"Enterocytozoon bieneusi and Cryptosporidium: a cross-sectional study conducted throughout Thailand".

BACKGROUND: Enterocytozoon bieneusi and Cryptosporidium spp. are prevalent zoonotic parasites associated with a high burden among children. To date only limited molecular epidemiological data on E. bieneusi and Cryptosporidium spp. in humans living in Thailand has been published. METHODS: PCR-based tools were used to detect and characterize E. bieneusi and Cryptosporidium spp. The internal transcribed spacer (ITS) region of the rRNA gene was used to investigate E. bieneusi, and the small subunit (SSU) rRNA gene was used to investigate Cryptosporidium spp., and 697 fecal samples from villagers and school children in rural areas in Thailand were analyzed. RESULTS: The infection rates were 2.15% (15/697) for E. bieneusi and 0.14% (1/697) for Cryptosporidium spp. The prevalence of E. bieneusi was significantly high in Loei province. Sequence analysis indicated that the Cryptosporidium isolate was C. parvum. Nine E. bieneusi genotypes were identified, EbpC, Peru12, TMH6, TMH3, TMH7, H, D, and two novel genotypes TMLH1 and TMLH2. E. bieneusi prevalence was significantly higher in male participants than in female participants, and in children aged 3-15 years than in participants aged > 15 years. CONCLUSIONS: The prevalence, genotypes, and zoonotic potential of E. bieneusi were found to vary significantly high even in one country. Transmission routes and key animal carriers of E. bieneusi may be associated with differences in hygiene, sanitation, and cultural behaviors. Further molecular studies including longitudinal studies will be required to unveil epidemiological characteristics of these opportunistic intestinal protozoa in all over the countries.

Blastocystis subtype 5: Predominant subtype on pig farms, Thailand.

Blastocystis is a unicellular protist most commonly detected in humans and a variety of animals. The predominant mode of its transmission is the fecal-oral route, but its zoonotic potential is not completely understood. The objective of this study was to determine the presence and genetic diversity of Blastocystis on pig farms in Nakhon Pathom Province, Central Thailand. A total of 154 human and 90 pig stool samples were collected and analyzed. Nested PCR detected Blastocystis in 35.55% of the pig samples and 6.49% of the human samples. Subtyping based on regions of the small-subunit ribosomal RNA (SSU rRNA) gene identified three Blastocystis subtypes in pigs and humans: ST1, ST3, and ST5. Blastocystis ST5 was the predominant subtype, followed by ST1 and then ST3. All the sequences from the Blastocystis-positive samples from both pigs and humans were closely related. This study reveals a possibility of low host specificity of Blastocystis STs (ST1, ST3 and ST5) on pig farms in Thailand. We tentatively suggest that close contact with or exposure to pig stools may be a significant source of Blastocystis detected in pig handlers. Further studies are required to confirm the zoonotic transmission of this organism in Thailand, because pigs may play an important role in the transmission of Blastocystis.

Blastocystis infection and subtype distribution in humans, cattle, goats, and pigs in central and western Thailand.

Blastocystis is a common intestinal pathogen of humans and a variety of animals, with various host-specific subtypes. The aim of this study was to determine the prevalence and subtype distribution of Blastocystis in humans and domestic animals, Thailand. 113 stool samples were collected from pigs, goats, and cattle in Ayutthaya Province (AP; central Thailand) and 218 stool samples were collected from pigs, dogs, cats, chickens, and humans in Kanchanaburi Province (KP; western Thailand). Blastocystis was detected by nested PCR targeting the SSU rRNA gene. Subtypes were identified by DNA sequencing, and phylogenetic analysis was conducted. The overall prevalence of Blastocystis in animals was 76.1% (86/113) and 11.88% (12/101) in AP and KP, respectively, and the prevalence in humans was 12.82% (15/117) in KP. The prevalence of Blastocystis in the AP and KP pigs were 87.88% (29/33) and 20.37% (11/54), respectively. Blastocystis ST5 was the most abundant in pigs in both areas while Blastocystis ST10 and ST12 were most frequently found in cattle and goats. In addition, low percentage of Blastocystis ST1 and Blastocystis ST14 were found in pigs and goats, respectively. In this study, Blastocystis ST3, followed by ST2 and ST1 were predominantly found in humans. In conclusion, pigs may be a natural host of Blastocystis and this ST may be the pig-adapted ST in the studied areas, in this study.

Acidosis and acute kidney injury in severe malaria.

