What caused woman's odd liver problem — dog or cat?

A woman in the Netherlands contracted an unusual bacterial infection that may have come from one of her pet cats, according to a new report of her case.

After a weeklong fever, the 46-year-old woman went to the hospital and told doctors she was tired, and was having night sweats and pain in her upper right abdomen symptoms that were "all very vague," said Dr. Marloes van Ierland-van Leeuwen, a gastroenterologist at Onze Lieve Vrouwe Gasthuis hospital in Amsterdam.

An ultrasound and a CT scan revealed cause for concern: the woman had large nodules around her pancreas and near the top part of her small intestine, called the duodenum. She also had other abnormalities, called lesions, throughout her body, according to the case report published Oct. 29 in the journal BMJ Case Reports. [16 Oddest Medical Cases]

The doctors thought the woman had cancer, Van Ierland-van Leeuwen said.

"There were so many lesions," he told Live Science. "We were really worried at the start."

But a biopsy of one of the nodules in the intestine showed not cancer, but rather an infectious disease. "So our search was to find out what it was," Van Ierland-van Leeuwen said.

Cat scratch disease

The doctors ran several tests, but they couldn't find any bacteria, fungi or common viruses in the woman's tissue samples.

Finally, blood work suggested the woman was infected with bacteria from the genus Bartonella. One species of the bacteria, Bartonella henselae,can lead to a condition called cat scratch disease. Also known as cat scratch fever, the illness can cause swollen lymph nodes, fever, headache, fatigue and poor appetite, according to the U.S. National Institutes of Health.

People can get cat scratch disease from house cats, about 35 percent of which carry the bacteria that cause it, said Dr. Greg Nelson, a veterinarian with Central Veterinary Associates, in Valley Stream, New York, who was not involved in treating the woman.

"[But] It doesn't really occur all that often," Nelson said. "There isn't a lot of transmission from cats to their owners."

Cats typically get the bacteria as kittens from fleas, or from other infected cats. When a kitten scratches or bites at the fleas on its skin, the flea droppings can get in their teeth or claws. Cats can then transmit the bacteria if they then bite or scratch a person, or lick an open cut on a person's skin, Nelson said.

In people with compromised immune systems, including children and the elderly, cat scratch fever can lead to painful and serious complications, such as warty lesions on the skin, as well as lesions in the liver or spleen.

The bacterial infection is usually seen at the location of the cat bite or scratch, but infection can also spread to other sites in the body, said Dr. Lucy Tompkins, a professor of medicine and infectious diseases at Stanford Medicine and the medical director of Infection Prevention and Control at Stanford Health Care in California, who was not involved in the study.

"These Bartonella bugs seem to have an affinity to our red blood cells," Tompkins said. "They stick to them."

Dog or cats?

But in the woman's case, whether her cats actually caused her infection remains unclear, the researchers said. The woman didn't remember getting scratched or bitten by her two pet cats, whereas she did remember that a young dog had bitten her leg about two weeks before her symptoms began, Van Ierland-van Leeuwen said.

It's possible that the woman had Bartonella henselae, or cat scratch disease, Van Ierland-van Leeuwen said. However, DNA testing for Bartonella henselae in a sample of the woman's duodenum came up negative, the study found. [Tiny & Nasty: Images of Things That Make Us Sick]

The doctors gave her antibiotics for five days, and in four months the woman's health had returned to normal.

In most cases, cat scratch disease goes away on its own, without the use of antibiotics, Nelson said.

Neither the cats nor the dog were tested for Bartonella henselae. There have been a few reports of dogs carrying Bartonella henselae, but typically cats are the main host, Nelson said.

Tomkins agreed that the cats were not clearly the cause of the woman's infection. "I would have called it a probable case," Tompkins said.

Other animals can carry the bacteria, too. For instance, 25 percent of rats in a New York City study carry species from the Bartonella genus, a study published Oct. 14 in the journal mBio reported.

Getting cat scratch disease from a pet is uncommon, Nelson said. People should be careful to keep their cats flea-free, and clean any cat bites or scratches with soap and water. A cat that has a tendency to scratch or play roughly should not be near immune-compromised people, he said.

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