Tawin Inpankaew

PCR-based coprodiagnostic tools reveal dogs as reservoirs of zoonotic ancylostomiasis caused by Ancylostoma ceylanicum in temple communities in Bangkok

A survey of gastrointestinal parasites of dogs and humans from temple communities in Bangkok revealed that 58% of dogs and 3.4% of humans, among those sampled, were infected with hookworms utilising faecal flotation techniques and microscopy. A previously established polymerase chain reaction (PCR)-RFLP approach was utilised to determine the species of hookworms infecting dogs found positive for hookworm eggs. Single infections with Ancylostoma ceylanicum and Ancylostoma caninum were recorded in 77% and 9% of hookworm positive dogs, respectively and mixed infections with both species of Ancylostoma were recorded in 14% of dogs. A single-step PCR for the multiplex detection of Ancylostoma species and Necator americanus DNA in human faeces was developed and applied to characterise the species of hookworms in microscopy positive individuals. Single infection with N. americanus was recorded in five and A.ceylanicum infection in two, out of seven individuals positive for hookworm. This study demonstrates that humans are at risk of acquiring infection with A. ceylanicum in communities where this species of hookworm is endemic in dogs.

Application of a Multiplex Quantitative PCR to Assess Prevalence and Intensity Of Intestinal Parasite Infections in a Controlled Clinical Trial

Background Accurate quantitative assessment of infection with soil transmitted helminths and protozoa is key to the interpretation of epidemiologic studies of these parasites, as well as for monitoring large scale treatment efficacy and effectiveness studies. As morbidity and transmission of helminth infections are directly related to both the prevalence and intensity of infection, there is particular need for improved techniques for assessment of infection intensity for both purposes. The current study aimed to evaluate two multiplex PCR assays to determine prevalence and intensity of intestinal parasite infections, and compare them to standard microscopy. Methodology/Principal Findings Faecal samples were collected from a total of 680 people, originating from rural communities in Timor-Leste (467 samples) and Cambodia (213 samples). DNA was extracted from stool samples and subject to two multiplex real-time PCR reactions the first targeting: Necator americanus, Ancylostoma spp., Ascaris spp., and Trichuris trichiura; and the second Entamoeba histolytica, Cryptosporidium spp., Giardia. duodenalis, and Strongyloides stercoralis. Samples were also subject to sodium nitrate flotation for identification and quantification of STH eggs, and zinc sulphate centrifugal flotation for detection of protozoan parasites. Higher parasite prevalence was detected by multiplex PCR (hookworms 2.9 times higher, Ascaris 1.2, Giardia 1.6, along with superior polyparasitism detection with this effect magnified as the number of parasites present increased (one: 40.2% vs. 38.1%, two: 30.9% vs. 12.9%, three: 7.6% vs. 0.4%, four: 0.4% vs. 0%). Although, all STH positive samples were low intensity infections by microscopy as defined by WHO guidelines the DNA-load detected by multiplex PCR suggested higher intensity infections. Conclusions/Significance Multiplex PCR, in addition to superior sensitivity, enabled more accurate determination of infection intensity for Ascaris, hookworms and Giardia compared to microscopy, especially in samples exhibiting polyparasitism. The superior performance of multiplex PCR to detect polyparasitism and more accurately determine infection intensity suggests that it is a more appropriate technique for use in epidemiologic studies and for monitoring large-scale intervention trials.

High prevalence of Ancylostoma ceylanicum hookworm infections in humans, Cambodia, 2012

Preventative chemotherapy without community hygiene and animal health programs may be leading to emergence of this zoonosis.

Transmission cycles of Giardia duodenalis in dogs and humans in Temple communities in Bangkok—A critical evaluation of its prevalence using three diagnostic tests in the field in the absence of a gold standard

The prevalence and associated risk factors for Giardia duodenalis in canine and human populations in Temple communities of Bangkok, Thailand were determined by evaluating three common diagnostic methods utilised to detect Giardia, namely zinc sulphate flotation and microscopy, an immunofluoresence antibody test and nested polymerase chain reaction (PCR) based on the SSU-rDNA gene. The diagnostic sensitivity and specificity together with the negative and positive predictive values of each test were evaluated in the absence of a gold standard using a Bayesian approach. The median estimates of the prevalence of infection with G. duodenalis in dogs and humans in Thailand were 56.8% (95% PCI, 30.4%, 77.7%) and 20.3% (95% PCI, 7.3%, 46.3%) respectively. PCR and immunofluorescence antibody tests (IFAT) were the most accurate tests overall with diagnostic sensitivity and specificity of 97.4% (95% PCI, 88.5%, 99.9%) and 56.2% (95% PCI, 40.4%, 82.9%) for the PCR and 61.8% (95% PCI, 40.8%, 99.1%) and 94.7% (95% PCI, 87.4%, 99.1%) for IFAT respectively Three cycles, anthroponotic, zoonotic and dog-specific cycles of G. duodenalis were shown to be operating among the human and canine populations in these Temple communities in Bangkok, supporting the role of the dog as a potential reservoir for Giardia infections in humans.

