The pair were found dead, along with one of their dogs, in their Santa Fe property on 26 February.

Dr Heather Jarrell, chief medical examiner for New Mexico, told a press conference that it was ‘reasonable to conclude’ that she died from the disease on 11 February.

Whereas Hackman, 95, was unlikely to have known his wife died, having passed away on 18 February from ‘hypertensive and atherosclerotic cardiovascular disease, with Alzheimer’s disease as a significant contributory factor’.

What is hantavirus pulmonary syndrome?

Gene Hackman’s wife Betsy Arakawa is likely to have died a week before the actor of a rare infectious disease at their home (Richard Corkery/NY Daily News Archive via Getty Images)

Hantavirus pulmonary syndrome is a rare but potentially fatal disease which spreads to humans through infected rodent droppings or saliva.

The virus is generally transmitted to humans via infected urine, droppings, or saliva of certain species of mice and rats.

Dr Jarrell noted that the mortality of the hantavirus strain in the south west of the United States is about 38 percent to 50 percent. Hantavirus is not transmissible from person to person.

In the UK, there have been only a few reports of hantavirus, other than those associated with exposure abroad.

Hantavirus pulmonary syndrome symptoms

The pair were found dead, along with one of their dogs, in their Santa Fe property on 26 February. (RONALDO SCHEMIDT/AFP via Getty Images)

According to the American Lung Association, initial symptoms of hantavirus include:

• fever

• dry cough

• body aches

• headaches

• diarrhea

• abdominal pain

“If the initial symptoms are connected to hantavirus exposure and are left untreated, late symptoms will onset rapidly,” they added.

“These symptoms include cough and shortness of breath, which are the result of leaky blood vessels and lead to collection of fluid in the lungs, bleeding and failure of the heart to pump.

“The combination of these changes can lead to shock, failure of several organs and even death.”

How did Gene Hackman die?

Hackman, 95, was unlikely to have known his wife died (Ron Galella, Ltd./Ron Galella Collection via Getty Images)

Dr Jarrell said she has ‘assumed’ that Hackman had been home with his wife for seven days until he passed.

“Hackman showed evidence of advanced Alzheimer’s disease. He was in a very poor state of health,” she said.

“He had significant heart disease, and I think ultimately that is what resulted in his in his death.”