Short report: Human Trichostrongylus colubriformis infection in a rural village in Laos

In Lahanam Village, Savannakhet Province, Laos, 125 of 253 villagers (49.4%) were found by fecal examination to harbor hookworm eggs. The eggs were heterogeneous in morphology and size, suggesting infections of mixed nematode species. To confirm the hookworm egg species, on a voluntary basis, 46 hookworm egg-positive participants were treated with albendazole, and post-treatment adult worms were collected from purged fecal samples. The common human hookworm was found in only 3 participants; 1 case of Necator americanus, and 2 cases of Ancylostoma duodenale. In contrast, adult Trichostrongylus worms were expelled from most participants (43 of 46, 93.5%). The Trichostrongylus species were confirmed by morphology and internal transcribed spacer 2 sequences; all worms were of the same species (T. colubriformis). In addition, some Trichostrongylus worms were obtained from a goat in the same village and identified as T. colubriformis. The results suggested that T. colubriformis was the main zoonotic species causing hookworm infections in the village.     

The second outbreak of trichinellosis caused by Trichinella papuae in Thailand

A human trichinellosis outbreak caused by Trichinella papuae occurred in the Uthai Thani Province of Thailand in September 2007. A total of 34 villagers suffering at least one of the symptoms suggestive of trichinellosis, or those who were asymptomatic but had a history of ingesting raw wild pig meat, were enrolled in the study. Twenty-two villagers had ingested undercooked pork from a hunted wild pig (Sus scrofa). One patient with a severe clinical picture was hospitalised and more than 80 non-encapsulated larvae were detected in the muscle biopsy. The larvae were identified as T. papuae by molecular analyses of the mitochondrial cytochrome c oxidase subunit I (COI) gene and the expansion segment 5 (ES5) of the large subunit rRNA. Of the 34 suspected cases, 27 agreed to be subjected to haematological and serological tests. Immunoblot analysis using crude antigens from T. spiralis muscle larvae revealed anti-Trichinella IgG in 20 of the 26 serum samples (1 serum sample could not be analysed). All infected people were successfully treated with mebendazole; the one patient with severe symptomatology was treated successfully with prednisolone.     

Conjunctiva philophthalmosis: a case report in Thailand

A 31-year-old Thai woman, a resident of Mapthaphut, Rayong Province, eastern Thailand, attended Rayong Provincial Hospital after suffering from consistent irritation of the eye for 5 days. Examination conducted by an ophthalmologist revealed a small worm moving on the conjunctiva of the right eye. The worm was removed and sent for identification. It was 2.9 mm in length, elongated oval, pharynx very large, ceca end close to the excretory pore, genital pore opens in front of the ventral sucker at the cecal bifurcation; it was identified as Philophthalmus sp., a trematode that parasitizes the eyes of birds. This is the first human case of Philophthalmus infection in Thailand.     

Health Status of Immigrant Children and Environmental Survey of Child Daycare Centers in Samut Sakhon Province,Thailand

Samut Sakhon is a Thai province popular among immigrants attracted to work in factories and the Thai food industry, especially people from Myanmar. Poor personal-hygiene behaviors, crowded accommodation and limited sanitation, result in health problems among immigrant workers. Various infectious diseases among this group are seen and managed by Samut Sakhon General Hospital. The impact of intestinal parasitic infections on public health is well known; they can spread from infected immigrant areas to uninfected areas via close contact and fecal-oral transmission from contaminated food and water. This study aimed to determine the prevalence of intestinal parasitic infections among 372 immigrant children at 8 child-daycare centers during their parents’ work time, by physical examination, fecal examination, and examination of the environment around the centers. Physical examinations were generally unremarkable, except that head-lice and fingernail examinations were positive in two cases (0.8 %). The results showed intestinal parasitic infections to be highly prevalent, at 71.0 %. These infections comprised both helminths and protozoa: Trichuris trichiura (50.8 %), Enterobius vermicularis (25.2 %), Ascaris lumbricoides (15.3 %), hookworm (11.6 %), Giardia lamblia (10.2 %), Endolimax nana (3.5 %), Entamoeba coli (2.7 %), and Blastocystis hominis (0.5 %). The environmental survey found a small number of houseflies near the accommodation to be positive for helminthic eggs (0.2 %), including A. lumbricoides, E. vermicularis, hookworms, Taenia spp., and minute intestinal flukes. Regarding the high prevalence of intestinal parasitic infections among children, it has been conjectured whether they were infected, along with their parents, during their daily lives before or after settling in Thailand. Intestinal parasites among immigrant children may involve a significant epidemiological impact, since immigrant children can serve as carriers and transmitters of disease.     

Host-finding behavior of Strongyloides stercoralis infective larvae to sodium cation, human serum, and sweat

The host-finding behavior of Strongyloides stercoralis infective larvae was examined by in vitro agarose assay method. As human body fluid contains 0.85% (ca 0.15 molar) NaCl, various concentrations of sodium chloride, from 0.5M to 0.01M (7 steps), were examined. Many larvae were attracted at concentrations between 0.5 and 0.05M of sodium chloride. The concentration of 0.05M attracted the most larvae. The concentration of 0.02M of sodium chloride showed greatly reduced larval attraction compared with 0.05M. Therefore, the threshold concentration was determined as 0.05M. Then, 0.05M of chemicals were examined in a further experiment. Chloride compounds (NaCl, KCl, CaCl2, MgCl2) were investigated. These chemicals are components of human body fluids. Distilled water was used as the control in all experiments. Only sodium chloride attracted the larvae. Next, alkaline compounds were examined [NaOH, KOH, Ca(OH)2, and Mg(OH)2]. Larvae accumulated only at the NaOH site. The results suggested that the Na cation is important for larval attraction. A high pH value did not influence attraction at all. Next, human serum was tested. The human serum used was from normal serum to 1:32 diluted sera by distilled water (7 steps). Hierarchical attraction was seen according to serum concentration. Next, human sweat was collected from a limited zone of chest skin where only eccrine glands were distributed. Non-diluted sweat attracted the most larvae. Sweat might act as one of the most probable factors for infection by this skin-penetrating nematode.