by Center for Disease Control (CDC)
With more questions than answers about the mysterious West Nile virus, dog owners are cautioned to arm themselves - and their dogs - against the deadly mosquito-borne disease.
Summer is fully upon us, and as a result, many dog owners are feeling the heat of flea, tick and mosquito season. According to the United States Geological Survey - and judging by the frequent use of insect repellent and calamine lotion - midsummer to early fall is the most active time for our nation's mosquito populations.
As we practice and play with our dogs in the backyard and exhibit at outdoor shows this year, especially along the Eastern seaboard, there is an even greater concern for both man and dog than an annoying itch. Many people are concerned that those pesky bites may bring with them the West Nile virus that first surfaced on our shores last year.
What is West Nile?
The West Nile virus is a strain of encephalitis, genetically similar to St. Louis encephalitis, that affects the central nervous system. West Nile causes a swelling of the brain that, though treatable, can be fatal. The disease is carried by birds and transmitted by mosquitoes that bite an infected bird and then bite a human or animal. Many scientists believe the disease can also be transmitted by infected ticks, but no connection has yet been proven.
According to the Centers for Disease Control, "There is no documented evidence of person-to-person, animal-to-animal or animal-to-person transmission of the virus. Veterinarians should take normal infection-control precautions when caring for an animal suspected to have this or any viral infection. It is possible that dogs and cats could become infected by eating dead, infected animals, such as birds, but this is unproven."
Although it is not known how long a dog can be infected with the virus, the typical incubation period (the time from infection to onset of disease symptoms) in humans is five to 15 days. Human fatality from West Nile ranges from 3 to 15 percent, with infants, the elderly and people with damaged immune systems having the highest risk.
New York State Department of Health authorities explain that viral encephalitis may not show any symptoms, but mild cases often include slight fever and headache. Severe cases usually result in rapid onset of high fever and head and body aches. Until last August, according to the Centers for Disease Control and Prevention, in Atlanta, there has never been a reported case of West Nile virus in the United States.
Some Surprising Statistics
But last summer and fall there were 62 cases of severe disease and seven deaths in humans in the New York metropolitan area, presumably from a virus brought to America from Africa or the Middle East. Many horses in the area were also affected, and a few died as a result. Although it was not widely publicized, there were a few cases of small companion animals becoming infected.
According to Kristine Smith, spokesperson for the New York State Department of Health's Arthropod-Borne Disease program, there were a few documented cases of dogs and cats becoming infected with the West Nile virus during last year's crisis, but there were no reports of dogs becoming ill with encephalitis or any serious illnesses or deaths attributable to the disease.
However, a sero-prevalence survey, a blood test that determines what number in a given population are infected and become ill, was conducted last year on dogs in New York and showed some surprising results. Five to 11 percent of dogs tested in the area of the epidemic were infected. None, thankfully, became seriously ill as a result.
Although these figures may seem alarming, some experts believe the fact that no dogs became sick as a result of infection suggests that dogs may be resistant to the illness. Researchers are working diligently to unravel the mysteries of the West Nile virus, but according to some scientists and veterinarians too little is yet known about the virus to fully explain the meaning or impact of such findings, in part because background data from the virus' place of origin is limited and unreliable.
What Can You Do?
With few hard facts and only a handful of statistics about the disease, most experts seem to agree that the question is When and where will it strike again? It seems likely that the answer is soon, and in the Northeast. In early June, three dead crows were found to be infected with the virus in New York and New Jersey. Smith is quick to point out that as of this writing there have been no cases reported this year of humans or pets becoming infected, though she recommends, as do most vets, protecting pets by following the same guidelines suggested for humans. (See sidebar above.)
The precautions owners can take - for themselves and for their dogs - that can minimize any potential risk include restricting outdoor activity at night and in the early morning, as well as limiting exposure to still or stagnant water, which is a typical mosquito breeding ground. These may seem simple, but for most dog fanciers they may require extra conscientiousness.
Because many fanciers kennel their dogs outside, care must be taken to not let any water pool on the ground or in receptacles and to change the water in outdoor dog bowls frequently. Owners should also limit early morning walks or training sessions, as this time of day leaves people and animals most susceptible to mosquito bites.
Performance competitors may want to take additional precautions, such as avoiding exposure to wild birds and fowl, and using safe insect repellent on themselves and their dogs when out in the field, especially when near small ponds. Finally, because the risk of transmission of West Nile from ticks is yet unknown, owners would be wise to keep their dogs on both oral and topical flea-and-tick control products.
Despite much media hype, there is no cause for panic about West Nile virus - but neither is there room for denial of the disease. With heightened awareness of the situation and appropriate and unobtrusive measures to protect themselves and their dogs, dog fanciers, according to authorities, are likely to enjoy a summer free of fear and full of fun.
Defending Yourself Against Mosquito Attacks
Although there are many different species of mosquito, it is the Culex pipiens, or common house mosquito, that is most typically associated with West Nile. These mosquitoes, like others, are most active in the summer and early fall, between dusk and dawn, and when the air is still. It is, in fact, only the female mosquitoes that bite to get blood to feed to their growing eggs. Although usually simply a nuisance, their bite can sometimes transmit disease.
To minimize risk of being bitten by mosquitoes, follow these simple steps provided by the New York State Department of Health:
Reduce or eliminate all stagnant water around your home, including in dog bowls, recycling containers, ceramic pots, garbage cans, discarded tires, bird baths, wading pools, roof gutters and ponds. Clean and chlorinate swimming pools, outdoor saunas and hot tubs.
Use landscaping to eliminate any puddles or stagnant water in your yard. Clean vegetation and debris from the edges of ponds.
If evidence of West Nile virus is found in your area, minimize outdoor activities between dusk and dawn. If there is no evidence of the virus, it is not necessary to limit outdoor exposure.
Wear shoes and socks, long pants and a long-sleeved shirt when outdoors for long periods of time or when mosquitoes are more active.
Consider the use of safe, effective mosquito repellents, according to directions, when it is necessary to be outdoors. Upon consultation with your veterinarian, apply the repellent externally to your dog.
For more information about mosquitoes, West Nile virus, encephalitis and insect repellents, visit http://www.usgs.gov and http://www.cdc.gov . You may also contact your local health department or write Fight the Bite, Box 2000, Albany, NY 12220.