VIRUS PRESENTS CHALLENGE FOR VECTOR DISTRICT

October 10, 2002 12:00 am

By Alice Perry Linker

Observer Staff Writer

The Union County-wide mosquito control district, operating on a shoestring, hopes the string doesn't break next year under the pressure of West Nile Virus.

District board member Mary Koza said she believes the district is doing all it can to prepare for the next mosquito season, as this year ends. During the mosquito season, from June through September, the vector control district spent $11,102 in salaries, chemicals, utilities and insurance.

"They're holding their own," said Union County Administrative Officer Marlene Perkins, who does the books for the small district. "We've got about $40,000 to carry over to next year."

The annual income for the vector district is about $24,000, funded from property taxes. Two years ago, voters defeated the district's request for a larger budget.

Perkins said the district may need to pay for aerial spraying in high-risk areas next year, especially near Union.

The district's Travis Lee, who worked alone analyzing the prevalence of mosquitoes and applying larvaecides and Malathion, said flood irrigation is a major source of mosquitoes.

"Many flood irrigators are aware of the West Nile Virus, and some are letting their fields dry completely before they flood again," he said.

Mosquito larvae cannot live outside ponds.

The district must submit a plan of operation to the state for approval by March, Perkins said.

This year, the district received 67 more requests for fogging than in 2001, according to a report prepared by Lee. Union and Island City appeared to be the most mosquito-infested of the 2002 season, as the district fielded 89 calls from the two communities.

In addition to applying larvaecides on stagnant ponds and fogging Malathion to kill adults, Lee had another weapon this year. He planted Gambusia fish in stock and other closed ponds where they feasted on mosquito larvae. The fish may not be planted in rivers or streams, because of possible impact on native fish, but they are good larvae killers in stock ponds, and the cattle don't seem to mind them, Lee said.

Neither the fish nor any chemical or biological larvaecide may be applied to Ladd Marsh, but Dave Larson, marsh director, said bat and swallow boxes have been built to encourage the mosquito-loving birds.

"They've been working real well," Larson said. "Almost every box is occupied."

Koza and Union County Public Health Department Director David Still agree that the arrival of the West Nile virus on the West Coast is not a cause for panic, but is a reason for caution.

Public health officials generally agree that West Nile is not expected to reach Oregon before next spring.

Birds are carriers of the disease, which infects humans through a mosquito bite. The state Department of Human Services has said that crows and magpies are the most common carriers of West Nile. On Oct. 2, a raven found in Northeast Washington tested positive for the virus.

Still said that most West Nile infections are mild, but the elderly and the very young, as well as people with compromised immune systems, are the most vulnerable to the disease.

Still said that a recent report posted on the Web site of the New England Journal of Medicine points to research that indicates that West Nile may cause polio-like symptoms and that the "spinal cord gray matter is a target of West

Nile virus." More research is expected.

There is also research into the use of a vaccine to prevent West Nile. According to the National Institutes of Health, several studies into vaccines are ongoing.

The vector district and the public health department are planning a joint public information meeting in early spring.