'Aussie mozzie' costs soar

The southern saltmarsh mosquito was first found in Napier in December 1998. Picture / Martin Sykes

Taxpayer funds poured into the battle against the "Aussie mozzie" - the southern saltmarsh mosquito species - have passed $51 million as Biosecurity NZ takes over the eradication effort from public health officials.

But the biosecurity involvement also signals the Government is considering the possibility of throwing in the towel.

"While it's a pest we can do something about, it does come at a significant cost," Biosecurity Minister Jim Anderton said last night.

"We're really keen to get rid of it, but at some point it's going to become a cost-benefit exercise.

"Right now, there's not enough information available to make final decisions.

"That's what we've asked Biosecurity New Zealand to provide."

Though the latest $11 million for control measures brings to more than $51 million the money spent on it, in the 2004 Budget the Government cut back its spending.

In 2004, it allocated extra spending of $6.288 million ($1.572 million in each of four years to 2009) for surveillance, down from the $1.602 million allocated in the 2004 financial year. But in the 2004 budget, it slashed the spending specifically on eradicating the mosquito by 75 per cent: from $12.794 million to $3.01 million.

Biosecurity NZ took over the Health Ministry's bid to eradicate the pest in July, shortly after three new breeding sites were discovered in a remote area of the Coromandel, just north of Colville.

The mosquito, Ochlerotatus camptorhynchus, was first found in Napier in December 1998, and has since been identified at Muriwai, Mahia, Porangahau, the Kaipara and Mangawhai harbours, Whitford, Whangaparaoa and in the South Island, at Wairau, near Blenheim.

It is an aggressive biter with the potential to cause significant nuisance for people, livestock and birds, and health authorities fear that if the spread continues, the nation will be put at risk of an epidemic of Ross River virus with huge costs in terms of both the economy and lifestyle.

Medical research has shown that a "virgin soil epidemic" could be started by just one mosquito picking up the virus from an infected tourist or returning NZ traveller.

There have been a dozen known cases of Ross River virus in New Zealand since 1980 in people thought to have caught it overseas, including a Waikato patient last year.

If saltmarsh mosquitoes in NZ picked up the virus from one of the three million travellers arriving here each year, it could become permanently established in feral animals, such as possums, or farm livestock.

A native mosquito species might also adapt to spreading the virus, which would expose the whole country to such infection, rather than mainly the people living in coastal, and river areas.

Ross River virus disease causes symptoms such as pain and tenderness in muscles and joints, fever, chills, sweating, headaches and tiredness. Though it is not fatal, the virus can cause an incapacitating disease known as epidemic polyarthritis that can cause chronic fatigue for up to a year.

An estimate in 2001 conservatively put the cost to the taxpayer of an outbreak of the disease in Auckland alone at more than $38 million.

Much of the cost would come from the effects on the workforce of large numbers of people suffering chronic fatigue, with initial estimated case rates of 10,000 people per 100,000 population.

If the mosquito continues to spread and Ross River virus is introduced, not only would the economy would be at risk of severe damage, but the traditional New Zealand outdoor lifestyle, would have to change, according to Pest Management Association president Frank Visser.

The species is an aggressive daytime biter - as well as at dusk and night like most NZ species. In infested areas, people would have to barricade their homes with insect-proof screens, and take extra care with activities such as camping, boating and barbecues, said Mr Visser, just back for a major conference in northern Queensland on mosquito control.

Mr Visser told NZPA few New Zealanders understood the serious health risk posed by mosquitoes.

"There are 40,000 cases of mosquito-borne illnesses in Australia a year and some of them are fatal," he said.

Australia had to cope with a wide range of diseases spread by mosquitoes.

The southern saltmarsh mosquito lives where salty water is available, such as coastal salt marsh, saltwater lagoons and reclaimed land near estuaries.

- NZPA