ABERDEEN, S.D. - The Indian Health Service in the Aberdeen-Area is on alert for West Nile Virus and residents on the Navajo Reservation are asked to take precaution.
Every state in the area has reported human cases of WNV, and the number of cases seems to be growing exponentially with more detected each day.
In South Dakota every county that has reported a human case lies on an Indian reservation. Although only two reported cases are American Indian, with the growth of the disease the IHS put all units on alert, said Darrell Russell, Aberdeen Area IHS official.
The Navajo Reservation reported that two horses have tested positive and that more cases were under investigation. This was the first evidence that the virus had reached the area. It was not expected until the year 2007, said Scott Bender, tribal veterinarian.
Horses across the reservation will be vaccinated over the next month, with allocations of $131,400 set aside for that purpose.
West Nile Virus is transmitted by mosquitoes. In the Aberdeen area, which includes North Dakota, South Dakota, Nebraska and Iowa there are between 40 and 50 varieties of mosquitoes of which nine carry West Nile.
"We are working through the Center for Disease Control, the state and with the tribes. There is some mosquito eradication taking place with the cooperation of the tribes and state," Russell said.
As the daily count of human cases rises in the entire area and in the west where large concentrations of American Indians live, people are altering their lifestyles by not staying outdoors at dusk and sales of insect repellent are on the rise in most retail stores.
In the western states an unusual amount of rain occurred in the spring, however, since July the western portion of the states have received very little moisture and have returned to drought-like conditions; not conditions that usually harbor mosquitoes, but some species have the ability to survive in low-moisture conditions, state health officials said.
Colorado reports the highest number of human cases of West Nile than any other state as of Aug. 20. The state has recorded two deaths. South Dakota, Nebraska, Iowa and North Dakota have not reported any deaths yet. Officials say it is only a matter of time.
The Culex Tarsalis, a species that is hardy and a known carrier of the virus is prevalent in the western halves of the states, South Dakota Health Department officials said. It is also the most effective carrier of West Nile and only bites at night.
In North Dakota there are 96 known human cases of the virus; South Dakota recorded 58; Nebraska 174 and Iowa six.
In Nebraska there have been cases of West Nile detected in horses, birds or humans in all 93 counties. The Winnebago, Omaha, Ponca and Santee tribes are all located in the northeastern part of the state and are adjacent to the Missouri River, which has abundant back waters that aid the development of the mosquito larvae.
New Mexico reported eight human cases, but did not identify a specific county or location.
The most recent reports of humans contacting the virus occurred in the western portion of the state and most counties reporting the disease were on Indian reservations. The Pine Ridge, Cheyenne River and Standing Rock reservations were most affected.
"Surprisingly enough, the more drought-stricken areas of our state are seeing the greatest numbers of West Nile cases. We are seeing new cases almost daily," said Dr. Lon Kightlinger, state epidemiologist.
He added that 33 percent of the human cases were diagnosed as the most severe type.
In Nebraska, the latest cases were in the southeastern and southern portion of the state. None of the cases were reported near the reservations.
"These cases tell us what we already knew - that West Nile is here and it's not going away," said Dr. Richard Raymond, the state's Chief Medical Officer.
"Most people who are infected by a mosquito have no symptoms or only mild flu-like symptoms. Less than one out of 100 people who get bitten by an infected mosquito and become infected will be severely ill," he said.
In 2002 the state of South Dakota recorded 37 human cases of the virus and in 2003 there are 58 cases to date and the season has more than a month to go. Of the 58 cases 16 people have been detected with meningoencephalitis, which is highest level of the disease and can cause death.
Colorado has recorded the most human cases of West Nile in the nation.
Some people will never know if they have contacted the disease. Mild cases of West Nile fever may include a slight fever and or headache. More severe cases will have a higher fever, head and body aches that usually occur within 15 days of exposure.
There are treatments for the infection and people are asked to report these symptoms to their nearest health care provider.
People at the highest risk of severe conditions are over 50 years of age or have immune deficiencies, such as people with diabetes or HIV. Most fatalities occur in people over 50 years of age.
The disease is found mostly in birds. Should people find dead birds that have died suspiciously they are asked to contact their state, county or tribal health department.
To help reduce the possibility of infection, people are asked to take preventive measures in their environment. Mosquitoes survive most in standing water, such as lakes, ponds, swamps, water in old tires, plastic containers or other vessels that will hold water. Containers around the home should be emptied and stored so that water can not accumulate, the Center for Disease Control said.
Clean clogged roof gutters regularly, turn over plastic wading pools and wheel barrows when not in use, and change water in bird baths to prevent stagnant water from collecting on yards and property.
Most mosquitoes are not infected with the virus, but taking the proper precautions will help to reduce the disease, health officials said.
Officials instruct people to be aware of mosquitoes and avoid areas where they are most likely to breed and to use an insecticide that contains DEET. People should wear clothing that covers arms and legs and spray the insecticide on exposed areas and on clothing.
Communities are strongly encouraged to spray for the larvae and the adult mosquito.