Hantavirus disease

Hantavirus Disease, otherwise known as Hantavirus Pulmonary Syndrome (HPS) manifests as flu-like symptoms which rapidly progresses into shortness of breath, difficulty breathing, internal bleeding, respiratory failure, and death. Hantaviruses (HTV) are distantly related to the ebola virus and have been recognized as causes of disease in China and Asia for many years. They first came to the attention of health authorities in the United States in 1993 when several healthy young adults developed flu-like symptoms and more than half of them died. HTV is carried by rodents and transmitted to humans through urine, feces, and dust contaminated with feces of infected rodents. While HPS is rare--only 110 cases have been reported in the U.S. since 1993--there is no effective treatment.

On May 1993, several people became ill and five died of an "unexplained illness" on an Indian Reservation in "Four Corners" in the southwest United States, an area where the borders of Utah, Colorado, New Mexico and Arizona meet. Immediately, departments of health from the four states, aided by the Navajo Nation Division of Health, embarked on intensive investigations to determine the cause of these illnesses and deaths. They soon linked the disease outbreakto the hantavirus and now believe this form of hantavirus has been present in the U.S. since at least as early as 1959. Since the 1993 outbreak, HPS hasbeen identified in more than half the states in the nation. Rodents carryingHTV have been found in at least 20 national parks, and may exist in all. Although authorities believe outdoor campers may be at a higher risk of infectionfrom HTV, only two cases have been reported following camping trips.

Hantavirus originates from the Hantaan Virus, (HTN), found in the Asian striped field mouse. Once transmitted to humans, it causes a severe diseaseknown as hemorrhagic fever with renal syndrome (HFRS) and which is estimated to infect more than 100,000 people in China each year. HTN was firstidentified in the western world in 1951 when many U.S. troops stationed in Korea became ill. Several and somewhat less severe illnesses are caused by related viruses, all of which are found in rodents indigenous to the Old World. Hantaviruses found in New World rodents appear to originate from the Prospect Hill (PH) virus carried by the meadow vole. This virus has not been implicated in human disease, but is believed to be the parent of the hantavirus, carried by deer mice and other rodents, which causes HPS. While carrier rodents do not manifest the disease, humans are at risk of developing HPS when they come into contact with infected rodent urine, feces, or dust contaminatedwith feces. The virus may enter the body with contaminated dirt or dust through a cut or wound, the eyes, by ingestion of contaminated water or food, orinhalation of contaminated dust. It does not seem to be passed from one humanto another, nor to be transmitted by bites from fleas, ticks, mosquitos, orother biting insects. Although cats and dogs are not know to be carriers, they may bring infected rodents into contact with humans.

Symptoms of hantavirus infection, including fatigue, fever and chills, severemuscle aches, headaches, dizziness, vomiting diarrhea, abdominal pain, and a dry cough, may not develop for several weeks following infection. Because so few cases of HPS are found, determining its incubation period is difficult. Sometimes, symptoms will alleviate for one or twodays, only to return with increased difficulty breathing caused by fluid seeping into the lungs and internal bleeding. Even treatment with oxygen therapy and respiratory support is only successful in 50 percent of severe cases. Experimental treatment with intravenous ribavirin--an antiviral drug--is undergoing clinical trials.