By Tim Bonfield
The Cincinnati Enquirer

The mosquitoes are nearly gone, but the debate has just begun: How much time and money should be spent to prevent West Nile virus next year?

Public health officials are worried that thousands more people could be sickened as a widely infected mosquito population comes out biting next spring. Ohio already ranks third in the nation for West Nile reports - 366 probable cases including 17 deaths, three of them in Greater Cincinnati, this year.

Todd Dudley, a worker for the Hamilton County Health District, walks around a pool of runoff in Harrison. The city put small Gambusia fish in the pool to help kill mosquitoes. (Ernest Coleman photo) | ZOOM |

"Every major community in the state should be making plans for increased mosquito control next year, and to make it a permanent service,'' says Dr. Richard Berry, chief of the Ohio Department of Health's vector-borne disease unit.

As frosty weather kills mosquitoes or sends them into hibernation, the public health story of the summer is far from over.

Epidemiologists at the federal Centers for Disease Control and Prevention and at many state and university laboratories will spend the next few months poring over case reports. They'll analyze the spread of the virus, which causes symptoms from mild fever to life-threatening encephalitis. At the same time, public health officials will discuss how to budget, staff and prepare public education plans.

Dr. Berry recommends forming regional mosquito-abatement districts that rely on a combination of larva control, eliminating sources of stagnant water, public education and far more use of chemical spraying to kill the flying insects than has been seen in the Tristate.

But such efforts aren't cheap, reaching into the millions. And spraying has vocal critics, too. They say pesticides have dubious impact, can aggravate breathing problems in some people and do unwanted harm to bees, butterflies and fish.

"Ohio does need better mosquito control, as long as it doesn't include the spraying of pesticides, which is almost totally ineffective," says Barry Zucker, director of the Ohio Coalition Against the Misuse of Pesticides.

A budget dilemma

Officials here are concerned about an increase in cases next year because of the way the virus spread this year. In Cleveland and Cuyahoga County, birds and mosquitos were widely infected in 2001, which resulted in more than 200 human cases there this year, the most in the state.

For Greater Cincinnati, the virus spent much of 2002 becoming established in mosquitos and birds, which in turn infected humans mostly later in the season. Now that the animal populations are widely infected here, they'll be able to pass the disease on to humans as early as the first mosquito bite next spring.

But expanding mosquito-control programs has significant budget implications, too.

This year, Hamilton County spent an estimated $80,000 to $120,000 on mosquito-control efforts - a minor budget burden, Hamilton County Health Commissioner Tim Ingramsays. By comparison, the Lucas County district spends $2 million, mostly from a local property tax assessment that amounts to about $10 a year for a $100,000 home.

The biggest difference: Lucas County maintains several specially equipped trucks and staff to conduct regular spraying to kill adult mosquitoes.

The trucks roll through neighborhoods at night on a rotating, publicized schedule, emitting a fog of insecticide. The department doesn't issue warnings for residents to avoid the spray, but people can ask to be called in advance if they have special medical concerns.

Hamilton County, however, has been hoping to avoid spraying to kill adult mosquitoes. Beyond the costs, some experts question the effectiveness of spraying.

Mr. Ingram has seen kill estimates ranging from 30 percent to 90 percent. And the effect lasts only a few days compared to as long as 30 days for treating stagnant water with larva-killing products called "dunks."

Mr. Ingram notes that Cleveland has used mosquito sprays for years, but that didn't stop the virus from striking hard there. And despite its highly praised program, 10 human cases of West Nile virus were reported in Lucas County.

Critics also raise health and environmental concerns. And one group, the Ohio Coalition Against the Misuse of Pesticides, helped file a lawsuit last month in Cuyahoga County seeking to block large-scale spraying there.

Risky situations

Despite extensive media coverage and health department tips on how to reduce West Nile virus risks, Mr. Ingram marvels at how often his staff still finds obvious mosquito breeding sites.

In Hamilton County, health inspectors acting on reports of human or horse infection check a half-mile radius around the victim's home or stable for sources of stagnant water. In almost every case, they find prime breeding grounds for mosquitoes.

They've found larvae at a home with a downspout feeding rainwater into a 55-gallon drum. They've found larvae in puddles as small as 6 inches across

They've winced at birdbaths that never get dumped and old tires that never get disposed. They've trudged through swampy areas strewn with plastic containers that can hold water indefinitely.

"I guess you just can't do enough public education," Mr. Ingram says. "People think it won't happen to them."

On a recent Tuesday, health department sanitarian Todd Dudley found 350 dead mosquitoes in a trap set in Harrison, even though overnight temperatures were dipping into the 40s. That means mosquitoes are still around, spreading disease.

"Per pound, these have got to be some of the deadliest things on Earth. Mosquitoes can cause so many diseases," Mr. Dudley says.

Hamilton County started the season with two staff members certified to apply mosquito larvicide "dunks" in standing water sources. By the end of summer, the county had trained nine more staffers and helped arrange certification for staff from 20 other townships and villages.

History offers hope

There's a chance that the worst-case scenario for Ohio won't happen at all. It is possible that enough birds and people were bitten by infected mosquitos - but did not suffer serious illness - that they built up a protective level of immunity from the virus.

That would sharply limit the chances of mosquitoes spreading the virus, which takes its name from the location of the first discovered case - a woman from Uganda in 1937.

If so, the West Nile disease trend could be similar to an outbreak of St. Louis encephalitis, a closely related, mosquito-borne virus that struck hard in the mid-1970s.

Ohio reported no cases of St. Louis encephalitis in 1974, then 416 cases in 1975, then 10 cases in 1976 and none since 1981, according to the Centers for Disease Control and Prevention. The Ohio outbreak stands as the nation's third biggest outbreak of St. Louis encephalitis since record keeping started in the mid-1960s.

Public health officials hope to see a similar drop-off for West Nile virus. But even if that happens, mosquito control still should be taken more seriously, Dr. Berry says.

"West Nile may come and go. But you never know when another one of these things is going to raise its head," he says.

E-mail tbonfield@enquirer.com

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