Vector-Borne Diseases

What are VBDs?

Vector-borne diseases are illnesses caused by viruses, bacteria, and parasites that are transmitted to humans by vectors. Examples of vector-borne diseases include West Nile, Malaria, and Zika. 

A vector is any animal capable of transmitting infectious pathogens between humans, or from animals to humans. Mosquitoes, ticks, and fleas are examples of vectors in Wyoming.

West Nile virus

West Nile virus (WNv) is the most common mosquito-borne illness in the United States. It is a zoonotic disease, meaning animals are involved in the transmission cycle. Numerous bird species serve as reservoir hosts in the environment. Certain Culex mosquitoes that feed on infected birds will become infectious and be able to transmit the virus during their next blood meal. This could be another bird, or large mammals like humans and horses. Humans and horses are referred to as incidental or dead-end hosts, because they do not contribute to further transmission. This means that a mosquito that bites a human or horse infected with WNv will not become infected. 

The majority of people who become infected with West Nile virus are either asymptomatic or only have mild febrile symptoms. Approximately 1 in every 150 cases (less than 1%), however, can be quite severe. This form of WNv infection is known as neuroinvasive disease which can be very serious. 

Horses can become seriously ill or even die from WNv. Fortunately, WNv vaccines are available. Yearly WNv vaccines for horses are available from your veterinarian or local feed and tack store. Culex mosquitoes that can transmit WNv will sometimes breed in horse troughs. Be sure to clean out the water in your horse trough once a week during the summer to prevent this vector species from breeding on your property.‍

Other Mosquito-Borne Diseases

When the District tests mosquito samples for West Nile virus, we are also testing for St. Louis Encephalitis virus (SLEV) and Western Equine Encephalitis virus (WEEV). Both of which are significantly more rare than West Nile virus. Like West Nile virus, WEEV can also impact horses. To read more about other diseases that may impact livestock or wildlife in Wyoming, visit the University of Wyoming State Veterinary Lab or the Wyoming Game & Fish Department. 

We often get asked questions about other mosquito-borne diseases such as Zika. Luckily, in Wyoming we do not currently have the invasive mosquito species (e.g. Aedes aegypti and Aedes albopictus) that are capable of transmitting Zika virus, as well as numerous others. We are constantly on the look out for invasive mosquito species through our extensive surveillance program.

To read more about other mosquito-borne diseases in the United States, visit the Centers for Disease Control and Prevention. To read more about other vector-borne diseases that can affect humans in Wyoming, visit the Wyoming Department of Health.

Tick-Borne Diseases

Ticks are adept at spreading diseases like Rocky Mountain Spotted Fever, Lyme disease, and many others. While Lyme disease and alpha-gal syndrome are well known for their impacts in the eastern United States, Wyoming residents and visitors are not immune to tick-borne diseases. In fact, Wyoming has historically had the highest incidence rate of Colorado Tick Fever in the United States.

Current range of the Rocky Mountain wood tick (Dermacentor andersoni) in the lower 48 states.

Wyoming is home to multiple tick species that have medical or veterinary significance. Additional species, both native and invasive to the U.S., are expanding their ranges throughout the country, some of which have been documented in Wyoming or neighboring states. Each of these species is capable of carrying a variety of diseases.

TCWP, along with partner organizations and citizen scientists, conducts field surveillance of ticks throughout Wyoming. Ticks are tested in the TCWP laboratory for pathogens that can impact public health. Members of the public are welcome to join the citizen science field surveillance efforts by completing the form below. Additionally, individuals may submit ticks that they find through the TCWP Passive Tick Surveillance Program detailed below.

Tick Bite Prevention

Ticks must attach and begin feeding to transmit pathogens to the host. There are simple steps that you can use to prevent tick bites and pathogen transmission.

  • Use Environmental Protection Agency (EPA)-registered insect repellents that contain DEET, picaridin, IR3535, Oil of Lemon Eucalyptus (OLE), para-menthane-diol (PMD), or 2-undecanone.
  • Wear loose-fitting, long clothing including long sleeves and long pants. Tuck pants into socks for extra protection.
  • Know where to expect ticks. Ticks live in grassy, brushy, or wooded areas; walk in the center of trails to prevent contact with ticks.
  • Take a shower. Showering within two hours of coming indoors can reduce the risk of ticks attaching and transmitting pathogens.
  • Tumble dry clothes on high heat for 10 minutes to kill ticks on dry clothing.
  • Treat clothing and gear with products containing 0.5% permethrin. Boots, clothing, and camping gear can be treated with permethrin. You can also purchase permethrin-treated clothing.
  • Prevent ticks on pets and check pets for ticks daily. Talk to your vet about tick prevention products for dogs. Do not apply tick prevention products to your cat without first talking to your vet.
  • Conduct a full body tick check on yourself, your child, and your pets after being outdoors.
Make sure to check your entire body when conducting a tick check.

Some tick species will attach quickly and others will seek out protected spots and crevices where they may not be easily found or dislodged. When conducting a tick check use a hand-held or floor length mirror to view all parts of the body including:

  • Under the arms
  • In and around the ears
  • Inside belly button
  • Back of the knees
  • In and around the hair
  • Between the legs
  • Around the waist

If you find an attached tick, remove it as soon as possible.

  1. Use fine-tipped tweezers to grasp the tick as close as possible to the skin's surface.
  2. Pull upward in a steady, even motion without twisting or jerking to prevent the mouth parts breaking off. If they do break off, try to remove with tweezers, but leave them if they do not remove easily.
  3. Clean the bite area and your hands with rubbing alcohol or soap and water.
  4. Do not crush the tick. Instead, dispose of the tick in rubbing alcohol, in a sealed bag/container, tightly wrapped in tape, or flushing it down the toilet.
  5. Follow up with your healthcare provider if you develop symptoms of tick-borne disease.
Passive Tick Surveillance Program

Individuals may submit found ticks to TCWP for testing through the Passive Tick Surveillance Program to help collect information including tick species richness, diversity, abundance, phenology, distribution, and tick-borne pathogen presence and prevalence. This program is for tick ecological research only. TCWP is not a diagnostic lab and cannot test any ticks that have bitten people who are seeking tick infection information. If you are interested in submitting a tick through this program, please review the Passive Tick Surveillance Standard Operating Procedures for details and instructions.

Become a Citizen Scientist

If you are interested in helping TCWP conduct active field surveillance for ticks, please submit the form below. Citizen Scientists will receive training on surveillance protocols and are expected to conduct several surveys throughout the season.