Dr Dicky Budiman, an epidemiologist who has helped formulate Indonesia's Ministry of Health pandemic management strategy for 20 years, also believes the real number of COVID-19 in Bali is much higher than the official tally.

He said the spread is going undetected because of a lack of testing and underreporting caused by cultural norms that encourage traditional healing at home.

He also theorised that many COVID-19 infections in Bali are being misdiagnosed as dengue fever - a disease spread by mosquitoes.

"There is an extraordinarily high number of dengue cases in Bali right now - more than 2,100 cases - and I believe that is because testing for dengue is easier, cheaper and faster than testing for COVID-19."

The theory is corroborated by a recent study in the peer-reviewed medical journal, The Lancet, which describes two patients in Singapore who received false-positive results for dengue and were later confirmed to have COVID-19.