Murray Valley Encephalitis in Grand Rapids, Michigan

Murray Valley encephalitis (MVE) is a serious but rare infection caused by the Murray Valley encephalitis virus, a mosquito-borne virus that can affect the brain. While this disease is more commonly reported in other parts of the world, global travel and changing climate patterns make mosquito-borne illnesses an important concern for residents of Grand Rapids and West Michigan.

If you live in or visit the Grand Rapids area—especially during warm, humid months—it’s important to understand how to prevent mosquito bites and when to seek medical care.

How Murray Valley Encephalitis Spreads

Spread by infected mosquitoes

Murray Valley encephalitis virus is spread to humans through the bite of an infected mosquito. The virus:

  • Is not spread directly from person to person
  • Is usually picked up by mosquitoes when they feed on infected water birds, such as herons or egrets
  • Is not spread to humans by touching or handling birds or other animals

In Grand Rapids and across Michigan, mosquitoes are most active:

  • From late spring through early fall
  • After periods of heavy rain or flooding, which create more standing water where mosquitoes can breed
  • Around wetlands, river corridors, and lakes, including areas along the Grand River and near the many inland lakes in West Michigan

While MVE itself is rare in the United States, these same environmental conditions also increase the risk of other mosquito-borne diseases that are more common in Michigan, such as West Nile virus and Eastern equine encephalitis (EEE). The prevention steps are very similar.

Who Is at Higher Risk in West Michigan?

People may be at higher risk of mosquito-borne infections, including Murray Valley encephalitis, if they:

  • Live, work, or spend a lot of time outdoors near wetlands, rivers, or wooded areas in Kent County and surrounding counties
  • Fish, camp, or hike frequently along the Grand River, Reeds Lake, or other local waterways
  • Work in outdoor occupations, such as construction, landscaping, farming, or park maintenance
  • Spend time outside at dawn or dusk, when many mosquitoes are most active

Older adults, young children, and people with weakened immune systems may be more likely to develop severe illness if infected.

Symptoms of Murray Valley Encephalitis

Most people infected with Murray Valley encephalitis virus:

  • Have no symptoms, or
  • Have mild, flu-like symptoms and make a full recovery

When symptoms do occur, they usually begin 7 to 12 days after being bitten by an infected mosquito. In some cases, symptoms may appear as early as 5 days or as late as 28 days.

Early or mild symptoms

Symptoms can include:

  • Fever
  • Headache or severe headaches
  • Muscle aches
  • Nausea and vomiting
  • Tiredness or feeling unwell

These symptoms can resemble flu or other viral illnesses common in Michigan, especially in late summer and early fall.

Signs of severe infection (encephalitis)

A small number of people (about 1 in 800) develop encephalitis, which is inflammation (swelling) of the brain. This is a medical emergency.

Severe symptoms may include:

  • Stiff neck
  • Sensitivity to bright light (photophobia)
  • Seizures or fits (especially in young children)
  • Drowsiness or difficulty staying awake
  • Confusion, disorientation, or personality changes
  • Loss of consciousness or coma

Encephalitis can lead to permanent brain damage or death if not treated promptly.

When to Seek Medical Care in Grand Rapids

Anyone with serious symptoms should seek urgent medical attention

Call 911 or go to the nearest emergency department (such as Corewell Health Butterworth Hospital or Trinity Health Grand Rapids) immediately if you or someone you are caring for has:

  • Seizures
  • Trouble staying awake or responding
  • Sudden confusion or changes in behavior
  • Severe headache with stiff neck and fever
  • Loss of consciousness

If you have milder symptoms (fever, headache, muscle aches) after multiple mosquito bites—especially if you have been near wooded or wetland areas—contact:

  • Your primary care provider in Grand Rapids
  • An urgent care clinic (Spectrum Health, Metro Health, or Mercy Health urgent care centers)
  • The Kent County Health Department for guidance on mosquito-borne illnesses

Diagnosis of Murray Valley Encephalitis

MVE can be diagnosed with medical tests performed in a hospital or clinic. Your healthcare provider may order:

  • Blood tests to look for antibodies to the virus
  • A lumbar puncture (spinal tap) to test the fluid around the brain and spinal cord
  • Urine tests in some cases
  • Brain imaging (CT or MRI) if encephalitis is suspected

Testing can show acute or past infection

  • Blood tests can sometimes show if the infection is recent (acute) or occurred in the past
  • Repeat testing is often needed to confirm the diagnosis

Because MVE is rare, your provider may also test for other, more common mosquito-borne diseases in Michigan, such as West Nile virus or EEE.

