Scratch from pet rat kills California boy

The tragic death from "rat-bite fever" of a 10-year-old San Diego boy highlights the risk carried by the pet rodents, according to a report from the U.S. Centers for Disease Control and Prevention.

"Rat-bite fever is a rare but potentially fatal illness that should be considered in persons with rash, fever and joint pain, and when a history of rodent exposure is reported," said a team led by Dr. Jessica Adam of the CDC's Epidemic Intelligence Service.

The case outlined in the report occurred in August of 2013. Adam's team said the boy, previously healthy, first developed a fever of 102.6 degrees and "experienced rigors, fevers, vomiting, headaches and leg pains."

His doctor initially diagnosed the illness as infection with a gastrointestinal virus. But "during the next 24 hours, the patient experienced vomiting and persistent fever. He was confused and weak before collapsing at home," the CDC report said.

By the time paramedics reached the boy he was "unresponsive," and he died in a hospital emergency department.

Blood tests and autopsy reports revealed infection with Streptobacillus moniliformis, a potentially deadly germ that causes rat-bite fever and "can be transmitted to humans through rodent bites or scratches; approximately one in 10 bites might cause infection," according to the CDC authors.

Adam and her colleagues said that the boy had two pet rats: the first one tested negative for S. moniliformis, but the second, recently acquired, tested positive. "The autopsy report noted that patient had been scratched by his pet rats," the researchers said.

Adam's team suggested that rat-bite fever could be under-reported because the condition does not have to be reported to health authorities in the United States.

Trying to determine its overall incidence, they looked through hospital records in San Diego County for 2000-2012 and found 16 cases during that time period, which did not include the one fatal case involving the 10-year-old in 2013.

"Most infections (94 percent) were pet-associated," the team noted. "One patient had an occupational exposure (rat breeder). Sixteen of 17 patients reported exposure to rats. Of these, 44 percent reported only having handled a rat, 38 percent reported being bitten and 13 percent reported a scratch."

Based on the findings, Adam's team said that doctors need to be alert to rat-bite fever when symptoms occur, and they stress that "nearly all domestic and wild rats carry S. moniliformis."

Quick treatment is crucial, because even though rat-bite fever is treatable with antibiotics, fatalities do occur in about 13 percent of untreated cases.

The researchers also stressed that a scratch or bite from the rat isn't necessary for transmission, since infection can occur "through ingestion of food or water contaminated with the bacteria."

Their advice to owners of pet rats? "Wear gloves and wash their hands thoroughly after handling rats or cleaning rat cages, avoid rat secretions and promptly seek medical care if they have rat-bite fever symptoms after contact with rats."

The findings are published in the Dec. 18 issue of the CDC journal Morbidity and Mortality Weekly Report.