Asymptomatic Human Paragonimiasis among the Karen People in Tak Province, Thailand: A Case Report.

During the mobile clinic activities in Tak Province, Thailand, Paragonimus sp. eggs were found in a fecal sample of a 72-year-old Karen resident. Paragonimus DNA was amplified from the stool sample and identified to P. heterotremus. The patient did not have any symptoms. Apparent pulmonary lesion was not found on the chest X-ray. The patient admitted habitual consumption of semi-cooked or roasted waterfall crabs for several years. The waterfall crabs collected from stream near the village were found negative for Paragonimus metacercariae. In northern Thailand, paragonimiasis remains as one of the public health concerns and should be ruled out for asymptomatic pulmonary patients.

A SIMPLE AND EFFECTIVE MULTIPLEX PCR TECHNIQUE FOR DETECTING HUMAN PATHOGENIC TAENIA EGGS IN HOUSEFLIES.

Taenia solium, T. saginata, and T. asiatica are cestode pathogens causing taeniasis in humans. Houseflies can transfer Taenia eggs to food. However, houseflies are thought to carry only small numbers of Taenia eggs, sometimes fewer than 10. Although several PCR-based methods have been developed to detect Taenia DNA, these require more than 10 eggs for adequate detection. We developed a multiplex PCR method with high specificity for the discrimination among the eggs of the three Taenia species, T. solium, T. saginata, and T. asiatica, using 18S ribosomal DNA (rDNA) as a genetic marker. This technique was found to be highly sensitive, capable of identifying the Taenia species from only one egg. This multiplex PCR technique using 18S rDNA specific primers should be suitable to diagnose Taenia eggs.

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.

Triplex polymerase chain reaction assay for detection of major soil-transmitted helminths, Ascaris lumbricoides, Trichuris trichiura, Necator americanus, in fecal samples.

Ascaris lumbricoides, Trichuris trichiura, and Necator americanus are medically important soil-transmitted helminths (STHs) occurring frequently worldwide including Thailand. Fecal examination using a microscope has been recommended as the gold standard for diagnosis of STH infections, but suffers from low sensitivity. Recently, highly sensitive and specific assays, such as multiplex quantitative PCR, has been established, but the high cost and need for special instruments are still barriers limiting their applications in routine diagnosis. Therefore, a conventional multiplex PCR assay, with its lower cost and greater simplicity, was developed, for the simultaneous detection of STHs in fecal samples. The multiplex PCR assay was species-specific to the three STHs, and could detect one copy of DNA target. Compared with microscopic examination of fecal samples, sensitivity and specificity of the multiplex PCR was 87% and 83%, respectively. This multiplex PCR assay provides an alternative method for routine diagnosis of STHs infection, and might be applied for epidemiological studies of STHs in endemic areas.

Gastrointestinal parasites of dogs and cats in a refuge in Nakhon Nayok, Thailand.

We collected fecal samples from 500 dogs and 300 cats from an animal refuge in Nakhon Nayok Province, Thailand to test for gastrointestinal protozoa and helminths using a formalin-ether concentration technique. The overall prevalence of parasites in stool from dogs was 36.2% (181/500), 35.7% (177/500) had helminths and 2.8% (14/500) had protozoa. The helminths were: hookworm (30.6%), Trichuris vulpis (16.0%), Toxocara canis (6.6%), Hymenolepis diminuta (1.2%), Spirometra mansoni (0.6%), and Dipylidium caninum (0.2%). Giardia duodenalis (2.8%) was found in the stool of dogs. The overall prevalence of parasites in stool from cats was 44.3% (133/300), 43.3% (130/300) were helminths and 6.0% (18/300) were protozoa. The helminths were hookworm (34.7%), T. cati (9.7%), S. mansoni (4.0%), Platynosomum fastosum (2.7%), Strongyloides sp (0.7%), and Echinostoma sp (0.3%). Two species of protozoa, Isospora sp (5.7%) and G. duodenalis (0.3%) were found in the stool of cats. Two percent of dogs and 5.0% of cats had mixed protozoan and helminthic infections. Dogs with double, triple, and quadruple helminthic infections were found at rates of 22.0%, 2.8%, and 0.2%, respectively. Cats with double and triple helminthic infections were found at rates of 9.7% and 1.0%, respectively. Quadruple helminthic infections were not found in cats, and double protozoan infections were not found in either dogs or cats.

