Role of cats in human toxocarosis

Abstract

Toxocara cati, the feline ascarid, is ubiquitous in domestic cats globally and is increasingly recognised as an important zoonotic species. In the definitive host, infections with the adult ascarid usually do not present any clinical signs; if clinical signs do appear, it is usually in kittens infected with T. cati, especially by the transmammary route. Diseases may include cachexia, a pot-bellied appearance, respiratory disorders, diarrhoea, vomiting, among other signs, and these may present as early as 3 weeks of age. However, infections with Toxocara spp. larvae in paratenic hosts (including humans and many other animals), can result in serious complications from the migration of larvae. Historically, there has been an assumption that Toxocara canis was the most likely cause of Toxocara spp.-related disease; while it is probably true that T. canis is responsible for the majority of infections, it is important that those caused by T. cati are accurately identified so that the contribution of this parasite to human disease can be established and then handled appropriately. Overall, the detection of infections in cats and the control of parasite stages in the environment are essential to minimise the infection risk to other animals or humans.

Keywords: Toxocara cati; control; human toxocarosis; prevention; zoonosis.

Figure 1.

Toxocara cati life cycle (artwork by Dr Sarah Sapp. U.S. Centers for Disease Control and Prevention (CDC)).

Figure 2.

Toxocara cati egg showing pitted shell (image courtesy of Dr. Rebecca Traub, University of Melbourne, Australia).

Figure 3.

Toxocara cati adult worm expelled in cat faeces (image courtesy of Dr. Andrei D Mihalca, University of Agricultural Sciences & Veterinary Medicine Cluj Napoca, Romania).

Figure 4.

The cephalic alae of Toxocara cati (A), the tail-end of the female (B), and male (C), egg (D) A, B, C: Bars indicate 1000 μm. / D: Bars indicate 100 μm. (Taken with permission from Toxocara Nematodes in Stray Cats from Shiraz, Southern Iran: Intensity of Infection and Molecular Identification of the Isolates. September 2013. Iranian Journal of Parasitology 8(4):593–600)