Doctors are working to save the life of a 9-year-old boy in New Mexico who has come down with a rare virus usually only seen in rodents. It all started with some relatively mild symptoms for young Fernando Herndez, and he was soon back in school when they first emerged in January, but they quickly started to worsen.

So young Fernando’s father, George Hernandez, decided to take him to the hospital where he got X-rays. Doctors were able to spot some unusual discoloration on his lungs and decided to give him some medicine, believing the situation would clear up. But things only got worse, according to Fox News.

It got so bad that Fernando was having trouble breathing and went back to the hospital, and was eventually airlifted to a special hospital in Colorado. After some more tests, doctors will still stumped, suggesting that it could be mold. An inspection of the Hernandez’s home turned up nothing, however.

The condition continued to worsen and Fernando needed a machine to help him breathe and pump blood. Eventually doctors realized the cause was Hantavirus, which is usually carried by infected deer mice and can be transferred to humans, although it is wear, via contact with urine or feces from the animals. It is a deadly disease that kills more than a third of victims, although it is not contagious between humans.

The family has set up a GoFundMe page to cover the boy’s medical expenses. He has been on life support.

There has been an outpouring of support on that page.

“Feel better, little man. Our 10 year old had an extended and terrifying hospitalization last year. She recovered completely, we are rooting that Fernando will do the same. Best Wishes, The Gomez Family,” wrote Karen Gomez.