Toxocara species

Mackenstedt, Ute, Jenkins, David & Romig, Thomas, 2015, The role of wildlife in the transmission of parasitic zoonoses in peri-urban and urban areas, International Journal for Parasitology: Parasites and Wildlife 4 (1), pp. 71-79 : 76

4.4. Toxocara species and Toxascaris leonina

The most important of these parasites is T. canis because of its impact on human hosts. Accidental ingestion of embryonated T. canis eggs, usually by children, results in visceral larval migrans and in some cases larvae migrate to the eyes, leading to blindness, commonly unilateral ( Stevenson and Hughes, 1988). T. cati and T. leonina have not been definitely implicated as causes of visceral larval migrans in humans, but T. cati has been shown to produce a similar impact in pigs ( Stevenson and Hughes, 1988).

T. canis occurs in wild dogs and foxes encroaching into peri-urban and urban areas; however, the prevalence of infection is commonly low, but can be unexpectedly high. In wild dogs from the Maroochy Shire, 5/108 (4.6%) of the animals examined were infected ( Jenkins et al., 2008), but none of 7 foxes examined was infected. Hovever, in the same study, 5/18 (27.8%) wild dogs from Fraser Island were infected, a likely reflection of the close proximity of the Fraser Island wild dogs with human habitation. In the Townsville study, Brown and Copeman (2003) did not recover T. canis in any of the 27 wild dogs examined in contrast to Smout et al. (2013) who reported a prevalence of 46% in their study in Townsville. Data from a survey of 25 road-killed urban foxes and 43 shot peri-urban foxes in and around Canberra ( Wilson, 1994), revealed prevalences of T. canis of 12% and 0%, respectively ( Craig, 1990).