Ocurrence of Toxocara canis in Students of Veterinary and Graphic Design in a Mexican University

Background: Human toxocariosis is a parasitic zoonosis caused by larval forms of the genus Toxocara. The eggs hatch after being ingested, penetrate the intestinal wall and migrate via the blood stream through to the liver, hence spread to other organs. Erratic larval migration by the different soft tissues in humans, generates four syndromes, Visceral Larva Migrans, Ocular Larva Migrans, neurotoxocariosis and covert toxocariosis. A seroprevalence study of Toxocara canis among students from Veterinary Medicine and Graphic Design in Mexico City was conducted, as the Veterinary student has regular contact with animals was compared with students who have no contact with animals in their study program. Materials, Methods & Results: In both groups of students blood samples were collected and centrifuged to obtain the serum was evaluated by Toxocara serology ELISA (enzyme-linked immunosorbent assay). All participants completed a questionnaire supplying personal data and specifics regarding dog ownership and hygiene practices. Serology data and results from the questionnaire were analyzed using the Fisher ́s exact test, Chi-square and odds ratio (OR) test. The frequency of Toxocara infection tended to be greater (P = 0.11) in veterinary students than in those from graphic design (13 % and 7.0 % respectively). Some of the risk factors that were considered were: do not wash your hands after eating, frequent contact with dogs, has dog at home, eating on the street and dewormed your dog, neither factor was associated nor were risk factors for Toxocara antibodies present. Discussion: The fact that almost twice as many veterinary students were seropositive indicates a higher risk of Toxocara canis infection in those individuals, which may be due to veterinary students having greater contact with sources of infection (animals, feces, soil, hair, and farms), regardless of the ownership of dogs. In a study in Canada researchers found no differences among veterinarians and other professionals in anti-Toxocara antibodies, finding similar values (8.8% and 9.6% respectively) in both, and also found no association between dog ownership and anti-Toxocara antibodies a study in Austria found that veterinarians were the second occupational groups that had more antibodies (27%) compared to the control group (2%) and the main source of infection was identified as cats and dogs. Many studies have shown that risk factors are very important in the epidemiology of toxocariosis, primarily the presence of dogs and cats living together with people. It has been reported higher infection in individuals who were in contact with dogs. In several cities of Mexico, highest percentages of dogs infested with Toxocara were reported, with a mean of 35.5% and a range from 19.0 to 63.36%. It has been reported up to 100% of stray puppies can be contaminated with Toxocara in samples collected from dorsal and perianal hair which constitutes a great potential of infection considered that 94% of the Toxocara eggs were embrionated. Other studies show less contamination of hair with eggs of T. canis (40.9%) but still shows the importance as a potential source of infection for humans. Eating in the street or poor hygiene before eating were not factors related to the disease. Although no association was found with the lack hand washing and Toxocara, other researchers have identified this problem as a risk factor associated with Toxocara. It can be assumed that depending on the degree of contamination by Toxocara exposed to each individual, the hygiene practices may have different impact on the presence of the parasite. The results indicate that veterinary students are more prone to infection with Toxocara.