Toxocara cati infections in stray cats in northern Iran M. Sharif 1 *, M. Nasrolahei 2 , S. P. Ziapour 1 , S. Gholami 1 , H. Ziaei 1 , A. Daryani 1 and A. Khalilian 3 1 Department of Parasitology and Mycology, 2 Department of Microbiology and Immunology and 3 Department of Social Medicine, School of Medicine, Mazandaran University of Medical Sciences, PC 48168-95475, Sari, Iran Abstract A cross-sectional survey was undertaken to study the prevalence and intensity of infection with Toxocara cati in 100 stray cats, from April to October 2004 in urban areas of Sari, northern Iran. A total of 44 cats (44%) were found to be infected with T. cati. There was a significant difference in the prevalence of infection relative to host age and weight (P ¼ 0.000). There was also a significant difference in the intensity of infection relative to body weight and urban sites (P , 0.05). No significant difference was found between the prevalence of infection relative to host gender, urban sites and season (P . 0.05), nor in the intensity of infection between host gender, age and season (P . 0.05). The intensity of infection ranged from 1 to 32 worms per cat, with a mean of 7.30 ^ 6.82. Introduction Toxocara cati is a common gastrointestinal nematode in cats worldwide, which not only infects young kittens but can also cause human toxocariasis (Dubinsky, 1999; Janitschke, 1999). Adult T. cati usually live in the upper small intestine of definitive felid hosts, where female worms may produce up to 200,000 eggs per day. Eggs passed in the faeces are not infective and require an incubation period in soil to embryonate (Glickman & Schantz, 1981). Embryonated eggs hatch in the small intestine where released larvae perforate the wall, enter a blood vessel and migrate through the liver and lungs to the left heart where they are disseminated by the systemic circulation (somatic migration). Eventually, these larvae penetrate through capillary vessels and migrate to surrounding tissues where they may survive for years without undergoing further development (‘hypobiosis’). The primary route of infection of kittens is by transmammary transmission of larvae that are found in milk (Burke & Roberson, 1985). Infective eggs are ingested by non-felid species, such as small rodents, as paratenic hosts and follow a similar somatic cycle, where the presence of larvae in tissues are potentially infective to predators. This type of trans- mission is called ‘paratenesis’. When a cat preys upon an infected paratenic host, larvae are liberated from the tissues during digestion and then complete their development in the intestinal tract (Glickman & Schantz, 1981). Paratenic hosts, such as man and small rodents, can infect themselves unintentionally by swallowing infective eggs (Beaver, 1969; Beaver et al., 1984). Dogs are the chief culprits in spreading human toxocariasis because of their indiscriminate defaecatory habits (Markell et al., 1992). So T. cati is regarded as less important in terms of potential exposure to humans, and despite case histories of human infection, historical factors have led to T. cati being under- recognized as a zoonosis, particularly when compared with the prominence given to Toxocara canis in dogs. Differentiation of the two infections remains challenging even today. It is recommended that further work be conducted to facilitate differentiation between the two species so that the importance of T. cati as a zoonosis can be clearly defined (Fisher, 2003). Toxocara cati is a common parasite of cats and Felidae, and has a cosmopolitan distribution (Yamaguti, 1961; Sadighian, 1970; Mirzayans, 1971; Vanparijs & Thienpont, 1973; McColm & Hutchison, 1980). The rate of infection in the human population depends on the history of pica, the abundance of pets, personal hygiene and public health, the prevalence of Toxocara in definitive hosts, and the abundance of eggs *Fax.: þ98 151 3247106 E-mail: msharifmahdi@yahoo.com Journal of Helminthology (2007) 81, 63–66 DOI: 10.1017/S0022149X07214117