Prevalence of Selected Zoonotic and Vector-Borne Agents in Dogs and Cats on the Pine Ridge Reservation

Experimental infection of cats with Cryptosporidium felis

OBJECTIVES

The aims of this study were to experimentally inoculate cats with Cryptosporidium felis oocysts and compare fecal detection by fluorescent antibody assay (FA) and quantitative PCR (qPCR), and document clinical signs associated with infection.

METHODS

Cryptosporidium felis oocysts were concentrated from the feces of a naturally infected cat and orally inoculated into six cats that tested negative for C felis by an FA and fecal flotation (FF). Cats were observed daily for the presence of clinical signs consistent with infection. Fecal samples from all cats on days 0 and 9, and one sample per cat (days 18-21), were evaluated by all assays. On day 31, two cats negative for C felis by FF and FA were administered methylprednisolone acetate and all assays were repeated on days 34, 36 and 38. Samples from all cats were tested by FF and FA on days 41, 43, 45 and 48.

RESULTS

A total of 41 samples were tested, 25 of which were compared by FA and qPCR. Cryptosporidium felis was detected in 2/25 (8%) and in 19/25 (76%) samples by FA and by qPCR, respectively; the other 16 samples were tested by FF and FA. None of the cats was positive for C felis by FF or FA in samples collected on days 0, 9 or 18-21. One, five and six samples tested positive by qPCR on days 0, 9 and 18-21, respectively. The cats administered methylprednisolone acetate tested positive for C felis by FA on day 36 and by qPCR on days 31, 34, 36 and 38. None of the cats showed clinical signs of disease.

CONCLUSIONS AND RELEVANCE

Clinical signs were not recognized in any of the cats for the duration of the study. FA was insensitive compared with qPCR for detecting cats with subclinical C felis infection.

Evaluation for associations amongst Giardia duodenalis assemblages and diarrhea in dogs

Giardia duodenalis is a species complex comprising at least eight assemblages. Most dogs harbor the host-adapted assemblages C and D and approximately 30 % harbor the zoonotic assemblages. Humans and dogs with giardiosis can exhibit a variety of clinical manifestations ranging from the absence of clinical signs to acute or chronic diarrhea. Human studies report conflicting results concerning associations between clinical signs and assemblage type. The objective of this study was to use results of molecular and phylogenetic analyses to evaluate associations between G. duodenalis assemblages and diarrhea in client-owned dogs from the United States. Fecal samples that were positive for Giardia cysts were classified as normal or diarrheal. Samples were analyzed by PCR assays of the beta-giardin (bg), glutamate dehydrogenase (gdh), and triose phosphate isomerase (tpi) genes. Sequences of the three genes were analyzed by BLAST analysis and phylogenetic analysis was performed by Neighbor-Joining analysis. Two hundred and eighty-eight Giardia-positive fecal samples were evaluated by the three PCRs. One or more genes were amplified from 95 normal samples and 93 diarrheal samples, 27 samples were positive for one or more genes but could not be sequenced due to low quality DNA, and 73 samples tested negative. Ninety seven percent of the samples (182/188) in both the diarrheal and normal groups typed as dog-specific assemblages (D or C) by at least one gene. Phylogenetic analysis of the three genes placed the isolates from assemblages A, B, C and D separated from each other with strong bootstrap support. Diarrhea was not associated with the Giardia assemblage or other parasitic co-infection in this sample set. Other factors, such as the role of gut microbiota in giardiosis should be considered in future studies.

Advances in molecular epidemiology of cryptosporidiosis in dogs and cats

The use of molecular tools has led to the identification of several zoonotic Cryptosporidium spp. in dogs and cats. Among them, Cryptosporidium canis and Cryptosporidium felis are dominant species causing canine and feline cryptosporidiosis, respectively. Some Cryptosporidium parvum infections have also been identified in both groups of animals. The identification of C. canis, C. felis and C. parvum in both pets and owners suggests the possible occurrence of zoonotic transmission of Cryptosporidium spp. between humans and pets. However, few cases of such concurrent infections have been reported. Thus, the cross-species transmission of Cryptosporidium spp. between dogs or cats and humans has long been a controversial issue. Recently developed subtyping tools for C. canis and C. felis should be very useful in identification of zoonotic transmission of both Cryptosporidium spp. Data generated using these tools have confirmed the occurrence of zoonotic transmission of these two Cryptosporidium spp. between owners and their pets, but have also shown the potential presence of host-adapted subtypes. Extensive usage of these subtyping tools in epidemiological studies of human cryptosporidiosis is needed for improved understanding of the importance of zoonotic transmission of Cryptosporidium spp. from pets.

Assessment of next generation amplicon sequencing of the beta-giardin gene for the detection of Giardia duodenalis assemblages and mixed infections

Giardia duodenalis is an enteric protozoan parasite commonly found in humans and many other animals around the world. The parasite is grouped into genetically related strains called assemblages which display differing degrees of host specificity. Although mixed assemblage infections have been documented the full extent of the occurrence and importance of mixed infections remains to be characterized as current sequencing technologies lack the sensitivity to readily detect mixed infections. Here we have developed a next generation amplicon sequencing (NGS) protocol and analysis pipeline for detecting Giardia assemblages using the beta-giardin gene. NGS was validated using 37 isolates that included Giardia muris and six assemblages (A-F) of Giardia duodenalis obtained from seven different hosts. NGS was compared to traditional PCR and direct Sanger sequencing for its ability to detect Giardia species, assemblages, and mixed assemblage infections. We demonstrate that NGS works as well as PCR and Sanger sequencing for assemblage detection as the same assemblage was observed in all samples by both methods. NGS has the further benefit of detecting mixed assemblage infections, low abundance assemblages, and intra-assemblage variation in samples which would have been missed using direct Sanger sequencing alone. NGS represents a powerful new tool for exploring Giardia infections not only in infected hosts but also in environmental specimens which may aide in understanding Giardia epidemiology.

