Hantavirus Information: All About This Mouse-Borne Virus!

Hantavirus: An Introduction

Also see: What You Need To Know To Prevent The Disease Hantavirus Pulmonary Syndrome (HPS)

Small But Deadly
Hantavirus Pulmonary Syndrome (HPS) has been recognized as a disease only recently in North America. So far, it's also fairly uncommon and the chances of becoming infected are low. However, HPS is potentially deadly and immediate intensive care is essential once symptoms appear.

The Mouse That Roared
Hantaviruses that cause HPS are carried by rodents, especially the deer mouse. You can become infected by exposure to their droppings, and the flu-like first signs of sickness (especially fever and muscle aches) appear one to six weeks later, followed by shortness of breath and coughing. Once this phase begins, the disease progresses rapidly, necessitating hospitalization and often ventilation within 24 hours.

Prevention is the best strategy, and it simply means taking some very practical steps to minimize your contact with rodents. HPS is not contagious from person-to-person in the United States

Hantaviru s Overview
Hantavirus pulmonary syndrome, commonly referred to as HPS, is a febrile illness simulating adult respiratory distress syndrome (ARDS) characterized by bilateral interstitial pulmonary infiltrates and respiratory compromise requiring supplemental oxygen. The typical prodrome consists of fever, chills, myalgias, headaches, and gastrointestinal symptoms. Typical clinical laboratory findings include hemoconcentration, left shift in the white blood cell count, neutrophilic leucocytosis, thrombocytopenia, and circulating immunoblasts.

Clinical Case Definition
An illness characterized by one or more of the following clinical features:

• A febrile illness (i.e., temperature >101 degrees F [38.30C]) occurring in a previously healthy person characterized by a) unexplained Adult Respiratory Distress Syndrome (ARDS) or b) bilateral interstitial pulmonary infiltrates with respiratory compromise requiring supplemental oxygen, developing within 72 hours of hospitalization.
• An unexplained respiratory illness resulting in death, with an autopsy examination demonstrating non-cardiogenic pulmonary edema without an identifiable cause.

Presentation and First Evaluation

Patients with HPS typically present in a very nonspecific way with a relatively short febrile prodrome lasting 3-5 days. In addition to fever and myalgias, early symptoms include headache, chills, dizziness, non-productive cough, nausea, vomiting, and other gastrointestinal symptoms. Malaise, diarrhea, and lightheadedness are reported by approximately half of all patients, with less frequent reports of arthralgias, back pain, and abdominal pain. Patients may report shortness of breath, (respiratory rate usually 26 - 30 times per minute). Typical findings on initial presentation include fever, tachypnea and tachycardia. The physical examination is usually otherwise normal.

HPS Clinical Presentation

Most Frequent	Frequent	Other
fever	headaches	shortness of breath
chills	nausea, vomiting	dizziness
myalgias	abdominal pain	arthralgia
	diarrhea	back or chest pain
	cough	sweats
	malaise

The diagnosis is seldom made at this stage, as cough and tachypnea generally do not develop until approximately day seven. Once the cardiopulmonary phase begins, however, the disease progresses rapidly, necessitating hospitalization and often ventilation within 24 hours.

Signs that make a diagnosis of HPS unlikely include rashes, conjunctival or other hemorrhages, throat or conjunctival erythema, petechiae, and peripheral or periorbital edema.

Laboratory Criteria for Diagnosis

• Detection of hantavirus-specific immunoglobulin M or rising titers of hantavirus-specific immunoglobulin G, or
• Detection of hantavirus-specific ribonucleic acid sequence by polymerase chain reaction in clinical specimens, or
• Detection of hantavirus antigen by immunohistochemistry

Surveillance Case Classification
Confirmed: A clinically-compatible case with laboratory criteria for diagnosis

Comment
Laboratory testing must be performed or confirmed at a reference laboratory. Because the clinical illness is non-specific and ARDS is common, a screening case definition should be used to determine which patients to test. In general, a predisposing medical condition (e.g., chronic pulmonary disease, malignancy, trauma, burn, and surgery) is a more likely cause of ARDS than hantavirus, and patients who have these underlying conditions and ARDS should not be tested for hantavirus.

Rodent-proof your Home to Keep Mice and Rats Out!

So now's the time to check your house to make sure rodents stay where they belong: outside. Here's how!

• See "Tips For Preventing Hantavirus, Indoors and Outdoors" for step-by-step help on how to keep mice and rats out of your home.

Get Rid of Mice and Rats Safely:
Our Prevention Pages Show You How

Think you have mice in your house? Concerned about how to clean up? Learn how to do it here. Only certain types of mice and rats can carry hantavirus However, because it's hard to tell one type of rodent from another, and because you can't tell if a mouse is carrying hantavirus or not, it's best to treat all rodents with caution.

• Learn the signs that you may have a rodent infestation: see our page "Some Common Signs of Rodent Infestion" .

Cleaning up:

• "Tips for Preventing Hantavirus: Cleaning Up Rodent-Infested Areas"
• "Special Precautions for Homes of Persons with Confirmed Hantavirus Infection or Buildings with Heavy Rodent Infestations will be useful if the rodent problem seems to be severe.
• Get the "Prevention of Hantavirus Disease" post-it card, free from the web! Nail it up in your shed, or barn, post it on your refrigerator!

Last points!

• The "All About Hantavirus" web page and its references do provide excellent resources for students at all levels. To find other sources of information about HPS, please see the " Research and Resources " page.
• We do not know the location of HPS cases in each state. Please contact your State Health Department for state-specific information. See the State Contacts page.
• We can't diagnose HPS or calculate your risk of exposure to hantavirus. If you think you have been in contact with rodent urine, droppings, or saliva, and you have the symptoms described in the "All About Hantavirus" Web page, please call your doctor right away. Mention your exposure and that you are worried about the possibility of hantavirus infection.

Fact Sheets:

	Hantavirus Pulmonary Syndrome Cases By State of Residence From the Centers for Disease Control and Prevention
	Link to Hantavirus - Public Health Fact Sheet From the Washington State Department of Health
	Link to How Do I Prevent HPS? From the Centers for Disease Control and Prevention
	Link to Prevent Hantavirus Pulmonary Syndrome From the Centers for Disease Control and Prevention
	Link to Clinical Manifestations of HPS From the Centers for Disease Control and Prevention

Figure 1


Return to top.

Figure 2


Return to top.
Figure 3


Return to top.
Figure 4


Return to top.
Figure 5


Return to top.
Figure 6


Return to top.
Figure 7


Return to top.
Figure 8