Classical pianist Betsy Arakawa died from a rare infection a full week before her husband, actor Gene Hackman, according to officials.
Arakawa, 65, and Hackman, 95, were both found dead inside their home on February 26.
Arakawa, who was found in the home's bathroom with an open prescription bottle and scattered pills nearby, died of hantavirus pulmonary syndrome.
Chief medical investigator Heather Jarrell spoke earlier today about Arakawa's rare infection.
"The mortality rate of [hantavirus] is about 38-50 per cent," Dr Jarrell said.
Arakawa's body showed signs of decomposition and mummification in the hands and feet by the time maintenance workers alerted authorities to the couple's open front door.
The pills found near her body, according to Dr Jarrell, were a thyroid medication and not connected to her death.
What is hantavirus?
Hantavirus can be found throughout the world and can spread by contact with rodents or with their urine or faeces.
It does not spread between people, and is typically reported in spring and summer.
There are no specific treatments or cure, but early medical attention can increase the chance of survival.
Medical experts have said that an infection can rapidly progress and become life-threatening.
Sonja Bartolome from the UT Southwestern Medical Center in Dallas said: "It really starts like the flu: body aches, feeling poorly overall."
"Early in the illness, you really may not be able to tell the difference between hantavirus and having the flu," she said.
According to the US Centers for Disease Control and Prevention (CDC), the virus can cause a severe and sometimes deadly lung infection called hantavirus pulmonary syndrome — which led to Arakawa's death.
The CDC has offered to test samples from Arakawa's case to learn more about the strain of virus that infected her and to perform pathology testing.
Majority of hantavirus cases in western US states
The CDC began tracking the virus after a 1993 outbreak in the Four Corners region, which is an area where Arizona, Colorado, New Mexico and Utah meet.
The majority of US cases since then have been in western states, especially the south-west.
Between 1993 and 2022, there were 864 reported US cases.
New Mexico reported a total of 129 cases of hantavirus pulmonary syndrome with 52 deaths between 1975 and 2023, according to the state health department.
That included seven in 2023 and another seven in 2024.
Symptoms start between one to eight weeks after exposure and initially can include fatigue, fever and muscle aches, according to the CDC.
As the disease progresses, symptoms can include coughing, shortness of breath and tightness in the chest as the lungs fill with fluid.
Outbreaks of hantavirus pulmonary syndrome generally occur in South and North America, according to the Coalition for Epidemic Preparedness Innovations.
Hantaviruses are not known to be present in Australian rodents and there has never been a recorded case in the country.
Minimising contact with rodents reduces risks of hantavirus
The CDC has said about a third of people who develop respiratory symptoms from the disease can die.
"If you are ill and then progressing to the sort of symptoms interfering with the things you would normally do during the day, you do need to seek medical attention," Dr Bartolome said.
The best way to avoid the germ is to minimise contact with rodents and their droppings.
Public health experts have cautioned against sweeping or vacuuming up droppings which can cause the virus to get into the air.
It's also advised to use protective gloves and a bleach solution for cleaning up rodent droppings.
ABC/AP
