Pathogen: Sin Nombre Virus (A Hantavirus of the Bunyaviridae family)
Transmission Electron Micrograph of Sin Nombre Virus
Note* The Sin Nombre Virus is the Hantavirus species primarily responsible for HPS. However, closely related strains (Bayou and Black Creek Canal viruses), found in the southeastern United States, may produce a variant of the syndrome that is characterized by a greater degree of renal failure. The New York virus is the cause of cases of HPS in New York and Rhode Island.
Category of Pathogen: Virus
Name of the disease caused by the pathogen: Hantavirus Pulmonary Syndrome
Symptoms of infection:
Symptoms can appear 3 days to 6 weeks after infection, but usually within 2 weeks.
Early symptoms (3 – 7 days of illness) include:
- fatigue
- fever (101 – 104 degrees F)
- chills
- headache
- vomiting
- nausea
- diarrhea
- dizziness
- muscle aches
Late symptoms (after the first 3 – 7 days of illness) include:
- coughing
- shortness of breath
- filling of lungs with fluid.
Note* These symptoms progress rapidly and requires prompt medical attention.
Primary Host(s): The deer mouse is the primary host of the hantavirus in the United States.
The deer mouse (Peromyscus Maniculatus) can be found almost everywhere in North America. The head and body is usually 2 - 3 inches long, and the tail adds another 2 - 3 inches. The color of its fur may range from gray to reddish brown, depending on its age. However, the underbelly is always white.
Other Host(s): Other rodents, such as the cotton rat, or the white-footed mouse, may be carriers of the virus as well.
The Cotton Rat (Sigmodon Hispidus) is usually found in the southeastern United States (as well as Central and South America). The head and body are 5 - 7 inches long, and the tail adds another 3 to 4 inches in length. Its fur has a grayish black color.
The White-footed Mouse (Peromyscus Leucopus) can be found through southern New England, the Mid-Atlantic and southern states, the midwestern and western states, as well as Mexico. The head and the body are about 4 inches long, and the tail normally adds 2 - 4 inches in length. Topside, its fur ranges from pale brown to reddish brown, while its underside and feet are white.
Route of Transmission: Transmission of the Sin Nombre Virus may occur either through direct contact with infected rodents, rodent droppings, nests, or through inhalation of aerosolized virus particles from rodent urine, droppings or saliva.
Fighting between infected and uninfected adult rodents has been suggested as the primary mechanism by which hantaviruses are amplified epizootically. The exchange of blood and saliva can occur during the fights, resulting in the spread of the virus. Mice may fight one another for breeding partners, food and territory.
Ro: There has been no evidence of human-to-human transmission of the Sin Nombre Virus.
Prevalence: Although prevalence varies temporally and geographically, on average approximately 10% of deer mice tested throughout the range of the species show evidence of infection with Sin Nombre Virus.
Hantavirus Pulmonary Syndrome is considered a rare disease. Since it was first recognized in 1993 through March 26, 2007, there have been a total of 465 cases of hantavirus pulmonary syndrome reported in the United States. (CDC)
Number of Hantavirus Pulmonary Syndrome Cases (1993 - 2007)
Prevalence in Colorado:
Hantavirus Pulmonary Syndrome human cases in Colorado by county of residence. Colored counties signifies cases identified. Red dots signify fatal cases, whereas green dots signify non-fatal cases. These points do not necessarily reflect the location of exposure.
Generation Time: N/A
Mortality Rate: 40 – 50%
Morbidity Rate: ~ 38%
Is it preventable? How? The risk of infection by hantavirus may be reduced by preventing rodents from living near human dwellings. This may be accomplished by eliminating food sources available to rodents, by limiting possible nesting sites, and by sealing possible entrances for rodents. Any rodent nests and/or droppings should be wetted down with disinfectant before removal.
Does the disease trigger long lasting immunity? Yes
Medical Treatment:
When was the pathogen first described and is there evidence that it was around much earlier than that?
The pathogen was first described in 1993, in a region of the south-western US known as Four Corners. Here, some people became afflicted by illness resembling influenza, and many of them developed severe lung disease and died. The region is normally very dry, but due to an unusual amount of rainfall, a burst of plant growth resulted, followed by explosions in the populations of small mammals. After some investigating, it was found that the deer mice were persistently infected with a new hantavirus.
By looking at samples of people who have died of unexplained lung disease, scientists have been able to discover this syndrome as far back as the late 1970′s. It may be that the Sin Nombre Virus have long been present in the region of the western United States, inhabited by deer mice, but was only recognized when its prevalence increased, resulting in human casualties.
Note* Hantaviruses are named after the River Hantaan in Korea, where the first of these viruses was isolated during the Korean War from soldiers who had developed hemorrhagic fever with renal syndrome.
Note** The Four Corners is a big tourist attraction. The local people did not want the newly identified virus to be named after the place, for it might discourage visitors. As a result, they chose the name Sin Nombre virus, which, in spanish, means virus with no name.
What is the economic impact of the disease? The economic impact of HPS can be substantial in certain areas. For example, one of Panama’s most celebrated festivals had to be cancelled due to an observed increase in the field mice population.
The coolest thing about the disease: I found it interesting that although the virus has been around for a long time, it was not discovered until the 1990′s. Native American stories indicate that even hundreds of years ago, medicine men and women knew of the deer-mouse vector and identified that the “spirit” of the disease was carried by aerosol particles. They also understood that to eradicate the disease, they had to burn everything which had come in contact with mice. This leads me to wonder what other viruses may be affecting people today that have yet to be discovered.
Citations:
Alex Lowther; “Eek, A Mouse”; Rock and Ice Magazine; August 17, 2007; Online News Article; <http://www.rockandice.com/inthemag.php?id=64&type=onlinenews>
“All About Hantaviruses: What are the symptoms of HPS?”; CDC; Last Updated August 5, 2004; Last Viewed: August 26, 2009; <http://www.cdc.gov/NCIDOD/DISEASES/HANTA/HPS/noframes/symptoms.htm>
“Hantavirus”; Directors of Health Promotion and Education; Last Viewed: August 27, 2009; <http://www.dhpe.org/infect/hanta.html>
“Hantaviruses”; auuuu.org; Last Viewed: August 26, 2009; <http://www.auuuu.org/respiratory/hantaviruses/>
“Hantavirus Pulmonary Syndrome”; Colorado Department of Public Health and Environment: Disease Control and Environmental Epidemiology Department; Last Visited: August 24, 2009; <http://www.cdphe.state.co.us/dc/Zoonosis/hanta/index.html>
Schonrich G., Rang A., Lutteke N., Raftery NJ., Charbonnel N., Ulrich RG.; “Hantavirus-induced immunity in rodent reservoirs and humans”; Immunological Reviews; 2008; 225:1 pp 163 - 189