Population structure of Angiostrongylus cantonensis (Nematoda: Metastrongylidae) in Thailand based on PCR-RAPD markers.

Angiostrongylus cantonensis is the causative agent of angiostrongyliasis, which is widely distributed throughout the world. It can specifically infect many species of intermediate and definitive hosts. This study examined the genetic differentiation and population structure using the RAPD-PCR method of parasites obtained from 8 different geographical areas of Thailand. Based on 8 primers, high levels of genetic diversity and low levels of gene flow among populations were found. Using genetic distance and neighbor-joining dendrogram methods, A. cantonensis in Thailand could be divided into two groups with statistically significant genetic differentiation of the two populations. However, genotypic variations and haplotype relationships need to be further elucidated using other markers.

Genetic differentiation of strongyloides stercoralis from two different climate zones revealed by 18S ribosomal DNA sequence comparison.

Over 70 countries in tropical and subtropical zones are endemic areas for Strongyloides stercoralis, with a higher prevalence of the parasite often occurring in tropical regions compared to subtropical ones. In order to explore genetic variations of S. stercoralis form different climate zones, 18S ribosomal DNA of parasite specimens obtained from Thailand were sequenced and compared with those from Japan. The maximum likelihood indicates that S. stercoralis populations from these two different climate zones have genetically diverged. The genetic relationship between S. stercoralis populations is not related to the host species, but rather to moisture and temperature. These factors may directly drive genetic differentiation among isolated populations of S. stercoralis.

Analysis of risk factors for a high prevalence of extended-spectrum {beta}-lactamase-producing Enterobacteriaceae in asymptomatic individuals in rural Thailand.

The prevalence of and risk factors associated with extended-spectrum ß-lactamase (ESBL)-producing micro-organisms have not been well studied in healthy individuals. The aim of this study was to determine this in healthy individuals in Thailand. Stool samples and questionnaires obtained from 445 participants from three provinces in Thailand were analysed. The antimicrobial susceptibility of the isolates was assessed using phenotypic and genotypic methods. PCR analysis was performed to detect and group the bla(CTX-M) genes. The prevalence of CTX-M-type ESBL-producing Enterobacteriaceae in the three provinces was as follows: 29.3 % in Nan (43/147), 29.9 % in Nakhon Si Thammarat (43/144) and 50.6 % in Kanchanaburi (78/154) (P<0.001). Of the 445 samples, 33 (7.4 %), 1 (0.2 %) and 127 (28.5 %) isolates belonged to the bla(CTX-M) gene groups I, III and IV, respectively. Escherichia coli was the predominant member of the Enterobacteriaceae producing CTX-M-type ESBLs (40/43, 39/43 and 70/78 isolates in Nan, Nakhon Si Thammarat and Kanchanaburi, respectively). No statistically significant association was observed between the presence of ESBL-producing bacteria and gender, age, education, food habits or antibiotic usage. However, the provinces that had the highest prevalence of ESBL-producing Enterobacteriaceae also had the highest prevalence of use and purchase of antibiotics without a prescription. Thus, this study revealed that faecal carriage of ESBL-producing Enterobacteriaceae is very high in asymptomatic individuals in Thailand, with some variations among the provinces. This high prevalence may be linked to antibiotic abuse.

Abnormal Taenia saginata tapeworms in Thailand.

Sixty-eight residents of Ban Luang and Ban Pang Kae villages, in Nan Province, northern Thailand, visited our mobile field station in September 2006 and March 2007, seeking treatment for taeniasis. After treatment, 22 cases discharged tapeworm strobila in their fecal samples and 17 scolices were recovered. Among these, 3 were morphologically abnormal, with six suckers on the scolex. To confirm the species of these tapeworms, the mitochondrial cytochrome c oxidase subunit I (COI) gene was used as a molecular marker. The partial COI sequences (800 bp) of the abnormal tapeworms were identical to the sequences of Taenia saginata deposited in Genbank.

