Josh Lee of the City Parks Department begins the process of spraying for mosquito larva with a larvicide known as VectoBac G along a marshy area just off of Disk Drive in Rapid City's north side Thursday afternoon. (Photo by Dick Kettlewell, Journal staff)

RAPID CITY - The battle against the bug continued in Rapid City on Thursday as word spread that a Pennington County resident was the state's second fatality of the year to the West Nile virus.

The South Dakota Health Department didn't give the name, sex or hometown of the Pennington County victim. That's part of the state policy to comply with a federal law protecting private medical information.

Health officials did say that the victim died from West Nile encephalitis, an inflammation of the brain developing from the virus. Like the first state victim this year, a resident of Hand County in north-central South Dakota whose death was reported July 24, the Pennington County victim was in the 80-to-89 age group.

The state has received reports of 46 human cases of the disease so far this year. And with the most dangerous part of the transmission season still to come, city and county pest-control crews are continuing mosquito-control work as health officials warn residents to take the West Nile threat seriously and limit their exposure to the insects.

State Health Department recommendations:

* Use mosquito repellents containing deet, picaridin or oil of lemon eucalyptus, and cover skin with loose-fitting clothing.

* Limit time outdoors at dusk and dawn when mosquitoes are most active.

* Eliminate standing water where mosquitoes can breed.

* Encourage local mosquito-control efforts.

Mosquito numbers are down from last year in some traditionally buggy areas of Pennington County. And the combination of drought and regular mosquito-control campaigns by the county and Rapid City seem to be limiting the populations of the pests.

But mosquitoes can show up even in controlled areas, as well as in spots throughout western South Dakota where the bugs are more common. So the threat of transmission remains for an illness that is a simply unpleasant for most but life threatening for some.

"This is the mosquito season, and people need to remember to protect themselves," Dr. James Gilbert, chairman of the emergency department at Rapid City Regional Hospital, said Thursday. "When you limit your exposure, you limit your risk of West Nile."

Regional officials will not say whether they've had a West Nile death or are treating any West Nile patients. And they can't confirm an admission without a person's name.

Gilbert said people should follow state guidelines for reducing exposure. Those include limiting time outdoors in the early morning and in the evening when mosquitoes are most active, wearing effective insect repellent and covering as much of the body as possible with loose-fitting clothing.

Gilbert said the good news about West Nile virus is that most people who contract the virus suffer relatively mild flu-like symptoms and recover fully. The bad news is the West Nile symptoms can be difficult to distinguish from other viral ailments, and the most serious forms of the illness can be life-threatening.

People suffering symptoms that are unusual or more severe than those typical of past viral illnesses should see their doctor, Gilbert said.

"If you feel significantly sicker than you have in the past, I would lean toward seeking treatment. Watch the neurological symptoms in particular," he said. "If they have significant headache, blurred vision, severe nausea and vomiting, that's when for sure you should seek help."

City and county crews are working to reduce the bugs that cause the bites that can lead to West Nile transmission. Every two weeks, city crews treat drainage areas, ponds and wet spots capable of producing mosquitoes with a chemical that kills the developing larvae. Crews also "fog" with in insecticide to kill adult mosquitoes in neighborhoods immediately adjacent to wet areas.

The fogging occurs late in the evening, generally after 9:30 p.m., when most people are in and most mosquitoes are out. That's especially true with the culex tarsalis mosquito, the main West Nile transmitter, which studies show is most active late in the evening.

Urban forester Gary Garner, who coordinates the city treatment program, said the insecticide used in the fog is considered safe for use in residential areas. But the city still prefers to use it when fewer people are outside, he said.

"By the time we start, there are usually very few people out," he said. "Then, you just try to avoid people that might be."

Garner said he hasn't had a complaint about mosquito numbers for weeks.

Pennington County Weed and Pest supervisor Scott Guffey said the county continues weekly larvicide treatments in problem areas, such as Rapid Valley. The treatments and dry conditions seem to be limiting mosquito numbers, a fact reflected in mosquito traps checked by the county.

"The trap counts are just down in general," Guffey said. "The numbers have been really high over East River this year, but they're down for us."

Again, pockets of the insects remain. And some parts of other counties, including Meade, have reported higher numbers of mosquitoes, Guffey said.

Standing water from recent rains around Rapid City have disappeared quickly in 90-plus-degree days, he said.

"Everything's drying up, so there isn't much water," he said.

But the control work will continue, as will public warning about the virus.

"This is the peak time for West Nile virus transmission, and it's critical that people take precautions to protect themselves, particularly those who are at high risk, such as the elderly," state epidemiologist Lon Kightlinger said Thursday in a written statement. "It's also time for communities to intensify their mosquito-control measures, especially when they host outdoor public events."

Contact Kevin Woster at 394-8413 or kevin.woster@rapidcityjournal.com