Human toxocariasis and direct contact with dogs

Area of Science:

• Veterinary Parasitology
• Human Epidemiology
• Infectious Diseases

Background:

• Toxocariasis is a human parasitic infection.
• Traditionally, infection is linked to ingesting eggs from contaminated soil.
• Disease manifestations include ocular and visceral larval migrans.

Purpose of the Study:

• To evaluate the traditional soil contamination hypothesis for toxocariasis.
• To explore direct contact with dogs as an alternative transmission route.
• To investigate the presence of Toxocara canis eggs in canine hair.

Main Methods:

• Collected hair samples from 60 dogs in Ireland and the UK.
• Examined hair for the presence and density of Toxocara canis eggs.
• Compared egg densities in hair to those reported in soil samples.

Main Results:

• Toxocara canis eggs were found in 25% of dog hair samples.
• A total of 71 eggs were recovered, with significant proportions embryonated.
• Egg densities in hair (up to 180 eggs/gram) were higher than typically found in soil.

Conclusions:

• Direct contact with infected dogs is a plausible route for human toxocariasis.
• The findings challenge the sole reliance on the soil contamination hypothesis.
• Further research into canine-to-human transmission is warranted.