BACKGROUND: In severe falciparum malaria metabolic acidosis and acute kidney injury (AKI) are independent predictors of a fatal outcome in all age groups. The relationship between plasma acids, urine acids and renal function was investigated in adult patients with acute falciparum malaria. METHODS: Plasma and urinary acids which previously showed increased concentrations in proportion to disease severity in patients with severe falciparum malaria were quantified. Patients with uncomplicated malaria, sepsis and healthy volunteers served as comparator groups. Multiple regression and multivariate analysis were used to assess the relationship between organic acid concentrations and clinical syndromes, in particular AKI. RESULTS: Patients with severe malaria (n = 90), uncomplicated malaria (n = 94), non-malaria sepsis (n = 19), and healthy volunteers (n = 61) were included. Univariate analysis showed that both plasma and creatinine-adjusted urine concentrations of p-hydroxyphenyllactic acid (pHPLA) were higher in severe malaria patients with AKI (p < 0.001). Multiple regression analysis, including plasma or creatinine-adjusted urinary acids, and PfHRP2 as parasite biomass marker as independent variables, showed that pHPLA was independently associated with plasma creatinine (ß = 0.827) and urine creatinine (ß = 0.226). Principal component analysis, including four plasma acids and seven urinary acids separated a group of patients with AKI, which was mainly driven by pHPLA concentrations. CONCLUSIONS: Both plasma and urine concentrations of pHPLA closely correlate with AKI in patients with severe falciparum malaria. Further studies will need to assess the potential nephrotoxic properties of pHPLA.

Development of a loop-mediated isothermal amplification technique and comparison with quantitative real-time PCR for the rapid visual detection of canine neosporosis.

BACKGROUND: Dogs are the definitive hosts of Neospora caninum and play an important role in the transmission of the parasite. Despite the high sensitivity of existing molecular tools such as quantitative real-time PCR (qPCR), these techniques are not suitable for use in many countries because of equipment costs and difficulties in implementing them for field diagnostics. Therefore, we developed a simplified technique, loop-mediated isothermal amplification (LAMP), for the rapid visual detection of N. caninum. METHODS: LAMP specificity was evaluated using a panel containing DNA from a range of different organisms. Sensitivity was evaluated by preparing 10-fold serial dilutions of N. caninum tachyzoites and comparing the results with those obtained using qPCR. Assessment of the LAMP results was determined by recognition of a colour change after amplification. The usefulness of the LAMP assay in the field was tested on 396 blood and 115 faecal samples from dogs, and one placenta from a heifer collected in Lopburi, Nakhon Pathom, Sa Kaeo, and Ratchaburi provinces, Thailand. RESULTS: Specificity of the LAMP technique was shown by its inability to amplify DNA from non-target pathogens or healthy dogs. The detection limit was the equivalent of one genome for both LAMP and qPCR. LAMP and qPCR detected positive N. caninum infection in 15 of 396 (3.8%) blood samples; LAMP detected 9/115 (7.8%) positive faecal samples, while qPCR detected 5/115 (4.3%) positive faecal samples. The placental tissue was shown to be positive by both techniques. Agreement between LAMP and qPCR was perfect in blood samples (kappa value, 1.00) and substantial in faecal samples (kappa value, 0.697). CONCLUSIONS: This is the first known LAMP assay developed for the amplification of N. caninum. The technique effectively and rapidly detected the parasite with high sensitivity and specificity and was cost-effective. This assay could be used in the field to confirm the diagnosis of canine or bovine neosporosis.

Seroprevalence of Toxoplasma gondii Infection in Refugee and Migrant Pregnant Women along the Thailand-Myanmar Border.

Toxoplasma gondii primary infection in pregnancy is associated with poor obstetric outcomes. This study aimed to determine the seroprevalence of Toxoplasma infection in pregnant migrant and refugee women from Myanmar attending antenatal care in Thailand. A random selection of 199 residual blood samples from first antenatal screen in 2014-2015 was tested for Toxoplasma IgG and IgM antibodies. Seroprevalence of Toxoplasma infection was 31.7% (95% confidence interval = 25.6-38.4). Avidity testing in the three positive IgM cases indicated all were past infections. Multiparity (≥ 3 children) was significantly associated with higher Toxoplasma seropositivity rates. Seroprevalence of T. gondii infection in this pregnant population is similar to the only other report from Myanmar, where multiparity was also identified as a significant association. Toxoplasma infection is important in pregnant women. Nevertheless, in this marginalized population, this infection may be given less priority, due to resource constraints in providing the most basic components of safe motherhood programs.

