The most menacing mosquitoes in Tennessee may not be what you think

The most affected county is Davidson, which has experienced 18 cases since 2010, including two in 2018. In total, 57 counties in Tennessee have had no cases since 2010, but those that have spread throughout # 39; State.

Since 2010, 151 human cases of West Nile virus have been reported in Tennessee, spread across 38 counties, according to data from the Tennessee Department of Health. (Photo: Mariah Timms / Tennesseean)

How can it make me sick?

Others, about 20 percent by TDOH, will develop flu-like symptoms for a few days: fever, headache, weakness, stiff neck, nausea, vomiting, muscle aches, rash, and in some cases , diarrhea and sore throat.

Only about 1% of infected people are actually affected by serious health problems due to West Nile.

People over the age of 50 are most at risk of developing the most severe reaction to the virus, as are immunocompromised patients, including those with HIV or undergoing chemotherapy, Ragson said.

According to the Center for Disease Control and Prevention, symptoms include high fever, headache, stiff neck, stupor, disorientation, coma, tremors, seizures, muscle weakness, vision loss , numbness and paralysis.

At worst, it can cause encephalitis, said Dr. William Schaffner, an infectious disease specialist at the Vanderbilt University Medical Center. Encephalitis is an infection of the brain that creates severe symptoms. West Nile can cause inflammation similar to the spinal cord.

By their very nature, these conditions can exacerbate existing conditions and pose a serious threat to people with cancer, diabetes, hypertension, kidney disease and organ transplant patients.

The bad news is that restoring the most severe reaction to West Nile virus can take weeks or months and in some cases can cause permanent damage to the central nervous system.

The CDC reports that about 10% of people with West Nile-related serious illness will die from it.

Is there a treatment?

"We do not have a West Nile drug," said Schaffner, "but we can take good care of you while your body gets rid of the virus."

Most treatment options for less severe symptoms are the same as for most viral infections: over-the-counter pain relievers to reduce fever, recommends the CDC.

In severe cases, anyone with a high fever and associated symptoms should seek prompt medical attention.

Schaffner explained that hospitals can offer supportive care to test for encephalitis and ensure that the heart, kidneys and other organs of the patient work as well as possible to fight the virus.

What is West Nile?

West Nile is a virus that, like other infections, affects a host so that it can replicate itself and pass it on to other hosts, Schaffner.

In particular, West Nile likes to infect birds.

"The West Nile virus is not after us," Schaffner said. "He would like to enter another bird and perpetuate himself."

The problem, however, is that mosquitoes do not only target birds.

"Sometimes they move away and bite us," said Schaffner, "then we got sick."

How do humans get it?

Ragson explained that some small animals can also be infected by the bite of an infected mosquito.

"We are a little accidental, from the point of view of the virus," he said.

Humans and horses become "dead end" hosts, Ragson said. Even if one person is infected, the virus will not circulate enough in the blood to infect another mosquito. Without the intervention of a mosquito, it will not be transmitted to another creature.

In most cases, Schaffner and Ragson agreed that the majority of people (about 80%, by TDOH) with West Nile virus would not even know it.

In some rare cases, West Nile has been transmitted by blood transfusion or organ transplantation, according to Tiffany Taylor, spokeswoman for the American division of the Tennessee Red Cross.

The American Red Cross examines all blood donations for several diseases, including West Nile.

"The Red Cross is testing each unit of blood from every region every year to detect the presence of the virus by using West Nile virus nucleic acid tests," Taylor said. an email. "In areas where West Nile virus is active, we are using even more sensitive NAT methods to detect the virus."

What can you do to prevent it?

"The West Nile, even at the height of its transmission, has never been what I would consider a serious public health problem," Ragson said. "It's more of a public relations problem." There are not enough people who get sick to justify resources and tests (for vaccine manufacturers) to make a vaccine. "

Most of the advice (from the CDC, Ragson, Schaffner) is simply to use common sense to avoid being bitten by mosquitoes.

"No one wants to be bitten, whether by an infected mosquito or not," said Ragson.

Insect repellents, long sleeves and pants, mosquito nets and air conditioning are good options to avoid pests.

The mosquito season may last until October, said Brian Todd, of the Metro's Department of Public Health, until the first freezing dead.

TO CLOSE

The summer pest can spread diseases, such as West Nile virus, encephalitis and Zika virus. Fortunately, we can reduce their numbers if we work together.
Russ Zimmer

What does the state do about the threat?

The Metropolitan Public Health Department in Nashville, which follows CDC guidelines that many municipal health departments also follow, runs a multi-pronged mosquito surveillance program from early March to late October.

The teams set up traps to collect batches of mosquitoes, which are sent to the state health department for testing.

When they are tested positive for West Nile, the department will alert the neighborhood where the lot was collected from the threat, Todd said.

"In Nashville, it's rare to have a human case," he said. "We find mosquitoes that are affected, but that does not mean that we also have human cases."

The department also organizes "yard inspection" days to help residents find potential breeding grounds for mosquito larvae.

Areas of stagnant water that have stagnated, whether large or small, can reproduce. Once hatched, they will stay close to a food source, such as a back patio where a family is present.

Gutters, if the water is at the bottom, can also be problematic.

Metro will also send teams to known problem areas, usually low-lying, where water will accumulate and stay, to apply a granular larva that kills mosquitoes but does not harm domestic animals. Todd said.