Treatment for Murray Valley Encephalitis

No specific antiviral treatment or vaccine

There is no effective antiviral treatment and no widely available vaccine for Murray Valley encephalitis at this time.

Supportive care

Treatment focuses on supporting the body while it fights the virus and easing symptoms. This may include:

  • Fluids to prevent or treat dehydration
  • Medications to reduce fever and pain
  • Close monitoring of breathing, blood pressure, and brain function

Hospital care may be needed

People with severe infection or encephalitis may need:

  • Hospital admission, often to an intensive care unit (ICU)
  • Breathing support (ventilator) if they cannot breathe well on their own
  • Medications to control seizures
  • Rehabilitation services (physical, occupational, or speech therapy) if there is brain injury

In Grand Rapids, serious cases are typically managed at major hospitals such as:

  • Corewell Health (Spectrum Health) Butterworth Hospital
  • Trinity Health Grand Rapids
  • University of Michigan Health–West (Metro Health)

Prevention: Protect Yourself from Mosquito Bites in Grand Rapids

Because there is no vaccine or specific treatment, prevention is the best protection against Murray Valley encephalitis and other mosquito-borne diseases.

Personal protection outdoors

When you’re outside in Grand Rapids—especially near the Grand River, local parks, or wooded areas—take these steps:

  • Cover up
    • Wear long sleeves and long pants
    • Choose loose-fitting, light-colored clothing (mosquitoes are attracted to dark colors)
  • Use insect repellent
    • Use repellents containing DEET or picaridin on exposed skin
    • Follow the product label carefully
    • Reapply as directed, especially if you are sweating or swimming
  • Plan outdoor activities wisely
    • Limit time outside at dawn and dusk, when many mosquitoes are most active
    • Use screens, fans, or mosquito netting on porches, tents, and open windows

Protecting babies and children

  • Always check the insect repellent label for age recommendations
  • For babies, you may apply repellent to their clothing instead of directly on their skin if advised on the label
  • Avoid applying repellent to:
    • Hands (children may put them in their mouths)
    • Eyes, mouth, or open cuts
  • Use mosquito netting over strollers, baby carriers, and playpens when outdoors

If you’re unsure which products are safe for your child, ask your pediatrician or a local healthcare provider in Grand Rapids.

Reduce mosquitoes around your home

Mosquitoes breed in standing water, which can be common around Grand Rapids after spring thaws, summer storms, and fall rains. At least once a week:

  • Empty and scrub:
    • Buckets
    • Birdbaths
    • Pet water bowls
    • Flower pot saucers
    • Kiddie pools
  • Clean gutters so water can drain properly
  • Cover or properly maintain rain barrels
  • Make sure window and door screens fit tightly and have no holes

You can also contact the Kent County Health Department or Grand Rapids Public Health for information on local mosquito control programs and seasonal advisories.

Local Resources in Grand Rapids, MI

If you are concerned about mosquito-borne illness or have symptoms:

  • Your primary care provider or local clinic
    • Many practices are affiliated with Spectrum Health, Trinity Health Grand Rapids, Metro Health, or Mercy Health
  • Urgent or emergency care
    • Visit the nearest emergency department if you have severe symptoms
  • Kent County Health Department
    • Information on mosquito surveillance, local disease activity, and prevention programs
  • Grand Rapids Public Health / City of Grand Rapids
    • Updates on community health alerts and environmental health services

For non-emergency health questions, you can also use nurse advice lines offered by major health systems in Grand Rapids (check your insurance card or health system website for 24/7 nurse triage numbers).

Key Points for Grand Rapids Residents

  • Murray Valley encephalitis (MVE) is a serious but rare mosquito-borne infection that can cause brain inflammation.
  • There is no specific treatment or vaccine for MVE.
  • Most infected people have no or mild symptoms, but a small number develop life-threatening encephalitis.
  • Symptoms can include fever, headache, muscle aches, nausea, vomiting, stiff neck, sensitivity to light, seizures, confusion, or loss of consciousness.
  • Anyone with severe symptoms should seek urgent medical attention at a local emergency department in Grand Rapids.
  • The best prevention is to protect yourself and your family from mosquito bites and reduce standing water around your home.
  • Stay informed through Kent County Health Department and local healthcare providers about mosquito-borne disease activity in West Michigan.

By taking simple, consistent steps to prevent mosquito bites, Grand Rapids residents can reduce their risk of Murray Valley encephalitis and other mosquito-borne illnesses common in Michigan’s warm-weather months.