Hantavirus Pulmonary Syndrome (HPS): Topic Overview

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Topic Overview

What is hantavirus pulmonary syndrome?

Hantavirus pulmonary syndrome (HPS) is a potentially deadly respiratory illness caused by certain types of hantaviruses, which are viruses found in the saliva, urine, and droppings of some rodents.

Although hantaviruses are found worldwide, the first outbreak in the United States was identified in 1993. Most cases of HPS have been reported in the southwestern region, in the "four corners" states of New Mexico, Arizona, Colorado, and Utah. But 31 states have reported cases of the infection.

HPS tends to occur in desert areas in seasons of above-average rainfall. Although HPS can develop throughout the year, most cases have occurred in the spring and summer.

What causes HPS?

In the U.S., most cases of HPS are caused by one strain of hantavirus primarily carried by the deer mouse. People can become infected by:

• Breathing in tiny airborne particles formed when rodents urinate.
• Coming into direct contact with infected rodent urine, saliva, or droppings.
• Being exposed to dust particles contaminated with the virus.

No cases of person-to-person spread have been reported in the U.S. HPS has not been spread to people from farm animals, pets, or insects. But your pet may bring an infected rodent into contact with you.

What are the symptoms?

HPS causes people who are generally healthy to suddenly become very sick. About 2 weeks (possibly a range from 1 to 5 weeks) after being infected with the virus, the person develops a fever and muscle aches. Other symptoms of HPS may include a headache, chills, nausea and vomiting, abdominal pain, and shortness of breath.

Within a few days, these symptoms may become worse and may be accompanied by coughing and severe shortness of breath. Breathing becomes rapid and more difficult as the lungs fill with fluid (pulmonary edema). After people become short of breath, they may die within hours. Most deaths caused by HPS occur within 1 to 2 days of when severe shortness of breath first began.

During the initial outbreak of the virus in 1993, about 70% of people who developed HPS died.¹ Today, the death rate has fallen to about 40%, perhaps because of improved treatment with fluids and other supportive care early in the illness.²

How is HPS diagnosed?

A careful medical history, physical exam, and other tests (such as a complete blood count and oxygen saturation test) may suggest HPS. These other tests may provide helpful information in the early stages of HPS or when there are breathing problems caused by HPS. But for you to be accurately diagnosed with HPS, tests must show that, along with having symptoms of the condition, the virus is or has been in your blood or tissues.

How can it be treated?

When symptoms of HPS develop, immediate intensive treatment is needed. Treatment is mainly supportive and includes using assisted mechanical breathing (mechanical ventilation) and maintaining fluid and electrolyte balance and blood pressure.

Can HPS be prevented?

The best way to prevent infection with hantaviruses is to avoid contact with rodents and their droppings. If you live in an area where hantaviruses have been found, and you believe your home may have a rodent infestation, set metal traps to catch rodents, and close all possible rodent entries into your home. Clear possible rodent bedding sites from around your house, and keep garbage in tightly covered containers. For more information, see the U.S. Centers for Disease Control (CDC) Web site at www.cdc.gov/ncidod/diseases/hanta/hps/index.htm.

Use extreme caution when cleaning rodent-infested areas. If you have an area that is heavily infested with rodents, call a professional exterminator to remove them.

Frequently Asked Questions

Last updated:	March 03, 2008
Author:	Maria G. Essig, MS, ELS
Reviewed By:	Anne C. Poinier, MD - Internal Medicine, Mark A. Rasmus, MD - Pulmonary, Critical Care and Sleep Medicine
Editors:	Susan Van Houten, RN, BSN, MBA, Pat Truman, MATC