Zoonotic potential of Enterocytozoon genotypes in humans and pigs in Thailand.

Enterocytozoon bieneusi is an opportunistic intestinal pathogen infecting humans and a variety of animals. Its mode of transmission and zoonotic potential are not completely understood. E. bieneusi has been frequently identified in pigs. The objective of our study was to investigate E. bieneusi in pigs and humans in Western and Central Thailand to determine its presence, genetic diversity, and zoonotic potential. A total of 277 human and 210 pig faecal samples were collected and analysed. E. bieneusi was found in 5.4% and 28.1% of human and pig samples, respectively, by nested PCR. Genotyping based on the internal transcribed spacer regions of the small subunit ribosomal RNA demonstrated three known genotypes (D, H, PigEb10) and eight novel genotypes (TMH1-8) in humans, and five known genotypes (D, EbpA, EbpC, H, O) and 11 novel genotypes (TMP1-11) in pigs. All known genotypes identified in humans and pigs had zoonotic potential. Further studies are needed to evaluate zoonotic risk of novel genotypes, as pigs may play an important role in the transmission of E. bieneusi.

Oyster is an effective transmission vehicle for Cryptosporidium infection in human.

OBJECTIVE: To determine the ability of oysters to trap and maintain viable Cryptosporidium oocysts, and the feasibility of Cryptosporidium multiplication in oysters' organs. METHODS: Seventy oysters were raised in experimentally seeded natural seawater for up to 3 months, with weekly oocysts inoculations. Cryptosporidium oocysts, viable and non-viable, as well as other stages were detected using two immunofluorescence vital staining techniques (Sporo-Glo and Merifluor(®)) with confocal microscopy. Viability rate at various times after inoculations were calculated. RESULTS: Cryptosporidium oocysts were found most concentrated in oysters' digestive organs than in gill and water inside the oysters. Oocysts numbers were 857.33 at 24 h after inoculation and strikingly decreased to 243.00 and 126.67 oocysts at 72 h and 7 days, respectively. The oocysts in oyster were also less viable over time; 70%, 60% and 30% viable at 24 h, 72 h and 7 days after inoculation, respectively. At 77 days, the number of oocysts was very low and none was found at 84 days onwards. Although some oocysts were ruptured with released sporozoites, there was no evidence throughout the study of sporozoites multiplication to indicate that oyster is a biological host. Despite the significant reduction in oocysts number after 7 days of inoculation, the remained viable oocysts can still cause cryptosporidiosis. CONCLUSION: The findings confirm that Cryptosporidium parvum does not multiply in oyster, and is therefore not a biological host. Nevertheless, the results suggest that oyster can be an effective transmission vehicle for Cryptosporidium oocysts, especially within 24-72 h of contamination, with viable oocysts present at up to 7 days post infection. Unless consuming well-cooked oyster dishes, eating raw oyster remains a public health concern and at least 3 days of depuration in clean sea water prior to consumption is recommended.

Development of a rapid, simple method for detecting Naegleria fowleri visually in water samples by loop-mediated isothermal amplification (LAMP).

Naegleria fowleri is the causative agent of the fatal disease primary amebic meningoencephalitis. Detection of N. fowleri using conventional culture and biochemical-based assays is time-consuming and laborious, while molecular techniques, such as PCR, require laboratory skills and expensive equipment. We developed and evaluated a novel loop-mediated isothermal amplification (LAMP) assay targeting the virulence-related gene for N. fowleri. Time to results is about 90 min and amplification products were easily detected visually using hydroxy naphthol blue. The LAMP was highly specific after testing against related microorganisms and able to detect one trophozoite, as determined with spiked water and cerebrospinal fluid samples. The assay was then evaluated with a set of 80 water samples collected during the flooding crisis in Thailand in 2011, and 30 natural water samples from border areas of northern, eastern, western, and southern Thailand. N. fowleri was detected in 13 and 10 samples using LAMP and PCR, respectively, with a Kappa coefficient of 0.855. To the best of our knowledge, this is the first report of a LAMP assay for N. fowleri. Due to its simplicity, speed, and high sensitivity, the LAMP method described here might be useful for quickly detecting and diagnosing N. fowleri in water and clinical samples, particularly in resource-poor settings.

Molecular identification of Cryptosporidium spp. in seagulls, pigeons, dogs, and cats in Thailand.

