Donor Passes Salmonella From His Pet Snake

By DENISE GRADY

n Oklahoma man who caught a salmonella infection from his pet snake passed the illness to two people through transfusions of his blood platelets, a doctor reported in a journal article published today. Both recipients became ill, and one died.

The case resulted from the convergence of two public health problems, researchers said: first, that reptile pets, like snakes, lizards and turtles, often carry salmonella and can spread it to their owners, and second, that platelets can transmit infection.

Even though the case was considered extremely rare, it has prompted the Oklahoma Blood Institute, which collected the platelets, to change its practices and prepare to perform bacterial cultures on all donated platelets. The medical director of the center, Dr. Ronald O. Gilcher, said he knew of no other regional blood centers that tested platelets for the bacteria. Dr. Gilcher is an author of the article about the case published today in The New England Journal of Medicine.

Platelets, components of the blood involved in clotting, are more likely than other blood products to spread infection because they must be stored at room temperature, which gives bacteria a chance to multiply.

The Food and Drug Administration says 17 people died in 2002 and 8 in 2001 from bacterial infections transmitted by platelets. Dr. Gilcher and his colleagues said that more cases of illness and death might occur but that patients' underlying illnesses might be mistakenly blamed.

New techniques to kill germs in blood, called pathogen inactivation or pathogen reduction, are used in some parts of Europe and are being studied in the United States but have not been approved for use here.

In the Oklahoma case, the donor, who did not feel ill, donated platelets on April 7, 2001. They were given to two patients, one on April 11 and one on April 12.

The first patient, a 51-year-old woman with leukemia, became ill before the transfusion was even completed, with nausea, vomiting, chills and fever. Her kidneys temporarily failed, and she needed dialysis for several weeks, but she recovered.

The second patient, a 50-year-old woman, was given platelets to treat bleeding in her digestive tract. Within an hour, she developed chills, fever, a rapid heartbeat and such severe breathing trouble that she needed a respirator. She died that day.

On April 19, after the transfusion recipients became infected, doctors tested the donor's blood and stool for salmonella, but did not find it. Doctors assumed that even though the donor had taken antibiotics and felt fine when he donated platelets, he must have been carrying bacteria in his blood. But they wondered how he had caught salmonella.

"It took some significant and lengthy questioning before we finally hit the right question and the donor told us he had a pet snake," Dr. Gilcher said, adding that the snake was a 9-foot boa constrictor. "Then it took a brave soul to go and culture the stool of that snake. And they don't defecate very often. It took about two weeks before the snake defecated."

Salmonella grew out of the specimen from the snake, and tests revealed it to be exactly the same type found in the patients. Dr. Gilcher said that the donor was barred from giving blood or platelets — unless he got rid of the snake.

Many reptiles are natural carriers of salmonella and do not get sick from it. But they excrete the bacteria, which may spread to anyone who handles the animal. Reptile owners are advised to wash their hands after handling their pets and to keep them away from food preparation. But Dr. Gilcher's article said that pet reptiles might account for 3 percent to 18 percent of the 1.4 million salmonella infections that occur every year in the United States. And those infected people are a potential source of tainted blood.