Risk of Toxocara canis eggs in stray and domestic dog hair in Egypt
Introduction
Toxocara canis is a nematode parasite, which is widespread throughout the world. Dogs, and other canids, are the definitive hosts, however T. canis can infect a wide range of species including humans. Dogs are infected with T. canis following ingestion of T. canis eggs, or via transmammary or transplacental transmission of larvae. Adult worms reside in the small intestine of dogs for 4–6 months and begin shedding large numbers of eggs, which are expelled in feces (Roberts and Janovy, 1996, Acha and Szyfres, 1989). Dogs may expel up to 200,000 eggs into the environment per day (Barriga, 1988, Acha and Szyfres, 1989, Lloyd, 1998), and after a maturation period of 2–7 weeks, eggs are embryonated (Schantz, 1991, Mizgajska-Wiktor and Uga, 2006).
Humans are infected following ingestion of embryonated T. canis eggs, from which larvae hatch. The principal route of Toxocara spp. transmission to humans is via contaminated soil, infection can also occur following ingestion of contaminated raw vegetables or fruits. Children have the highest risk of infection as they have an increased opportunity of exposure to contaminated soil or sandpits while playing outdoors (Overgaauw, 1997). Few larvae are required to cause disease in humans and there are three recognized disease syndromes resulting from T. canis infection; visceral larva migrans, ocular larva migrans and covert toxocariasis (Taylor, 1993, Oge and Oge, 2000). Visceral larva migrans produces an inflammatory reaction with fever, bronchospasm, abdominal pain, anorexia and occasionally myocarditis or respiratory failure. Ocular larva migrans mainly occurs in older children and young adults, clinical manifestations include decreased vision, leucocoria, chorioretinitis and retinal fibrinosis, in addition unilateral or bilateral blindness may occur in a small number of those infected. Covert toxocariasis is the most common presentation of T. canis, which presents as febrile illness in children, symptoms, which include abdominal pain, cough and headaches, are usually mild (Taylor and Holland, 2001, MacPherson, 2005).
Few studies (Wolfe and Wright, 2003, Roddie et al., 2008, Aydenizöz-Özkayhan et al., 2008) have investigated the presence of T. canis eggs on dogs’ hair as another possible source of infection, those were preliminary investigations and did not address whether T. canis eggs were likely to have been transferred to dogs’ hair via self-contamination, or picked up from soil. The aim of this study was to assess whether T. canis eggs were present on the hair of stray and domestic dogs, to identify risk factors for the presence of T. canis eggs on dog hair and to assess the relationship between T. canis eggs on dog's hair and infection status.
Section snippets
Study design
Between November 2009 and April 2010, a total of 64 stray and 56 domestic dogs were sampled from Kafrelsheikh governorate (KG), Egypt. This governorate's economy is heavily reliant on agriculture activities and its inhabitants frequently keep dogs as guard dogs, sheep dogs or companion animals. Stray dogs were trapped in multiple fields in close proximity to households or farmland. Each morning trained investigators collected hair and fecal samples from trapped dogs, these dogs were tagged to
Results
Multisite sampling of dog's hair enhanced the efficiency of egg recovery, increasing the accuracy of the results. Hair samples were collected from 64 stray and 56 domestic dogs (24 companion, 15 shepherds and 17 guard dogs). Of dogs sampled; 17 (26.6%) stray and 6 (10.7%) domestic dogs had at least one T. canis egg present in their hair samples. Of the dogs which were positive for T. canis eggs, embryonated eggs were present on 15 out of 17 (88.2%) stray and 5 out of 6 (83.8%) domestic dogs.
Discussion
Very few previous studies have investigated the presence of Toxocara eggs in dog's hair. The present study also demonstrated a novel method of sampling, to our knowledge it is the first study to sample dog hair from eight different sites, increasing the efficiency of egg recovery. Embryonated T. canis eggs were recovered from the hair of both stray and domestic dogs. Humans may become infected with T. canis through direct contact with dogs (Wolfe and Wright, 2003), although prevalence of T.
Conclusion
Identification of embryonated T. canis eggs on domestic dog hair indicates that direct contact with dogs may be a potential risk factor for human exposure. In addition to self-contamination, environmental contamination is thought to be a route for T. canis contamination of stray dog's hair. Whereas, in domestic dogs, the primary route of T. canis egg adherence to hair is likely to be via self-contamination. There may also be a higher risk of human exposure from contact with puppies and male
Conflict of interest
The authors wish to declare that they have no competing interests.
Acknowledgements
We would like to thank the investigators Samy Ali, Magdi Ragb, Hussen Mohamed and Ahmed Mohsen for their help in collecting the samples.
References (23)
- et al.