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Developed a next generation sequencing (NGS) protocol to detect Giardia

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Comparison of NGS to Sanger sequencing for sensitivity and accuracy

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NGS improved detection of mixed assemblages and detects low abundance assemblages

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NGS allowed detection of intra-assemblage variabilities

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Mixed assemblages may be far more common than previously thought

Toxocara canis and Toxocara cati in domestic dogs and cats in the United States, Mexico, Central America and the Caribbean: A review

Toxocara prevalence ranges from 0 to >87% and 0 to >60% in dogs and cats, respectively, within the United States, Mexico, Central America and the Caribbean. Higher prevalence occurs in animals less than 1 year of age. Overall, prevalence is higher in cats compared to dogs. The lowest prevalence occurs in the US owned dog population. Specific populations in this industrialized nation, in animal shelters or resource-limited locations, have prevalences similar to those seen in populations from other regions reviewed here. Conversely, subpopulations in Central America and the Caribbean have very low prevalence. Apparent contributors to prevalence, excluding animal age and climate, are socio-economic factors, attitudes towards pet management and animal population density. The lack of data from some regions pose a challenge in assessing trends; however, with the exception of the US owned dog population, there is no strong indication of any decrease in prevalence from historical levels.

Molecular epidemiology of giardiasis from a veterinary perspective

A total of eight Giardia species are accepted. These include: Giardia duodenalis (syn. Giardia intestinalis and Giardia lamblia), which infects humans and animals, Giardia agilis, Giardia ardeae, Giardia psittaci, Giardia muris, Giardia microti, Giardia peramelis and G. cricetidarum, which infect non-human hosts including amphibians, birds, rodents and marsupials. Giardia duodenalis is a species complex consisting of eight assemblages (A-H), with assemblages A and B the dominant assemblages in humans. Molecular studies to date on the zoonotic potential of Giardia in animals are problematic and are hampered by lack of concordance between loci. Livestock (cattle, sheep, goats and pigs) are predominantly infected with G. duodenalis assemblage E, which has recently been shown to be zoonotic, followed by assemblage A. In cats and dogs, assemblages A, B, C, D and F are commonly reported but relatively few studies have conducted molecular typing of humans and their pets and the results are contradictory with some studies support zoonotic transmission but the majority of studies suggesting separate transmission cycles. Giardia also infects a broad range of wildlife hosts and although much less well studied, host-adapted species as well as G. duodenalis assemblages (A-H) have been identified. Fish and other aquatic wildlife represent a source of infection for humans with Giardia via water contamination and/or consumption of undercooked fish and interestingly, assemblage B and A predominated in the two molecular studies conducted to date. Our current knowledge of the transmission dynamics of Giardia is still poor and the development of more discriminatory typing tools such as whole genome sequencing (WGS) of Giardia isolates is therefore essential.

Clinical evaluation of outdoor cats exposed to ectoparasites and associated risk for vector-borne infections in southern Italy

BACKGROUND

Cats can be carriers of infected arthropods and be infected with several vector-borne pathogens (VBP) but there is limited knowledge about their pathogenic role in cats.

RESULTS

A cross-sectional controlled study investigated the clinical status and antibody (Bartonella henselae, Rickettsia conorii, Ehrlichia canis, Anaplasma phagocytophilum, Babesia microti and Leishmania infantum) and/or blood PCR (Mycoplasma spp., Bartonella spp., Rickettsia spp., Ehrlichia/Anaplasma spp., piroplasmids, L. infantum, Hepatozoon felis) prevalence in 197 cats. Outdoor cats lacking ectoparasiticide treatment or hosting ectoparasites (study group [SG], n = 134) and indoor cats treated against ectoparasites (control group [CG], n = 63) were enrolled. Clinical data and retroviral co-infections were compared between the two groups. Multivariable analysis tested associations between variables and VBP exposure. Lymphadenia, stomatitis, and various haematological abnormalities were statistically more frequent in SG. Antibodies against R. conorii, B. henselae, A. phagocytophylum, B. microti, E. canis and L. infantum were detected. Bartonella henselae, Bartonella clarridgeiae, Mycoplasma haemofelis, "Candidatus Mycoplasma haemominutum" and "Candidatus Mycoplasma turicensis" DNA were identified. Very high antibody (87.8%) and PCR (40.1%) positivity to at least one pathogen were detected and were significantly higher in SG. Co-infections were confirmed in about one-third of the cats and were more frequent in SG cats. Molecular and overall (antibody and PCR) positivity to Bartonella and antibody positivity to R. conorii were higher in SG. Multivariable analysis found significant associations of Bartonella spp. infection with Feline Immunodeficiency Virus (FIV) infection and increased globulins, and of Mycoplasma spp. infection with adult age, FIV infection, anaemia, and increased creatinine.

CONCLUSIONS

A very high prevalence of exposure to zoonotic VBP was found in cats, with Rickettsia and Bartonella infections being most prevalent. Some risk factors were documented namely for Mycoplasma spp. and Bartonella spp. The lifestyle of cats is clinically relevant and requires specific preventative measures to protect their health.