Helen Bradshaw

Detection of Echinococcus granulosus coproantigens in Australian canids with natural or experimental infection

Coproparasitological and purging methods for diagnosing canids infected with the intestinal helminth Echinococcus granulosus, an important zoonotic parasite, are unreliable. Detection of coproantigens in feces of infected dogs by enzyme-linked immunosorbent assay (ELISA) is suitable for detecting patent and prepatent infections with a high degree of sensitivity and specificity. In the present study, natural and experimental infections in domestic and wild Australian canids were investigated using a coproantigen capture ELISA. Experimental infection of dogs with E. granulosus was detected at between 14 and 22 days postinfection (PI), and optical density (OD) values remained high until termination of experiments 35 days PI. After chemotherapy, coproantigen levels in infected dogs dropped rapidly, becoming negative 2–4 days after treatment. In experimentally infected red foxes (Vulpes vulpes), the coproantigen excretion profile was different, with ELISA OD levels peaking 15–17 days PI, then falling to low or undetectable levels by 30 days PI. Coproantigens were detected in the feces of naturally infected Australian wild dogs (dingoes, dingo/domestic dog hybrids) with infection levels ranging between 2 worms and 42,600. Preliminary data on the stability of coproantigen in dog feces exposed to environmental conditions indicated that there was no change in antigenicity over 6 days. The results suggest the coproantigen ELISA could be successfully used to monitor E. granulosus prevalence rates in Australian domestic dogs, foxes, and wild dogs.

Dot immunogold filtration assay (DIGFA) with multiple native antigens for rapid serodiagnosis of human cystic and alveolar echinococcosis

A new 3-min rapid dot immunogold filtration assay (DIGFA) for serodiagnosis of human cystic and alveolar echinococcosis was developed using four native antigen preparations: crude and partially purified hydatid cyst fluid extracts from Echinococcus granulosus (EgCF and AgB), E. granulosus protoscolex extract (EgP) and Echinococcus multilocularis metacestode antigen (Em2). The overall sensitivity of DIGFA in a hospital diagnostic setting was 80.7% for human cystic echinococcosis (CE) (n=857) and 92.9% for human alveolar echinococcosis (AE) (n=42). Highest specificity was 93.4% with AgB extract for CE, and 90.3% with Em2 antigen for AE when CE versus AE cross-reactivity was excluded. Anti-AgB antibodies were present in 35.5% of AE cases and anti-Em2 in 7.4% of CE cases. In endemic communities in northwest China screened for echinococcosis, the sensitivity of DIGFA ranged from 71.8% to 90.7% in comparison to abdominal ultrasound; specificity for CE using AgB was 94.6% and for AE using Em2 was 97.1%. This simple eye-read rapid test can be used for both clinical diagnostic support, as well as in conjunction with ultrasound for mass screening in endemic CE and AE areas.

Echinococcus granulosus infection in domestic dogs in urban and rural areas of the Coquimbo region, north-central Chile

Hydatidosis is a zoonotic disease caused by the cystic stage of the cestode parasite Echinoccocus granulosus, in which the definitive hosts are mainly domestic dogs. This parasite is regarded mainly as a rural disease, where man is exposed through contact with eggs excreted by definitive hosts; however, some studies have shown that domestic dogs can get infected within urban areas. This study was conducted to assess differences in prevalence of E. granulosus in urban and rural sites in Coquimbo region of Chile. From 2005 to 2006 a cross-sectional household questionnaire survey was conducted in Coquimbo and Ovalle cities, in three towns and in rural sites along two transects from these cities to the Fray Jorge NP in the Coquimbo region. Faecal samples were collected from dogs during the questionnaire survey and tested for Echinococcus coproantigens. Positive dogs were found in urban areas. Analysis of risk factors indicated that dogs inhabiting the borders of urban areas were at greater risk of being coproantigen positive than those in the centre of these areas. These results are likely to be related to the custom of slaughtering livestock at home in urban areas during local celebrations, which could favour the importation of E. granulosus to urban areas by acquiring livestock contaminated with cysts from rural sites. This study shows that surveillance and control measures in livestock and domestic dogs need to be introduced in urban areas as well as rural areas of the Coquimbo region to reduce the public health risk of hydatid disease.

Echinococcus in the wild carnivores and stray dogs of northern Tunisia: the results of a pilot survey.

Abstract Echinococcus granulosus is endemic throughout Tunisia and E. multilocularis has previously been reported as the cause of two cases of human alveolar echinococcosis in the north–west of the country. The aim of the present study was to screen wild carnivores from the north–western Jendouba governorate and semi-stray dogs from the Siliana and Sejnane regions of northern Tunisia for these two zoonotic cestodes. The results of the coproscopy, coproELISA and coproPCR that were undertaken were compared with those of necropsy, where possible. Overall, 111 faecal samples (51 from wild carnivores and 60 from stray dogs) were tested by coproELISA for Echinococcus antigen and by coproPCR for E. granulosus and E. multilocularis species-specific DNA. All 60 dogs and seven of the wild carnivores were necropsied. Eleven (18.4%) of the dogs and one golden jackal (Canis aureus) were found positive for E. granulosus at necropsy. The jackal was found to be carrying 72 E. granulosus tapeworms, which were confirmed to be of the common sheep-dog (G1) genotype. Faecal samples from 10 (19.6%) of the wild carnivores — putatively, four golden jackals, two red foxes (Vulpes vulpes atlantica), one hyaena (Hyaena hyaena) and three genets (Genetta genetta) — gave a positive result in the Echinococcus coproELISA. In the coproPCR-based follow-up, E. granulosus DNA was detected in faecal samples from five jackals, two foxes and six stray dogs. The DNA of E. multilocularis was not, however, detected in any of the faecal samples investigated. This is the first report from Tunisia of (coproPCR-)confirmed E. granulosus infections in golden jackals and red foxes. The possible role of such wild hosts in the transmission of E. granulosus in Tunisia should be investigated further. The possibility of the active transmission of E. multilocularis in Tunisia still remains an open question.