Zoonotic Cryptosporidium spp., particularly C. meleagridis, C. canis, and C. felis, are enteric protozoa responsible for major public health concerns around the world. To determine the spread of this parasite in Thailand, we conducted molecular identification of Cryptosporidium spp. from animal samples around the country, by collecting and investigating the feces of seagulls (Chroicocephalus brunnicephalus and Chroicocephalus ridibundus), domestic pigeons (Columba livia domestica), dogs, and cats. Seagull and pigeon samples were collected at the seaside and on the riverside to evaluate their potential for waterborne transmission. Ten pigeon samples were combined into one set, and a total of seven sets were collected. Seventy seagull samples were combined into one set, and a total of 13 sets were collected. In addition, 111 dog samples were collected from cattle farms, and 95 dog and 80 cat samples were collected from a temple. We identified C. meleagridis in pigeons, Cryptosporidium avian genotype III in seagulls, C. canis in dogs, and C. felis in cats. In the temple, the prevalence was 2.1% (2/95) for dogs and 2.5% (2/80) for cats. No Cryptosporidium was found in dog samples from cattle farms. These are the first findings of C. meleagridis in domestic pigeons, and Cryptosporidium avian genotype III in seagulls. Our study invites further molecular epidemiological investigations of Cryptosporidium in these animals and their environment to evaluate the public health risk in Thailand.

Toxoplasma gondii infection: What is the real situation?

The prevalence of chronic Toxoplasma infections reported in the literature varies enormously. We hypothesize that one factor could be due to the different methods used in the evaluation of infections. Serological evidence of Toxoplasma infections in 450 pregnant women (PW) and 300 HIV-infected patients (HIV) were investigated by the Sabin-Feldman dye test and two other commercial ELISA kits (kit1 and kit2). Anti-Toxoplasma IgG antibodies obtained from the Sabin-Feldman dye test, ELISA kit1 and ELISA kit2 in the PW subjects were 14.7%, 29.6% and 38.7%, and in the HIV subjects were 13%, 34.7% and 36.3%, respectively. So there were significant differences in the seroprevalences when different diagnostic tests were used (P<0.05). Regarding Sabin-Feldman dye test as the gold standard for anti-Toxoplasma antibodies detection, we found that the sensitivity and specificity of the ELISA kit1 and kit2 was in the range of their specification. However as the two ELISA kits used in our study identified a much higher prevalence of Toxoplasma infections which indicated that false positive cases were being reported. Based on results obtained, it is therefore highly recommended that research workers should be aware that the reports of serological studies in terms of high positive results should be treated with some skepticism until additional precise diagnostic tools are developed.

Presence of zoonotic Enterocytozoon bieneusi in cats in a temple in central Thailand.

Enterocytozoon bieneusi is a common opportunistic intestinal pathogen in humans and animals. To investigate the prevalence, genotype and host specificity of E. bieneusi, 111 dog faecal samples were collected from dairy cattle farms, and 95 and 80 faecal samples were collected from dogs and cats, respectively, in a temple in central Thailand. E. bieneusi was found in 25 (31.3%) cats by nested PCR, but not in dogs. Genotyping analysis targeting the internal transcribed spacer of the rRNA gene identified genotype D - and other novel genotypes very similar to genotype D - which is a zoonotic genotype reported in both HIV patients and villagers in rural communities in Thailand. This is the first study to find E. bieneusi genotype D in cats, and it may be that cats are found to play an important role in E. bieneusi zoonotic transmission to humans. The present study indicates that further molecular epidemiological investigations of E. bieneusi among cats are necessary to evaluate their possible role as reservoir hosts and the potential risk they represent to humans.

Zoonotic potential of Enterocytozoon bieneusi among children in rural communities in Thailand.

Enterocytozoon bieneusi is a common opportunistic intestinal pathogen worldwide. Genotype distribution of E. bieneusi differs by geography and host immunity. In order to investigate the prevalence, genotype characteristics, and host specificity of E. bieneusi in the community, we conducted a preliminary cross-sectional study among children in Western and Northern Thailand. Seventy-eight (78) and 102 stool samples were collected; the prevalence of E. bieneusi was 3.8% and 2.9% by nested PCR in Western and Northern Thailand, respectively. Three genotypes were identified: Genotype D predominated, followed by EbpC, and then novel genotype ETMK1. The first two genotypes have zoonotic potential. Analysis of the genetic proximity of the E. bieneusi ITS sequences from our study, compared with those published in genetic databases, showed that all positive samples were classified into Group 1, the largest group consisting of various host specificity. The present study demonstrates the possible zoonotic transmission of E. bieneusi in rural communities in Thailand. A large-scale investigation of both human and animal samples, as well as improvements in the available phylogenetic tools, will be required to elucidate transmission routes of E. bieneusi in this area.

