Hantavirus is a family of viruses spread mainly by rodents and can cause varied disease syndromes in people worldwide. In North America, hantavirus infections are spread by deer mice, cotton rats, and rice rats. People can get hantavirus when they breathe in air contaminated with the virus after touching mouse or rat urine, droppings, or nesting materials that contain the virus. Some hantaviruses can cause hantavirus pulmonary syndrome (HPS), which can be fatal. Early symptoms of HPS include fatigue, fever, and muscle aches, especially in the large muscle groups—thighs, hips, back, and sometimes shoulders. These symptoms are universal. There may also be headaches, dizziness, chills, and abdominal problems, such as nausea, vomiting, diarrhea, and abdominal pain. About four to 10 days after the initial phase of illness, the late symptoms of HPS appear. These include coughing and shortness of breath.
How Do People Get Infected with Hantavirus?
People are usually exposed to hantavirus by breathing air contaminated by rodent urine, droppings, or saliva that contains the virus. People can also become infected when they touch something contaminated with rodent urine, droppings, or saliva, and then touch their nose or mouth. Hantavirus infection has not been shown to spread from person to person. Rare cases are thought to have occurred from a bite from an infected rodent. Specific risk factors for hantavirus infection include:
- Having contact with rodents or disturbing rodent nesting areas and burrows, especially in rural cabins or outbuildings that have not been used for a while
- Cleaning areas where rodents have recently been active
- Working in areas where wild rodents are known to live, such as logging operations and national parks
- Living in dwellings with indoor rodent infestations
The deer mouse is the primary reservoir of Sin Nombre virus, the hantavirus strain that causes most hantavirus infections in North America. The deer mouse is found throughout North America. Deer mice are mostly nocturnal and do not prefer highly populated areas. They inhabit remote cabins, barns, sheds, garages, and the peridomestic environment.
What Are the Symptoms of Hantavirus?
Hantavirus causes two primary types of disease in humans, hemorrhagic fever with renal syndrome and hantavirus pulmonary syndrome. Symptoms vary depending on the specific virus but may include:
Early Symptoms
The early symptoms of hantavirus are similar to the flu and can include:
- Fever
- Chills
- Body aches
- Fatigue
- Headache
- Nausea and vomiting
- Diarrhea
- Abdominal pain
These initial symptoms develop between 1 and 5 weeks after exposure to the virus. The acute phase lasts for about 3-7 days.
Late Symptoms of HPS
After the acute phase, late symptoms of hantavirus pulmonary syndrome (HPS) can develop quickly. These include:
- Coughing
- Shortness of breath
- Fluid buildup in the lungs
- Low blood oxygen levels
As the lungs fill with fluid, breathing becomes increasingly difficult. HPS can rapidly progress to respiratory failure and shock. About 40% of HPS cases are fatal.
Hemorrhagic Fever Symptoms
Some hantaviruses cause hemorrhagic fever with renal syndrome (HFRS), which has different symptoms. These include:
- Low blood pressure
- Kidney failure
- Internal bleeding
- Fluid accumulation under the skin
- Low platelet counts
HFRS has a mortality rate of 0.1% to 15% depending on the virus.
Who is at Risk for Hantavirus?
While anyone exposed to hantavirus is at risk for infection, some groups have a higher risk:
- People who work with rodents – farmers, ranchers, pest control workers
- People who live in rodent-infested dwellings
- People exposed to rodents in cabins, worksheds, and other enclosed spaces
- Hikers and campers who sleep on infested ground
Men account for around 90% of HPS cases in the United States. The reasons for this gender difference are not fully understood but likely relate to occupational and recreational exposures. Hantavirus occurs year-round but peaks in spring and summer when outdoor activities increase.
Diagnosing Hantavirus
Diagnosing hantavirus early is critical but challenging because early flu-like symptoms are easily mistaken for other illnesses. Hantavirus should be suspected if:
- Flu-like symptoms develop 1-5 weeks after rodent exposure
- The patient works with rodents or has been around rodent-infested areas
- The patient develops shortness of breath after initial flu-like symptoms
Blood tests can detect hantavirus antibodies but results may take days. Samples of blood, saliva, or tissue may also be tested for viral RNA. Chest X-rays or CT scans often show fluid in the lungs. Low oxygen levels can be revealed through pulse oximetry. There are no rapid tests available.
Hantavirus Treatment
There are no vaccines or specific treatments for hantavirus infections. However, supportive medical care can help patients through the course of the illness. For HPS, care focuses on managing respiratory complications and maintaining adequate oxygenation. Dialysis may be needed for kidney function support. Extracorporeal membrane oxygenation (ECMO) can provide temporary lung and heart support for severe HPS cases. Patients usually need intensive care. With supportive care, the mortality rate for HPS is around 40%.
Preventing Hantavirus Infections
The best way to prevent hantavirus is to avoid contact with rodents and eliminate any rodent infestations. Prevention tips include:
- Seal up any holes or openings in homes and sheds larger than 1/4 inch to prevent rodent entry
- Clear brush, grass, and junk from around structures
- Elevate hay, woodpiles, and garbage cans off the ground
- Keep food in airtight containers and dispose of garbage regularly
- Use disinfectants or bleach solution to clean up rodent urine and droppings
- Wear protective gloves, mask, and goggles when cleaning rodent-infested areas
- Avoid sweeping or vacuuming rodent droppings – dampen first to avoid stirring up dust
- Ventilate infested areas for at least 30 minutes before working
When hiking or camping:
- Avoid sleeping near rodent burrows or droppings
- Store food in rodent-proof containers
- Use tents with floors, cots, and sleeping pads
There is currently no FDA-approved vaccine for preventing hantavirus infections in humans. However, research is ongoing to develop effective vaccines. Strict control of rodent populations and public education can help lower risk. Promptly seeking medical care for flu-like symptoms after rodent exposure allows for better outcomes with supportive treatment.
Conclusion
Hantavirus is spread by infected rodents and causes varied disease syndromes. In North America, the main carrier is the deer mouse. Hantavirus pulmonary syndrome starts with universal flu-like symptoms then progresses to cough and shortness of breath as fluid builds up in the lungs. Hemorrhagic fever with renal syndrome causes low blood pressure, kidney failure, and internal bleeding. While anyone can get hantavirus, those with occupational or recreational rodent exposure are at highest risk. There is no specific treatment, but supportive medical care can greatly improve outcomes. Rodent control and avoiding contact with droppings are key for prevention. Hantavirus should be suspected if flu-like symptoms develop after potential rodent exposure.
