Supaporn Nuamtanong

Sympatric Occurrence of Taenia solium, T. saginata, and T. asiatica, Thailand

We confirmed sympatric occurrence of Taenia solium, T. saginata, and T. asiatica in western Thailand. DNA analysis of morphologically identified T. saginata, in a dual infection with T. solium, indicated it was T. asiatica. To our knowledge, this report is the first of T. asiatica and a dual Taenia infection from Thailand.

Diagnostic values of IgG4 in human gnathostomiasis

The diagnostic values of immunoglobulin G subclass antibodies from patients with gnathostomiasis were assessed by immunoblot technique. Antigen was prepared from crude extracts of Gnathostoma spinigerum advanced third‐stage larvae obtained from naturally infected eels. The sera were obtained from 14 parasite‐confirmed gnathostomiasis cases, 63 patients with other helminthic infections and 13 healthy controls. Nine prominent IgG4 reactive bands appeared with molecular weights of 94, 51, 47, 43, 38, 24, 21, 20 and 15 kDa. The diagnostic sensitivity of each of the nine reactive bands ranged from 100% to 64.3% in 14 parasite‐confirmed gnathostomiasis cases. All (100%) confirmed cases recognized the 21 kDa antigenic band, but not other helminthic infections or parasite‐free control. Recognition of 21 kDa antigen in G. spinigerum advanced third‐stage larvae crude extracts is the most specific diagnostic marker for human gnathostomiasis, with 100% sensitivity and specificity. The 20 and 24 kDa protein bands were additional diagnostic bands for confirming diagnosis of infection where the 21 kDa band was faint. No specific binding of IgG1, IgG2, or IgG3 antibodies was observed in any sera from confirmed gnathostomiasis cases.

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.

Haplorchis taichui as a Possible Etiologic Agent of Irritable Bowel Syndrome-Like Symptoms

The aim of this study is to clarify the clinical features of Haplorchis taichui infection in humans in Nan Province, Thailand, and to correlate the clinical features with irritable bowel syndrome (IBS)-like symptoms. In this study area, only H. taichui, but neither other minute intestinal flukes nor small liver flukes were endemic. The degree of infection was determined by fecal egg counts and also by collecting adult worms after deworming. The signs and symptoms of individual patients together with their hematological and biochemical laboratory data were gathered to evaluate the relationship between the clinical features and the severity of infection. Special emphasis was made to elucidate the possible similarities of the clinical features of H. taichui infection and IBS-like symptoms. The results showed useful clinical information and the significant (> 50%) proportion of haplorchiasis patients complained of abdominal pain, lassitude, and flatulence, which were the important diagnostic symptoms of IBS. This study has reported a possible link between H. taichui and IBS, and H. taichui might probably play a role in the etiology of these IBS-like symptoms.

Monophyly of Opisthorchis viverrini populations in the lower Mekong Basin, using mitochondrial DNA nad1 gene as the marker.

The liver fluke, Opisthorchis viverrini, causes serious public-health problems in the Lower Mekong Basin. This study aimed to clarify whether O. viverrini populations may be genetically divided into sub-specific taxa. We collected 6 populations of O. viverrini from different places in Cambodia, Lao PDR, and Thailand, along both sides of the Mekong River, and analyzed the population structure of these using the mitochondrial nad1 gene as a marker. The results of the DNA polymorphism measurements, by theta-w (thetaw) and -pi (thetapi) values, neutrality tests, and mismatch distribution, suggested that the population of O. viverrini has expanded under the influence of purifying selection and selective sweep. The analysis of molecular variance (AMOVA) test revealed no significant genetic differences among the O. viverrini populations on opposite sides of the Mekong River. O. viverrini haplotypes occurred in multiple populations, and no distinct geographical clade. The star-like haplotype network confirmed a demographic expansion of the O. viverrini population. Overall, the genetic data from these populations suggested that the postulated existence of an O. viverrini species complex should be rejected. The bio-geographical diversity of O. viverrini populations should be explored further, using other appropriate markers and a wider range of samples from geographically different areas.

Discovery of Opisthorchis lobatus (Trematoda: Opisthorchiidae): A New Record of Small Liver Flukes In the Greater Mekong Sub-Region

Abstract Metacercariae, morphologically similar to those of small liver flukes, were found to parasitize red-tailed snakehead fish, Channa limbata, collected from the city of Vientiane, Lao Peoples Democratic Republic. Adult worms that were recovered from experimentally-infected hamsters showed characteristics distinctly different from Opisthorchis viverrini, but closely similar to Opisthorchis lobatus, which was first reported in poultry (Anas sp.) from Pakistan. The present study aimed to redescribe O. lobatus based on the adult worms recovered from experimentally-infected hamsters. Additionally, it aimed to document the genetic relationships among O. lobatus and other opisthorchiid liver flukes using the mitochondrial cytochrome c oxidase subunit 1 (COI) gene and the internal transcribed spacer 2 (ITS2) region. DNA alignment of the O. lobatus and O. viverrini COI partial sequences (330 bp) showed 3.03% fixed differences (2.72% of amino acids changed) while the ITS2 region (350 bp) indicated a 0.86% difference for nucleotides. Species boundaries between the 2 parasites were determined by neighbor-joining analysis using the molecular sequence data. The phenogram confirmed that O. lobatus was distinctly different from O. viverrini, representing the first reported instance of O. lobatus in the Greater Mekong Sub-region (GMS) and the first record of C. limbata as the second intermediate host of a small liver fluke. Questions regarding human infection and the extent of the geographic distribution of these species should be investigated further.

