We usually think of mosquitoes in terms of buzz and itch.

But West Nile virus reminds us that these critters are really very dirty hypodermic needles with wings.

The virus, which first appeared in the United States in 1999, has been in Utah for the past four years. It originates in birds, and is carried to horses, humans and other animals by mosquito bites. This year's rain and runoff have improved mosquito breeding grounds, and the number of reported cases has risen sharply. As of Tuesday, there were 65 verified human cases of West Nile throughout the state, compared to 12 in 2005. Twenty-nine of those are in Utah County, where two people have died.

In humans, the signs of West Nile virus range from flu-like symptoms to swelling of the brain. But this bug is not the only one mosquitoes are responsible for spreading. They were responsible for outbreaks of western equine encephalitis in the 1950s and 1970s in Utah, for example. And they can infect dogs with heartworm. In other parts of the world, mosquitoes carry malaria and the frightful dengue fever.

For these reasons, mosquito abatement has been a priority with health departments. The local West Nile virus outbreak has caused mosquito control officials to redouble their efforts.

The assault on the mosquitoes began in the early spring, when surveys of breeding areas sought larvae in the water. Once larvae were found, the water was treated with a bacterium to kill them. Catch basins and other places where water can accumulate were also treated.

However, it is impossible to kill every mosquito or larva out there. With thousands of acres of marshland, irrigation ditches, ponds and other breeding grounds, there is not enough staff or money. To fight adult mosquitoes, abatement crews use chemical weapons. In Utah County they fog large areas with insecticides, and this year they hired aircraft to spray around Utah Lake. Lance Madigan, Utah County Health Department spokesman, said the current chemical, derived from chrysanthemums, is effective at reducing mosquito populations.

However, some believe that West Nile calls for a bigger gun -- maybe even dichloro-diphenyl-trichloroethane, otherwise known as DDT. It has been banned in the United States since 1972.

Before you throw your ams up in panic, read on.

DDT was developed in World War II to combat insect-borne diseases such as malaria and typhus. It was seen as a miracle chemical because it was both cheap to manufacture and effective. It continues to be used in many parts of the world. Used in modest amounts, it doesn't cause a lot of trouble.

Unfortunately, the overuse of DDT and the fact that it remains in the environment for up to 15 years nearly drove American bald eagles and peregrine falcons to extinction. The raptors would eat fish laced with DDT, which weakened the birds' egg shells.

With West Nile increasing, however, there are now calls to bring it back, albeit in moderation. Henry I. Miller, a research fellow at the Hoover Institution at Stanford University, said in a 2003 Hoover Digest article that the government should reconsider DDT in light of the fact that there is no human vaccine as yet for West Nile virus. He said data show that malaria increased in foreign countries that outlawed DDT, which proves its effectiveness.

On the other hand, the group Environmental Defense argues that mosquitoes can become resistant to DDT, rendering it ineffective. Its use, the group argues, will kill far more birds than the West Nile virus, possibly pushing some to the brink of extinction. (But aren't a lot of these birds carrying West Nilefi)

Health officials, such as Madigan and Sammie Dickson of Salt Lake City's mosquito abatement district are also skeptical. They say current chemicals are proving effective and are safer for the environment. Dickson said DDT would be better for developing countries where budgets keep them from engaging in a U.S.-style program.

As a practical matter, the only way DDT could be brought back is if West Nile is declared a public health emergency. The federal regulation that banned it includes an exception for epidemics.

West Nile virus may expand to just that. If it does, we may wish we had started earlier.

This story appeared in The Daily Herald on page A8.