Harvey shire principal environmental health officer Scott Dandridge is on the front line in the battle against mosquito-borne viruses.
While Mr Dandridge and his team put themselves at risk surveying sites and performing aerial sprays, he said some of the greatest battlegrounds against diseases such as Ross River Fever were in the backyards of residents.
“People don’t take into account their contribution to breeding — a little bird bath could have up to 2000 mosquitoes in it,” he said.
He said mismanaged water tanks and small backyard ponds could be prolific breeding sites.
Since July, there have been 59 cases of Ross River Fever in the South West, six of those in the City of Bunbury and three each in the shires of Harvey and Dardanup.
Dr Dandridge this month defended the council’s record on mosquito control, after the Australian Medical Association implied not enough was being done.The Shire of Harvey program — which operates with Bunbury and Dardanup authorities as part of the Leschenault mosquito management group — covers 23 sites across 55ha.
All sites are surveyed on foot before a mosquito growth regulator is delivered from the air.
“For every aerial treatment done, there are probably 20 man hours in it,’’ Mr Dandridge said.
“What we can achieve in a helicopter in an hour, we couldn’t cover on the ground in a week.”
Days after an aerial treatment, Mr Dandridge collects samples to determine whether larvae died.
Mr Dandridge said people underestimated the risk they faced by being bitten by mosquitoes.
He said recent humid weather meant mosquitoes were progressing from egg to adult in half the time it usually took.
“We have seen water temperatures around 42C and larvae are still active,” he said.
“If you continue to get bitten, one day you’re going to get unlucky.”
Mr Dandridge said some residential areas — including Buffalo Road in Leschenault and Koombana Bay Caravan Park — were at particular risk because they were close to mosquito breeding sites.
“Buffalo Road was not a real problem 10 years ago because no one lived there,’’ he said.The treatment program is supported by scientists from the University of WA, who have been trapping mosquitoes for more than 20 years to test numbers, species and the presence of viruses.