CDC: West Nile Virus cases up in 2012

Following a mild winter, we have had one of the hottest summers on record. This has led to an abundance of animal births and a huge increase in the insect population. Because of the severe drought, animals and birds congregate near water where insects proliferate. Consequently, there have been numerous mosquito, tick and flea bites, as well as contact with flies, all of which can transmit infections from animals to man.

This year has seen the largest epidemic of West Nile Virus infections in history. The virus is spread from birds to man by mosquitoes. The Centers for Disease Control and Prevention (CDC) reported that, by late August, 1,590 cases of West Nile Virus had been reported, leading to 65 deaths. Although cases have been reported in 49 states (all but Nevada), five states (Texas, Mississippi, South Dakota, Louisiana and Mississippi) account for 68 percent of the total cases.

The next few weeks look particularly bleak because the highest incidence of infection occurs in late August and September. The actual number of infections is much greater than that reported, as only 20 percent of patients infected with the West Nile Virus develop symptoms. These symptoms occur three to 15 days after being bitten, and include fever, headache, generalized muscle aches, enlarged lymph nodes and occasionally a rash on the trunk of the body.

About 1 percent of infected patients develop inflammation of the brain and spinal cord. Of these patients, 10 percent will die. Symptoms of brain inflammation include neck stiffness, confusion, headache, visual loss, convulsions, numbness and weakness of limbs. Those who survive often have permanent neurological problems. Sadly, there is no known treatment.

West Nile Virus infections tend to be more serious in the very old, the very young and those with a compromised immune system due to illness or medications used to treat rheumatoid arthritis or cancer.

While West Nile Virus is making headlines, tick-borne infections, including Rocky Mountain spotted fever and Lyme disease, are much more prevalent.

Fleabites can transmit a number of serious diseases, the most common of which is cat scratch disease. And flies that have been exposed to contaminated plant or animal products can transmit infections to people, causing gastroenteritis, upper respiratory infections and urinary infections.

As insect-borne infections are so common, we must do all we can to avoid insect bites. Many communities throughout the country are attempting to reduce the mosquito population by using aerial spraying helicopters. This has led to some opposition by those who believe the potential adverse effects of spraying outweigh the benefits.

While the CDC does state that spraying is the least effective way to control the insect populations, the risks to the general public are small. Humans and their pets should avoid direct contact with aerial spray, which has been shown, albeit rarely, to cause asthma, cough and an occasional skin rash.

More important than spraying is what we individually can do to reduce the risk of being bitten by an infected insect. When outdoors, always use an insect repellent that contains an EPA-registered active ingredient. The most common, DEET, does not kill, but repels, insects.

Because DEET is directly applied to human skin, its potential toxicity has been extensively studied. Virtually no adverse effects have been reported. Some environmentally conscious individuals prefer using lemon eucalyptus oil or PMD, a biopesticide repellant. If used properly, these insecticides will protect against mosquito, tick and flea bites. As extra precaution, wear long sleeves and pants in the early morning and dusk when most bites occur.

Keep insects out of the house by putting screens on windows and doors, and reduce the mosquito population by getting rid of stagnant water around the house. Pay particular attention to birdbaths, pet water dishes and standing water in flowerpots or buckets.

While insect-borne infections are serious, the threat to an individual is small. With the appropriate precautions, the health benefits of being outdoors far outweigh any potential risks.