The first-ever reported case in Maine of a potentially fatal respiratory condition spread by the common house mouse was diagnosed in Somerset County at the end of April. Hantavirus pulmonary syndrome, or HPS, has a rapid onset of illness, no effective vaccine or cure, and a fatality rate of 30 percent to 40 percent.
Mainers should not be unduly alarmed, said Dr. Stephen Sears, the state epidemiologist. There are many potentially dangerous diseases associated with the white-footed mouse, the deer mouse and other common rodents, he said on Wednesday, and the presence of hantavirus in Maine comes as no surprise to epidemiologists or other public health officials.
“This raises the issue that you really need to clean up if your environment includes mice and other rodents,” he said Wednesday. Especially in camps and cottages where mice may become well established during the winter months, people should be careful when handling droppings, nests and other sources of contamination.
Because the most common form of transmission is airborne particles, it is important to wet down mousy areas before cleaning, he said. If dusty conditions are unavoidable, a paper face mask can help. The virus also can be passed if droppings or other materials come in contact with broken skin or through a bite from an infected rodent. In heavily contaminated areas, it would be prudent to wear rubber gloves and use a mild bleach solution to wipe down contaminated surfaces, Sears said.
HPS was first identified in 1993 in New Mexico, after an outbreak of severe respiratory illness in young adults. A number of individuals died in that outbreak. Since then, the virus has affected humans in several states, including Pennsylvania and New York, Sears said.
It may take a week or two for illness to develop after exposure, Sears said.
“But once you start getting symptoms, the time to the development of severe illness is relatively short, maybe two days,” he said.
Early symptoms include shortness of breath, fever, chills and muscle aches. Headache, dizziness, nausea, vomiting and diarrhea also may develop. The illness can progress quickly to severe coughing and respiratory distress as the lungs fill with fluid. Hospitalized patients typically are placed on mechanical respirators to help them breathe and given oxygen to help them through the crisis.
The Somerset County man diagnosed last month is in his 70s, Sears said.
“He became very ill very quickly,” Sears said, and was treated in the intensive care unit of a nearby hospital. Doctors suspected HPS and sent a blood specimen to an out-of-state laboratory. The presence of hantavirus was confirmed at the U.S. CDC in Atlanta.
Thanks to a quick medical response, the man survived the episode but continues to recover in a rehabilitation facility. Sears said he expects the man will be able to return to his own home.
State inspectors visiting the man’s property found mouse contamination in an outbuilding, Sears said.
“We take it for granted in Maine that living with mice is part of living in the country,” Sears said. But this case, he noted, shows that Mainers should be vigilant about controlling mice and other rodents in their homes and cleaning up after them carefully.