Molecular and serological prevalence of Babesia bovis and Babesia bigemina in water buffaloes in the north region of Brazil

Bovine babesiosis is a tick-borne disease caused mainly by Babesia bovis and Babesia bigemina, which are associated to considerable economic losses in cattle herds worldwide. Approximately 60% of buffalo herds in South America are located in Northern Brazil. Little is known about the impact of babesiosis on buffalo herds in Brazil. The present work aimed to verify the occurrence of B. bovis and B. bigemina in 542 water buffaloes in the state of Pará, Northern Brazil, using molecular and serological techniques. The percentage of seropositive animals for B. bovis and B. bigemina was 41.2% and 19.0%, respectively, by ELISA. B. bovis and B. bigemina DNA were detected in 15 and 16% of sampled buffaloes, respectively. A high correlation (Kappa index of 0.9) between serological and molecular tests suggests that the combination of the utilized techniques in the present study is suitable for babesiosis diagnosis in an endemic unstable area. Significantly difference of positivity for serological and molecular assays was verified to localities and reproductive status of sampled animals, but not between buffalo breeds. The immune status of sampled buffaloes associated to the circulation of babesiosis agents in sampled population suggests that the studied area is at risk to clinical babesiosis outbreaks. Furthermore, this study demonstrated that this region can be classified as endemically unstable.

The prevalence and diversity of intestinal parasitic infections in humans and domestic animals in a rural Cambodian village

In Cambodia, intestinal parasitic infections are prevalent in humans and particularly in children. Yet, information on potentially zoonotic parasites in animal reservoir hosts is lacking. In May 2012, faecal samples from 218 humans, 94 dogs and 76 pigs were collected from 67 households in Dong village, Preah Vihear province, Cambodia. Faecal samples were examined microscopically using sodium nitrate and zinc sulphate flotation methods, the Baermann method, Koga Agar plate culture, formalin-ether concentration technique and Kato Katz technique. PCR was used to confirm hookworm, Ascaris spp., Giardia spp. and Blastocystis spp. Major gastrointestinal parasitic infections found in humans included hookworms (63.3%), Entamoeba spp. (27.1%) and Strongyloides stercoralis (24.3%). In dogs, hookworm (80.8%), Spirometra spp. (21.3%) and Strongyloides spp. (14.9%) were most commonly detected and in pigs Isospora suis (75.0%), Oesophagostomum spp. (73.7%) and Entamoeba spp. (31.6%) were found. Eleven parasite species were detected in dogs (eight helminths and three protozoa), seven of which have zoonotic potential, including hookworm, Strongyloides spp., Trichuris spp., Toxocara canis, Echinostoma spp., Giardia duodenalis and Entamoeba spp. Five of the parasite species detected in pigs also have zoonotic potential, including Ascaris spp., Trichuris spp., Capillaria spp., Balantidium coli and Entamoeba spp. Further molecular epidemiological studies will aid characterisation of parasite species and genotypes and allow further insight into the potential for zoonotic cross transmission of parasites in this community.

Molecular epidemiology of Blastocystis in pigs and their in-contact humans in Southeast Queensland, Australia, and Cambodia

Blastocystis, an intestinal protist commonly found in humans and animals worldwide, has been implicated by some as a causative agent in irritable bowel syndrome in humans. In pigs, infection with Blastocystis is commonly reported, with most pigs shown to harbour subtypes (ST) 1 or 5, suggesting that these animals are potentially natural hosts for Blastocystis. Although ST5 is considered rare in humans, it has been reported to be a potential zoonosis from pigs in rural China. To test these hypotheses, we conducted molecular analysis of faecal samples from pigs and in-contact humans from commercial intensive piggeries in Southeast Queensland (SEQ), Australia, and a village in rural Cambodia. The prevalence of Blastocystis in SEQ and Cambodian pigs was 76.7% and 45.2%, respectively, with all positive pigs harbouring ST5. It appears likely that pigs are natural hosts of Blastocystis with a high prevalence of ST5 that is presumably the pig-adapted ST in these regions. Amongst the SEQ piggery staff, 83.3% were Blastocystis carriers in contrast to only 55.2% of Cambodian villagers. The predominant STs found in humans were STs 1, 2 (Cambodia only) and 3. Interestingly, ST5 which is usually rare in humans was present in the SEQ piggery staff but not in the Cambodian villagers. We conclude that in intensive piggeries, close contact between pigs and their handlers may increase the risks of zoonotic transmission of Blastocystis.

