Humans don't usually contract HPS directly from rodents. Rodents shed hantavirus particles in their saliva, urine and droppings. Humans usually contract HPS by inhaling particles that are infected with the hantavirus.

HPS is an airborne infectious disease. The virus becomes airborne when the particles dry out and get stirred into the air (especially from sweeping a floor or shaking a rug). Humans then inhale these particles, which leads to the infection.

Other possible methods of contracting HPS include: (a) being bitten by a rodent that is carrying the hantavirus, (b) eating food or drinking water that has been exposed to a hantavirus carrier, or (c) bringing hantavirus-infected particles or droplets into contact with your nose, eyes, or mouth (e.g. licking your hands).

Ticks, fleas, and other biting insects have not been found to trasmit HPS from rodents to humans. In fact, no other animals (apart from the carrier rodents) are believed to be directly involved in HPS transmission to humans. However, it is possible for domestic dogs and cats to bring infected rodents into contact with humans.

It is generally believed that humans cannot spread HPS to other human beings, but cases from an HPS outbreak in Argentina (in late 1996) suggest that this may be a possibility. At any rate, human-to-human transmission is considered the least-likely method of contracting the disease, especially in the United States.

Since HPS is not considered a highly infectious disease, people usually contract HPS from long-term exposure. If rodents can be found in your home or workplace, you may be at risk for contracting HPS.

Since transmission usually occurs through inhalation, it is easiest for a human being to contract HPS within a contained environment, where the virus-infected particles are not thoroughly dispersed. Being in a small house, a crawl space, or a barn where rodents can be found poses elevated risks for contracting HPS.

The environments that provide the greatest risk are unoccupied buildings, such as an abandoned house, a cabin, or the toolshed in your back yard. Rodents can thrive in such places, especially in cold weather. The gathering dust will only increase the infectiousness of the disease.

A very common scenario for contracting HPS is cleaning out a dirty shed: if the shed has been a long-standing home to any carrier rodents, then sweeping the floor will aerosolize the virus particles and make their inhalation much more likely.

Travelling to a place where the hantavirus is known to occur is not considered a risk factor. Camping, hiking, and other outdoor activities also pose insubstantial risks, especially if steps are taken to reduce rodent contact.

Absolutely. Untreated cases of HPS are almost always fatal. However, if you can get yourself treated for HPS before the disease progresses to acute respiratory distress, then your chances of surviving are greatly increased. Thanks to improved methods of diagnosis, care, and a greater HPS awareness within the medical community, the mortality rate of HPS has rapidly decreased over the past few years.

The very first symptoms can occur anywhere between five days and three weeks after infection. They almost always include fever, fatigue, and aching muscles (usually in the back, shoulders, and/or thighs). Other early symptoms may include headaches, dizziness, chills, and abdominal discomfort (such as vomiting, nausea, and/or diarrhea).

These early symptoms are very difficult to distinguish, and as such they are usually overlooked. In fact, these symptoms are frequently described as "flu-like", because they indicate that the body's immune system is kicking in to defend itself against a viral infection, flu or otherwise. Most people experience these symptoms at least once a year, and HPS will almost never be diagnosed at this point.

(Conversely, rashes, sore throats, and earaches are not typical symptoms of HPS. These symptoms are sometimes used diagnostically to determine when a hantavirus infection is unlikely. Also, HFRS will lead to hemmorhages and severe kidney disfunction, which HPS does not.)

HPS starts to distinguish itself in its later symptoms, which usually occur between three to five days later. These pronounced symptoms include coughing and shortness of breath. This is known as the "cardiopulmonary phase" of the disease, where the body reacts as the lungs start to fill up with fluid. From here, the disease progresses very rapidly; the shortness of breath leads to acute repiratory distress, often within 24 hours.

Breathing will become extremely labored and difficult, and in many cases, it will eventually become impossible for the victim to breathe unassisted. The heart rate will also slow down considerably. If the victim is not receiving medical assistance during this phase of the disease, they will likely die.

The primary cause of death will be excessive proteinaceous fluid in the lungs. The fluid, essentially plasma, is leaked from capillaries into the lungs' air sacs. Autopsies of HPS victims have found that their lungs were so severely fluid-filled, that they weighed twice as much as expected. However, death is frequently associated with shock and heart failure instead of "drowning"; the body's response to the trauma is actually more damaging than the trauma itself.

If someone survives the cardiopulmonary phase of the disease, they usually recover very rapidly. Sometimes a recovering HPS patient can have kidney difficulties, such as excessive urination ("polyurea"), but usually convalesce quickly. During the course of the disease, if damage happens to occur to the lungs or lung vasculature, then the patient may experience minor respiratory difficulty after recovery.

Seek medical attention immediately. Most HPS victims who receive prompt medical attention are likely to survive the infection. (However, the overall mortality rate is still near 50%, so even immediate medical attention will not guarantee recovery.)

Haste is a very important consideration with fighting HPS. The disease can become acute very rapidly; people have died within hours of suspecting that they were even sick.

HPS is a viral infection; if a severe viral infection cannot be prevented by a vacciene, then it can only be controlled with "aggressive supportive care", where the patient is provided continued medical assistance and (hopefully) kept alive long enough for their body to develop antibody resistance.

In the case of HPS, the patient will usually receive antibiotics initially, until the diagnosis of HPS is certain. Once HPS is proven, the patient will be transferred to an intensive-care unit, where they are carefully monitored for fluid balance, electrolyte balance, and blood pressure.

During the onset of the cardiopulmonary phase, the patient may need to be hooked up to a ventilator, which will hopefully keep them breathing. In some occasions, antiviral medication (such as Ribavirin and Bradycor) will be administered intravenously, although it hasn't shown much promise when fighting HPS. Interestingly enough, Ribavirin does appear to be an effective weapon against HFRS.