One child has tragically died from the illness.
A HSE chief has said that new cases of hepatitis in children are a "cause for concern", but that the illness is still very rare.
Dr Colm Henry made the comments during an Oireachtas Health Committee meeting discussing the HSE's National Service Plan 2022.
"It is a cause for concern when something new comes along that hasn't been identified before that you can't correspond to the known hepatitis cases," Henry said.
"We've had a small number in this country, six, with another seven under investigation.
"Fortunately, we have very good public epidemiological links with other countries and we're getting daily reports from our own HPSC on the patterns seen in the UK.
"What we're seeing is that it is rare, thankfully.
"We're seeing in children that do get sick, some of them get very ill and we've seen including a relatively high proportion requiring liver transplantation, and sometimes, children tragically not surviving.
"It is a very rare condition, but nevertheless a new condition and what we're doing in the best tradition of epidemiology is tracking all the cases, looking for common experiences, common exposures, anything that suggests a common trait between them.
"There may be an association with a virus called adenovirus, and there's some association that it may be a reaction to the adenovirus."
Henry said that the adenovirus theory was not agreed upon internationally but that pooling resources together around the world would lead to a breakthrough in discovering the cause of the virus.
The unexplained type of hepatitis has been appearing worldwide, with less than 500 cases confirmed so far.
Most cases have been confirmed in the UK, with 131 cases confirmed by the European Centre for Disease Prevention and Control so far.
The disease has also appeared in Belgium, Cyprus, Denmark, Greece, Ireland, Italy, the Netherlands, Norway, Poland, Serbia, Slovenia, Spain, and Sweden.
