Las Vegas Sun

August 24, 2019

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How to avoid mosquito-borne illnesses in Southern Nevada


James Gathany/Centers for Disease Control and Prevention / AP

This 2006 photo provided by the Centers for Disease Control and Prevention shows a female Aedes aegypti mosquito in the process of acquiring a blood meal from a human host.

Why do mosquito bites hurt?

Their saliva can cause an allergic reaction (itchiness and redness).

The arid desert keeps mosquitos more or less at bay—we have it way better than Louisiana or Florida. But that doesn’t mean we’re completely in the clear. “The Las Vegas area has disease rates similar to other metropolitan areas in the United States, and mosquitoes have been found in ZIP codes around Clark County,” said Stephanie Bethel, Public Information Office for the Southern Nevada Health District. In the past few summers, there have been three cases of West Nile virus and three cases of St. Louis encephalitis reported in the region. One case of West Nile resulted in the death of an elderly man.

West Nile Virus

The Southern Nevada Health District reported cases of West Nile Virus in people every year since 2004, with one exception. In 2010, there were no cases reported.

• Symptoms: About 20 percent have a fever, headache, body aches, joint pain, vomiting, diarrhea and/or rash. It can take months to make a full recovery. About 80 percent of individuals have no symptoms; 0.6 percent have severe illness attacking the central nervous system, which can lead to brain or spinal cord inflammation, and in 10 percent of cases, death.

• Treatment: Over-the-counter pain medications or intravenous fluids

St. Louis Encephalitis Virus

The Southern Nevada Health District reported an increase of St. Louis encephalitis in 2016. However, no cases were reported in 2017.

• Symptoms: 99 percent have no symptoms. Less than 1 percent experience fever, headache, dizziness, nausea or malaise. The disease either clears on its own or can go on to attack the central nervous system, causing stiff neck, disorientation, tremors and possibly coma or death.

• Treatment: There is no specific protocol, but you should see a doctor for diagnosis and treatment of symptoms.

Mosquitoes found in Clark County

More than 200 species of mosquitoes live in the U.S., but fortunately not all of them live around here. Since 2004, when West Nile virus was first discovered in Southern Nevada, Clark County has administered a Vector Surveillance program for mosquitoes.


The Centers for Disease Control and Prevention has reported no mosquito-borne Zika virus transmission in the U.S., but travelers can catch Zika in destinations such as the Caribbean, Mexico, Central America and South America. The Southern Nevada Health District has tested six people for Zika so far this year, along with 91 last year and 156 in 2016.

• Symptoms and complications: Symptoms can include fever, rash, headache, joint pain, red eyes and muscle pain. Most individuals have few to no symptoms.

A Zika infection during pregnancy can cause miscarriage, stillbirth or severe birth defects, including microcephaly (a smaller than normal head and brain).

Zika is linked to Guillain-Barré syndrome, which may cause muscle weakness or paralysis.

• Transmission: People can catch Zika from mosquitoes, exposure to infected blood or by sexual transmission. The CDC recommends couples use condoms for six months if a male partner traveled to a region with Zika and eight weeks if a female partner traveled to a region with Zika. The CDC recommends that “travelers take all precautions to protect themselves from mosquito bites while they are on vacation, even if they are not traveling internationally.” Pregnant women should not travel to areas with Zika.

• Testing and treatment: A blood or urine test can detect Zika. There is no known cure for Zika. You can treat symptoms with rest, fluid and Tylenol.

Mosquito prevention tips

• Wear pants and long-sleeved shirts to reduce mosquito exposure when outdoors.

• Eliminate areas of standing water around your home, including noncirculating ponds, “green” swimming pools and sprinkler runoff.

Do citronella candles actually work?

Citronella candles have a distinctive smell and are sold alongside outdoor supplies. They’re mildly effective, but not much more than any other candle that produces smoke.

Insect repellents

Some insect repellents offer big promises but little protection. Use an Environmental Protection Agency-registered mosquito repellent to ensure both safety and effectiveness. EPA-registered repellents have been evaluated to have a “reasonable certainty of no harm” to users and the environment. Follow the package directions and be sure they contain at least one ingredient from this list:


• Picaridin

• IR3535

• Oil of lemon eucalyptus (OLE)

• 2-undecanone

Life cycle of a mosquito

They survive four days to one month, depending on conditions.

Here are their stages:

1. Egg: Can survive in a dry spot for months, but needs water to hatch

2. Larva: Molts and feeds in water

3. Pupa: Lives in water for two to seven days

4. Adult: Only female mosquitoes suck blood from mammals (i.e., dogs, horses, humans) for nourishment to produce eggs. Otherwise, mosquitoes eat plant nectar.

What about ticks?

The Southern Nevada Health District does not survey for ticks. “Lyme disease is rarely seen here because the ticks that cause it are uncommon in this area,” an SNHD spokesperson says. “The health district does receive reports of cases; however, these generally are reported in people with a history of travel to areas where the disease is more common.”

Take the same precautions to prevent against tick bites as you would mosquito bites (wear repellents, wear long pants and long-sleeved shirts).

What to do if you get a tick bite:

• Remove the tick as soon as possible.

• Use tweezers to grasp the tick as close as possible to the skin’s surface. Pull upward.

• Dispose of the tick by putting it in alcohol, placing it in a sealed container, wrapping it tightly in tape or flushing it down the toilet

• Thoroughly clean the bite area and your hands with rubbing alcohol or soap and water.

• Call your doctor if you develop a rash after a tick bite.


• Wait for it to detach on its own.

• Use folk remedies, such as covering the tick with nail polish or using heat to make it detach.

• Twist or jerk the tick (a portion of the tick can break off and remain in the skin.)

• Crush a tick with your fingers.

This story originally appeared in the Las Vegas Weekly.