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

Toxocara cati Infection in Cats (Felis catus): A Systematic Review and Meta-Analysis

Introduction: Toxocariasis is an infection caused in canines, felines, humans, and other vertebrates by species of the genus Toxocara, such as T. canis and T. cati. The embryonated eggs of these parasites are the primary means of acquiring the infection for both definitive hosts, dogs and cats, respectively, and for intermediates, such as humans and other vertebrates. When deposited on park soils, environmental contamination becomes a risk to environmental, human, and animal health. Objective: To determine the global prevalence of Toxocara cati in cats (Felis catus). Methods: A systematic review of the literature was carried out in six databases (Scopus, PubMed, ScienceDirect, SciELO and Google Scholar) to evaluate the global prevalence of Toxocara cati in cats, defined by coproparasitological, histological, and molecular techniques. A meta-analysis was performed using a random effects model to calculate pooled prevalence and 95% confidence intervals (95% CI). A two-tailed 5% alpha level was used for hypothesis testing. Results: Two hundred and eighty-nine studies were included. The global pooled prevalence of Toxocara cati in cats using coproparasitological methods was 17.0% (95.0% CI: 16.2-17.8%). In the subgroup analysis according to country, Nepal had the highest prevalence of T. cati infection (94.4%; 95% CI 89.7-99.2%). The pooled prevalence of T. cati infection by PCR in four studies was 4.9% (95.0% CI: 1.9-7.9%). Conclusions: This systematic review underscores the need for preventive action against toxocariasis due to its widespread prevalence. The interplay between animal and human health should be emphasised, necessitating measures like deworming cats, hygiene practices, and public education to mitigate risks. Safeguarding feline health can also reduce human transmission, benefiting both species.

Prevalence and public health relevance of enteric parasites in domestic dogs and cats in the region of Madrid (Spain) with an emphasis on Giardia duodenalis and Cryptosporidium sp

BACKGROUND

Pet dogs and cats exert an unquestionable beneficial effect in the well-being of their owners, but can also act as a source of zoonotic infections if improperly cared.

OBJECTIVES

We investigated the occurrence, risk factors, genetic variability and zoonotic potential of intestinal parasites in dogs and cats attended in a clinical veterinary setting in Spain.

METHODS

Canine (n = 252) and feline (n = 35) faecal samples were collected during 2017-2019 and analysed by coproparasitological methods. A rapid lateral immunochromatographic test (ICT) was used for detecting Giardia duodenalis and Cryptosporidium sp. Samples positive at microscopy examination and/or ICT were reassessed by molecular methods.

RESULTS

Overall, 48.8% (123/252) of dogs and 48.6% (17/35) of cats were infected by enteric parasites. In dogs, G. duodenalis was the most prevalent species (40.9%), followed by Cystoisospora sp. (7.1%), and Toxocara canis (5.2%). In cats, Joyeuxiella sp. and Toxocara cati were the dominant species (20.0% each), followed by G. duodenalis (14.3%), D. caninum (5.7%) and Cystoisospora felis and Toxascaris leonina (2.9% each). Pups and kittens were more likely to harbour intestinal parasites and develop clinical signs. Sequence analyses of dog isolates revealed the presence of assemblages A (n = 1), C (n = 4), D (n = 4) and C+D (n = 1) within G. duodenalis; C. parvum (n = 1) and C. canis (n = 4) within Cryptosporidium and PtEb IX (n = 1) in Enterocytozoon bieneusi. A novel C. canis subtype family, named XXi, is reported.

CONCLUSIONS

Our results highlight that (i) well-cared dogs carry zoonotic enteric protozoan parasites of public health relevance, (ii) proper hygiene practices and routine veterinary treatment are essential to prevent zoonotic infections, (iii) vulnerable populations should avoid contact with pups/kittens with diarrhoea and (iv) infected dogs might be major contributors to the environmental contamination with soil-transmitted helminths (STHs) eggs.

Toward anthelmintic drug candidates for toxocariasis: Challenges and recent developments

Infections caused by parasitic helminths rank among the most prevalent infections of humans and animals. Toxocariasis, caused by nematodes of the genus Toxocara, is one of the most widespread and economically important zoonotic parasitic infections that humans share with dogs and cats. Despite the completion of the Toxocara canis draft genome project, which has been an important step towards advancing the understanding of this parasite and the search for drug targets, the treatment of toxocariasis has been dependent on a limited set of drugs, necessitating the search for novel anthelmintic agents, specially against Toxocara larvae in tissues. Given that research, development, and innovation are crucial to finding appropriate solutions in the fight against helminthiasis, this paper reviews the progress made in the discovery of anthelmintic drug candidates for toxocariasis. The main compounds reported in the recent years regards on analogues of albendazole, reactive quinone derivatives and natural produts and its analogues. Nanoparticles and formulations were also reviewed. The in vitro and/or in vivo anthelmintic properties of such alternatives are herein discussed as well as the opportunities and challenges for treatment of human toxocariasis. The performed review clarify that the scarcity of validated molecular targets and limited chemical space explored are the main bottlenecks for advancing in the field of anti-Toxocara agents.

