Despite the cool summer weather San Diego County has seen this summer, the number of birds found infected with West Nile Virus has been heating up. So far, this year’s total count in San Diego County is 216 dead birds, eight sentinel chickens, five mosquito pools, one horse and three human illnesses, according to County Vector Control officials.
“In years previous, we generally would not expect to see a large increase in the number of birds testing positive until we get into August, and the fact that we’re not even through July yet and we’re already poised to break previous records is definitely cause for concern,” said Chris Conlan of the Department of Health Vector Control in an interview last week.
There are contributing factors that may indicate a rationale for the increase in positive cases this year. However, because the disease is relatively new, it has not been present long enough to identify a pattern that links one year’s stats to the next.
According to Conlan, this year his staff has seen a large number of abandoned pools, ranging from kiddie pools and full-sized swimming pools. Standing water makes for perfect mosquito breeding grounds.
The virus is spread by mosquitoes and birds serve as reservoirs for the virus. They become infected with the disease and in turn infect mosquitoes that bite them. Once the mosquito becomes infected, it can pass the virus on to any being it bites there after.
West Nile Virus can only be spread and contracted through a mosquito bite, not through casual contact or picking up dead birds.
Most animals do not have an issue with the virus, explained Conlan.
“Dogs and cats usually don’t have a problem with it, unless they are already severely health compromised,” he said.
Horses and humans can become infected as well.
A horse will become sick three to 15 days after contracting the virus. Symptoms for horses involve loss of appetite along with any combination weakness, convulsions or paralysis of hind limbs, according to Dr. Gundula Dunne, Veterinary Medical Officer at Animal Disease Diagnostic Laboratory.
There is no specific treatment for WNV in horses, however there is a vaccination.
“Whenever there is an increase in activity of positive birds and mosquitoes, that is a precursor that tells you that the risk to humans is present and they are at more of a risk catching it now,” Conlan said.
Human symptoms range from mild to serious including headaches, fever, skin rash and swollen lymph glands to coma, muscle weakness and paralysis. However, four out of five people do not develop symptoms at all. Currently there is not a vaccine for humans.
There has only been one reported human illness case in San Diego County so far ” a 24-year-old man who developed symptoms similar to those of the WNV infection and was hospitalized with encephalitis.
The several species of birds that have an issue with the virus are crows, jays, ravens, and birds of prey such as hawks.
The county is encouraging residents to call Vector Control at (888) 551-4636 if they find any dead susceptible species so they can be picked up and tested to determine if they had the virus.
The bird must be dead for less than 24 hours with an intact carcass intact and cannot have died from a logical cause, such as being hit by a car. This is because the virus begins to degrade after the bird dies, making it difficult to detect after about a day and diminishes the worth of testing to see what really killed it, Conlan said.
Infected birds have been found in Pacific Beach, La Jolla, Camp Pendleton, Carlsbad, Carmel Valley, College Area, Del Mar, El Cajon, Kearny Mesa, Lakeside, La Mesa, Lemon Grove, Miramar, Mira Mesa, Oceanside, Poway, Ramona, Rancho Bernardo, Rancho Santa Fe, Scripps Ranch, Solana Beach, Sorrento Valley, University City, Valley Center and Vista. The mosquito pools were found in Del Cerro and Oceanside.
To prevent mosquito bites, keep screens and windows intact. Empty or remove backyard water sources, such as children’s toys, old spare tires or anything that can retain standing water to prevent the creation of mosquito breeding areas. Mosquito fish can be used to manage larger areas of water such as swimming pools. Wear long sleeves and pants during dawn and dusk, which are peak mosquito biting hours, and wear repellents.
“If ever there was a time to listen to us, this is it. Put your repellent on this year because it’s not looking good,” Conlan said.
For more information visit www.SDFightTheBite.com.