Impact of hookworm deworming on anemia and nutritional status among children in Thailand.

Hookworm infection is associated with anemia, especially among children and deworming can improve anemic status; however, little information is available about the degree to which anemia improves after deworming. We chose hookworm-endemic rural areas of Thailand, Nan Province in the north, Kanchanaburi Province in the west and Nakhon Si Thammarat Province in the south, to evaluate this problem. Subjects were selected by primary school-based stool egg examinations. Blood tests of 182 hookworm-positive primary school children, composed of 22 heavy, 65 moderate and 95 light infections, were compared with a control group of 57 children who were helminth-free both before and after receiving deworming medicine. Before deworming, the red blood cell (RBC), hemoglobin (Hb), hematocrit (Hct), mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration (MCHC) and albumin levels of the hookworm-infected groups were significantly lower than the helminth-free control group. The Hb and Hct levels showed an inverse relationship with intensity of hookworm infection. After deworming, the Hb, Hct, total protein and albumin levels of the hookworm-infected children improved within 2 months to become comparable with the helminth-free control group. One year after deworming, the mean blood test results in the 2 groups were not significantly different from each other.

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.

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.

High prevalence of CTX-M beta-lactamase-producing Enterobacteriaceae in stool specimens obtained from healthy individuals in Thailand.

OBJECTIVES: To determine the prevalence of CTX-M beta-lactamase-producing Enterobacteriaceae in stool specimens obtained from healthy individuals in a rural area of Thailand. METHODS: Bacteria in stool specimens were screened for extended-spectrum beta-lactamase (ESBL) production on McConkey agar with cefotaxime and confirmed by the double-disc synergy test. Genetic detection and genotyping of CTX-M-type ESBL was performed by PCR with bacterial DNA extracted from isolates. RESULTS: A markedly high number (82 of 141, 58.2%) of the specimens showed the presence of CTX-M beta-lactamase-producing Enterobacteriaceae, as confirmed by both phenotypic and genetic examinations. The majority of the CTX-M beta-lactamase-producing bacteria were Escherichia coli (85.1%). CONCLUSIONS: The study revealed the wide dissemination of CTX-M beta-lactamase-producing Enterobacteriaceae in the healthy population.

Egg laying capacity of Haplorchis taichui (Digenea: Heterophyidae) in humans.

Quantitative fecal egg counts represented as the number of eggs per gram of feces (EPG) are generally a reliable parameter to estimate the worm burden of intestinal and hepatic parasitoses. Although Haplorchis taichui (Digenea: Heterophyidae) is one of the most common minute human intestinal flukes, little is known about the relationship between EPG and the actual worm burden in patients or the severity of the disease. In the present study, fecal samples were collected from 25 villagers in northern Thailand before and after praziquantel treatment. The EPG values of each participant were determined by the modified cellophane thick smear method, and adult worms were collected from the whole stool after the treatment. Eggs per day per worm (EPDPW) of H. taichui were estimated 82 from egg counts and expelled worms. The EPG was not well correlated with the worm burden, and a reverse correlation was observed between the EPDPW and the worm burden.

Anchitrema sanguineum (Digenea: Anchitrematidae) accidentally found during colonoscopy of a patient with chronic abdominal pain: a case report.

In November 2007, a 46-year-old male Thai patient presented with chronic abdominal pain for over 3 years. Colonoscopy revealed a small parasite of about 2 x 1 mm in size attached to the cecum mucosa. The worm was removed endoscopically, fixed, and stained for morphological observations. The specimen was identified as Anchitrema sanguineum (Digenea: Anchitrematidae), a trematode first reported in a reptile, Chamaeleo vulgaris, from Egypt, and then sporadically found in the intestines of insectivorous bats and other mammals. The patient was treated with praziquantel but no more worms were found in his stool. His symptoms improved slightly but not cured completely. It remains unclear whether the chronic abdominal pain of the patient was caused by this trematode infection. Whatever is the pathogenicity of this trematode, this is the first human case of A. sanguineum infection in the literature.

