Fewer mosquitoes this year, but West Nile still a threat

Lawson reports that he and his assistants have collected far fewer mosquitoes so far this year than they had entering July of 2005, but the samples have included a limited number of Culex mosquitoes, the carriers of the virus, and precautions should be taken again.

The virus is spread when a Culex bites a human after it has bitten an infected bird. Lawson said so far no birds suspected of having the virus have been found in this area

Lawson and his two student helpers, Ruby Anderson of Crawford and Jackie Davies of Hemingford, have set mosquito traps in Dawes and Sheridan counties. They also receive mosquitoes that have been collected in Scotts Bluff, Lincoln, Cherry and Garden counties, then sort the Culex from the other species which are not carriers.

A microscope is needed to determine the differences in the pests. The Culex has a rounded body; the others are more pointed.

This past week, the Nebraska Department of Health and Human Services reported that a woman in Platte County (Columbus) was hospitalized with West Nile fever and two crows collected in Omaha and a sample of mosquitoes from nearby Sarpy County tested positive for the virus.

Last year, the first mosquitoes to test positive in the state were collected in Dawes County in early July.

“Eastern Nebraska has had more rain than we have had this year. Maybe that’s why West Nile has been detected there first,” said Lawson. “So far, we’ve found only about 100 Culex in the samples we’ve collected while last year we found many more. But the threat is still with us. Everybody needs to be cautious and use a repellant if they are going to be in an area where there are lots of mosquitoes.”

Culex generally hatch later than other mosquitoes, but Lawson noted that nearly everything is developing earlier this year.

Lawson is asking people living in the northern Panhandle to call him at 432-6298 if they find a sick or recently dead bird from any of the four species that are the primary carriers of West Nile. They are crows, blue jays, magpies and pinyon jays. The latter are rare in this area.

Owls and hawks also will be collected and tested.

“If we start finding quite a few birds that test positive, they we’ll know we’ve got a problem,” Lawson stated.

The birds and mosquitoes collected in the area are sent to the University of Nebraska Medical Center in Omaha for testing.

West Nile fever was first detected in the United States in New York in 1999, some 42 years after it broke out in Uganda. Since ’99 it has swept across the nation from east to west. During the past two years, it has hit California and Arizona the hardest. While the disease usually lingers in what is called an endemic pattern, its impact has greatly declined in the U.S. after the first wave took its toll, but it is still prevalent.

Last year, WNF hit Nebraska much harder than it had in 2004. The Department of Health and Human Services reported that 188 people and 53 blood donors tested positive for it and that five human deaths were attributed to it in 2005. The previous year, there were 54 positive tests and no human deaths reported in the state.

“We just want everyone to be aware that the danger is still with us and to take precautions,” Lawson said. “We also are asking for their help in collecting birds from any of the species that are the carriers.”

A national website on West Nile says only one in 150 people infected with WNV will develop serious illness. Severe symptoms include high fever, headache, neck stiffness, stupor, disorientation, tremors, coma, numbness and paralysis. The symptoms may last several weeks and the neurological effects can be permanent.

People over 50 years of age are at the greatest risk of developing severe illness.

Meanwhile, Lawson has another project this summer than allows him to work with much more appealing insects than mosquitoes. Each Friday, he collects butterflies in the vicinity of the Hudson-Meng Bison Kill Site northwest of Crawford and will build a display that will be placed in the visitor center there.

So far, he said about 20 different species have been found. He suspects that at least 20 more species are in the area. He expects to have the project completed by the end of July.