County’s first human case of West Nile virus is suspected

Dan Kulin, Mary Manning and Ed Koch

Thursday, July 22, 2004 | 11:15 a.m.

A Clark County resident is suspected of having the disease, the first possible case of a person contracting the West Nile virus in Nevada, local health officials said this morning.

The victim, whom the Clark County Health District identified only as a county resident under the age of 50, is recovering from an ailment which state tests have determined to be a virus that is at least in the same family as the potentially deadly West Nile virus.

Health District spokeswoman Jennifer Sizemore said the Centers for Disease Control and Prevention laboratory in Atlanta is conducting further tests to determine whether the person has the West Nile virus. Sizemore said the results should be available in about a week.

"This would be the first Nevada-acquired case of the West Nile virus," Sizemore said, noting that the initial state test results were received Wednesday afternoon. "The person is recovering at home, but they were hospitalized."

West Nile is a mosquito-borne illness with flu-like symptoms that can last up to a week. One in 150 cases of human West Nile virus can also involve meningitis or encephalitis, which can be fatal.

In California, a person who died last month was killed by the West Nile Virus, Orange County health officials said today.

It was the first known case of the infection in Orange County, said spokesman Howard Sutter. There have been more than 30 cases so far of West Nile statewide.

Tests confirmed the infection and cause of death Wednesday, Sutter said. No information about the victim's identity was released.

At today's Clark County Health Board meeting, one of the board members asked Clark County Chief Health Officer Dr. Donald Kwalick if there was anything new on West Nile and Kwalick told the board about the possible first Nevada case.

The victim may have been bitten by the infected mosquito while on a camping trip in the Tonopah area around the Fourth of July, Sizemore said, adding that there also is the possibility that the affected mosquito bit the person in Clark County.

Sizemore said Health District staff captured mosquitoes from around the person's home Wednesday and will take some samples from the camping area today to test for the presence of the virus.

State and Clark County experts have been trapping mosquitoes and checking dead birds for signs of the West Nile virus. It has been found in a dead crow this week in Carson City as well as in some mosquitoes in Lyon County, 350 miles north of Las Vegas.

So far, no people, mosquitoes or birds anywhere in Clark County have been confirmed to have tested positive for the virus, which has appeared in California, Arizona and Colorado in the past year.

Four out of five people who contract the virus after a mosquito bite have no symptoms, health officials said.

Clark County Vector Control Officer Richard Hicks, an entomologist, said the disease has moved rapidly, starting in the East in 1999.

"Just because it may show up here is not a cause for alarm," he said.

"Only certain areas of our valley have mosquitoes, primarily the drainage areas in the southeast part of the Vegas Wash, which goes into Lake Mead, but not Lake Mead, where there is a wave action. Mosquitoes prefer stagnant, weedy, smaller areas like puddles (for their eggs).

He noted that Las Vegas' blistering summer temperatures quickly dry up such locations, leaving mosquitoes even fewer places to breed.

"The best way to avoid mosquitoes is stay out of mosquito haunts," Hicks said. "Campers should take precautions, such as using repellent on their face or cap, wear more clothing at night and take other such precautions."

Unattended pools with unmaintained water, Hicks said, are excellent nesting grounds for for mosquitoes. Such pools have water that becomes green and black with algae and organic matter.

"We've had a lot of calls in the last couple of days from people reporting unattended pools," Hicks said. "If the homes are unoccupied we go in and take care of them. If someone lives there we point out the need to properly maintain their pools and most times they are cooperative."

Hicks said people who want to report a stagnant pool can call (702) 455-7543 or go to the Web site accessclarkcounty.com, click on public works and then click on environmental and neighborhood services for mosquito information.

To help keep the mosquito population down, homeowners also should check their yards for standing water in containers, old tires or even wading pools, he said.

The virus is carried in birds. When mosquitoes bite crows, ravens or magpies infected with the virus, the mosquitoes become carriers. Then if the insects bite other birds, horses or people, the virus can be spread.

People, however, can only get the disease from a mosquito and on rare occasions from a blood transfusion, but not from a bird or other animal, Hicks said.

Mosquitoes caught overnight in traps placed near the Las Vegas Wash are expected to be sent to a state laboratory today, Hicks said.

Anywhere from 50 to 1,000 mosquitoes could be captured in a single trap, Hicks said.

"I don't think we've seen anything out of the ordinary this year," he said of Southern Nevada's mosquito population, adding that he rarely sees as many as 1,000 insects in a single trap. More often the traps capture about 50 insects.

In what might be viewed as a positive outcome from the drought, the dry conditions in Southern Nevada are keeping mosquito populations low.

"The population appears to be lower than average," Hicks said.

Clark County and the Nevada Division of Agriculture have monitored and controlled mosquitoes in the valley for at least 30 years.

Nationwide 9,858 people were diagnosed with health problems caused by the virus in 2003, and 262 died. The virus, which is called West Valley fever in its milder form, poses a more dangerous threat to those 50 years old and older.

Through last week the federal Centers for Disease Control and Prevention reported a total of 108 cases of human West Nile virus nationwide, three of which were fatal.

The state of California reported a total of 32 new cases of West Nile virus in the Southern California area this year.

In addition to West Nile, mosquitoes carry other diseases, such as malaria and western equine encephalitis.

Malaria spread by mosquitoes threatens public health in Africa, South America and southern Mexico to this day. Because of mosquito eradication programs in the U.S., malaria is not considered a threat.

The combined efforts of state and county agencies are helped by citizens who take the time to call in about standing water and dead birds, which could be victims of West Nile. A dead sparrow hawk, reported by a citizen, was sent to a state laboratory on Wednesday, said Tom Smigel of the state Agriculture Department.

People are calling about all kinds of dead birds, he said, but the most important ones that could carry the West Nile virus are crows, ravens and magpies.

Northern Nevada reported no new findings Wednesday of West Nile virus, said Martha Framsted, spokeswoman for the Nevada State Health Division. com. The Associated Press contributed to this report.

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