Evaluation of a commercial coproantigen immunoassay for the detection of Toxocara cati and Ancylostoma tubaeforme in cats and Uncinaria stenocephala in dogs

Coproantigen immunoassays (IDEXX Fecal Dx® antigen tests) were evaluated for their ability to identify Toxocara cati and Ancylostoma tubaeforme infections in cats and Uncinaria stenocephala infection in dogs. Five cats were experimentally infected with 500 embryonated eggs of T. cati, eight cats with 500 third-stage larvae (L3) of A. tubaeforme and seven dogs with 500 L3 of U. stenocephala. In addition to the three coproantigen tests, the course of infection was monitored by a combined sedimentation-flotation method with ZnSO₄ as flotation medium (specific gravity: 1.28-1.30) and a modified McMaster method in case of copromicroscopically positive samples. Eggs of T. cati were first observed between 28 and 54 days post infection (dpi) in four of the five infected cats. In these four cats, positive roundworm coproantigen signals were obtained between 16 and 44 dpi. Positive coproantigen signal always preceded egg observations, but the interval varied between 6 and 30 days. Hookworm-specific positive coproantigen signals were detected in seven of the eight A. tubaeforme infected cats between 10 and 52 dpi, while consecutive egg excretion was observed in three cats between day 26 and 54 pi. Of these three, coproantigen signal preceded egg observation by 12 to 24 days. Four cats had positive coproantigen results in the absence of egg excretion, and one cat never achieved a positive result for egg or coproantigen. In six of seven U. stenocephala infected dogs, infection was confirmed by copromicroscopy between 16 and 24 dpi as well as for hookworm coproantigen between 10 and 14 dpi. Coproantigen signal was detected prior to egg observation by 2 to 14 days. No cross-reactions between the roundworm, hookworm und whipworm tests occurred in study animals. The results of this study demonstrate the ability of the coproantigen tests to detect the common roundworm and hookworm infections in cats and U. stenocephala infections in dogs as well as the ability to detect the prepatent stage of infection.

Prevalence of endoparasitic and viral infections in client-owned cats in metropolitan Bangkok, Thailand, and the risk factors associated with feline hookworm infections

The prevalence of enteric parasites in cats in metropolitan Bangkok has not been updated in over 13 years. The main objectives of this study include updating the prevalence of endoparasitism in client-owned cats, status of retroviral infections and determining the association between feline hookworm infection and possible risk factors. A total of 509 fecal samples were collected from client-owned cats in 2014-2015 and examined by a wet fecal mount technique. If additional sample remained, a PBS-ethyl acetate sedimentation was done (n = 229), and ZnSO₄ centrifugal flotation was also performed if there was sufficient remaining sample (n = 105). At least one parasite was observed in 32.0% (163/509) of cats, with Ancylostoma being the most common intestinal parasite detected in 21.6% (110/509) of cats. Other parasitic infections detected by fecal examinations included Toxocara (6.9%; 35/509), Platynosomum (3.7%; 19/509), Cystoisospora (3.5%; 18/509), Taenia (2.9%; 15/509), Spirometra (1.6%; 8/509), Dipylidium (0.4%; 2/509), and Opisthorchis-like trematode (0.2%; 1/509). Examination for Giardia infection was conducted with the SNAP® Giardia Test, a coproantigen test, on a subset of the fecal samples (233/509) and revealed a positive result on 3.9% (9/233) of samples. Plasma samples were analyzed using the SNAP® Triple Test detecting antigens of Feline Leukemia Virus (FeLV) and Dirofilaria immitis while also detecting antibodies to Feline Immunodeficiency Virus (FIV). Antigens of FeLV and antibodies to FIV were found in 7.1% (19/269) and 5.2% (14/269) of cats, respectively. None of the cats were found to have circulating antigen of Dirofilaria immitis using this test. No association between retroviral and endoparasitic infections was found. From multivariable logistic regression examining associated factors, the ability of cats to access the outdoors (adjusted OR = 3.22, 95% CI; 1.42-7.87) and having tapeworm segments or adult helminths in feces (adjusted OR = 3.31, 95% CI; 1.34-8.21) were significantly associated with the finding of hookworm eggs in feces. This work presents the most up-to-date data on enteric feline parasite prevalence in the metropolitan Bangkok area from which fecal samples were directly collected from cats. Consequently, this study emphasizes that diagnosis of parasitic infections and the routine use of antiparasitic medications should be encouraged by veterinarians and to owners in order to reduce the reservoir of potentially zoonotic parasites.

