A health check at a single school in Tonga has identified more than 50 children aged between 5 and 10 years old with heart disease.
Radio Tonga says the check was carried out at 'Atele Primary School in Ha'ateiho by doctors and nurses from the Ministry of Health and heart experts from Australia.
The diagnosis was made as part of a general health check of primary school children across the Kingdom.
The examinations found that some children were born with a heart problem but the condition is only labeled as heart disease once the child turns three.
An Australian expert, Shona Evans, says they found young children with congenital abnormalities, severely leaking valves and rheumatic heart disease.