West Nile Virus: What You Need to Know

West Nile virus was introduced in the United States in 1999, with the first stateside cases discovered in New York City. While the disease remained on the nation’s radar with fewer than 100 annual cases in its first three years, it exploded into an outbreak in 2002 with 4,156 reported cases and 284 confirmed deaths. The number of reported cases more than doubled in 2003, and has remained the top mosquito-borne disease threat in the country since that time.

As of June 14, 2024, the CDC has reported that 7 states have been affected by West Nile Virus, and over 7 cases have been confirmed in 2024.

While nearly 8% of those infected with West Nile virus will not develop any symptoms, those that do might experience fever, head and body aches, pain in joints, vomiting, diarrhea, or a rash. In extreme cases, victims can develop serious neurological illnesses, including encephalitis or meningitis. According to the CDC, neurologic illnesses can lead to comas, tremors, seizures, paralysis, or even death.

West Nile virus is most commonly transmitted to humans, horses, and other mammals via the bite of an infected mosquito. While mammals cannot pass the virus onto another feeding mosquito, bird hosts can, keeping the disease transmission cycle alive.

The Culex species, one of the most common mosquitoes throughout the United States, is the primary vector of West Nile virus. This species prefers to breed in standing water, typically found in sewage systems, man-made sources such as buckets and rain barrels, roadside ditches, and catch basins.

Because Culex mosquitoes will seek any source of standing water for breeding, the most critical preventative measure the general public can take is to remove standing water wherever possible to eliminate breeding sites. Make every effort to eliminate standing water in buckets, old tires, gutters, birdbaths, flower pots, and more. Additionally, residents should protect themselves indoors with the use of air conditioning and adequately maintained window screens and outdoors with the use of loose-fitting clothing and mosquito repellents containing DEET . More mosquito prevention tips for homeowners can be found at mosquito-awareness.com.

The key to successfully controlling the Culex and other species of mosquitoes is to establish an integrated mosquito management (IMM) approach that includes surveillance of breeding sites and the early use of larvicides for prevention and the use of adulticides to address problem adult mosquito populations. IMM is designed to attack mosquitoes at each stage of their life cycle. No two mosquito habitats are alike – and neither are the ways they need to be treated. The mosquito products from Central Life Sciences provide solutions for both easy-to-access and difficult-to-treat areas.

For the most efficient control of Culex mosquitoes, larvicides should be proactively administered to known breeding sites. Altosid^® larvicides are available in multiple formulations containing (S)-methoprene, an insect growth regulator (IGR) that stops mosquitoes from becoming breeding biting adults. For an alternate approach, FourStar^® Microbials feature a larvicide that kills mosquito larvae before they become adults by using the naturally occurring bacteria Bacillus sphaericus (Bsph) and Bacillus thuringiensis israelensis (Bti).

For the remaining adult populations, adulticides kill the fully developed mosquitoes that spread diseases and offer the quickest approach to reduce the size of mosquito populations. Zenivex^® adulticides feature Etofenprox, and they are classified as reduced risk by the EPA.

For more information, contact a representative near you.