The first positive West Nile virus mosquito sample of the 2011 season was trapped in the City of Maricopa on Friday, June 24, 2011.  Pinal County, in central Arizona, performs routine surveillance to detect the presence of West Nile virus in the mosquito population.

Substantial West Nile virus activity was reported in 2010, and it is unknown how serious 2011 will be.  To date, state health officials report a total of 15 mosquitoes were positive for West Nile in Arizona.  Public Health officials at the state and local level urge people to take protective measures to avoid mosquito bites and reduce the places mosquitoes live and breed.

Pets are also susceptible to the disease. West Nile virus can cause severe illness in people and animals, although not everyone who is infected will develop symptoms.  There is a vaccine available for horses, but to date, no vaccine has been developed for other species.

According to the CDC, "Dogs and cats become infected when bitten by an infected mosquito. There is also evidence that cats can become infected with the virus after eating experimentally infected mice."

In addition to West Nile Virus, heartworm is an ongoing threat to animals. Heartworm, an often fatal illness, is transmissible by mosquitoes. A monthly heartworm preventative is strongly recommended in any area where mosquitoes are abundant.

Never use an insect repellent on pets that has been designed for human use only. Since animals are highly sensitive to insect-repellents that contain active ingredients, we suggest that you speak with a veterinarian to identify ways you can help your pet to avoid getting bitten. There are a number of all-natural repellents on the market, but as with any remedy, you should discuss the benefits with a pet health professional.

Here are some ways to “Fight the Bite” by taking proactive steps to avoid mosquitoes and the diseases they may carry:

• Avoid outside activity between dusk and dawn, when mosquitoes are most active.
• If you must be outdoors when mosquitoes are active, wear lightweight clothing that covers your arms and legs and use a mosquito repellent containing an EPA registered active ingredient such as DEET, Picaridin, oil of lemon eucalyptus, PMD or IR 3535. Always follow the directions on the label.
• Make sure doors and windows have tight fitting screens and remain closed. Repair or replace screens that have tears or holes in them.
• Eliminate mosquito-breeding sites around the home by removing standing water in potted plants, tires, bird baths and other containers where water may collect.
• Ensure that swimming pools and decorative water features are properly maintained.
• Change water in flowerpots, birdbaths and pet watering bowls located outdoors at least twice per week.

What Are the Symptoms of West Nile?

No Symptoms in Most People.

• Approximately 80 percent of people (about 4 out of 5) who are infected with West Nile will not show any symptoms at all.

Milder Symptoms in Some People.

• Up to 20 percent of the people who become infected have symptoms such as fever, headache, and body aches, nausea, vomiting and sometimes swollen lymph glands or a skin rash on the chest, stomach and back.  Symptoms can last for as short as a few days, though even healthy people have become sick for several weeks.

Serious Symptoms in a Few People.

• About one in 150 people infected with West Nile will develop severe illness.  The severe symptoms can include high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness and paralysis.  These symptoms may last several weeks, and neurological effects may be permanent.

Click here for vaccination guidelines for equines.