Summer Safety Series | Mosquitoes, ticks, deer flies can spread infections while feasting on your flesh

By Kristy Bleizeffer Jul 1, 2016

Beware mosquitoes and other blood-thirsty insects that want to puncture you with their probing mouthparts this holiday weekend.

Something to remember while planning your summer picnic with family and friends: Mosquitoes, ticks and deer flies are hoping to make a picnic out of you. 

Natrona County’s wet spring created prime habitat for these blood suckers. Ticks love the tall grass while mosquitoes had plenty of stagnant water holes in which to lay their eggs. Horse and deer flies seem to thrive everywhere at any time.

Bug bites aren’t just itchy and annoying. A man in Big Horn County died a couple of years ago in an outbreak of tularemia that sickened 22 people, said Mark Dowell, M.D., an infectious disease specialist at Wyoming Medical Center and Rocky Mountain Infectious Diseases.

Here’s a look at the infections these blood suckers could spread after puncturing your skin with their flexible probing mouthparts this holiday weekend. If you experience any of the symptoms below, inform your healthcare provider about possible exposures.

Tularemia

  • What it is: Disease caused by bacterium Francisella tularensis; Small mammals such as rabbits and rodents are especially susceptible.
  • Spread by: Bites from infected ticks, horse and deer flies, along with exposure to infected rabbit and rodent carcasses.
Deer fly (Photo credit: 'Chrysops callidus' by Bruce Martin)
  • Symptoms: High fever with an ulcer forming at site of bite that will not heal. Somewhere near the ulcer, you may have swollen lymph glands. You may also be infected by eating or drinking contaminated food or water, handling sick or dead animals, or breathing dust with the bacteria.
  • Treatment: Though life-threatening if not treated, it responds quickly to antibiotics. Because symptoms can mimic other illnesses and it is relatively rare, be sure to tell your health provider if you have any possible tularemia exposure.
  • Prevalence: Before last year’s outbreak, Dr. Dowell saw maybe 12 cases in Wyoming in the last two decades. In 2015, there were 22 cases in Wyoming including one death, highlighting the need for awareness. 
  • An infected cut: This year, a man showed up to Dr. Dowell’s practice, Rocky Mountain Infectious Diseases, with a wound on his finger that hadn’t healed for three months. He’d been to other doctors who tried different treatments, none of which were working. The man reported feeling sick and not getting better. While reporting his medical history, the man mentioned that he had cut his finger while skinning rabbits. He was treated for tularemia and recovered, Dowell said. It’s important to tell your doctor your full history and possible exposures so they can make a good diagnosis.

Rocky Mountain Spotted Fever

  • What it is: Potentially fatal disease caused by bacterium Rickettsia rickettsia.
  • Spread by: Bites from infected ticks.
  • Symptoms: 2-14 days after tick bite, sudden onset of fever and headache, progressing in some cases to rash, nausea, abdominal pain, red eyes and other symptoms. It may be fatal if not treated correctly. Because early symptoms may be non-specific, it may be difficult to make a positive diagnosis, so tell your healthcare provider if you have been bitten by a tick.
  • Prevalence: It is now rare in Wyoming, but it is still present. A case occured here just this May. However, the hotbeds are now in the South.
  • Treatment: Antibiotic doxycycline administered within first five days of symptoms.

Colorado Tick Fever

  • What it is: A rarely diagnosed viral infection affecting people in the western United States or western Canada who are 4,000 to 10,000 feet above sea level.
  • Spread by: Bites from infected ticks.
  • Symptoms: It’s sometimes called Spotless Rocky Mountain Spotted Fever because it has similar symptoms but does not cause the rash. (Even though Colorado Tick Fever is caused by a virus and Rocky Mountain Spotted Fever is caused by a bacterium.) People may feel sick for a few days, get better and think they’re over it, and then get sick again with a milder form of the illness days later.
  • Treatment: No treatment or vaccine available. Treat symptoms with supportive care.
  • Prevalence: Dr. Dowell has seen one Wyoming case in 24 years, but there are likely more infections than are reported. “It’s oftentimes mild and oftentimes missed.”

West Nile

  • What it is: A virus first reported in the United States in 1999 in New York City. It migrated to Wyoming over the next several years. “You could just watch the virus start off on the east coast and work its way west,” Dowell said.
Mosquito larvae (Photo credit: 'Culex sp Larvae' by James Gathany, CDC
  • Spread by: Bites from mosquitoes that have previously feasted on an infected bird or horse.
  • Symptoms: 70 to 80 percent of infected people will not develop symptoms; 1 in 5 infected people will develop a fever with joint pain, vomiting, diarrhea or rash. Fewer than 1 percent will develop a serious neurologic illness. “Very few people will have it invade their nervous system and those are usually people who are older than 55 or who have other health problems at the same time,” Dowell said.
  • Treatment: No treatment is available other than supportive care to relieve symptoms. Focus on prevention.
  • Prevalence: In the early 2000s, Wyoming had 100 cases in a year, but the number has dropped off significantly as people and animals have developed immunity from previous exposure. “Now, we may get 40 to 50 cases some years and we may see five cases the next year. The susceptible population is not there anymore,” Dowell said.

Mark Dowell M.D.

Dr. Mark Dowell is an infectious disease specialist with Wyoming Medical Center and Rocky Mountain Infectious Diseases (RMID), 1450 E. A St. He is the Natrona County health officer and is board certified in infectious disease and internal medicine.  RMID offers a full-breadth of outpatient infectious disease care. For more information, appointments or referrals, call RMID at (307) 234-8700. 

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