Doctors' Views

DOCTOR'S VIEW ARCHIVE

Hantaviruses…Update

ATLANTA-In the Four Corners area of Arizona, Utah, Colorado, and New Mexico in the summer of 1993, there were reported a cluster of patients that were afflicted by a deadly virus infection involving the lungs which later was identified as a hantavirus. The disease that affected these individuals has come to be known as the hantavirus pulmonary syndrome (HPS).

Hantaviruses are a family of viruses that can lead to bleeding in the lungs (hemorrhagic fever) and kidney damage. Prior to the outbreak in the southwestern United States, they were best known to cause disease from western Europe to eastern Asia.

A recent update of hantavirus infection by authors from the Centers for Disease Control and Prevention (CDC) was published in the medical journal HOSPITAL PRACTICE (1997;32:93-108).

Anne K. Pflieger, former coordinator of HPS U.S. national surveillance, and Dr. Ali S. Khan, an epidemiologist with the CDC, authored the article which outlined new features of hantavirus disease as well as current thoughts on both treatment and prevention.

The virus originally responsible for the outbreak in the U.S. has now been named the Sin Nombre (SNV) virus. ("Sin Nombre" means "without name" in Spanish!) This virus is transmitted by deer mice which are most common in the western states.

HPS cases totaled 160 as of May, 1997.

Symptoms of HPS include an early phase of fever for 3 to 5 days, with muscle aches, headaches, dizziness, rapid heart rate, chills, nausea and vomiting. Patients can develop abdominal pain. Next, shortness of breath rapidly becomes severe as the lungs fill up with bloody fluid. Blood pressure drops and soon patients require mechanical (artificial) breathing machines. Some patients develop serious kidney disease. Death occurs by an average of 5 days as a result of heart and lung failure.

The diagnosis of hantavirus infection is suspected on finding the typical early phase symptoms without signs of other infections (such as rashes, redness of the eyes or throat, and swelling of the limbs or eyes) as well as the rapid lung disease phase. Patients frequently have elevated white blood cell counts with a particular type of unusual white cell in the blood called an immunoblast. Chest x-rays, which may be normal initially, rapidly demonstrate fluid build-up in the lungs.

The diagnosis is confirmed by specialized testing of the blood for antibodies against the virus.

The treatment of HPS involves supporting the heart and lungs as necessary while the body's immune system (own infection- fighting system) fights off the virus. Intravenous fluids are given to correct abnormally low blood pressure.

Trials of a special antibiotic drug called ribavirin to combat the hantavirus are in progress.

Patients who survive recover completely without ongoing problems.

There are now rare reports of patients with documented acute hantavirus infection and minimal or mild symptoms.

The authors of the report emphasize that hantavirus is spread to humans by inhaling virus particles or through direct contact with rodent urine or excrement. The average incubation period is 2 to 3 weeks (though periods as short as 6 days and as long as 5 weeks have been reported).

The authors further emphasize that prevention of hantavirus disease is focused on avoiding exposure to rodents. Hantaviruses can be inactivated by bleach and household disinfectants. In cleaning out rodent-infested areas, it is recommended that the area first be wetted with disinfectant to minimize the risk of inhaling active virus particles. For big clean-out jobs, wearing mobile respirators with filters is recommended.

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