Real-time PCR: Benefits for Detection of Mild and Asymptomatic Giardia Infections.

The majority of Giardia infections are transmitted by the fecal-oral route and cause giardiasis. Children who live in crowded conditions or low socio-economic areas are the risk group for Giardia infection. Interestingly, most of them are asymptomatic or only mildly infected and can shed the Giardia cysts in the environment. Thus, the diagnosis of Giardia infection in asymptomatic or mild infection plays an important role in achieving control of Giardia duodenalis transmission. The objective of this study was to examine parasitic infections using microscopy and to develop a real-time PCR method for detection of Giardia infection in the stool samples of children living on the Thai-Myanmar border. Both species-specific primers and fluorescent labeled G. duodenalis probe were designed using small-subunit ribosomal RNA (ssrRNA). The results showed that 10 (7.69%) and 40 (30.77%) of 130 stool samples were positive for G. duodenalis by microscopy and real-time PCR respectively. Only 3 out of 9 liquid stools revealed G. duodenalis positive using microscopy, but all of them were G. duodenalis-positive using real-time PCR. The detection limit of real-time PCR for G. duodenalis was 0.1 pg/25 µl reaction. It can detect both mild and asymptomatic Giardia infections in children living on the Thai-Myanmar border.

Seasonal variation and potential sources of Cryptosporidium contamination in surface waters of Chao Phraya River and Bang Pu Nature Reserve pier, Thailand.

Using molecular techniques, a longitudinal study was conducted with the aims at identifying the seasonal difference of Cryptosporidium contamination in surface water as well as analyzing the potential sources based on species information. One hundred forty-four water samples were collected, 72 samples from the Chao Phraya River, Thailand, collected in the summer, rainy and cool seasons and 72 samples from sea water at Bang Pu Nature Reserve pier, collected before, during and after the presence of migratory seagulls. Total prevalence of Cryptosporidium contamination in river and sea water locations was 11% and 6%, respectively. The highest prevalence was observed at the end of rainy season continuing into the cool season in river water (29%) and in sea water (12%). During the rainy season, prevalence of Cryptosporidium was 4% in river and sea water samples, but none in summer season. All positive samples from the river was C. parvum, while C. meleagridis (1), and C. serpentis (1) were obtained from sea water. To the best of our knowledge, this is the first genetic study in Thailand of Cryptosporidium spp contamination in river and sea water locations and the first report of C. serpentis, suggesting that humans, household pets, farm animals, wildlife and migratory birds may be the potential sources of the parasites. The findings are of use for implementing preventive measures to reduce the transmission of cryptosporidiosis to both humans and animals.

A promising diagnostic tool for toxoplasmic encephalitis: tachyzoite/bradyzoite stage-specific RT-PCR.

OBJECTIVES: To determine the diagnostic accuracy, technical benefit, and clinical application of the duplex reverse transcription-PCR (duplex RT-PCR) assay specific to bradyzoite (BAG1) and tachyzoite (SAG1) genes, for diagnosing toxoplasmic encephalitis (TE) in HIV-infected patients, using the US Centers for Disease Control and Prevention (CDC) recommended diagnostic criteria as the reference standard. METHODS: Advanced HIV-infected individuals with central nervous system opportunistic infections were enrolled in a prospective study, performed from July 2007 to January 2009; patients were classified as TE- or non-TE subjects in accordance with the CDC recommended criteria. Blood and cerebrospinal fluid samples were assayed by duplex RT-PCR to detect tachyzoite, bradyzoite, both, or none. RESULTS: A total of 61 advanced AIDS patients were included in the study, eight with TE and 53 as non-TE subjects. The duplex RT-PCR assay showed high diagnostic accuracy, with 100% specificity and positive predictive value, as well as 87.5% sensitivity. Its efficacy reached 98.3%. This diagnostic method was rapid, needed only moderately skilled technicians, and was four times cheaper than procedures used in the CDC diagnostic recommendations. It worked very well for blood samples, even after drug treatment had been started. CONCLUSIONS: The duplex RT-PCR assay is simple and rapid, and provides high efficacy with lower costs than the reference standard procedures. This is a promising alternative diagnostic tool for TE in HIV/AIDS individuals, especially in resource-limited settings.

