Hantavirus Pulmonary Syndrome
A respiratory illness caused by a new strain of hantavirus (a group of viruses carried by rodents) that causes its victims to gasp for air as their lungs fill with fluid. It kills about half the people it infects, usually within a week. Hantaviruses can be found throughout the world, where more than 170 names have been given to the hantavirus infections, including the often-fatal hemorrhagic fever. The syndrome was first diagnosed in the United States in 1993 at a Navajo reservation in the Four Corners area of New Mexico, Colorado, Utah, and Arizona.
Until 1993, hantaviruses around the world had been linked to the development of hemorrhagic fever, but the strain that was discovered in Four Corners provoked a new disease, with debilitating flu-like symptoms and respiratory failure. Today the number of infections with the hantavirus in the United States is rising, reaching 131; almost half have been fatal, according to the Centers for Disease Control and Prevention. More than 50 of the 131 cases occurred before the Navajo reservation outbreak. Since the Navajo outbreak, more than 100 cases of hantavirus pulmonary syndrome have been reported in 21 states (including New York). In addition, seven cases have been diagnosed in Canada and four in Brazil.
Cause
The hantaviruses are a group of viruses carried by rodents responsible for a variety of diseases including hantavirus pulmonary syndrome and hemorrhagic fever. They are not passed directly from human to human. The severity of the illness it causes depends on the strain.
Each hantavirus infects primarily one type of rodent. The Hantaan, Seoul, Puumala, Prospect Hill, and Porogia strains are five viruses within the Hantavirus genus, the newly added fifth genus within the Bunyaviridae family. The Hantaan virus was isolated in a Korean lab in 1976 from the lungs of a striped field mouse. The Seoul virus infects domestic rats, and the Puumala virus affects the bank vole. Deer mice carry the U.S. strains.
Hantavirus pulmonary syndrome (HPS) is caused by a hantavirus named Muerto Canyon (Valley of Death) virus for the spot in New Mexico where it was isolated. The disease can be spread by several common rodent species (deer mice, whitefooted mice, and cotton rats) and has been found in 24 states; it is most common in New Mexico, which has had 28 cases; in Arizona, with 21 cases, and in California, with 13 cases. Hantaviruses are not passed directly from human to human.
Scientists believe the outbreak was triggered by climate irregularities associated with the most recent El Niño (the occasional warming of waters in the tropical Pacific). While it is believed that the mice who carry the virus probably were infected for years, the climate-induced explosion in the deer mouse population may have fueled the spread of the disease in humans.
People can become infected with the virus after being bitten by rodents, and many people who have developed the disease live in mice-infested homes. Researchers do not know why some people are susceptible to the infection while others are not. The hantavirus does not appear to be highly infectious, and it almost always occurs in isolated cases. There were only four instances in which more than one case occurred at the same time and place.
Symptoms
Hantavirus pulmonary syndrome begins as a flulike illness with fever and chills, muscle aches, and cough; it can be easily misdiagnosed as HEPATITIS or an inflamed pancreas. The virus goes on to damage the kidneys and lungs, causing an accumulation of fluid that can overwhelm the lungs. The disease is fatal in 40 percent of cases.
Treatment
There is no treatment approved specifically for hantavirus. However, if the infection is recognized early and the child is taken to an intensive care unit, some may do better. In intensive care, patients are intubated and given oxygen therapy to help them through the period of severe respiratory distress. The earlier the child is brought in to intensive care, the better. Patients experiencing full distress are less likely to survive.
Children who have been around rodents and have symptoms of fever, deep muscle aches, and severe shortness of breath should see a doctor immediately. Parents should be sure to inform the doctor that the child has been around rodents, which will alert the physician to look closely for any rodent-carried disease such as HPS. Although the antiviral drug Virazole (ribavirin) is effective in a related disease (hemorrhagic fever) caused by Old World hantaviruses, it is not effective against HPS and is not recommended. Ribavirin is not available for this use under and existing research protocol.
Prevention
For the first time, in October 2003 scientists demonstrated that an experimental vaccine against hantavirus pulmonary syndrome (HPS) triggered a strong antibody response—a response that is key to preventing the virus from causing infection. In addition, the antibodies, produced in nonhuman primates that received the vaccine, protected hamsters from disease even when administered five days after exposure.
The Centers for Disease Control (CDC) cautions homeowners about rodent excretion, even though hantavirus is a rare disease. People should assume that all rodent excretions are infected and should handle the droppings only after spraying them with disinfectant and wearing gloves.
Tags: caused by a new strain of hantavirus, group of viruses carried by rodents, Hantavirus Pulmonary Syndrome, respiratory illness
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