Health Encyclopedia

Hantavirus

Definition

Hantavirus is a disease characterized by symptoms that resemble the flu, followed by respiratory failure.

Alternative Names

Hantavirus pulmonary syndrome

Causes, incidence, and risk factors

Hantavirus has probably caused people to get sick for years in the United States, but it was not recognized until recently.

A 1993 outbreak of fatal respiratory illness on an Indian reservation in the Four Corners area led epidemiologists to the discovery of hantavirus as the cause. (The Four Corners area is at the border of Utah, Colorado, New Mexico, and Arizona.) Since that discovery, hantavirus disease has been reported in every western state, and in many eastern states.

Hantavirus is carried by rodents, particularly deer mice, and is present in their urine and feces. The virus does not cause disease in the carrier animal. Humans are thought to become infected when they are exposed to contaminated dust from the nests or droppings of mice.

The disease is not, however, passed between humans. Contaminated dust is often encountered when cleaning long-vacated dwellings, sheds, or other enclosed areas.

The federal Centers for Disease Control and Prevention (CDC) reported that rodents carrying hantavirus have been found in at least twenty national parks and that it is possible that the virus is in all of the parks.

Epidemiologists at the CDC suspect that campers and hikers may have a higher chance of contracting the disease than most people. This is due to the fact that they pitch tents on the forest floor and lay their sleeping bags down in musty cabins.

So far, however, of the more than 100 cases that have been reported in the U.S., only two were directly linked to camping or hiking. Most people who are exposed have come into contact with rodent droppings in their own homes.

The initial symptoms of hantavirus disease closely resemble the flu. The disease begins abruptly with fever, chills, muscle aches , headache, nausea and vomiting, and malaise. A dry cough may be present. The fever may be higher in younger people than in older people.

For a very short period, the infected person feels somewhat better, but this is followed within a day or two by an increased respiratory rate caused by a seepage of fluid into the lungs. The initial shortness of breath is subtle and the patient may be unaware of it, but progression is rapid. The patient ultimately develops respiratory failure.

An effective treatment for hantavirus is not yet available. Even with intensive therapy, more than half of the diagnosed cases have been fatal.

Symptoms

Chills
Dry cough
Fever
General ill feeling (malaise)
Headache
History of exposure to mice droppings, nest, or contaminated dust
Muscle aches
Rapid shallow breathing
Respiratory failure
Shortness of breath

Signs and tests

A doctor may notice signs of:

Hypoxia (decreased levels of oxygen in the blood, causing the skin to have a bluish tinge)
Hypotension (decreased blood pressure)
Acute respiratory distress syndrome (ARDS)

Tests include:

CBC (will show elevated white blood count)
Platelet count (will be less than 150,000 and decreasing)
X-ray of the chest (may show material invading the lungs, involving both lungs)
Liver enzymes (LDH will be elevated)
Serum albumin (levels will be decreased)
Hematocrit (will be increased, showing an increase in the levels of red blood cells)
Serological testing for hantavirus

Treatment

Because the breathing problems progress rapidly and there is a high death rate, treatment must occur in the hospital, often with admission to an intensive care unit.

Oxygen therapy is used, and regulated by close monitoring of the blood gases. Respiratory support with a breathing tube (endotracheal tube) and ventilator becomes necessary in severe cases.

IV ribavirin treatment is experimental and is under evaluation for its effectiveness. Ribavirin is an antiviral medicine.

Expectations (prognosis)

Hanta virus is a serious infection with a death rate (even with aggressive treatment) exceeding 50%.

Complications

Cardiorespiratory failure
Death

Calling your health care provider

Call your health care provider if you develop flu-like symptoms after being exposed to mouse urine or feces (excreta), or dust that may have been contaminated with mouse excreta.

Prevention

Avoid exposure to rodent urine and feces. When hiking and camping, pitch tents in areas without rodent droppings, avoid rodent dens, drink disinfected water, and sleep on a ground cover and pad.

Keeping a clean home diminishes the chance of contracting hantavirus. This includes clearing out potential nesting sites and maintaining a clean kitchen.

If you must work in an area where contact is possible, follow these recommendations from the Centers for Disease Control and Prevention (CDC):

When opening an unused cabin, shed, or other building, open all the doors and windows, exit the building, and allow the space to air out for 30 minutes.
Return to the building and spray the surfaces, carpet, and other areas with a disinfectant. Leave the building for an additional 30 minutes.
Spray mouse nests and droppings with a 10% solution of chlorine bleach or equivalent disinfectant, allow to sit 30 minutes, and using rubber gloves place the materials in plastic bags, seal, and dispose of the bags in the trash or incinerator. Dispose of gloves and cleaning materials in the same manner.
Wash all potentially contaminated hard surfaces with a bleach or disinfectant solution. Vacuuming should be avoided until the area has been thoroughly decontaminated and then should only be done (the first few times) with adequate ventilation. Surgical masks may provide some protection.

Review Date:1/29/2007
Reviewed By:D. Scott Smith, M.D., MSc, DTM&H, Chief of Infectious Disease & Geographic Medicine, Kaiser Redwood City, CA & Adjunct Assistant Professor, Stanford University. Review provided by VeriMed Healthcare Network.

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