MOLECULAR PREVALENCE OF DIFFERENT GENOTYPES OF THEILERIA ORIENTALIS DETECTED FROM CATTLE AND WATER BUFFALOES IN THAILAND

Abstract Here we report on an epidemiological study regarding the molecular prevalence of different genotypes of Theileria orientalis present among domestic cattle and water buffalo populations bred in Thailand. A phylogenetic analysis based on the parasitic gene encoding a major piroplasm surface protein revealed the presence of 5 genotypes (Types 1, 3, 5, 7, and N-3) in cattle and 7 genotypes (Types 1, 3, 4, 5, 7, N-2, and N-3) in water buffaloes. Types 4, 7, and N-3 of T. orientalis were reported for the first time in water buffaloes. The previously reported C and Thai types from Thailand clustered as types 7 and 6, respectively, in the present analysis. Great similarities were observed among nucleotide sequences of isolates of the same genotype from cattle and water buffaloes, and, therefore, water buffaloes were considered to serve as a reservoir for these genotypes of T. orientalis in Thailand. In conclusion, T. orientalis parasites circulating in Thailand are more diverse in their genetic characters than previously anticipated.

Diversity of Blastocystis subtypes in dogs in different geographical settings.

BackgroundBlastocystis is a ubiquitous, globally distributed intestinal protist infecting humans and a wide range of animals. Several studies have shown that Blastocystis is a potentially zoonotic parasite. A 1996 study reported a 70% Blastocystis prevalence in Brisbane pound dogs while another study found that pet dogs/cats of 11 symptomatic Blastocystis infected patients harboured at least one Blastocystis subtype (ST) in common with the patient. These results raised the possibility that dogs might be natural hosts of Blastocystis. In this study, we aimed to investigate this hypothesis by estimating the prevalence of Blastocystis carriage and characterising the diversity of STs in dogs from three different environmental settings and comparing these STs with the range that humans harbour.MethodsTwo hundred and forty faecal samples from dogs from three different geographical regions with varying levels of socio-economic development and sanitation, namely i) 80 pet and pound dogs from Brisbane, Australia, ii) 80 semi-domesticated dogs from Dong Village, Cambodia and iii) 80 stray dogs from the densely populated cities of Sikkim, Delhi and Mumbai in India, were screened for Blastocystis using PCR and subtyped based on the “barcode region” of the small subunit ribosomal RNA (SSU rRNA) gene.ResultsThe prevalence of Blastocystis in dogs from Brisbane and Cambodia was 2.5% (2/80) and 1.3% (1/80), respectively, in contrast to 24% (19/80) in stray dogs from India. Stray dogs in India carried a diverse range of Blastocystis STs including ST 1, 4, 5 and 6 while the dogs from Brisbane carried only ST1 and one Cambodian dog carried ST2.ConclusionThe results suggest there is geographical variation in Blastocystis prevalence and STs between dog populations as reported in human studies. In addition, the greater diversity of STs and higher prevalence of Blastocystis in Indian stray dogs compared to pet/pound and community dogs in Australia and Cambodia could reflect close proximity to humans and other animals and exposure to their faeces. It appears that dogs are not natural hosts for Blastocystis but rather are transiently and opportunistically infected with a diversity of STs.

Seroprevalence of Babesia infections of dairy cows in northern Thailand

The present study was conducted to demonstrate the epidemiological distribution of bovine babesiosis in the northern regions of Thailand. A total of 700 serum samples of dairy cows in the northern provinces (Chiang Rai, Chiang Mai, Lumpang, and Mae Hong Sorn) were tested for antibodies against Babesia bovis and B. bigemina. Species-specific enzyme-linked (rRAP-1/CTs) were performed. According to the results, 517 (73.8%) and 484 (69.1%) were positive for B. bovis and B. bigemina, respectively. In addition, 370 (52.9%) were positive for mixed infections by both ELISAs. On the other hand, all samples were also examined by the indirect fluorescent-antibody test (IFAT) with B. bovis- and B. bigemina-infected blood smears. According to the IFAT, 482 (68.8%) and 531 (75.8%) were positive for these infections, respectively. The overall concordances between the ELISA and IFAT techniques were 93.6% and 90.7% for B. bovis and B. bigemina infections, respectively. These results indicated that babesia infections are widespread in the northern parts of Thailand. To our knowledge, this is the first report describing the epidemiology of Babesia infections using rRAP-1/CT-based ELISAs in these areas.