WA had a record 531 cases of dengue fever last year - more than any other State - and three-quarters of them were contracted in Bali.
A sharp rise in Australian cases of the mosquito-borne viral infection, fuelled mostly by West Australians holidaying in Indonesia, has raised fears of more local transmission and the infection becoming endemic in Queensland.
A WA Health Department spokesman said yesterday that 79 per cent of last year's record WA dengue fever cases were from Indonesia, almost all contracted in Bali.
It topped the previous high of 508 cases in 2010.
"Reflecting the large numbers of West Australians who travel to Bali, more cases of dengue fever have been reported in WA in each of the past three years than in any other Australian State or Territory, including Queensland which is the only part of Australia where there is local transmission of dengue virus," the spokesman said.
Tropical and subtropical mosquitoes spread dengue fever.
Symptoms include high temperature and feeling generally unwell, but serious complications include dengue haemorrhagic fever and dengue shock syndrome.
There is no specific medical treatment or vaccine.
A recent report by the Health Department and National Arbovirus and Malaria Advisory Committee urged travellers to take precautions against mosquito bites in South East Asia.
The researchers said though the number of Australians going to Indonesia, particularly from WA, had risen sharply in recent years, it did not completely explain the big increase in dengue fever in those returning.
They speculated the rise could be related to changes in the presence of dengue fever in places such as Bali or because tourists were behaving differently and putting themselves at greater risk of infection.
They also warned that dengue fever could become endemic in Queensland and the type of mosquito which carried the virus could move into northern parts of WA and the Northern Territory.
"Infected travellers returning to north Queensland and transiting to other States can also present the risk of starting local outbreaks," they said.