The number of Lyme disease cases being reported are just the tip of the iceberg, according to Professor Jack Lambert.
He believes there could be up to 2,500 cases diagnosed each year.
Lyme disease is an infection caused by a spiral-shaped bacteria that's transmitted to humans by bites from ticks infected with the bacteria.
Latest available data from the Health Protection Surveillance Centre (HPSC) shows there were just four cases in Ireland last year.
Prof Lambert is professor of infectious diseases at the UCD School of Medicine.
He told The Pat Kenny Show cases are being missed.
"I think the diagnosis is being missed all the time, because people said 'You never saw a tick'.
"A tick is the size of a sesame seed - you might need see a sesame sized tick on the back of your leg.
"Half the people don't get the rash that's classic for it, they might just get kind of flu-ish.
"And the antibody testing is not 100% - so I think the numbers that are reported to the HSE are just the tip of the iceberg.
"There's a lot more patients in Ireland with this condition".
'You might not see it'
He said the classic 'bullseye' rash is not the only thing people can be looking out for.
"If you get it on your face it might not look like a bullseye, it can be elliptical, it can be different shapes.
"And people with different skin colour... you might not see it, it's being missed all the time.
"And half the people don't get the rash, and that's the misinformation that is out there.
"People say 'You have to see the tick, you have to see the rash, you have to be antibody positive'.
"Then you're going to probably miss 75%+ of the cases".
And he said the disease is not limited to rural areas.
"It's all over the world - gease carry the ticks, deer are always mentioned because they're huge and they carry thousand and thousands of ticks.
"But all sorts of small animals carry the ticks.
"It's probably more common in rural communities and certain areas of the country.
"But I know people that never left south Dublin - Dundrum - got it in their back garden.
"I know people in Belfast that that their dog brought it home to their kitchen.
"So you don't have to be in the country to get it, ticks are everywhere.
"Global warming, people are closer to the environment and I think it's on the rise because of that", he added.