Toxoplasmosis and neosporosis among beef cattle slaughtered for food in Western Thailand.

Beef is a main type of meat consumed by Thais. The prevalences of anti-Toxoplasma gondii and anti-Neospora caninum antibodies were investigated among beef cattle slaughtered for food in western Thailand. A total of 389 blood samples obtained from beef cattle from 24 herds were collected at 3 slaughterhouses in 3 western provinces of Thailand: Kanchanaburi, Ratchaburi and Nakhon Pathom. An indirect immunofluorescent antibody test (IFAT) was performed using cut-off values of 1:128 for T. gondii and 1:200 for N. caninum. The antibodies to T. gondii were found in 100 samples (25.7%) and antibodies to N. caninum were found in 23 samples (5.9%) a significant difference (p < 0.001) in prevalences, indicating the cattle tested had a greater exposure to T. gondii than N. caninum, and they should be regarded as a potential source of T. gondii infection to humans. The low prevalence of neosporosis in this study is still a risk for morbidity among cattle, including abortions. This is the first study in Thailand finding both T. gondii and N. caninum antibodies among beef cattle.

Transplacental transmission in cattle: is Toxoplasma gondii less potent than Neospora caninum?

We compared the transplacental-transmission ability of Toxoplasma gondii and Neospora caninum in cattle. One uninfected pregnant heifer served as control, while three were inoculated with N. caninum K9WA strain and four with T. gondii RH strain at their midgestational period. Both infected groups showed clinical signs and antibodies either to N. caninum or T. gondii, while the control animal was normal. Two (50%) Toxoplasma dams aborted on days 6 and 11 postinoculation. T. gondii tachyzoites were found in various organs of those dams that had abortions but not in their fetuses. Two Neospora dams did not abort but gave birth to subclinically infected calves. The remaining two Toxoplasma dams and one from Neospora group became recumbent. Those two dams and their fetuses showed disseminated Toxoplasma DNA, but no Neospora DNA was found. Our findings suggest that maternal toxoplasmosis could be a cause of abortion and congenital toxoplasmosis in cattle, especially when they are infected by virulent strains.

Is Sabin-Feldman dye test using T. gondii tachyzoites from animal inoculation still the best method for detecting Toxoplasma gondii antibodies?

Although the Sabin-Feldman dye test is the gold standard for detecting Toxoplasma antibodies in human, it is performed only in reference laboratories because live virulent T. gondii are used for the test. We collected 210 human serum samples and tested them by the dye test using in vivo tachyzoites (conventional method) then compared these results with three other methods: a dye test using cell culture-derived T. gondii tachyzoites and indirect immunofluorescent antibody tests (IFAT) using in vivo and in vitro tachyzoites. We found the conventional dye test detected the highest percent of cases (4.3%), followed by the IFAT using parasites from mice (3.8%), then the dye test and the IFAT using cell culture tachyzoites (both 2.8%). Agreement with the dye test when using mouse and cell culture derived tachyzoites was 96.7%. Using in vivo tachyzoites for the dye test and the IFAT gave 94.3% agreement, while using in vitro tachyzoites gave 94.8% agreement. When compared with the conventional dye test, the IFAT had 75% sensitivity and 100% specificity. The T. gondii tachyzoites obtained from cell culture had a lower virulence, as indicated by a three times longer survival period in the inoculated mice. We favor the conventional dye test as the gold standard for Toxoplasma antibody detection. In vitro tachyzoites can be used routinely in the dye test but false negative results may occur in some cases. The IFAT, using either in vivo or in vitro tachyzoites, are alternatives for laboratories where provision of live tachyzoites is limited.

Epidemiology of Toxoplasma gondii infection of stray cats in Bangkok, Thailand.

The objective of this study was to investigate the epidemiology of toxoplasmosis in stray cats in Bangkok. Sera were collected during 2006 and examined by Sabin-Feldman dye test. Five hundred sixty-four male and 926 female cats in and around monasteries from 50 districts were collected. Toxoplasma gondii was detected in 72 (4.8%) of 1,490 cats. The prevalence was significantly higher in females (5.6%) than in males (3.6%). Cats more than 5 years old had the highest infection rate (5.1%). Fifty-six percent (28/50) of areas were positive for T. gondii in cats. Our results show T. gondii is widespread in stray cats in Bangkok. It is essential to control the number of stray cats in order to reduce the transmission of toxoplasmosis to animals and humans.