Hantavirus Pulmonary Syndrome (HPS)
Last Updated 05/07/2020
Author:Masooma Aqeel, MD, and Jayshil J. Patel, MD
About Hantavirus Pulmonary Syndrome (HPS)
- People exposed to rodent urine, droppings, or saliva or who have traveled recently to rural areas are at risk for developing hantavirus pulmonary syndrome (HPS).
- Symptoms of HPS include abrupt onset of fever, chills, weakness, nausea, vomiting, and abdominal pain followed by difficulty breathing.
- HPS can be fatal if not diagnosed and treated quickly.
- There’s no vaccine to protect against HPS. Treatment focuses on helping you breathe and reducing your symptoms.
Hantavirus pulmonary syndrome (HPS) is a rare viral illness that can be life threatening. The virus is transmitted to humans when they inhale urine, droppings, or saliva from infected rodents, such as rats and mice. Even healthy adults can develop this illness.
What causes HPS?
HPS was first identified in the southwestern United States in 1993, when a group of healthy adults suddenly had trouble breathing followed by respiratory failure. Blood samples from these patients tested positive for hantavirus. An rodent-catching campaign led to the discovery of a large population of infected deer mice near these patients. Between 1993 and 2013, more than 600 cases of HPS were seen in both North and South America.
How HPS affects your body
Hantavirus can infect both rodents and humans. Rodents don’t seem to get sick, but humans can develop severe symptoms and even die.
Hantavirus enters your body when you inhale virus particles from infected rodent urine, droppings, or saliva. The virus affects the heart, lungs, and kidneys, reducing their ability to function. The virus also enters the bloodstream, where it continues to spread and cause further organ damage.
Your body attempts to fight the virus by creating inflammation. The combination of the virus infecting your organs and the inflammation that your body produces leads to intense damage to your organs and tissue. The virus causes blood vessels throughout your body to “leak.” In the lungs, leaky blood vessels cause flooding in the air sacs, making breathing difficult. When the virus infects your heart, the damage reduces your heart’s ability to pump blood through your body. When your heart can’t pump and your blood vessels leak, blood flow is reduced, and your blood pressure drops. (In other words, your body goes into shock). Oxygen is no longer available to the cells in your body, which can rapidly lead to organ failure and death.
HPS is an extremely serious and life-threatening disease. According to the Centers for Disease Control and Prevention (CDC), 728 cases of HPS were identified in the United States between 1993 and 2014. About a third of these patients died. Cases have been identified in 34 states, with more than 90% identified in states west of the Mississippi River.
Several strains of the virus have been identified, as well, with the sin hombre virus and Andes virus associated with the most severe form of the illness. Mild infections can cause death in about 10% to 30% of cases. In severe cases, fatality rates are as high as 50%.
Symptoms of HPS
HPS has 4 phases:
- Phase 1: Incubation. The virus is inhaled into the lungs. Immune cells ingest the virus, which is then transported through the bloodstream to other organs. This phase lasts 2 to 3 weeks, but there are no symptoms, yet.
- Phase 2: Fever, dry cough, body aches, headaches, diarrhea, and abdominal pain appear. Heart and lung failure can develop during this phase, as well. Blood vessels become leaky, and fluid builds up in the lungs. Bleeding and heart failure follow. This phase lasts 2 to 8 days, and all these changes lead to shock and often death.
- Phase 3: Changes in urination. Patients may alternate between making a lot of urine and making very little urine.
- Phase 4: Recovery. Patients who survive the first 3 phases begin to improve, and their organs start to function properly again. It may take several weeks before patients feel completely well again. The symptoms of HPS seem to disappear as quickly and dramatically as they first appeared.
Key symptoms and signs to watch for (especially if you have a history of rodent exposure) include:
- Fever higher than 101 degrees F, chills, body aches, and headaches
- Nausea, vomiting, and abdominal pain
- New rash (faint red spots)
- A dry cough, followed rapidly by difficulty breathing
What are the risk factors of HPS?
People who live in rural areas and are exposed to wild rodents are at risk. There have been cases of patients developing HPS who haven’t had any obvious exposure to rodents, but those patients may not have realized that they had been exposed to rodents. If you live in a rural area and know of others in your community who have been diagnosed with HPS, be alert to suspicious symptoms, and call your health care provider: Early diagnosis leads to early treatment.
Diagnosing HPS can be challenging. Its symptoms are vague, and your health care provider can easily mistake them for other viral illnesses, such as flu. Your provider must suspect hantavirus so that he or she can order additional tests for HPS.
How is HPS diagnosed?
Diagnosis relies on finding antibodies against hantavirus in your bloodstream. Antibodies are proteins that your immune system produces to fight infections. So, if you have antibodies against hantavirus, your provider can use them to confirm that you have a hantavirus infection.
If you have unexplained fever, body aches, abdominal pain, diarrhea, headaches, dry cough, or severe difficulty breathing, you should see your health care provider – especially if you have been exposed to large rodent populations.
There is no cure for HPS, but your health care team can manage your symptoms with oxygen therapy, fluid replacement, and medications to support blood pressure. Because your ability to breathe can deteriorate rapidly, you should be admitted to a hospital that has an intensive care unit with access to mechanical ventilation (a respirator) and kidney dialysis.
Sometimes, health care providers use antiviral drugs, such as ribavirin, to treat other strains of hantavirus and associated infections. However, no large clinical trials have proven that these medications work.
Living with HPS
About 4 out of 10 patients with HPS don’t survive their illness. Patients who do survive usually recover quickly. Supportive treatment during the most severe stages of the illness helps your body rest and defend itself as the virus runs its course.
With treatment, HPS can resolve completely, and you can return to your normal life. No long-term (chronic) infection with hantavirus has been reported, and there don’t seem to be long-term effects from HPS.
Managing and preventing HPS
The best treatment for HPS is to prevent infection in the first place. To do that, minimize your exposure to rodents:
- Seal up (using cement or other patching material) holes or cracks through which rodents can enter your home or work environment. Remember, they can get through much smaller openings than you may think!
- Identify potential nesting sites, and clean up debris, clear bushes, and trap rodents to remove them.
- Open and air out any rodent-infested spaces that have been shut up for a long time before you enter them.
- If you know of an area heavily infested with rodents, contact state or federal health officials about cleaning the area up.
The American Lung Association recommends that patients and caregivers join its Living With Lung Disease Support Community to connect with others facing this disease. You can also call the American Lung Association’s Lung HelpLine at 1-800-LUNGUSA to talk to a trained respiratory professional who can help answer your questions and connect you with additional support.
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Questions to ask your health care provider
Making notes before your visit and taking a trusted family member or friend with you can help you through the first appointment with your provider. For example, ask:
- Have there been cases of hantavirus infections reported near my home or work environment?
- What are the common surroundings that are prone to rodent exposure (alleys; dark, closed rooms; shrubs; farm spaces)?
- Can pet mice and squirrels be infected?
- What are the most common symptoms of HPS?
- How many days does it take for symptoms of infection to appear?
- How can I prevent infection?