“The occurrence of three cases in a short period has me worried, especially this early in the year,” said Mono County Public Health Officer Dr. Tom Boo. “Historically, we tend to see Hantavirus cases later in the spring and in the summer.”
The only source of Hantavirus in the area is from deer mice, a species native to the Americas, as no other rodents in the Eastern Sierra region carry the disease, MCPH said.
Contact with mouse waste, urine, and saliva is the most common way for the virus to be transmitted, as rodent bites occur rarely.
Local and state investigators found numerous mice living in one person’s home, but found no such indication in the other two homes, MCPH said. They did find traces of mice in places the three people had worked, but nothing unusual.
“None of these deceased individuals engaged in activities typically associated with exposure, such as cleaning out poorly ventilated indoor areas or outbuildings with a lot of mouse waste,” Boo said.
“Instead, these folks may have been exposed during normal daily activities, either in the home or the workplace. Many of us encounter deer mice in our daily lives and there is some risk. We should pay attention to the presence of mice and be careful around their waste,” he added.
Most often, infection occurs through inhalation, as dusting and vacuuming mouse waste can aerosolize waste particles, leading to infection. Touching the mouth with contaminated hands will also lead to infection, but the virus cannot be transmitted from person to person.
The health agency advises cautionary measures, such as sealing up gaps larger than a pencil’s width to prevent mice from entering your home, storing food in rodent-proof containers, and wearing gloves and an N95 (or higher) mask when cleaning to prevent inhaling the airborne virus.
Areas with mouse waste should be sprayed with disinfectant or a freshly made 10 percent bleach solution. After spraying, let the solution sit for five minutes before wiping clean.
One indicator is that muscle aches tend to be severe.
Often, though not always, the infection will spread to the lungs within four to 10 days after the first symptoms and cause Hantavirus Pulmonary Syndrome (HPS). Patients will begin coughing and soon experience shortness of breath, as the lungs begin the fill with fluid. HPS frequently worsens rapidly, with death occurring within one or two days.
According to the Centers for Disease Control and Prevention (CDC), 38 percent of people who develop respiratory symptoms do not survive HPS.
In some cases, hantavirus infection leads to Hemorrhagic Fever with Renal Syndrome (HFRS), a severe and sometimes deadly disease that affects the kidneys. Intense headaches, back and abdominal pains, fever, nausea, and blurred vision are common symptoms.
According to the CDC, 5 to 15 percent of HFRS cases are fatal.