The hantaviruses are a relatively newly discovered genus of viruses. Several thousand United Nations soldiers became ill with “Korean haemorrhagic fever” (now called HFRS) during the Korean War. This outbreak sparked a 25-year search for the etiologic agent. The isolation of Hantaan virus, or HTNV, was reported by Ho-Wang Lee of South Korea in 1978.
In 1993, an outbreak of Hantavirus pulmonary syndrome (HPS, see below) occurred in the Four Corners region in the southwestern United States. The viral cause of the disease was found only weeks later and was called the Sin Nombre virus (SNV, in Spanish, “Virus sin nombre”, for “nameless virus”). Its rodent host, Peromyscus maniculatus, was first identified by Terry Yates, a professor at the University of New Mexico. In addition to Hantaan virus and Sin Nombre virus, several other hantaviruses have been implicated as etiologic agents for either HFRS or HPS. Other identified hantaviruses have not been associated with disease.
What is hantavirus pulmonary syndrome?
Hantavirus pulmonary syndrome (HPS) is a lung infection caused by viruses found in the saliva, urine, and droppings of some rodents. The illness is rare but can be deadly.
The first known outbreak of HPS in the United States occurred in 1993. Most of the U.S. cases have happened during the spring and summer in the Southwest.
What causes HPS?
Most cases of HPS in the U.S. are caused by one type of hantavirus found in the deer mouse. People can become infected by:
- Breathing in tiny airborne particles that come from rodent urine.
- Touching rodent urine, saliva, or droppings.
- Coming in contact with dust contaminated with the virus.
- Being bitten by an infected mouse.
North America has never had a known case of one person spreading the illness to another. And people do not get HPS from farm animals, pets, or insects. But your pet may bring home an infected rodent.
What is the infectious agent that causes hantavirus pulmonary syndrome?
Hantavirus pulmonary syndrome is caused by the Sin Nombre virus. This virus is a type of hantavirus. Most hantaviruses attack the kidneys, but the Sin Nombre virus attacks the lungs. It infects the walls of the capillaries (tiny blood vessels in the lungs), making them leak and flooding the lungs with fluid.
What are the symptoms?
Symptoms usually start 2 to 3 weeks after a person has been exposed to the virus. Early symptoms may include:
- A fever and chills.
- Muscle aches and headache.
- Fatigue.
- Nausea, vomiting, diarrhea, and belly pain.
You quickly will become very sick. Within a few days, you’ll start to have more serious symptoms, such as:
- Shortness of breath.
- Coughing.
- A fast heartbeat and fast breathing. These are signs of fluid buildup in the lungs (pulmonary edema).
After a person with HPS starts having trouble breathing, he or she may die within hours. Most deaths occur within 1 to 2 days after severe breathing problems begin. About 4 out of 10 people who get HPS do not survive.1
How is HPS diagnosed?
Your doctor will do a physical exam and ask you questions about your symptoms, past health, and exposure to rodents. You may have other tests, such as chest X-rays, a complete blood count, and anoxygen saturation test.
Your doctor will know for sure that you have HPS only if you have the signs of HPS and if tests show that the virus is or has been in your blood or tissues.
How is it treated?
HPS requires treatment in a hospital right away, even if the case is mild. You will get treatment to support you through the illness, such as intravenous (IV) fluids and medicines. You may need a ventilator to help you breathe.
People who survive the illness usually recover quickly. Most are able to leave the hospital after 7 days.
Where is hantavirus pulmonary syndrome found?
Hantaviruses are found in rodents in different parts of the world. Each hantavirus has a preferred rodent host. The Sin Nombre virus is carried by the deer mouse, the cotton rat, and perhaps other rodents common throughout North America. These rodents live in semi-rural and rural areas and infest camps, old buildings, barns, and homes.
How do people get hantavirus pulmonary syndrome?
Wild rodents spread HPS to people. The Sin Nombre virus is passed in the saliva, urine, and droppings of infected rodents. The virus can live for a few days in contaminated dirt and dust. People are infected when they breathe in tiny particles of these materials in dust from places where rodents are living and active. People can also be infected by handling contaminated materials and then touching the mouth or nose.
HPS is not spread from person to person. Cats and dogs do not spread the illness either, although they can bring infected rodents into contact with humans.
How is hantavirus pulmonary syndrome diagnosed?
Because the early symptoms are not specific and vary from person to person, HPS is hard to identify in its early stages. It is usually detected only when it affects the lungs and causes breathing problems.
Who is at risk for hantavirus pulmonary syndrome?
Unlike many illnesses that mainly strike people with weakened immune systems, HPS has hit mostly strong, healthy persons. Those who work, play, or live in closed spaces with active rodent infestation are at risk, although the chances of infection are low. The risk to campers, hikers, and tourists is very small.
People who should take special precautions against HPS are: 1) people who often handle or are exposed to rodents, such as wildlife biologists and exterminators, 2) people who clean or work in attics or crawl spaces where rodents might be living and active, and 3) people who clean or renovate buildings that might be actively infested with rodents.
Can HPS be prevented?
The best way to prevent hantavirus infection is to avoid contact with rodents and their droppings. If you live in or visit an area where the viruses have been found:
- Set metal traps to catch rodents, and block areas where rodents can get into your home.
- Keep garbage in tightly covered containers.
- Clean up rodent bedding sites around your house. You may need to call a professional exterminator. If you do the cleanup yourself, be very careful and:
- Air out closed buildings well before you go inside to clean them.
- Wear gloves and a mask.
- Clean with a wet mop and disinfectant soap (rather than sweeping or vacuuming).
- When you are camping or hiking, avoid rodent droppings, burrows, and possible rodent shelters. Use only bottled water or water that has been disinfected.
- Do not use a cabin or any other closed shelter that has rodents until it has been aired out, cleaned, and disinfected.
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