Demographic and Pathogens of Domestic, Free-Roaming Pets and the Implications for Wild Carnivores and Human Health in the San Luis Region of Costa Rica

Habitat loss and degradation, restricted ranges, prey exploitation, and poaching are important factors for the decline of several wild carnivore populations and additional stress from infectious agents is an increasing concern. Given the rapid growth of human populations in some regions like Costa Rica, pathogens introduced, sustained, and transmitted by domestic carnivores may be particularly important. To better understand the significance of domestic carnivore pathogens for wildlife, we determine the prevalence of infection and possible mechanisms for contact between the two groups. The demographics, role in the household, and pathogens of pet dogs and cats was studied during three annual spay/neuter clinics in San Luis, Costa Rica. Most dogs were owned primarily as pets and guard animals, but ~10% were used for hunting. Cats were owned primarily as pets and for pest control. Both roamed freely outdoors. We detected high prevalences of some pathogens (e.g., carnivore protoparvovirus 1 and Toxoplasma gondii). Some pathogens are known to persist in the environment, which increases the probability of exposure to wild carnivores. This study demonstrated that domestic pets in San Luis, home to a number of protected and endangered wildlife species, are infected with pathogens to which these wild species are potentially susceptible. Additionally, results from our questionnaire support the potential for domestic and wild animal contact, which may result in disease spillover.

An Integrated Study of Toxocara Infection in Honduran Children: Human Seroepidemiology and Environmental Contamination in a Coastal Community

(1) Background: Infections caused by Toxocara canis and T. cati are considered zoonoses of global importance. Reports from North and South America indicate that human infections are widespread in both continents, but epidemiological information from Central America is still lacking. (2) Methodology: In the present cross-sectional multi-year study, we aimed to undertake the first seroepidemiological and environmental study on toxocariasis in Honduras. This included the determination of seroprevalence of anti-Toxocara spp. antibodies in children using a Toxocara spp. purified excretory-secretory antigens enzyme-linked immunosorbent assay (TES-ELISA) and a confirmatory Western blot. As well, through statistical analysis including logistic regression we aimed at identifying relevant biological and epidemiological factors associated with seropositivity. The study also entailed detection of parasites' eggs in the soil samples both through Sheather's concentration method and a nested polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. (3) Results: The study was undertaken in a coastal community of Honduras in 2 different years, 2015 and 2017. A total of 88 healthy schoolchildren completed the study, with participation of 79% (73/92) and 65% (46/71) of the student body in 2015 and 2017, respectively. Thirty-one children participated in both years (i.e., dual participants). Through both serological tests, seropositivity was confirmed in 88.6% (78/88) of children. Due to the high number of seropositives, logistic regression analysis was not possible for most socio-economic and epidemiological variables. Eosinophilia, on the other hand, was associated with seropositivity, independently of other intestinal helminthic infections. Continued seropositivity was observed in most of the dual participants, while seroconversion was determined in 8 of these children. Microscopic examination of soil samples did not yield any positive results. Through nested PCR-RFLP, 3 of the 50 samples (6%) were positive for Toxocara spp.; two were identified as T. canis and one as T. cati. (4) Conclusions: This work documents for the first time, high levels of human exposure to Toxocara spp. in Honduras. These findings, along with the country's favorable epidemiological conditions for this zoonosis, emphasize the need for more research to determine whether this infection is underreported in the country.

Toxocara prevalence in dogs, cats and the environment in Russia

The toxocariasis incidence in Russia is relatively low (1.8 cases per 100,000 individuals) and the parasite is not a major healthcare concern. However, the proportion of primary hosts testing positive for the parasite is high and varies between 3% and 100% in dogs (on average 33%), and between 6% and 52% in cats. Higher prevalence was observed in Volga, Urals and Siberia regions. Levels of contamination of soil, children's playgrounds and sandboxes is also high, with up to 100% contamination rates determined in some studies, but more commonly prevalence of contamination around 40% was reported. There is a pronounced seasonality in the prevalence of Toxocara in primary hosts and the soil, with peaks in the summer and autumn. Most likely, a lack of permissive conditions for the development of eggs in the winter determines observed seasonal patterns, which are different than those observed in most other countries. Toxocara eggs were found in 4-10% of vegetables and greenery samples tested, suggesting that they can contribute to the transmission of Toxocara.