nayok and Prachin Buri Provinces, central Thailand, the prevalences of Gnathostoma infection in eels were 38.1% and 24.0%, respectively. Most of the positive eels harbored only 1-9 larvae. In Nakhon Nayok, about 12,000 fresh-water fish were examined: 8 out of 72 species were found to be infected with gnathostome larvae. The infection rates in Monopterus albus, Anabas testudineus, Channa striata, Clarias macrocephalus and Channa micropeltes were 30.1%, 7.7%, 7.4%, 6.7% and 5.1%, respectively. The overall positive rate for G. spinigerum eggs in dog fecal samples, which were collected from 21 localities in Nakhon Nayok, was 1.2%. In Bangkok, no infections with G. spinigerum were found in the stomachs and intestines of 200 stray dogs; negative results for the worm eggs were also obtained with fecal samples of 370 cats and 518 dogs. A cyclops survey in each of two areas (Ban Phrao, Nakhon Nayok and Tha Ngam, Prachin Buri) found no evidence of natural cyclops infection.

Keywords : Gnathostoma, gnathostomosis, current status, Thailand