The recent outbreak of West Nile virus is one of the largest on record since the first human cases were reported in the United States in 1999.
Cases peaked in 2002 and 2003 when severe illnesses reached nearly 3,000 and deaths surpassed 260. Last year was mild with fewer than 700 cases nationwide.
This year, cases jumped dramatically in August, increasing to 1,331 with 43 deaths, according to the Centers for Disease Control and Prevention. In an average year, fewer than 300 cases are reported by mid August. Only one month ago, there were only 25 cases reported.
These numbers will likely rise since August to October is the peak of West Nile virus activity in Florida and other Southern states.
Nearly half of all U.S. cases this year are in Texas. The hot, dry weather across the nation's midsection has created ideal conditions for some species of mosquitoes. The heat speeds up their life cycle, which accelerates the virus replication process.
The mosquito species that can carry West Nile virus — as well as St. Louis encephalitis, Eastern equine encephalitis and dengue fever — are always present in Pasco County. Residents should be vigilant after the recent rains that created an abundance of standing water in ditches and back yards. Some areas received over 15 inches of rain in the end of June as a result of Tropical Storm Debby, and the steady rainfalls continue to keep Pasco County saturated.
As rainfall continues to create ideal breeding grounds for mosquitoes, more cases could potentially appear throughout Florida. State health officials confirm that positive samples from 14 humans and 83 sentinel chickens have been received from 13 Florida counties. A mosquito-borne illness alert was issued recently for Jacksonville by the Duval County Health Department after 11 human cases of West Nile virus were confirmed. Others cases are in Escambia and Leon counties.
Every week during the mosquito season, the Pasco County Mosquito Control staff draws a small amount of blood from sentinel chickens in cages throughout the county. The health department 's Tampa branch lab checks the blood for signs of several diseases potentially transmitted by mosquitoes. So far this year, only one sentinel chicken in Pasco County tested positive for West Nile virus.
According to the Florida Department of Health, many people infected with West Nile virus never experience symptoms. Those who do can develop headaches, fever, pain and fatigue, lasting from a few days to two weeks. There is no specific medication or treatment for people infected with the disease. The best plan is to avoid mosquito bites. One way is to stay indoors at dawn and dusk, the peak flying time for mosquitoes. If you're outside, wear insect repellent or clothing that covers your skin.
This year, the Pasco County Mosquito Control District will set a record for the number of acres sprayed because of our very wet summer. It is our hope that our proactive approach to aggressively control mosquitoes in Pasco County will avoid a similar situation to what's happening in Texas.
Residents can also help by removing mosquito-breeding sites. Tip or remove empty pots and buckets, and dispose of old tires, drums, bottles and cans. Replace water in birdbaths and pet dishes at least once a week. Remove leaves and other debris from gutters. Avoid overwatering the lawn. Wash out bromeliads and other water-holding plants weekly and cover or drain unused swimming pools.
To learn more, visit cdc.gov/westnile or our website at pascomosquito.org.
Dennis Moore is director of the Pasco County Mosquito Control District.