Light Shed Light on Cat Scratch Fever : Medicine: Though its symptoms mimic those of maladies as serious as cancer, new tests help doctors diagnose this sometimes-deadly disease.
Despite the fever, seizures and eventual coma, Richard Simms is adamant. He refuses to get rid of his 4-year-old cat, Max. Not that family and friends haven’t tried to persuade him. But Simms knows that Max didn’t mean to harm him. It was just a playful scratch.
“I am absolutely attached to the cat, and I would not even consider that,” said Simms, 26, who lives in Conyers, Ga.
Some people would think that sounds odd from a man who contracted a nasty case of cat scratch disease from Max two years ago. The symptoms--blurred vision, irritability, fatigue--were sudden, Simms recalled. “I started cussing people out, which isn’t my nature,” he said.
When Simms collapsed abruptly and started having convulsions, his parents said it took four paramedics to place him on a stretcher. The family later learned that combative behavior was not an uncommon reaction from a man in the throes of a brain seizure.
Simms spent the following two days in a coma. At Emory University hospital, he was diagnosed with encephalitis, a brain inflammation. The cause: cat scratch fever.
This mysterious disease is usually a benign bacterial infection that causes illness only in people, not cats. Experts say that Simms had a very severe and rare reaction. About 1% of the 22,000 cases reported each year in the United States result in a life-threatening condition like encephalitis, according to the Centers for Disease Control and Prevention in Atlanta (CDC).
For most people, cat scratch is a mild illness that causes a low-grade fever, fatigue, headaches and swollen lymph nodes. The disease occurs more often in men than in women. In the United States, most cases occur from September through February.
Now scientists are zeroing in on the culprit bacteria. In the New England Journal of Medicine, researchers have reported that the bacteria known as Rochalimaea henselae may cause the disease and that kittens are more likely to transmit the infection than adult cats. Evidence that this bacteria causes cat scratch disease has enabled scientists to develop experimental blood and skin tests to make the diagnosis.
One problem is that people often fail to take a cat scratch or bite seriously and rarely seek medical attention for deep puncture wounds.
That may change as the incidence of the disease increases. “It is much more common than people think,” said Bradley Perkins, a CDC epidemiologist. “If a young, healthy person is suddenly in a coma in the intensive care unit, we would certainly like to know what we can do to prevent that from happening.”
A recent study also found a larger proportion of patients with severe cases than previous reports had indicated. While none of the people in the study died, 10 of the 60 patients--17%--required hospitalization.
The rising incidence of cat scratch is linked to the increased popularity of cats, veterinarians say. Cats, once considered mysterious and unpredictable animals, are now much more in vogue, said Diane R. Eigner, a Philadelphia veterinarian who operates The Cat Doctor, an animal hospital specializing in cat care. “Because of their independence, cats fit in to the chaotic lives we all lead.”
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Cat scratch disease presents physicians and researchers with a challenge: Not only is the disease extremely difficult to diagnose, it is even harder to treat. Until a blood test or a skin test becomes widely available, most physicians diagnose the disease by ruling out other ailments. CDC’s Perkins estimates that physicians will have a blood and skin test available to them in about two years.
The symptoms--fever, swollen lymph nodes and headaches--mimic the signs of more serious illnesses, such as cancer or tuberculosis. Physicians may order a series of expensive blood tests in order to diagnose the illness.
Because lymph nodes in the neck or under the arms can remain swollen for several months, doctors may suspect lymphoma--cancer of lymph nodes--and order a biopsy, an invasive test that involves removing a piece of tissue for further study. The procedure can cost about $2,000.
The prospect of cancer seriously frightens people who think they or their children may have a life-threatening illness.
When Catherine Luck of Fredericksburg, Va., discovered two swollen lymph nodes in her neck and felt pain and tenderness in her right breast, she was convinced that she had breast cancer. “I was sure of it,” said the 51-year-old aerobics instructor. “I was afraid of the big C for three months before I went for a mammogram.”
Even though the mammogram was negative, Luck was still uncertain. The pebble-size lymph nodes were very tender and painful. It was only after a friend suggested cat scratch that she remembered being scratched by one of her five cats.
A mild case of the disease was ultimately diagnosed by Andrew Margileth, a Fredericksburg pediatrician who has treated a number of patients with cat scratch. He used an experimental skin test to detect the disease.
The diagnosis “did bring me much peace of mind,” Luck said. “Had I known something about cat scratch, I would not have worried about cancer.”
It’s not just the illness--which is usually mild--but the psychological trauma connected with getting a correct diagnosis that concerns many physicians. Most people don’t suspect cat scratch disease when they develop symptoms.
Says Frank MacMurray, a District of Columbia internist who treated his first case of cat scratch fever in 1950, “If somebody gets a big lymph node and they have a fever and a cat, they should think of cat scratch disease.”
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Although cats are the most likely animal to transmit the disease, people have gotten infected from dog bites. Kittens, especially ones that carry fleas, are strongly implicated in passing the disease to people.
Veterinarians are concerned that people will automatically think they should get rid of their cats or dogs. In fact, CDC officials and physicians advise people against taking such an extreme action. After one case of cat scratch, people rarely contract the disease again.
Researchers suspect that people may build up an immunity against cat scratch disease. There is also evidence that cats are only infectious for a short period of time. By the time a person is found to have the illness, it is likely that the cat no longer carries the disease, Perkins said. “So there is no need to do anything to the cat.”
“People can get more serious illnesses from other humans than they can from cats,” said veterinarian Eigner. “People need to keep that in perspective.”
