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Posted on: June 7, 2021

First case of hantavirus reported in Michigan - case is in Washtenaw County

deer mouse

Español: Primer caso de hantavirus reportado en Michigan - el caso está en el Condado de Washtenaw

A confirmed case of Sin Nombre hantavirus was recently detected in Washtenaw County. This very rare but severe disease is transmitted through infected rodents. It is most commonly caused by exposure to urine or droppings but also from rodent bites. Exposure is most likely through inhaling contaminated particles while cleaning or working in an infested area such as a house, barn or shed. The hantaviruses that cause human illness in the United States cannot be transmitted from one person to another.

Given the normal range of the species of rodents that carry Sin Nombre Hantavirus, there is a small chance that Washtenaw County residents may encounter a rodent that carries this virus. You can prevent exposure to hantavirus or other diseases by taking steps to keep mice and rats out of your home and properly cleaning rodent urine, dropping and nesting materials (including using disinfectant) if you see rodents or evidence of rodents around your home.

Things such as seeing a rodent while out for a walk or a hike pose no risk to you. Similarly, if your pet finds or kills a rodent, neither dogs nor cats can transmit hantavirus to humans. If that happens, be sure to dispose of the rodent using gloves or a plastic bag and clean any affected area using the instructions on this webpage. Or in these documents from the Centers for Disease Control and Prevention (CDC): Facts About Hantavirus Brochure [pdf] and Español: Información sobre los Hantavirus [pdf]

Below is a press release from the Michigan Department of Health and Human Services with more information and resources. 

June 7, 2021 - The Michigan Department of Health and Human Services (MDHHS) and the Washtenaw County Health Department are investigating the first confirmed human case of Sin Nombre hantavirus detected in Michigan. An adult female in Washtenaw County was recently hospitalized with a serious pulmonary illness from Sin Nombre hantavirus. The individual was likely exposed when cleaning an unoccupied dwelling that contained signs of an active rodent infestation.

Hantavirus was first discovered to be responsible for hantavirus pulmonary syndrome (HPS) in ill patients in the southwest United States in 1993. HPS has since infected people throughout the U.S. and the Americas. Hantavirus infections are associated with domestic, occupational or recreational activities that bring humans into contact with infected rodents. Most cases have been identified in adults and tend to occur in the spring and summer.

“HPS is caused by some strains of hantavirus and is a rare but severe and sometimes fatal respiratory disease that can occur one to five weeks after a person has exposure to fresh urine, droppings or saliva from infected rodents,” said Dr. Joneigh Khaldun, chief medical executive and chief deputy for health at MDHHS. “Anyone who comes into contact with rodents that carry hantavirus is at risk for HPS and healthcare providers with a suspect case of hantavirus should contact their local health department to report the case and discuss options for confirmatory testing.”

Humans become infected when freshly dried materials contaminated by rodent excreta are disturbed and inhaled, get into breaks in the skin or on mucous membranes or when ingesting contaminated food or water. Bites from rodents can also transmit hantavirus. The highest risk of exposure takes place when entering or cleaning rodent-infested structures. There are not any documented person-to-person cases of hantavirus transmission in the U.S.

Symptoms of HPS can be non-specific at first and include fever, chills, body aches, headache and gastro-intestinal signs such as nausea, vomiting, diarrhea and abdominal pain. The illness can progress to include coughing and shortness of breath. HPS has a 40% fatality rate.

“We can prevent and reduce the risk of hantavirus infection by taking precautions and being alert to the possibility of it,” says Dr. Juan Luis Marquez, medical director with Washtenaw County Health Department. “Use rubber, latex, vinyl or nitrile gloves when cleaning areas with rodent infestations, ventilate areas for at least 30 minutes before working, and make sure to wet areas thoroughly with a disinfectant or chlorine solution before cleaning.”

Hantaviruses are a family of viruses spread mainly by wild rodents and occur worldwide. Several hantaviruses that can infect people have been identified in the U.S. and each hantavirus has a primary rodent host. The most important hantavirus in the U.S. that causes HPS is the Sin Nombre virus, which is spread by the deer mouse and white footed mouse.

The greatest risk for hantavirus infection is associated with opening or cleaning closed-up buildings with rodent infestations without proper protection. Healthcare providers with a suspect case of hantavirus should contact their local health department to report the case and discuss options for confirmatory testing.

Hantaviruses are viruses and are susceptible to most disinfectants (diluted chlorine solutions, detergents, general purpose household disinfectants including those based on phenols, quaternary ammonium compounds and hypochlorite). Depending on environmental conditions, these viruses probably survive less than one week in indoor environments and much shorter periods (hours) when exposed to sunlight outdoors. Special precautions should be taken when cleaning up after rodents. In cases of heavy rodent infestation, it is recommended to consult with a pest-control professional.

For more information about HPS, visit Cdc.gov/hantavirus.

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