New research by zoologists at Trinity College has identified the entrances to public parks and children's playgrounds in Dublin as hotspots for potentially infective roundworm eggs, with dog poo being the main source.
The eggs were found at 75% of park entrances sampled.
The research is published in the international journal PLOS Neglected Tropical Diseases.
The study found most of the eggs were from Toxocara Canis - a roundworm species commonly found in dogs - and were potentially infective to both dogs and humans.
Although human infection by this type of roundworm is rare and hard to diagnose, it can cause a condition called toxocariasis.
Most people do not become ill after coming into contact with the roundworm eggs.
Nevertheless, the worms can spread to parts of the body such as the liver, lungs or eyes, where they can occasionally cause serious problems like difficulty breathing or loss of vision.
Other research has also linked asthma, epilepsy and cognitive decline to this parasite.
Consumption of eggs from items contaminated with dog faeces is the most common method of infection for humans, especially in children and young adults under the age of 20 years.
It is estimated that a single infected puppy can produce more than 100,000 roundworm eggs per gram of faeces.
The findings of the research has now pinpointed the hotspot locations for targeted interventions to reduce the risk of human infection.
Dr Jason Keegan, from Trinity’s School of Natural Sciences, is the first author of the research article.
He said: "Toxocara is one of the most common parasitic infections across the globe and while there are many potential routes of infection, it is widely believed that the most common one for people is coming into contact with soil containing infective eggs and then accidentally ingesting them.
"This new research specifically pinpoints the hotspots in Dublin’s public parks where egg counts are highest in soil samples, and that tells us where we need to target our intervention efforts. By providing more signage, bins and a means to clean up after dogs in these locations, we could reduce the level of contamination.
"With that in mind, it is important to underline that many dog-fouling reduction interventions are not assessed for their effectiveness after implementation, so it’s imperative that such an assessment is built into any plan in the future.
"Of the assessments that have been completed, we know posters made by schoolchildren can be useful, perhaps underlining that involving the local communities most impacted by dog faeces in their recreational areas could be an opportunity worth exploring."
