Hantavirus infection is caused by a group of viruses that can infect humans with two serious illnesses: hemorrhagic fever with renal syndrome (HFRS), and hantavirus pulmonary syndrome (HPS).
Hantaviruses are found without causing symptoms within various species of rodents and are passed to humans by exposure to the urine, feces, or saliva of those infected rodents. Ten different hantaviruses have been identified as important in humans. Each is found in specific geographic regions and therefore is spread by different rodent carriers. Further, each type of virus causes a slightly different form of illness in its human hosts:
At least 30 additional species of hantavirus have been identified, most with little or no known effect on human health.
Hantaviruses that produce forms of hemorrhagic fever with renal syndrome (HFRS) cause a classic group of symptoms, including fever, malfunction of the kidneys, and low platelet count. Because platelets are blood cells important in proper clotting, low numbers of circulating platelets can result in spontaneous bleeding, or hemorrhage.
Patients with HFRS have pain in the head, abdomen, and lower back and may report bloodshot eyes and blurry vision. Tiny pinpoint hemorrhages, called petechiae, may appear on the upper body and the soft palate in the mouth. The patient's face, chest, abdomen, and back often appear flushed and red, as if sunburned.
After about five days, the patient may have a sudden drop in blood pressure; often it drops low enough to cause the clinical syndrome called shock. Shock is a state in which blood circulation throughout the body is insufficient to deliver proper quantities of oxygen. Lengthy shock can result in permanent damage to the body's organs, particularly the brain, which is very sensitive to oxygen deprivation.
Day 11 often brings further chemical derangements, with associated confusion, hallucinations, seizures, and lung complications. Those who survive this final phase usually begin to turn the corner toward recovery at this time, although recovery takes approximately six weeks.
Hantavirus pulmonary syndrome (HPS) develops in four stages. They are:
Serologic techniques help diagnose a hantavirus infection. The patient's blood is drawn, and the ELISA (enzyme-linked immunosorbent assay) is done in a laboratory to identify the presence of specific immune substances (antibodies)—substances which an individual's body would only produce in response to the hantavirus.
It is very difficult to demonstrate the actual virus in human tissue or to grow cultures of the virus within the laboratory, so the majority of diagnostic tests use indirect means to demonstrate the presence of the virus.
The first stage in the public health response to a reported hantavirus infection is likely to be confirmation of the existence of the disease by testing of the individual involved. In many cases it may be necessary to send the sample collected from a victim to the U.S. Centers for Disease Control and Prevention for confirmation of diagnosis. A public health agency may then conduct a survey to determine the source from which the disease was obtained and the way it may have been spread among other community members. Identification of a hantavirus infection should intensify and improve any existing educational programs about the disease and its prevention or, if no such program exists, initiate one. A program of this kind normally includes not only information to individuals who may be at risk for the disease, but also materials with which a prevention program can be conducted, such as cleaning materials, rat and mouse traps, and the like. Some forms of hantavirus, such as hantavirus pulmonary syndrome, are reportable diseases, so data for infected individuals must be sent to the National Notifiable Diseases Surveillance System at the CDC.
The anti-viral agent ribavirin has been approved for use in early treatment of hantavirus infections.
The diseases caused by hantaviruses are extraordinarily lethal. About 6–15% of people who contract HFRS die. Almost half of all people who contract HPS will die. This gives HPS one of the highest fatality rates of any acute viral disease. It is essential that people living in areas where the hanta-viruses exist seek quick medical treatment should they begin to develop an illness that might be due to a hantavirus.
As of 2018, there were no immunizations currently available against any of the hantaviruses. Developments in genetic science are expected to help researchers work on a possible vaccination and therapy for several versions of hantavirus, including the Sin Nombre virus that causes HPS. With further work, a gene-based vaccine could become available in the future. However, the only known forms of hantavirus prevention involve rodent control within the community and within individual households. The following is a list of preventive measures:
See also Hemorrhagic fevers ; Rodents ; Viruses .
Beltz, Lisa A. Emerging Infectious Diseases: A Guide to Diseases, Causative Agents, and Surveillance. San Francisco: Jossey-Bass, 2011.
Fong, I.W., and Ken Alibek. New and Evolving Infections of the 21st Century. New York: Springer, 2007.
Schmaljohn, C. “Vaccines for Hantaviruses.” Vaccine 27, Supp. 4 (2012): D61-D64.
Clement, J., et al. “A Unifying Hypothesis and a Single Name for a Complex Globally Emerging Infection: Hantavirus Disease.” European Journal of Clinical Microbiology & Infectious Diseases 31, 1 (2012): 1–5.
Hantavirus. Centers for Disease Control and Prevention. http://www.cdc.gov/hantavirus/ (accessed August 18, 2012).
Hantavirus. PubMed Health. http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002358/ (accessed August 18, 2012).
Janie F. Franz
Teresa G. Odle