Pennsylvania sees first case of West Nile virus in a dove
Port Matilda, Pa. — An ongoing Pennsylvania study that began in 2015 strongly links the ruffed grouse population decline to invasion of West Nile virus. Now, at least one more Keystone State game species – the mourning dove – was also found to have died from the disease.
A sick dove was observed near Port Matilda in late August. The bird expired before the finders could take it to their local wildlife rehabilitator. Because of the bird’s symptoms and no obvious signs of trauma, Centre County West Nile virus coordinator Bert Lavan was contacted.
Although Lavan said that no doves had ever been known to die from the disease in the state, he offered to have the bird tested.
The following day, Lavan used a sterile cotton swab to collect a sample of saliva from the dead dove, and it was sent to Harrisburg. The results were back a few days later. The mourning dove tested positive for West Nile virus – a Pennsylvania first.
While the Zika virus gets most of the press these days, West Nile virus is another mosquito-borne disease that can kill. It infects birds and mammals, including humans. While people might worry about Zika being spread by mosquitoes in Pennsylvania, West Nile virus is already here and is greatly affecting some bird species – including game birds.
West Nile virus was first isolated in the West Nile province of Uganda in 1937. The earliest-recorded outbreaks of West Nile encephalitis occurred in Israel in 1951, 1954, and again in 1957. It reached the United States in 1999, when it was detected in four northeastern states.
Seven people from New York died from the disease that year.
The virus was first identified in Pennsylvania (19 counties) in 2000. By 2003, West Nile virus was found in all 67 Pennsylvania counties. According to Pennsylvania Game Commission game bird biologist Lisa Williams, this lines up exactly with the time that the state’s ruffed grouse populations sharply declined.
“West Nile virus seemed to peak in Pennsylvania in 2003, with 1,400 dead birds testing positive and 237 documented human cases,” Lavan said. “The birds really took a hit that year.”
The number of counties with “positives” varies from year to year, with another peak occurring in 2012. According to the state website – a joint project of the departments of Environmental Protection, Health, and Agriculture – so far this year, West Nile virus has been detected in 37 counties, including Centre.
Certain species of birds have been shown to be very susceptible to the virus – crows, blue jays, raptors and ruffed grouse. Since mourning doves are not known to be one of the susceptible species, Game Commission wildlife pathologist Justin Brown cautioned about reading too much into one dead dove.
“A high number of bird species can be infected with West Nile virus, but few actually are affected enough to die from the disease,” Brown explained. “Almost all crows and most grouse die if infected with the virus, but the case of this mourning dove dying from the virus might just be the result of individual variability.”
With that said, Brown and Lavan noted that most dead birds are neither found nor tested for the disease. As of mid-September, out of the 30 birds submitted, only seven birds from five different counties had tested positive.
“The Game Commission regularly tests and often does a necropsy on large game animals that are found dead, but a bear is something big and obvious,” Brown said. “The chances of locating a highly-camouflaged forest bird like a ruffed grouse, if it dies, are very unlikely. It would take a lot of luck and the bird would have to be found quickly after it dies.”
Centre Wildlife Care rehabilitator Robyn Graboski has treated many birds with the symptoms of West Nile virus – including a Franklin County turkey vulture that died in May and many other raptors. She described what to look for.
“Birds with West Nile virus show general signs of weakness – they often can’t stand or fly. Sometimes saliva is dripping from their mouths,” Graboski explained.
“Another sign is head tilt or a bird that flips backwards on its perch. We recently had a red-tailed hawk with West Nile virus. Its head tilted back, and it would fall off of its perch,” she said.
“In 2012, we had a real deluge – over 60 birds with West Nile virus symptoms, mostly crows, red-tailed hawks, great-horned and barred owls and even a couple bald eagles.”
Citizens can help by reporting dead birds to their county West Nile virus coordinator. Twenty-five counties have coordinators. That list and a general number for all counties can be found at the state website www.westnile.state.pa.us. Sick birds can be transported to the closest wildlife rehabilitator.
Hunters can help, too. Last year, cooperating hunters used a special free kit supplied by the commission to collect more than 200 grouse blood samples for the agency. Thirteen percent of those grouse tested positive for West Nile virus antibodies.
Grouse hunters can help by becoming Grouse Hunter Cooperators. Simply download the forms from the ruffed grouse page on the Pennsylvania Game Commission’s website (www.pgc.pa.gov) or by calling 717-787-5529.
Humans can get West Nile virus, too. Common symptoms for humans include headaches, fever, fatigue and body aches. For most, the symptoms dissipate – even if untreated. However, for about 1 percent of the cases, the disease becomes more severe – developing into encephalitis, meningitis or worse.