Pila ampullacea and Pomacea canaliculata, as new paratenic hosts of Gnathostoma spinigerum.

Aquatic snails, Pila ampullacea and Pomacea canaliculata were experimentally found to be suitable paratenic hosts for advanced third-stage larvae (L3) of the nematode Gnathostoma spinigerum, the causative parasite of gnathostomiasis in humans. G. spinigerum (L3) were found to be encapsulated in the tissue of the snail's foot and its internal organs. The infection, intensity and survival of third-stage larvae of G. spinigerum in both species of aquatic snails are described. This is the first evidence to reveal that not only vertebrates but also invertebrates (snails) can serve as paratenic hosts to this parasite. Aquatic snails are one of several sources of human gnathostomiasis in Thailand.

Capillariasis: chronic watery diarrhea--not only from microorganisms.

A 54-year-old male Thai patient from Prachin Buri Province presented with a history of chronic watery diarrhea for many years. He passed stool five to ten times per day with occasionally colicky pain, abdominal distension, nausea and vomiting. He had visited hospitals and private clinics and received treatment but with no improvement. He presented to the Hospital for Tropical Diseases, Bangkok, Thailand, where on physical examination, he had moderate dehydration, weakness, abdominal distension and a gurgling abdomen. The eggs, larvae and adult worms of Capillaria philippinensis were found on stool examination. The patient was admitted and treated with Mebendazole for 20 days, whereupon his symptoms resolved. Two months previously, he had ingested a raw small fresh-water fish dish called "Phra-Pla Siw/Soi". Small fresh-water fish near the patient's home were collected and examined for Capillaria philippinensis larva. The results were negative for parasitic organisms.

Paragonimiasis prevalences in Saraburi Province, Thailand, measured 20 years apart.

Saraburi Province, Central Thailand has been a paragonimiasis-endemic area since 1956. This study compared the prevalences of human paragonimiasis in two villages near Chet Khot Waterfall, Kaeng Khoi District, investigated in 1984-1985 and 2005. The results from the 1980s showed 6.3% and 1% of villagers were positive for Paragonimus eggs in sputum and stool, respectively. In 2005, Paragonimus eggs were not found in feces or sputum. An IgG-ELISA for paragonimiasis was conducted on 33 serum samples collected in the 1980s, 23 collected in 2005 and 25 diagnosed with other parasitic infections. Ninety percent of the samples from the eighties were positive for paragoimiasis, and 43% from 2005 were positive, equivalent to 10.9% and 4.9% of the total population examined in the 1980s and 2005, respectively. Serodiagnosis is currently the best method for detecting paragonimiasis. The positive cases in the 1980s were age 10-60 years and in 2005 were age 34- 67-years-old. The prevalence and intensity of Paragonimus metacercariae in fresh Waterfall crabs collected from Chet Khot Waterfall were significantly lower in the 1980s than in 2005. The prevalence of paragonimiasis in this endemic area has decreased to the level that no egg-producing cases were detected. No infections were found in villagers age < 30 years, despite the high density of metacercariae in the crabs, indicating a change in the habit of eating raw food among the younger people.

Gnathostoma infection in fish caught for local consumption in Nakhon Nayok Province, Thailand I. Prevalence and fish species.

Between August 2000 and August 2001, 12,216 fish of 73 species were purchased from several local markets in Nakhon Nayok Province, Thailand, and examined for the presence of Gnathostoma larvae. Almost all species were fresh-water fish that had grown naturally, rather than raised commercially. Eight species were found to be infected with gnathostome larvae. The overall prevalence was 5.1% (626/12,216) and a total of 5,969 larvae was recovered. The highest rate of infection (30.1 %) was found in Monopterus albus (swamp eel). The rates in the remaining infected fish were as follows: Anabas testudineus (climbing perch) 7.7%, Channa striata (striped snake-head fish) 7.4%, Clarius macrocephalus (Gunther's walking catfish) 6.7%, Channa micropeltes (giant snake-head fish) 5.1%, Channa lucius (blotched snake-head fish) 4.0%, Clarius batrachus (Batrachian walking catfish) 1.4%, and Ompok krattensis (butter sheatfish) 0.6%. The mean number of larvae/fish was highest in swamp eels (10.0 larvae/eel), and the maximum number of 698 larvae was recovered from one eel. The body sizes of the recovered G. spinigerum advanced third-stage larvae were 2.70-5.10 mm in length (average, 3.97+/-0.50 mm) and 0.29-0.60 mm in width (average, 0.40+/-0.04 mm). The average number of cephalic hooklets of the larvae from rows 1 to 4 were 41.8+/-0.5 (range, 40-43), 43.6+/-0.6 (range, 42-45), 46.1+/-0.9 (range, 44-48) and 49.3+/-0.7 (range, 48-51), respectively.