Johnson County citizens have so far been able to ward off any signs of West Nile Virus, but officials say citizens still need to be vigilant.

Around the nation, reports of West Nile Virus have escalated, with Texas being particularly affected. In Iowa, five confirmed cases were reported in Grundy, Linn, Lyon, Page, and Plymouth Counties, according to the Iowa Department of Public Health website.

The Centers for Disease Control and Prevention said that cases of the West Nile Virus, a disease spread by mosquitoes, are at the highest level since the organization began tracking the disease in 1999.

This year the CDC has recorded 1,118 confirmed cases of the virus in 47 states, including 41 deaths as a result of the disease. Most of the reports of the virus have come from Southern states. In fact, Texas alone is responsible for over half of the reported cases of the virus, with 537 this year.

The five cases in Iowa are not unusual, Deputy State Epidemiologist Ann Garvey said.

“It’s been consistent with previous years,” she said. “We had nine confirmed cases all of last year, and we will continue to watch for reports. We have several cases that we are currently investigating.”

Fall is also the prime season for the West Nile Virus, Garvey said, with August and September in particular being the months with the highest number of cases.

Iowa State University Associate Professor Ken Holscher, who specializes in human and livestock pests, said mosquito populations are exceedingly low this year.

“From spring to the present, we just have not been seeing the number of mosquitoes we usually see,” he said.

Mosquitoes like to breed in temporary pools of water, he said.

“What we usually see, such as in the summer of 2010 with heavy rainfall, is low-lying areas that flood and create pools of water that are perfect for mosquitoes to lay eggs in,” he said, noting that the drought over the summer has affected the breeding patterns of mosquitoes.

With the drought, he said, those pools of water were very hard to find, as the resulting effect on the mosquito population shows.

However, while the mosquitoes lay eggs in water, Garvey said, the Iowa River  is not a prime location for mosquitoes.

“They mostly breed in stagnant, standing water,” she said. “However, any body of water can be suspect.”

But Lyric Bartholomay, the supervisor of the Iowa State Medical Entomology Laboratory, said that particularly during a drought, even the running water of the Iowa River can create breeding areas for mosquitoes.

“There is tremendous potential for mosquitoes to breed in previously rapid, flowing water, because in times of drought standing pools of water can be created, even in rivers,” she said.

Although the drought may have created some conditions for mosquitoes to breed, Holscher believes it is currently too late in the season to see more mosquitoes, even if Iowa receives more rain in the coming weeks.

“I just don’t think we’re going to be inundated with West Nile cases from here until the end of the year,” Holscher said. “[In order for mosquitoes to lay eggs], water has to remain for a period of a week to 10 days.”

While no local cases of West Nile have turned up, Bartholomay and Iowa officials say citizens should keep their guard up.

“The West Nile Virus is a really, really serious disease,” she said. “While the vast majority who contract it don’t get sick, some get West Nile Fever, which can get so serious you have to be hospitalized.”

The Public Health Department also has several steps for citizens to take to protect themselves against the West Nile Virus and other mosquito-borne diseases, including using insect repellent, avoiding outdoor activities at dusk and dawn, when mosquitoes are most active, and wearing long-sleeved clothing whenever possible outdoors.

Holscher and other officials say it’s hard to predict how much a threat West Nile poses.

“I have no clue how mosquito populations will look next spring, because precipitation patterns flow so much, from the flood of 2008 to the heavy rainfall of the summer of 2010,” Holscher said. “We’ll just have to wait and see what happens.”