The investigation of Toxocara canis eggs in coats of different dog breeds as a potential transmission route in human toxocariasis
Vet. Parasitol.
(2008) - et al.
An estimation of Toxocara canis prevalence in dogs, environmental egg contamination and risk of human infection in the Marche region of Italy
Vet. Parasitol.
(2003) - et al.
Patent Toxocara canis infections in previously exposed and in helminth-free dogs after infection with low numbers of embryonated eggs
Vet. Parasitol.
(2008) - et al.
Epidemiologic and zoonotic aspects of ascarid infections in dogs and cats
Trends Parasitol.
(2010) Human behaviour and the epidemiology of parasitic zoonoses
Int. J. Parasitol.
(2005)- et al.
Quantitative comparison of various methods for detecting eggs of Toxocara canis in samples of sand
Vet. Parasitol.
(2000) - et al.
Zoonotic parasites in fecal samples and fur from dogs and cats in The Netherlands
Vet. Parasitol.
(2009) - et al.
Contamination of dogs’ hair with eggs of Toxocara canis
Vet. Parasitol.
(2008) - et al.
Statistical comparison of dog and cat guard hairs using numerical morphology
Forensic Sci. Int.
(2006) Parasitic zoonoses in perspective
Int. J. Parasitol.
(1991)
Zoonoses and Communicable Diseases Common to Man and Animals
Cited by (44)
Seroprevalence and risk factors of Toxocara canis infection in children aged 2–15 years from the southwest Iran
2022, Comparative Immunology, Microbiology and Infectious DiseasesVertebrates as uninfected disseminators of helminth eggs and larvae
2022, Advances in ParasitologyCitation Excerpt :The ability of propagules to attach to fur may depend on a number of factors. Adhesive properties of hair may rest on the pseudohost species, strain, or size which may influence the age, length, diameter and dynamic properties of the fur (El-Tras et al., 2011; Farag et al., 2015; Sato et al., 2006). Different kinds of hair may predominate on different parts of the body.
Urban public squares as potential hotspots of dog-human contact: A spatial analysis of zoonotic parasites detection in Gran Santiago, Chile
2021, Veterinary Parasitology: Regional Studies and ReportsEpidemiology of Toxocara spp. in dogs and cats in mainland China, 2000–2019
2020, Advances in ParasitologyCitation Excerpt :A total of 68 eligible papers were retrieved from Web of Science, PubMed and CNKI databases, including 24,490 dogs and 844 cats in mainland China from January 2000 to July 2019 (Table 1). In this review, 17.34% (4246/24,490) of the examined dogs were positive with T. canis infection, which was higher than that in some countries, such as the 6.93% (16/231) in dogs in south central West Virginia, USA (Savilla et al., 2011), 7.62% (67/879) in dogs in Crete, Greece (Kostopoulou et al., 2017) and 9.29% (55/592) in dogs in Ponte de Lima, Portugal (Mateus et al., 2014); but lower than the 27.00% (27/100) in domestic dogs in northern Iran (Sarvi et al., 2016) and 29.00% (29/100) in dogs in Egypt (El-Tras et al., 2011). 22.04% (186/844) of the examined cats were positive with T. cati infection in this review, which was higher than that in some countries, such as the 7.16% (48/670) in cats in Netherlands (Nijsse et al., 2016), 8.33% (22/264) in cats in Crete, Greece (Kostopoulou et al., 2017), 10.31% (56/543) in stray cats in Peninsular Malaysia (Mohd Zain et al., 2013) and 20.29% (84/414) in household cats in Transylvania, Romania (Mircean et al., 2010); but lower than the 38.27% (62/162) in stray cats in Lisbon, Portugal (Waap et al., 2014).
Seroepidemiology of human toxocariasis in North Africa
2020, Advances in ParasitologyHuman toxocariasis – A look at a neglected disease through an epidemiological ‘prism’
2019, Infection, Genetics and EvolutionCitation Excerpt :Humans acquire Toxocara infection(s) by accidentally ingesting infective eggs from contaminated soil, water, fruit or vegetables (e.g., Dubná et al., 2007; Poeppl et al., 2013). Humans may also become infected through direct contact with dogs or cats (Poeppl et al., 2013) – although eggs have been detected on the hairs of definitive hosts (El-Tras et al., 2011; Roddie et al., 2008; Overgaauw et al., 2009), the numbers of embryonated eggs on well cared-for dogs are negligible (Holland, 2015; Keegan and Holland, 2010). People can also become infected by ingesting larvae present in raw or undercooked meat or organs from paratenic hosts, such as rabbits, ruminants and poultry (cf. Dutra et al., 2014; Salem and Schantz, 1992; Taira et al., 2004; Yoshikawa et al., 2008).