School-based health education for the control of soil-transmitted helminthiases in Kanchanaburi province, Thailand

Abstract Soil-transmitted helminthiases are major parasitic diseases that cause health problems world-wide. School-based health education is one of several basic interventions currently recommended by the World Health Organization for the control of these infections. A 3-year programme of health education for the control of soil-transmitted helminths (STH) has recently been completed in four primary schools in the Hauykayeng subdistrict of Thong Pha Phum district, in the Kanchanaburi province of Thailand. Overall, the percentage of the schoolchildren found infected with STH increased between the start of year 1 of the intervention (16.6%) and the end of year 2 (23.8%) but showed signs of falling by the end of year 3 (19.4%). Although none of these year-on-year changes in overall prevalence was statistically significant, some significant trends were detected when the six school grades (i.e. age-groups) were considered separately. The grade showing the highest prevalence of STH infection changed, from grade 6 (representing the oldest children investigated) at the start of year 1 (when grade-1 children were excluded from the survey) to grade 1 (representing the youngest children) at the ends of year 2 and year 3. By the end of year 3, the children in grades 5 and 6 had significantly lower prevalences of infection than the grade-1 subjects. The prevalence of STH infection in the grade-1 children was significantly higher than that in any of the older grades at the end of year 2 and significantly higher than that in grades 3–6 at the end of year 3. These results indicate that the health education had a greater impact on the children in the higher grades (who, presumably had better levels of understanding and practised better, personal, infection prevention) than on the younger children. Although school-based interventions can serve as a useful entry point for parasite control, more effort, including anthelminthic treatment, may be required among the youngest children. The activities need to be sustainable and supported by appropriate school-health policies.

Prevalence and clinical aspects of human Trichostrongylus colubriformis infection in Lao PDR

There have been few studies on human trichostrongyliasis in Southeast Asia, information on its clinical manifestations is also sparse. Trichostrongyliasis occurs predominantly in areas where poor hygiene is common especially where human/animal feces are used as a fertilizer, thereby contaminating vegetables and stream water. The intimate coexistence of domestic animals and humans explains the prevalence of Trichostrongylus infection in such areas. The goal of the current study was to determine the prevalence of trichostrongyliasis among villagers in Thakamrien village, Sonkon district, Savannakhet province, Laos, and to investigate potential relationships between clinical features, laboratory data, and severity of infection. Of 272 villagers examined, 160 (58.8%) were determined positive for helminthic infections by fecal examination, and 59 (36.9%) of these were infected with Trichostrongylus. Only 58 cases were in the inclusion criteria of the study and then underwent further assessment, including a questionnaire on personal behaviors, physical examination, and laboratory tests. Villagers in the trichostrongyliasis group were more likely than the control group to have consumed fresh vegetables, not washed their hands before meals or after using the toilet, and to have had close contact with herbivorous animals (goats and cows). Similarly, villagers in the trichostrongyliasis group were more likely than the control group to have a history of loose feces, rash, or abdominal pain; however, no obvious clinical symptoms were observed during physical examination of the trichostrongyliasis patients. The degree of infection was determined by both fecal egg counts and quantification of adult worms after deworming. Laboratory data were evaluated for any relationship with severity of infection. No significant differences were found in laboratory values between the trichostrongyliasis and control groups, with most values being within normal limits; however, both groups had high eosinophil counts. This study demonstrated that the useful clinical characteristics of trichostrongyliasis patients include history of loose feces, rashes, and abdominal pain, as well as in personal behaviors, such as the regular consumption of fresh vegetables, lack of hand washing, and close contact with cattle.

Non-encapsulated Trichinella spp., T. papuae, diminishes severity of DSS-induced colitis in mice.

BACKGROUND Helminths use various mechanisms to avoid host immunity and protect themselves from being eliminated. Despite evading host immune responses, immunosuppression and regulation mechanisms elicit functions that diminish the adverse effects of unrelated inflammatory diseases. OBJECTIVE We investigated whether helminthic infections can ameliorate inflammatory diseases. METHODS Mice were infected with Trichinella papuae and then subjected to induced colitis through the oral administration of dextran sulfate sodium (DSS). Macroscopic and microscopic examinations measured weight loss, stool consistency, gross bleeding, colon length, and tissue inflammation. In addition, cytokine expression was observed in colon tissue by SYBR real-time RT-PCR to investigate the Th1, Th2, and regulatory cytokines. RESULT The results showed that T. papuae infection decreased the severity of DSS-inducedcolitis, including weight loss, bloody diarrhea, shortening of colon, and colon tissue damage in mice (p <0.05). The expression level of IL-4 was high in the colons of DSS-treated mice without helminthic infection, while infected mice with DSS treatment had lower IL-4 levels (p <0.05). Uninfected DSS-treated mice failed to produce IL-10 mRNA in colon tissue, which may cause more severe colitis. In contrast, prior T. papuae infection DSS-treated mice had IL-10 levels in the colon significant lower than the normal and infected control groups. CONCLUSION Our data provide the evidence that prior T. papuae infection can ameliorate DSS-induced colitis in mice and may be considered for a novel therapeutic strategy against immunological diseases in the future.