Title: Sin Nombre?
Author: Janet Phillips
Date: 15 May 2009
Abstract: In this paper I discuss the outbreak of Hantavirus pulmonary Syndrome (HPS) in the four corners region of the United States in 1993. I discuss some structures of the virus and how it is transmitted. I go over the treatment available and preventative measures to use to avoid contact with the virus.
Introduction: In 1993 in the "Four Corners" region of the United States, several young, previously healthy adults developed acute respiratory illness, half of them soon died (CDC.gov). The CDC, Indian Health Services, the Department of Health from each of the four states, and the Navajo Nation Division of Health launched an investigation. It was soon determined that the illness was Hantavirus Pulmonary Syndrome (HPS) and was caused by a form of Hantavirus, which is transmitted by rodents. Due to a previous heavy rain season, there was a very large population of several different rodents. Researchers took tissue samples from rodents they trapped and compared them to samples taken from the victims of HPS. The principal carrier was identified as the Deer Mouse.
Before the cause of the pulmonary illness in the “four corners” was known, it was being called the “Four corners Virus”. Representatives of the local tourist industry feared that this name would cause people to not visit the area so they requested that the name be changed. Researchers changed the name to “Sin Nombre” which means no name in Spanish.
HPS has now been recognized throughout the contiguous United States and the Americas. As of June 6, 2002, a total of 318 cases of HPS have been identified in 31 states, with a case fatality of 37% (Nills et al, 2002). 41 of these cases were in California and 25% of those were fatal (EDC Dept. of Environmental Health). In 2006, a 52 year old Los Angeles County man died of HPS (CA Deprt. of Health Services).

Prior to the outbreak in 1993, Hantavirus illness were thought to be a "tropical region" issue.

Discussion: Hantaviruses are enveloped viruses with three single-stranded RNA segments. Each segment encodes for a different protein. The proteins each have a different function. One forms nucleocapsids, one forms glycoproteins, and the last forms a protein that functions as a viral transcriptase. According to the CDC, researchers believe Hantavirus gains entry into host cells through attachment of virions to cellular receptors and subsequent endocytosis. Nucleocapsids enter the cytoplasm and transcription of viral genes is started (CDC). Once transcription iand translation are completed, virions are released from secretory vesicles by exocytosis (CDC). The virions then spread throughout the body, completing the same process.

HPS is caused by Hantavirus which individuals contract through coming into contact with the urine and droppings of infected deer mice (EDC dept. of Environmental Health). Small particles of the dried urine and droppings can be stirred up and then inhaled. It is important to note that the infected rodents are carriers and do not develop illness, nor do they appear ill. All known hantaviruses seem to have one unique, species-specific, natural rodent reservoir (Table 1.) The rodents are chronically infected without any visible symptoms. Virus is spread to man via aerosolised rodent excreta. Man-to-man transfer of the viruses has not been reported (Telia).

Table 1.
Striped field mouse
Central and Eastern Asia
Yellow-necked field mouse
Eastern Europe
Bank vole
North and central Europe
Sin Nombre
Deer mouse
Treatment for HPS is supportive in nature. There is no known cure and no vaccine (CDC). The supportive measures include monitoring in the ICU with administration of fluids, electrolytes, and blood pressure monitoring. Even with supportive care in the ICU, HPS is fatal in approximately 30% of cases.
Hantavirus infections are associated with activities that bring people into contact with infected rodents. HPS cases have been reported throughout the year, but are more prevalent in the spring and summer months.

Hantavirus infection (resulting in HPS or HFRS) has been epidemiologically associated with the following situations (Mills et al, 2002)
  • increasing numbers of host rodents in human dwellings;
  • occupying or cleaning previously vacant cabins or other dwellings that are actively infested with rodents;
  • cleaning barns and other outbuildings;
  • disturbing excreta or rodent nests around the home or workplace;
  • residing in or visiting areas where substantial increases have occurred in numbers of host rodents or numbers of hantavirus-infected host rodents;
  • handling mice without gloves;
  • keeping captive wild rodents as pets or research subjects;
  • handling equipment or machinery that has been in storage;
  • disturbing excreta in rodent-infested areas while hiking or camping;
  • sleeping on the ground; and
  • hand plowing or planting.
The most effective means of prevention of HPS is rodent control in and around the home (Hantavirus).
  • Avoid areas, especially indoors, where wild rodents are likely to have been present.
  • Wear plastic gloves and spray areas contaminated with rodent droppings and urine with diluted bleach.
  • Place the waste in double plastic bags, each tightly sealed, and discard in the trash.
  • Wash hands thoroughly afterward.
  • Do not touch or handle live rodents and wear gloves when handling dead rodents.
  • Spray dead rodents with diluted bleach and dispose of in the same way as droppings. Wash hands thoroughly after handling dead rodents.
  • Keep rodents out of buildings by removing stacked wood, rubbish piles and discarded junk from around homes and sealing any holes where rodents could enter.
  • Keep food in tightly sealed containers and store away from rodents.
  • If there are large numbers of rodents present in a home or other building, contact a pest control service to remove them.

Literature Cited:

Eldorado County Department of Environmental Health website. Retrieved May 5, 2009
From http://www.edcgov.us/emd/envhealth/hantavirus.html

Hantavirus. Published online. Retrieved May11, 2009 from http://web.telia.com

Mills, J., Corneli, A., Young, J., Garrison, L., Khan, A., and Ksiazek, T.
Hantavirus Pulmonary Syndrome---United States: Updated Recommendations for
Risk Reduction. Published online in CDC: MMWR 51(RR09);1-12.
National Center for Infectious Diseases Special Pathogens Branch. All About
Hantaviruses. CDC Website. Retrieved May 12, 2009 from http://www.cdc.gov/ncidod/diseases/hanta/hps/noframes/phys/treat.htm
Preventing HPS. Published online by Hantavirus.net. Retrieved May14, 2009
From http://www.hantavirus.net/info3.html

Tortura, . J., Funke, B. R., and Case, C. L. 2006. Microbiology: an Introduction.
Pearson, San Francisco.