SEATTLE, Wash. -- Last October when my 17-year-old cat, Abby, came down with a rattly chest, I took her to the vet thinking maybe a quick course of antibiotics would fix her right up. I had no idea she would end up contributing to science.

My vet did prescribe antibiotics, and Abby seemed to improve, but a couple weeks later, she suddenly couldn't walk on her back leg. Another trip to the vet turned up nothing – just a pulled muscle, we thought.

Then I noticed strange, dime-sized lumps under Abby's skin on several areas of her body. I rushed her to the vet once again. She had lost almost a pound in less than a week. Lab tests on the lumps determined that Abby had Cryptococcus, a fungus.

What? I'd never heard of that.

The treatment is up to a year of antifungal medication and even then the prognosis isn't good. In her frail state and at her advanced age, Abby would not have survived the treatment, so I made the painful decision to let her go.

Of course, I questioned my decision, as we pet owners always seem to do, but Cryptococcus can affect the lungs and the nervous system so my vet assured me it was best for Abby.

"(The illness) went from no symptoms to everywhere so I think it just spread through Abby like wildfire," she said. "We would not have wanted to see what the progression of the illness would have been."

Then she advised me to see MY doctor because Cryptococcus can affect humans as well as animals.

Again, I was stunned, but then things got even more involved.

Further testing was needed to determine which strain of Cryptococcus Abby had. A sample was sent to the Centers for Disease Control in Atlanta. The CDC is closely watching one strain - Cryptococcus gattii - the rarest form and potentially the deadliest to both pets and humans.

I immediately began researching C. gattii.

Strain originated in tropical regions

"Cryptococcosis" caused by C. gattii is an "emerging infection" – a new or changing (and perhaps increasing in number or severity) infection, something scientists are just learning about that might become a significant health concern. It's caused by breathing in the fungus. It's not transmitted from person to person or from animal to person.

The Washington State Health Department is tracking C. gattii on orders from the CDC.

"We have known about the pathogen for a while, but it has expanded into a new area," Washington State Department of Health Epidemiologist Hanna Oltean told me. "Prior to 2006, there were no human cases known to have been exposed in Washington."

Oltean said preliminary data shows that there were five confirmed human cases in Washington state in 2014 – one each in Clark, Skagit, Snohomish, Thurston, and Whatcom counties. None of those were fatalities.

Months after Abby's death I got the results from the CDC – Abby did indeed have C. gattii.

She was one of two animal cases identified in King County last year. The other was a bird. Three cats in Snohomish, Whatcom and Okanogan counties were also identified. I don't know if those pets survived.

But how could Abby get this? She never went outside.

Dr. Ron Wohrle, Washington State Public Health Veterinarian, said spores of C. gattii have been found on car tires, shoe treads, etc.

"So it's reasonable to conclude there is a possibility for people to carry the spores around and possibly inside," he said.

C. gattii was previously limited to tropical regions such as Australia but turned up on Vancouver Island in 1999, where it infected more than 200 people and killed nearly 9 percent of them.

It then spread to the B.C. mainland on down the West Coast to California. It's been found in Douglas fir and Western Hemlock trees, in soil and in both freshwater and sea water.

Scientists don't know why the fungus showed up in the Northwest. Studies have suggested climate change could play a role and that the fungus can adapt to new environmental niches.

Long incubation period

Cryptococcus can take between 2 and 13 months to incubate after exposure. Fortunately, not many people or pets exposed to the spores will become ill.

People who have compromised immune systems or who smoke have a higher risk of illness.

But again, illness from C.gattii is very rare.

"Remember, 10 cases is the most we've had in any year in Washington, a state of nearly 7 million people," said Oltean.

Not only is it rare, but there's nothing that can be done to prevent C. gattii infection and illness.

"Because there are really no precautions that people can take - we'd have to not breathe - it isn't productive to worry about it," said Dr. Wohrle.

But, Oltean said, "Anyone with persistent or severe illness should consult their health care provider, especially after travel or outdoor activity in the Pacific Northwest, including British Columbia."

"Be alert for long lasting or severe symptoms of fever, cough, shortness of breath, pneumonia, or meningitis and consult a health care provider for early diagnosis and treatment."

I wanted to write about Abby's case not to scare people, but to make people aware.

I'll never know where the C. gattii came from. I was in British Columbia last summer – did I bring the fungus back on my shoes? Is it in the trees in the park across the street from my home?

I miss little Abby terribly but I take comfort in knowing I did the best for her, and that she may just help other pets and people.

Facts about C. gattii infection

The disease is not transmitted from person to person but rather by breathing in the spores of the Cryptococcus fungus.

The incubation period of C.gattii is not well-established. A few studies have shown that symptoms of C. gattii infection can appear between two and 13 months after breathing in the fungus, with an average of approximately six to seven months.

Symptoms in humans

In the lungs Cough Shortness of breath Chest pain Fever

In the brain (cryptococcal meningitis) Headache Fever Neck pain Nausea and vomiting Sensitivity to light Confusion or changes in behavior

Symptoms in animals

Runny nose Breathing problems  Nervous system problems  Raised bumps under the skin.