Hantavirus Infections

Hantavirus infections are infections of the lungs caused by hantaviruses. There are five known types of hantaviruses, which differ only slightly from one another. These types are: Hantaan, Seoul, Puumala, Prospect Hill, and Sin Nombre. The Sin Nombre virus was the cause of the 1993 outbreak in the Southwestern United States, which led to a greater understanding of the virus and its transmission to humans.

The hantavirus are named for the Hantaan River in Korea. In 1976, a virus found near this river was shown to be the cause of a deadly disease, which was dubbed the Hantaan River disease. This same type of virus was likely responsible for a disease that appeared in United Nations troops stationed in Korea in 1951. Indeed, a 1990 study that examined the serum that has been collected and saved from Korean War victims found that over 90% of the sera contained antibodies to hantavirus.

Until the early 1990s, reports of hantavirus infections were confined to the Far East. Then, in 1993, an illness outbreak occurred in the United States Southwest, where the states of Colorado, Arizona, New Mexico, and Utah meet (an area known as the Four Corners). A disease that initially appeared similar to the flu quickly progressed to a life-threatening illness within 24 hours to a few days. Lung function dramatically reduced as fluid accumulated in the lungs. Kidney failure also occurred in several victims. At least seven people died from hantavirus infections in the early stages of the Four Corners outbreak.

After state health departments and Indian Health Services in the Four Corners area tested the victims for all known disease agents, the Special Pathogens branch of the United States Centers for Disease Control (CDC) assisted with the intense public health investigation into the 1993 Four Corners outbreak The cause of the outbreak was found to be a hantavirus dubbed Sin Nombre virus (from Spanish, meaning no name). The lung infection became known as hantavirus pulmonary syndrome. The virus was shown to live naturally in rodents, particularly the deer mouse. Mouse feces, urine, and saliva can contain the virus.

The 1993 outbreak is suspected to have arisen because of a period of heavy rain that occurred in the Four Corners region. The wet conditions produced an explosion in the deer mouse population. The virus could then be spread from mice to humans more easily.

Dusty environments are particularly important in the spread of hantavirus. The virus particles left behind upon the drying of feces or saliva can be distributed into the air and inhaled into the lungs.

Hantavirus pulmonary syndrome has also occurred in South America. Indeed, it is more common in South America than in North America. Additionally, the hantavirus types found in North and South America cause a more serious disease than the hantavirus types that are found in the Far East.

Treatment of hantavirus pulmonary syndrome is mostly supportive and can be difficult. One reason is because the patient deteriorates so fast that diagnosis and hospitalization must occur very quickly. A second reason is that viral diseases are not treatable using antibiotics. Treatment mainly consists of clearing fluid from the lungs to preserve lung function, maintaining blood pressure and, if necessary, initiating kidney dialysis (hemodialysis). For those who survive, recovery is almost as rapid as was the progression of the infection.

Currently, an antiviral drug called ribavirin is being evaluated as a hantavirus treatment. This drug has shown some potential in the treatment of infections caused by the human immunodeficiency virus (HIV). For the present time, the best defense against hantavirus is to avoid environments where exposure to rodent droppings could occur.