2012 On Course To Be Worst Year Yet for West Nile

By  //  September 5, 2012

Healthcare Alert

(VIDEO by ABCNews)

EDITOR’S NOTE: West Nile Virus has been reported in some areas of the United States. A few human cases of West Nile infection and several positive sentinel chickens have been reported in North and West Florida. Currently, no human cases have been reported in Brevard County this year. Our Sentinel Chicken Flocks have tested negative for the West Nile Virus. Brevard County Health Department and Brevard County Mosquito Control are urging residents to protect themselves against mosquito-borne illness.

BREVARD COUNTY, FLORIDA–The Centers For Disease Control (CDC) recently reported that with 1,118 cases of  West Nile virus (WNV) resulting in 41 deaths so far, Americans are facing what may be the largest outbreak of West Nile virus since the disease was first detected in the U.S. in 1999.

The West Nile virus is most often transmitted through mosquito bites. (Shutterstock Image)

WNV is a potentially serious illness caused and spread primarily by bites from infected mosquitoes. It is established as a seasonal epidemic in North America that flares up in the summer and continues into the fall. Since 1999, more than 30,000 people in the United States have been reported as getting sick with WNV, which can cause serious, life altering disease.


The CDC describes three specific prognostic categories based on symptoms:

  • Serious Symptoms in a Few People.About one in 150 people infected with WNV 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.

    Fever and headache most common symptoms in WNV symptom categories. (Shutterstock Image)
  • 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.
  • No Symptoms in Most People. Approximately 80 percent of people (about 4 out of 5) who are infected with WNV will not show any symptoms at all.
Biggest Outbreak in US History, But No Cases in Brevard Yet

“There have been more cases reported to us than ever before,” said Lyle Petersen, MD, director of the agency’s Division of Vector-Borne Infectious Diseases, in an August 21st telephone briefing to reporters. Over the period of a month there has been a prodigious increase in cases from only 25 to the present 1,118. If the trajectory continues, “this will be amongst the biggest or the biggest outbreak we’ve ever experienced in the United States,” Petersen said.

Lyle Peterson, MD (CDC Image)

Usually in WNV outbreaks, Southern states bear the brunt, Petersen said, and “we’re following that pattern.”  47 states, with the exception of Alaska, Hawaii, and Vermont, have reported WNV activity in people, birds, or mosquitoes, while 38 states have reported human cases. Five of those 38 states — Texas, Mississippi, Louisiana, South Dakota, and Oklahoma — account for 75% of the reported cases and Texas alone accounts for almost half. As of Tuesday, 13 cases have been identified in Florida, none in Brevard or surrounding counties, 2 in Escambia County and 11 in Duval County. 

Majority Of Cases The Most Dangerous ‘Neuroinvasive’ Type

Petersen pointed out that it is hard to predict the magnitude of a WNV outbreak “until it’s almost over,” and the numbers reported to the CDC may be an underestimate because cases of WNV fever may not be reported to doctors and, if they are reported, may be misdiagnosed by the physician.

Texas has been the hardest hit state, with over half of the overall cases and deaths from WNV across the country.

Reported numbers of neuro-invasive WNV disease, such as meningitis or encephalitis, are usually accurate because most require hospital admission, in which well documented specific microbiological diagnosis is expected and usually complete. “So far this year, 56% of the reported cases (629) have been neuro-invasive,” Petersen said.

In Texas, where 323 of the reported cases have been neuro-invasive, including 142 of the 270 cases in Dallas County, airplanes are being used to spray for mosquitoes, primarily in Dallas County, replacing land-based spraying. The aerial spraying is being funded with a combination of federal and state funds, and officials in other areas of the state are now also requesting aerial spraying.

Minimize Risk–Protect From Mosquito Bites

Here are preventive measures recommended by the CDC that you and your family can take to protect yourself from mosquito bites:

  • Apply insect repellent to exposed skin. Generally, the the more active ingredient a repellent contains the longer it can protect you from mosquito bites. A higher percentage of active ingredient in a repellent does not mean that your protection is better—just that it will last longer. Click here for more on insect repellent active ingredients. Choose a repellent that provides protection for the amount of time that you will be outdoors.
    • Repellents may irritate the eyes and mouth, so avoid applying repellent to the hands of children.
    • Whenever you use an insecticide or insect repellent, be sure to read and follow the manufacturer’s DIRECTIONS FOR USE, as printed on the product.
    • For detailed information about using repellents, see the Insect Repellent Use and Safety questions.
  • Spray clothing with repellents containing permethrin or another EPA-registered repellent since mosquitoes may bite through thin clothing. Do not apply repellents containing permethrin directly to exposed skin. Do not apply repellent to skin under your clothing.
  • When weather permits, wear long-sleeved shirts and long pants whenever you are outdoors.
  • Place mosquito netting over infant carriers when you are outdoors with infants.
  • Consider staying indoors at dawn, dusk, and in the early evening, which are peak mosquito biting times.
  • Install or repair window and door screens so that mosquitoes cannot get indoors.

Help reduce the number of mosquitoes in areas outdoors where you work or play, by draining sources of standing water. In this way, you reduce the number of places mosquitoes can lay their eggs and breed.

  • At least once or twice a week, empty water from flower pots, pet food and water dishes, birdbaths, swimming pool covers, buckets, barrels, troughs and cans.
  • Check for clogged rain gutters and clean them out.
  • Remove discarded tires, and other items that could collect water.
  • Be sure to check for containers or trash in places that may be hard to see, such as under bushes or under your home.

Note: Vitamin B and “ultrasonic” devices are NOT effective in preventing mosquito bites.