Hantavirus pulmonary syndrome

Overview

Hantavirus pulmonary syndrome is a rare infectious disease that begins with flu-like symptoms and progresses rapidly to more severe disease. It can lead to life-threatening lung and heart problems. The disease is also called hantavirus cardiopulmonary syndrome.

Several strains of the hantavirus can cause hantavirus pulmonary syndrome. They are carried by different types of rodents. The most common carrier in North America is the deer mouse. Infection is usually caused by inhaling hantaviruses that have become airborne from rodent urine, droppings or saliva.

Because treatment options are limited, the best protection against hantavirus pulmonary syndrome is to avoid contact with rodents and safely clean up rodent habitats.

Symptoms

The time from infection with the hantavirus to the start of illness is usually about 2 to 3 weeks. Hantavirus pulmonary syndrome advances through two distinct stages. In the first stage, which can last for several days, the most common signs and symptoms are:

• Fever and chills
• Muscle aches or pain
• Headache

Some people also experience:

• Nausea
• Stomach pain
• Vomiting
• Diarrhea

As the disease progresses, it can lead to damaged lung tissues, fluid build-up in the lungs, and serious problems with lung and heart function. Signs and symptoms may include:

• Cough
• Difficulty breathing
• Low blood pressure
• Irregular heart rate

When to see a doctor

The signs and symptoms of hantavirus pulmonary syndrome can worsen suddenly and may quickly become life-threatening. If you have flu-like symptoms that progressively worsen over a few days, see your health care provider. Get immediate medical care if you have trouble breathing.

Causes

Rodent carriers

Hantavirus pulmonary syndrome is a human disease found only in North and South America. Each strain of the hantavirus has a preferred rodent carrier.

The deer mouse is the most common carrier of the virus in North America and Central America. In the United States, most of the infections occur in the states west of the Mississippi River.

Other carriers in North America include the rice rat and cotton rat in the Southeast and the white-footed mouse in the Northeast. Rodent carriers in South America include the rice rat and the vesper mouse.

Transmission

The virus is present in the rodent's urine, feces or saliva. You can come in contact with the virus in the following ways:

• Inhaling viruses — the most likely form of transmission — when they become airborne from disturbed rodent droppings or nesting materials
• Eating food contaminated with mouse saliva, urine or droppings
• Touching things contaminated with the virus, such as a nest, and then touching your mouth, eyes or nose
• Being bitten or scratched by an infected rodent

Person-to-person transmission of the virus has only been recorded with a strain of the virus found in South America called the Andes virus.

Effect of the virus

When hantaviruses reach the lungs, they invade tiny blood vessels called capillaries, eventually causing them to leak. Your lungs fill with fluid (pulmonary edema), resulting in severe dysfunction of the lungs and heart.

Related disease

Another disease caused by different strains of the hantavirus is called hemorrhagic fever with renal syndrome, which causes severe kidney disease. These variants of the virus have other animal carriers in Africa, Asia and Europe.

Risk factors

In the United States, hantavirus pulmonary syndrome is most common in rural areas of the West. However, any exposure to rodent habitats can increase the risk of disease.

Common sites for exposure to rodent nests, urine and droppings include:

• Farm buildings
• Infrequently used buildings, such as storage sheds
• Campers or seasonal cabins
• Camp sites or hiking shelters
• Attics or basements
• Construction sites

Activities that can increase the risk of exposure to the hantavirus include:

• Opening and cleaning long unused buildings
• Cleaning up rodent nests or droppings without appropriate precautions
• Working in a field that increases exposure to rodents, such as construction, utility work, pest control and farming

Complications

Hantavirus pulmonary syndrome can quickly become life-threatening. Severe disease can result in failure of the heart to deliver oxygen to the body. Each strain of the virus differs in severity. The death rate due to the strain carried by deer mice ranges from 30% to 50%.

Prevention

Keeping rodents out of your home and workplace can help reduce your risk of hantavirus infection. Try these tips:

• Block access. Mice can squeeze through holes as small as 1/4 inch (6 millimeters) wide. Seal holes with wire screening, steel wool, metal flashing or cement.
• Close the food buffet. Wash dishes promptly, clean counters and floors, and store your food — including pet food — in rodent-proof containers. Use tightfitting lids on garbage cans.
• Reduce nesting material. Clear brush, grass and junk away from a building's foundation.
• Set traps. Spring-loaded traps should be set along baseboards. Exercise caution while using poison-bait traps, as the poison also can harm people and pets.
• Move rodent-friendly yard items. Move woodpiles or compost bins away from the house.
• Air out unused spaces. Open up and air out cabins, campers or infrequently used buildings before cleaning.

Safe cleanup procedures

Safe cleaning will help prevent the spread of viruses. Follow these steps:

• Wear a mask and rubber or plastic gloves.
• Spray the nest, droppings or dead rodent with a household disinfectant, alcohol or bleach and water solution. Let it sit for five minutes.
• Use paper towels to clean up and dispose of towels in garbage.
• Mop or sponge the area with a disinfectant.
• Wash gloved hands and dispose of gloves and mask.
• Wash your hands thoroughly with soap and water.

Diagnosis

Blood tests can reveal if your body has made antibodies to a hantavirus. Your doctor may order other laboratory tests to rule out other conditions with similar symptoms.

Treatment

Specific treatment options for hantavirus pulmonary syndrome are limited. But the prognosis improves with early recognition, immediate hospitalization and adequate support for breathing.

Supportive therapy

People with severe cases need immediate treatment in an intensive care unit. Intubation and mechanical ventilation may be needed to support breathing and to help manage fluid in the lungs. Intubation involves placing a breathing tube through your nose or mouth into the windpipe (trachea) to help keep your airways open and functioning.

Blood oxygenation

Severe disease may require a treatment called extracorporeal membrane oxygenation (ECMO) to help ensure you retain a sufficient supply of oxygen. This involves continuously pumping your blood through a machine that removes carbon dioxide and adds oxygen. The oxygenated blood is then returned to your body.

Preparing for an appointment

You might first see your family doctor. However, when you call to set up an appointment, your doctor may recommend urgent medical care. If you're having difficulty breathing or know you have been exposed to rodents, seek emergency medical attention.

What you can do

Before your appointment, you may want to write a list of answers to the following questions:

• What symptoms are you experiencing? When did they begin?
• Have you recently cleaned any rarely used rooms or buildings?
• Have you had any recent exposure to mice or rats?
• Do you have any other medical problems?
• What medications and supplements do you routinely take?

What to expect from your doctor

Your doctor is likely to ask you a number of questions. Being ready to answer them may reserve time to go over any points you want to spend more time on. Your doctor may ask:

• Have your signs and symptoms included flu-like discomfort, such as fever, muscle aches and fatigue?
• Have you had any gastrointestinal problems, such as diarrhea or vomiting?
• Have you noticed your heart beating faster than normal?
• Are you having difficulty breathing? If so, is it getting worse?
• Is anyone else in your life having similar signs or symptoms?