Hantavirus pulmonary syndrome


Hantavirus pulmonary syndrome is one of two potentially fatal syndromes of zoonotic origin caused by species of hantavirus. These include
Black Creek Canal virus, New York orthohantavirus, Monongahela virus, Sin Nombre orthohantavirus, and certain other members of Hantavirus genera that are native to the United States and Canada.
Specific rodents are the principal hosts of the hantaviruses including the hispid cotton rat in southern Florida, which is the principal host of Black Creek Canal virus. The deer mouse in Canada and the Western United States is the principal host of Sin Nombre virus. The white-footed mouse in the eastern United States is the principal host of New York virus. In South America, the long-tailed mouse and other species of the genus Oligoryzomys have been documented as the reservoir for Andes virus.

Signs, symptoms and disease progression

Initially, HPS has a incubation phase of 2-4 weeks, in which patients remain asymptomatic. Subsequently, patients can experience 3-5 days of flu-like prodromal phase symptoms, including fever, cough, muscle pain, headache, lethargy, shortness of breath, nausea, vomiting and diarrhea. In the following 5-7 day cardiopulmonary phase, the patient's condition rapidly deteriorates into acute respiratory failure, characterized by the sudden onset of shortness of breath with rapidly evolving pulmonary edema, as well as cardiac failure, with hypotension, tachycardia and shock. In this phase, patients may develop acute respiratory distress syndrome. It is often fatal despite mechanical ventilation and intervention with diuretics. After the cardiopulmonary phase, patients can enter a diuretic phase of 2-3 days characterized by symptom improvement and diuresis. Subsequent convalescence can last months to years. Overall, patient mortality from HPS is 36%.

Transmission

The virus can be transmitted to humans by a direct bite or inhalation of aerosolized virus, shed from stool, urine, or saliva from a natural reservoir rodent. In general, droplet and/or fomite transfer has not been shown in the hantaviruses in either the pulmonary or hemorrhagic forms.

Prevention

Rodent control in and around the home or dwellings remains the primary prevention strategy, as well as eliminating contact with rodents in the workplace and at campsites. Closed storage sheds and cabins are often ideal sites for rodent infestations. Airing out of such spaces prior to use is recommended. People are advised to avoid direct contact with rodent droppings and wear a mask while cleaning such areas to avoid inhalation of aerosolized rodent secretions.

Treatment

There is no cure or vaccine for HPS. Treatment involves supportive therapy, including mechanical ventilation with supplemental oxygen during the critical respiratory-failure stage of the illness. Although ribavirin can be used to treat hantavirus infections, it is not recommended as a treatment for HPS due to unclear clinical efficacy and likelihood of medication side effects. Early recognition of HPS and admission to an intensive care setting offers the best prognosis.

Epidemiology

Hantavirus pulmonary syndrome was first recognized during the 1993 outbreak in the Four Corners region of the southwestern United States. It was identified by Dr. Bruce Tempest. It was originally called Four Corners disease, but the name was changed to Sin Nombre virus after complaints by Native Americans that the name "Four Corners" stigmatized the region. It has since been identified throughout the United States.