Update on West Nile Virus

Four years ago, West Nile virus (WNV) made its way to North America.  Since then the disease has spread rapidly throughout the United States.  According to the CDC website, in 1999 62 human cases of WNV were reported with 7 deaths occurring.  In 2000, 21 cases were reported, including 2 deaths.  In 2001, there were 66 human cases of the disease reported and 9 deaths.  And last year there were 4,156 reported cases with 284 deaths.  Statistics are not yet available for 2003. 

WNV is of particular interest to RROKI because of its deadly effect on raptors.  So many raptors are dying that federal wildlife officials can't keep up with the testing that would confirm that the suspected culprit is West Nile virus. 

Birds serve as the host for the West Nile virus, which is spread by mosquitoes to other birds as well as to humans, horses, squirrels, even canines.  Sick birds appear to suffer depression, high fever, aversion to food and weight loss. These symptoms are followed by head tremors, mental dullness, blindness, unawareness of surroundings, paralysis, tremors, and sometimes seizures.  .Wildlife officials are currently investigating whether the disease is spread only by mosquito bites, or also by Hippoboscid flies or "flat flys," commonly found on raptors.  It is also not certain at this time if the birds are getting the disease from eating infected rodents.

Raptors in Midwestern states seem to be hardest hit by the WNV.  There are a few theories as to why the Midwest is experiencing more bird deaths from WNV than other parts of the country.  One theory is that eastern raptors have been exposed to the virus for a longer period of time and have therefore had a chance to build up an immunity to the disease.  Another is that the virus might have mutated into a more deadly strain as it moved west.  Still another theory is that birds in the Midwest are genetically different than birds in the east and might be more susceptible to WNV.  While theories abound, there is no known reason why the Midwest is suffering more bird deaths than other regions. 

Kentucky is one of 26 states conducting WNV surveillance on birds.  With the unusually wet spring we've experienced, some health officials are predicting a heavy WNV season for 2003.  If you find a dead bird, take precautions by wearing rubber gloves when handling it.  Although there are no cases of the disease being transmitted from birds to humans, it's best to be careful.  In Kentucky, report dead birds by calling (800) 858-1549, ext. 352, or by contacting the local health departments.  To submit a dead bird:

• Try to determine how long the bird has been dead.  The local health department would prefer that submitted carcasses be in good condition with no visible signs of decay or odor.  This will most likely be the case only in birds that have been dead less than 24 hours. 



• Place the bird in a good quality, sealable, plastic bag.  Remember to use rubber gloves when handling.  Chill carcasses immediately



• Call your local health department for further instructions.  The decision to submit a dead bird is at the discretion of the local health authorities. 

A good source of information for WNV in Kentucky is the Kentucky Cabinet for Health Services "West Nile Virus" website http://chs.ky.gov/publichealth/west_nile_virus.htm

Experts say that West Nile is here to stay in North America.  It is hoped that common bird species will develop immunities to the disease and will not be decimated.  It remains to be seen, however, what the effect will be on birds with small populations in restricted geographical areas.