The family of a 10-year-old-boy who died from rat bite fever is now suing Petco for the boy's death.

Aiden Pankey died last summer from rat bite fever, a disease reportedly carried by a rodent purchased from a Petco in San Diego, Calif., according to the San Diego County Medical Examiner's Office.

The family, as a result, filed a lawsuit and is now waiting for a response from the national company.

"He was such a good care taker and so loving," Sharon Pankey, the boy's grandmother, told ABC News. "The dilemma is that taking care of the rat and wanting her to have a family ultimately lead to him dying."

(Credit: Gomez Trials Attorney)

The boy and his grandmother went to the pet store on Memorial Day last year to buy a companion for his pet rat Oreo. The family called it their "the summer science project."

Two weeks after buying the male rat, the boy was struck with what his grandmother called "flu-like symptoms" and died over the course of 48 hours.

She described the moments before his death as "numbing" and "soul biting."

"I put him to bed after a day at the doctor's office and the next thing I knew it just was too late," she said. "I went into his room and he couldn't speak. He was unstable on his feet. I got him down to my room and he collapsed on the floor. I called 911 because it was scaring me that his breathing was shallow and he seemed to be losing his ability to function."

The San Diego Medical Examiner's office said in a report issued to ABC News that "despite aggressive resuscitative efforts, death was pronounced."

"We didn't know what he died from at first," Sharon said. "When I took him to doctor he said he had the flu, but you don't die from flu in less than 48 hours."

She said that it wasn't until Christmas - more than six months after the boy's death - that the medical examiner reportedly confirmed to the family that Pankey had died from the infectious disease.

Hamilton Arendsen, the family's lawyer, told ABC News that his client is suing Petco for failing to have sufficient procedures in place to prevent incidents like this to occur.

"Obviously the family is devastated," said Hamilton Arendsen. "This was an all-around great ten year old boy doing everything ten year old boys like to do. He loved his friends, loved his family, and loved playing with animals. One day he was doing what normal 10-year-old boys do and the next day he is dead."

A general manager at Petco who would not identify themselves briefly commented on the incident and said they are waiting to receive more information before commenting further.

"We are saddened by what has happened and we take their claims very seriously," he said.

Petco officials also expressed their sympathy today.

"We are deeply saddened by the Pankey family's tragic loss," the company said in a statement to ABC News. "The health and safety of people and pets is always our top priority and we take the family's concerns very seriously. We are investigating the claims and will respond when we have more information."

The boy's family is suing Petco for strict liability and negligence and will be seeking compensatory and punitive damages, the lawyer said.

Rat-bite fever can caused by two different bacteria and when not treated can be serious or even fatal disease, according to the CDC's website. The disease is usually passed on from infected rodents or consumption of contaminated food or water.

(Credit: Gomez Trials Attorney)