Hantavirus
Realm: Riboviria Phylum: Negarnaviricota Class: Ellioviricetes Order: Bunyavirales Family: Hantaviridae Subfamily: Mammantavirinae Genus: Orthohantavirus
A single-stranded, enveloped, negative-sense RNA virus, normally infect rodents, but do not cause disease in them.Humans may become infected with hantaviruses through contact with rodent urine, saliva, or feces. Some strains cause potentially fatal diseases in humans, such as hantavirus hemorrhagic fever with renal syndrome (HFRS), or hantavirus pulmonary syndrome (HPS), also known as hantavirus cardiopulmonary syndrome (HCPS),while others have not been associated with known human disease.HPS (HCPS) is a “rare respiratory illness associated with the inhalation of aerosolized rodent excreta (urine and feces) contaminated by hantavirus particles.
Hantavirus pulmonary syndrome (HPS) is found in North, Central and South America.It is an often fatal pulmonary disease. In the United States, the causative agent is the Sin Nombre virus carried by deer mice. Prodromal symptoms include flu-like symptoms such as fever, cough, muscle pain, headache, and lethargy. It is characterized by a sudden onset of shortness of breath with rapidly evolving pulmonary edema that is often fatal despite intervention with mechanical ventilation and potent diuretics. The fatality rate is 36%.
Hantavirus pulmonary syndrome was first recognised 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” stigmatised the region.It has since been identified throughout the United States. Rodent control in and around the home remains the primary prevention strategy.
Each hantavirus serotype has a specific rodent host species and is spread to people via aerosolized virus that is shed in urine, feces, and saliva, and less frequently by a bite from an infected host. The most important hantavirus in the United States that can cause HPS is the Sin Nombre virus, spread by the deer mouse.
Hantavirus Pulmonary Syndrome (HPS) is a severe, sometimes fatal, respiratory disease in humans caused by infection with hantaviruses. Anyone who comes into contact with rodents that carry hantaviruses is at risk of HPS. Rodent infestation in and around the home remains the primary risk for hantavirus exposure. Even healthy individuals are at risk for HPS infection if exposed to the virus.
How People Get Hantavirus Infection
Where Hantavirus is Found
Cases of human hantavirus infection occur sporadically, usually in rural areas where forests, fields, and farms offer suitable habitat for the virus’s rodent hosts. Areas around the home or work where rodents may live (for example, houses, barns, outbuildings, and sheds) are potential sites where people may be exposed to the virus. In the US and Canada, the Sin Nombre hantavirus is responsible for the majority of cases of hantavirus infection. The host of the Sin Nombre virus is the deer mouse (Peromyscus maniculatus), present throughout the western and central US and Canada.
Several other hantaviruses are capable of causing hantavirus infection in the US. The New York hantavirus, carried by the white-footed mouse, is associated with HPS cases in the northeastern US. The Black Creek hantavirus, carried by the cotton rat, is found in the southeastern US. Cases of HPS have been confirmed elsewhere in the Americas, including Canada, Argentina, Bolivia, Brazil, Chile, Panama, Paraguay, and Uruguay.
Not known to be transmitted by any types of animals other than certain species of rodents. Dogs and cats are not known to carry hantavirus; however, they may bring infected rodents into contact with people if they catch such animals and carry them home.
How People Become Infected with Hantaviruses
In the United States, deer mice (along with cotton rats and rice rats in the southeastern states and the white-footed mouse in the Northeast) are reservoirs of the hantaviruses. The rodents shed the virus in their urine, droppings, and saliva. The virus is mainly transmitted to people when they breathe in air contaminated with the virus.
When fresh rodent urine, droppings, or nesting materials are stirred up, tiny droplets containing the virus get into the air. This process is known as “airborne transmission“.
There are several other ways rodents may spread hantavirus to people:
- If a rodent with the virus bites someone, the virus may be spread to that person, but this type of transmission is rare. Scientists believe that people may be able to get the virus if they touch something that has been contaminated with rodent urine, droppings, or saliva, and then touch their nose or mouth.
- Scientists also suspect people can become sick if they eat food contaminated by urine, droppings, or saliva from an infected rodent. The hantaviruses that cause human illness in the United States cannot be transmitted from one person to another. For example, you cannot get these viruses from touching or kissing a person who has HPS or from a health care worker who has treated someone with the disease.
People at Risk for Hantavirus Infection
Anyone who comes into contact with rodents that carry hantavirus is at risk of HPS. Rodent infestation in and around the home remains the primary risk for hantavirus exposure. Even healthy individuals are at risk for HPS infection if exposed to the virus.
Any activity that puts you in contact with rodent droppings, urine, saliva, or nesting materials can place you at risk for infection. Hantavirus is spread when virus-containing particles from rodent urine, droppings, or saliva are stirred into the air. It is important to avoid actions that raise dust, such as sweeping or vacuuming. Infection occurs when you breathe in virus particles.
Potential Risk Activities for Hantavirus Infection:
- Opening and Cleaning Previously Unused Buildings
- Housecleaning Activities
- Work-related Exposure
- Campers and Hikers
Signs and Symptoms
Due to the small number of HPS cases, the “incubation time” is not positively known. However, on the basis of limited information, it appears that symptoms may develop between 1 and 8 weeks after exposure to fresh urine, droppings, or saliva of infected rodents.
Early Symptoms
Early symptoms include fatigue, fever and muscle aches, especially in the large muscle groups—thighs, hips, back, and sometimes shoulders. These symptoms are universal.
There may also be headaches, dizziness, chills, and abdominal problems, such as nausea, vomiting, diarrhoea, and abdominal pain. About half of all HPS patients experience these symptoms.
Late Symptoms
Four to 10 days after the initial phase of illness, the late symptoms of HPS appear. These include coughing and shortness of breath, with the sensation of, as one survivor put it, a “…tight band around my chest and a pillow over my face” as the lungs fill with fluid.
Is the Disease Fatal?
Yes. HPS can be fatal. It has a mortality rate of 38%.
Diagnosing HPS
Diagnosing HPS in an individual who has only been infected a few days is difficult, because early symptoms such as fever, muscle aches, and fatigue are easily confused with influenza. However, if the individual is experiencing fever and fatigue and has a history of potential rural rodent exposure, together with shortness of breath, would be strongly suggestive of HPS. If the individual is experiencing these symptoms they should see their physician immediately and mention their potential rodent exposure.
Are there any complications?
Previous observations of patients that develop HPS from New World Hantaviruses recover completely. No chronic infection has been detected in humans. Some patients have experienced longer than expected recovery times, but the virus has not been shown to leave lasting effects on the patient.
Treating HPS
There is no specific treatment, cure, or vaccine for hantavirus infection. However, we do know that if infected individuals are recognised early and receive medical care in an intensive care unit, they 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 patient is brought in to intensive care, the better. If a patient is experiencing full distress, it is less likely the treatment will be effective.
Therefore, if you have been around rodents and have symptoms of fever, deep muscle aches, and severe shortness of breath, see your doctor immediately. Be sure to tell your doctor that you have been around rodents—this will alert your physician to look closely for any rodent-carried disease, such as HPS.
