Mosquitoes can spread many illnesses, one of which is Cache Valley virus. Cache Valley virus doesn’t often infect humans in the U.S., but when it does it can lead to encephalitis, meningitis, and even death.
What Is Cache Valley Virus?
Cache Valley virus is a virus that causes fever and flu-like symptoms. This virus is zoonotic, meaning it can spread between humans and animals, including bugs and insects. Lyme disease, rabies, and West Nile virus are all examples of zoonotic diseases.
Cache Valley virus most commonly affects sheep and goats. The virus looks very different in these animals, causing issues like infertility, pregnancy loss, and birth defects. Other animals that can be infected with Cache Valley virus include cattle, deer, and horses.
What Causes Cache Valley Virus in Humans?
Cache Valley virus spreads to humans through bites from infected mosquitoes. Mosquitoes can become infected with Cache Valley virus by taking a blood meal from an infected animal. They then pass that virus on to the next human or animal they bite.
There is no existing evidence that a mosquito can become infected if it bites a human who has the virus. Humans don’t typically have a high enough level of Cache Valley virus in their blood to pass it on. As a result, humans are labeled as “dead-end” hosts, meaning that if the virus ends up in a human, it will not be passed on.
While several different types of mosquitoes can carry the virus, it’s rarely found in humans. So far, fewer than 10 U.S. cases have been reported. Cases have been discovered in Missouri, New York, North Carolina, and Wisconsin. All cases have happened during warmer months, from late spring to early fall.
There is a possibility that Cache Valley virus is more common than the medical community is aware of. Because the virus is rare in humans and the initial symptoms of the virus are similar to that of other illnesses, labs don’t test for it very often.
Cache Valley Virus Symptoms
The initial symptoms of Cache Valley virus include:
- Fatigue
- Fever
- Headache
- Nausea
- Rash
- Vomiting
The virus may progress to cause encephalitis and meningitis, which can be deadly.
Encephalitis. Encephalitis is a condition in which the tissues of the brain become inflamed. This can happen because of an autoimmune response or due to an infection, such as Cache Valley virus. Symptoms of encephalitis may include:
- Anxiety
- Coma
- Confusion
- Double vision
- Fever
- Headache
- Hearing or speech impairment
- Hallucinations
- Irritation
- Loss of consciousness
- Memory loss
- Psychosis
- Seizures
- Sensitivity to light and sound
- Stiffness in your neck
- Weakness or partial paralysis in your arms and legs
The first documented human patient diagnosed with Cache Valley virus became ill with encephalitis and did not survive.
Meningitis. Meningitis is a condition in which the fluid and membranes around your brain and spinal cord become inflamed. Most cases of meningitis in the U.S. are caused by a viral infection such as Cache Valley virus, although infections caused by bacteria, fungi, and parasites can lead to meningitis as well. Symptoms of meningitis include:
- Confusion
- Difficulty concentrating
- Difficulty walking
- Headache that includes nausea and vomiting
- High fever that comes on suddenly
- Lack of appetite and thirst
- Seizures
- Sensitivity to light
- Sleepiness
Cache Valley Virus Diagnosis
If your doctor suspects that you have Cache Valley virus, there are two types of tests that they may order.
The first type looks at samples of blood or cerebrospinal fluid, the fluid within your spinal cord and brain, for Cache Valley virus antibodies. Antibodies are proteins your body produces to remove foreign substances like bacteria and viruses. The other type of test, a viral culture, takes blood, cerebrospinal fluid, or tissue samples and looks for viral growth.
If you’re diagnosed with Cache Valley virus, your results must be sent to local health authorities. This is so that the proper authorities can prepare for possible outbreaks.
Cache Valley Virus Treatment
There is no cure for Cache Valley virus.
Mild cases of Cache Valley virus involve treating the symptoms and taking care of your body. Over-the-counter pain relievers can reduce pain and fever. Take care of your body by getting plenty of rest and getting plenty of fluids.
More severe cases of Cache Valley virus will need supportive measures. This may include intravenous fluids or medications to prevent vomiting. Patients who end up with encephalitis or meningitis may need additional supportive care.
Encephalitis. Supportive measures for encephalitis may include:
- Antiseizure medications or treatment
- Breathing tubes if you’ve lost consciousness
- Feeding tubes if you’ve lost consciousness
- Urinary catheter if you’ve lost consciousness
Meningitis. Supportive care for meningitis may include:
- Antiseizure medications or treatment
- Corticosteroids to reduce swelling in your brain
Preventing Cache Valley Virus
Cache Valley virus is spread to humans through mosquito bites, and as a result, the best way to avoid infection with Cache Valley virus is to avoid mosquito bites.
Mosquitoes are responsible for more human deaths than any other creature in the world. Some estimates place fatalities from mosquito-borne illnesses at over one million each year. The most common mosquito-borne viruses in the U.S. include:
- Dengue virus. Dengue virus causes dengue fever. An estimated 390 million dengue virus infections happen each year, causing 36,000 deaths.
- West Nile virus. West Nile virus is the most common mosquito-borne virus in the U.S. In 2021, 2695 cases of West Nile virus were reported to the CDC. Of those, 1885 were reported to have caused a neuroinvasive disease such as encephalitis or meningitis.
- Zika virus. Cases of Zika virus spiked in 2016 but have dropped since then. In 2020, there were 61 cases of Zika reported to the CDC.
There are a few things you can do to reduce your exposure to mosquitoes.
Insect repellent. The best way to avoid mosquitoes is by applying an EPA-registered insect repellent with one of the following active ingredients:
- 2-undecanone
- DEET
- IR3535
- Oil of lemon eucalyptus (OLE)
- Para-menthane-diol (PMD)
- Picaridin
Wear the right gear. To protect your skin from mosquito bites, wear long-sleeved shirts and long pants. Gear treated with permethrin will also help prevent mosquito bites.
Keep mosquitoes out of your environment. Take steps to keep mosquitoes out of your home and yard. Try things like:
- Using screens on windows and doors, and repairing screen holes right away.
- Emptying places with standing water, like buckets, toys, and birdbaths.
By avoiding mosquito bites, you’re keeping yourself safe from Cache Valley virus as well as other mosquito-borne viruses and illnesses.