Echinococcus granulosus and other intestinal helminths: current status of prevalence and management in rural dogs of eastern Australia

OBJECTIVES Ascertain the prevalence of intestinal helminths in rural dogs from eastern Australia and Tasmania. Identify farm management practices contributing to the perpetuation and transmission of Echinococcus granulosus. METHODS Helminth infection in dogs was determined microscopically through faecal flotation. Infection with E. granulosus was determined via faecal antigen-capture ELISA and coproPCR. Taeniid eggs were identified using molecular methods. Data on dog management and owner understanding of hydatid disease were collected via questionnaire. RESULTS Faeces were collected from 1425 Australian rural dogs (1119 mainland; 306 Tasmania). Eggs of hookworms were most prevalent, up to 40.2%, followed by whipworms (Trichuris vulpis), up to 21.2%. Roundworms (Toxocara canis and Toxascaris leonine) were least common, up to 6.1%. Taeniid eggs were found in 11 dogs (5 Taenia pisiformis; 2 T. serialis; 4 T. hydatigena); 2 of the T. hydatigena-infected dogs were also E. granulosus coproantigen-positive. Of the 45 dogs found to be E. granulosus coproantigen-positive, 24 were in Tasmania, 16 in NSW, 3 in Victoria and 2 in Queensland. Three Tasmanian coproantigen ELISA-positive dogs were also coproPCR-positive. The most common dog ration was commercial dry food, but half the owners fed raw meat to their dogs and some fed offal of lambs (8.9%) or mutton (7.8%). More than half (69%) of owners weighed their dogs before deworming. Few dewormed their dogs often enough to ensure they remained cestode-free and owners hunting wildlife usually left carcases where they were shot. CONCLUSIONS E. granulosus is still present in Australian rural dogs, including Tasmania, but at low levels. Owner behaviour perpetuates transmission of cestodes.

A molecular and ecological analysis of the trematode Plagiorchis elegans in the wood mouse Apodemus sylvaticus from a periaquatic ecosystem in the UK.

The prevalence of the digenean Plagiorchis sp. was investigated in a natural wood mouse population (Apodemus sylvaticus) in a periaquatic environment. Classical identification was complemented with the use of molecular differentiation to determine prevalence and verify species identity. Use of the complete ITS1-5.8S rDNA-ITS2 and partial 28S rDNA gene sequences have confirmed that the species reported at this location was Plagiorchis elegans and not Plagiorchis muris as reported previously. This underlines the difficulties in identification of these morphologically similar parasites. Plagiorchis elegans is typically a gastrointestinal parasite of avian species but has also been reported from small mammal populations. Although the occurrence of this digenean in A. sylvaticus in the UK is rare, in the area immediately surrounding Malham Tarn, Yorkshire, it had a high prevalence (23%) and a mean worm burden of 26.6 ± 61.5. The distribution of P. elegans followed a typically overdispersed pattern and both mouse age-group and sex were determined to be two main factors associated with prevalence. Male mice harboured the majority of worms, carrying 688 of 717 recovered during the study, and had a higher prevalence of 32.4% in comparison to only 8.7% in the small intestine of female mice. A higher prevalence of 43% was also observed in adult mice compared to 14% for young adults. No infection was observed in juvenile mice. These significant differences are likely to be due to differences in the foraging behaviour between the sexes and age cohorts of wood mice.

The contribution of spotted-tailed quolls ( Dasyurus maculatus ) to the transmission of Echinococcus granulosus in the Byadbo Wilderness Area, Kosciuszko National Park, Australia

Scats were collected from 19 wild spotted-tailed quolls (Dasyurus maculatus) caught in a region of south-eastern mainland Australia where hydatidosis (Echinococcus granulosus) occurs commonly in swamp wallabies (Wallabia bicolour) and other wildlife. All scats were tested for coproantigens of E. granulosus tapeworms. None of the scats tested had detectable coproantigens of E. granulosus. These data and previous unsuccessful attempts to experimentally infect other species of dasyruid with E. granulosus suggest that spotted-tailed quolls may be refractory to infection with E. granulosus.

Echinococcus granulosus infection in foxes in Coquimbo District, Chile

Echinococcus granulosus es un cestodo de importancia zoonotica que afecta a una amplia gama de especies. El principal hospedero definitivo de este parasito es el perro domestico, sin embargo, en algunas areas del mundo se ha reportado la infeccion de carnivoros silvestres con este, estos potencialmente podrian tener un rol en la mantencion de la infeccion en dichas areas. Este estudio examina la presencia de E. granulosus en carnivoros silvestres en la Region de Coquimbo en Chile; para esto se obtuvieron muestras fecales de zorros chilla y culpeo capturados en seis sitios rurales de esta region entre 2005 y 2006. Mediante una prueba de ELISA coproantigeno se determino una coproprevalencia a E. granulosus en chillas de 7% (2/28), la que vario entre 0% a 20% en los diferentes sitios estudiados. Solo cinco culpeos fueron capturados y ninguno fue positivo. Se discuten las implicancias que la presencia de E. granulosus en carnivoros silvestres podria tener para la mantencion del parasito en el area estudiada