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.

Enterobiasis: a neglected infection in adults.

In this study, adult patients were treated with praziquantel to expel intestinal flukes. Unexpectedly, dozens of adult Enterobius vermicularis worms with disfigured morphology, which had not been detected on fecal examination using Kat's modified thick-smear technique, were expelled from 6 of 33 patients.

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.

Soil-transmitted helminthiases and health behaviors among schoolchildren and community members in a west-central border area of Thailand.

The prevalence of soil-transmitted helminthic infections and health behaviors related to infections in schoolchildren and villagers of a community (4 hamlets) was studied in Hauy Kayeng subdistrict, Thong Pha Phum district, in the north of Kanchanaburi Province. The intestinal helminth infection rate of the schoolchildren was 15.6%. Hookworm infection was the most prominent (9.8%), followed by Trichuris trichiura (6.2%), and Ascaris lumbricoides (2.2%). The community showed higher prevalence rates and was infected with more types of intestinal helminths than the schoolchildren. Thirty-five point two percent (35.2%) of the residents were infected with soil-transmitted helminths, 30.5% with hookworm, 3.4% with A. lumbricoides and 2.2% with T. trichiura. Almost all hookworm cases (94.3%) were light intensity infections, while only 1.3% were heavy infections. Moreover, the hookworm infection rate in the community was found to be much higher when a stool culture method was used (39.1%). With this technique, 2.3% Strongyloides stercoralis infections were detected in the community population. Examination of the health behavior of the study samples showed that approximately 75% always defecated in a toilet. Schoolchildren who always wore shoes comprised 67%, which was lower than the community, at 85%.

Gnathostoma infection in Nakhon Nayok and Prachin Buri, Central Thailand.

Gnathostoma infection in Nakhon Nayok and Prachin Buri Provinces, Central Thailand, was investigated. The prevalence and intensity of infection of swamp eels were determined; dog fecal samples and fresh-water copepods were examined for evidence of infection. The overall prevalence of eel infection was 38.1% (117/307) in Nakhon Nayok and 24.0% (74/308) in Prachin Buri--the former rate being significantly higher than the latter. Most of the positive Nalkhon Nayok eels (53.8%) harbored only 1-9 larvae; only one eel bore more than 50 larvae. In Prachin Buri, 67.6% of the positive eels harbored 1-9 larvae; again, only one eel bore more than 50 larvae. The mean number of 11.0 +/- 10.4 larvae/eel in Nakhon Nayok was not significantly different from that of Prachin Buri (9.3 +/- 11.4). A total of 1,292 gnathostome larvae were recovered from 307 eels in Nakhon Nayok. Of these, 52.3% had accumulated in the liver and 47.7% had spread throughout the muscles. In eels from Prachin Buri, 50.6% and 49.4% of the total of 688 larvae (from 308 eels) were found in the liver and muscles, respectively. The larvae preferred encysting in ventral of muscles rather than dorsal part; they preferred the middle portion to the anterior and posterior portions. The average length of gnathostome larvae recovered from Nakhon Nayok eels was 4.0 +/- 0.5 mm (range 2.5-5.1 mm) and the average body width was 0.40 +/- 0.05 mm (range 0.29-0.51 mm). Those from eels in Prachin Buri were 3.9 +/- 0.5 mm (range 2.2-5.1 mm) and 0.34 +/- 0.05 mm (range 0.20-0.48 mm), respectively. The mean body length and width of the larvae from eels in Nakhon Nayok were significantly greater than those of the larvae from eels in Prachin Buri. In Ban Phrao, Nakhon Nayok, none of the first 44 fecal specimens examined was positive. Of the second (68) and the third (70) specimens, one (1.5%) and two (2.9%) samples were positive. However, six months after the third fecal collection, no eggs were found. In Tha Ngam, Prachin Buri, no eggs were found in all three batches (109, 115, and 100 fecal samples). A cyclops survey of 4,000-5,000 crustacea from each of two areas (Ban Phrao and Tha Ngam) found no evidence of natural cyclops infection.