West Nile Surges in Several State; Prevention Is Key

Though summers end is nearing, West Nile virus (WNV) continues to infect Americans across the country and case counts have risen significantly in recent weeks.

So far this year, public health officials have reported more than 1,000 West Nile infections, which are caused by mosquito bites. Most of those cases have been diagnosed within the past month. Illinois officials reported 56 new WNV cases just last week, raising the states total this year to 105. Nearly all of those are in the Chicago area, primarily Cook County (46). California, which for the second straight year has the most WNV cases (521 so far this year, 779 in 2004), is seeing a slow decline after a peak in August.

West Nile virus activity peaks in August and September, according to the Centers for Disease Control and Prevention (CDC), and floodwaters and rain from Hurricane Katrina has heightened concern in many states. The CDC last year reported of 2,749 human cases of WNV, with 900 having the serious neuroinvasive disease, and 88 deaths.

Though WNV has declined since 2003, it is not going away. Jonathon Day, PhD, a medical entomologist with the University of Florida, says regional outbreaks of West Nile will regularly occur.

West Nile Virus is definitely here to stay in the United States, Day says. Once a virus such as West Nile reaches an area, it will stay forever in low levels. It may even die out for a period of time. Then, if the key factors all come together, particularly certain weather patterns, a major epidemic can occur.

Other mosquito-borne diseases threaten public health, such as Eastern equine encephalitis. Though rare, EEE kills nearly half of those who become infected. The most recent EEE epidemic was in North Carolina, where 26 cases were reported in 2003. This year four cases of EEE have been diagnosed in New Hampshire. Last year four Massachusetts residents contracted EEE and unfortunately two died.

Three steps experts frequently recommend for preventing both mosquito and tick bites are avoiding spots where mosquitoes and ticks are plentiful, wearing protective clothing and applying insect repellents, particularly those containing DEET.

DEET has long been the gold standard for effectiveness against mosquitoes, ticks and many other insects, and DEET has been used by consumers with confidence for nearly 50 years, said Susan Little, executive director of the DEET Education Program, which is sponsored by leading companies that manufacture DEET and formulate DEET-based repellents.

According to a New England Journal of Medicine article in 2002, DEET offers superior protection against insect bites. The study compared protection against mosquitoes provided by numerous repellents.

Our study shows that only products containing DEET offer long-lasting protection after a single application, the researchers wrote.

Based on that study and other research, the CDC, along with the American Academy of Pediatrics, have recommended DEET-based repellents to protect against mosquitoes and ticks.

The CDC this year revised its recommendations on insect repellents. The federal agency now tells consumers to use products registered with U.S. Environmental Protection Agency (EPA), which reviews evidence of safety and effectiveness. Of the EPA-registered product types, CDC says two have demonstrated a higher degree of efficacy in the peer-reviewed, scientific literature. Those are DEET and picaridin.

No repellent products in the world have been used more extensively than those with DEET as the active ingredient, according to Little.

Read label instructions carefully and follow them, she said. Apply repellents to exposed skin. To apply to your face or your childs face, put product on your hands and them hand-apply to the face. This helps keep the product out of the eyes and mouth.

The American Academy of Pediatrics says repellents containing up to 30 percent DEET can be used on children over two months of age. Little recommends using DEET on clothing only if it is thin and tight-fitting enough for mosquitoes to bite through. She cautioned that some products can damage synthetic fibers but are fine to use on cotton and other natural fibers.

The most commonly reported problem with DEET-based repellents is stinging from repellent in the eyes, which Little says is quickly remedied by flushing the eyes with water or saline solution, according to the product's precautionary statements on the label.

To help prevent West Nile virus and other mosquito- and tick-borne diseases, the DEET Education Program conducts nationwide outreach including presentations at professional meetings. The DEP works with leading organizations focused on Lyme disease to spread messages about prevention.

Operating under the auspices of the Consumer Specialty Products Association, the program provides educational brochures, available in English and Spanish, free of charge to the public and healthcare professionals.

The DEET Education program this summer has donated nearly 20,000 containers of DEET-based insect repellents to low-income Californians and were making additional donations in other states to help prevent West Nile, said Little. Along with our donations, we have co-sponsored with West Nile prevention education events, in cooperation with public health agencies, in Sacramento, Los Angeles, Fresno and more than a dozen other cities.

Contact the DEP through its toll-free hotline (888-No-Bites or 888-662-4837) or http://www.deetonline.org with questions or brochure requests.