Flea Control Advisory Issued : New Warning on Pet-Related Illness

County health officials have reiterated a warning--first issued last summer--that house cats in a 12-square-mile area north of downtown Los Angeles may inadvertently become carriers for a low-grade form of the fever disorder typhus.

Health officials advise cat owners to take aggressive steps to control fleas on their animals and in their yards. But a variety of experts say that, while cats emerging as typhus carriers is a new wrinkle in public health, house pets--despite sometimes draconian warnings in the media--remain generally quite safe to handle and even share a bed with.

Good advice for loving cat and dog owners, one prominent veterinarian said, is, while it’s generally all right to sleep with your pet in close proximity, “don’t kiss your dog or cat on the mouth. You don’t know where that tongue has been.”

Periodically, noted several veterinarians and medical doctors, alarms are sounded about pet health and diseases that can be transmitted to humans. The question has even been responsible for at least one major controversy: Whether pregnant women should have any contact with cats and, if so, how much. The controversy stems from disagreement over the means of transmission of a disease called toxoplasmosis, a sometimes-serious parasitic infection that can be passed by a mother to her unborn child.

But the reality, these experts agreed, is that many possible pet-related disorders have little more than a theoretical danger to humans. Basic hygiene--particularly keeping children out of contact with pet feces or outdoor settings contaminated by cat and dog droppings--can avert most pet-related disease in humans. In the case of toxoplasmosis, there is controversy over whether it is more common to get the disease from contact with cat feces or by handling or serving uncooked meats.

Still, there’s nothing wrong with caution of the type advocated in a medical journal editorial by a veterinarian employed by the U.S. Department of Agriculture. Somewhat facetiously, Dr. William Hubbert urged two years ago that, just as cigarettes carry a health warning label, perhaps it would be appropriate to stick a little tag on dogs, cats and even snakes and birds that says: “Caution, this pet may be a hazard to your health.”

The immediate concern in Los Angeles County is with a modest outbreak--first identified in 1984 and 1985--of cases of so-called murine (meaning “flea-born”) typhus that appears to be limited so far to a confined area including the Los Feliz, Silver Lake, Mount Washington and Eagle Rock neighborhoods in the city, the southern portion of Glendale and parts of South Pasadena.

Nineteen cases were reported in the county in 1984 and 1985--14 of them in the affected area, said Art Tilzer, head of a health department unit that tracks disease transmission pathways. None of the cases was serious. No episodes have been reported in 1986, Tilzer said, but he and physicians questioned by The Times agreed that, because symptoms of murine typhus are similar to a bad cold, the disease is often misdiagnosed.

Tilzer said the health department assumes there have been cases of the disease of which the agency has not become officially aware. “Conditions are still being monitored closely,” Tilzer said after the department published a renewed notification of the possible outbreak last month in a newsletter for physicians. “We were expecting some additional cases, so this may be the slowing of a trend,” he said.

Urging caution, health officials added that murine typhus is a far less serious disease than the so-called epidemic form of typhus and that both of those disorders are totally unrelated to typhoid fever, even though the names are a bit similar.

Murine typhus is characterized by chills, headache and fever, and there is sometimes a skin rash. In most patients, the fever disappears on its own after about 12 days, and fatalities are rare--though they have sometimes been reported in elderly patients. There is no vaccine. In epidemic typhus, on the other hand, symptoms are more severe and fatality rates can reach as high as 60% in older patients.

It isn’t certain exactly how cats in the affected Los Angeles area neighborhoods entered the typhus transmission chain initially, but county health officials noted that murine typhus carriers include tree rats and possums--both species with which house cats in hillside neighborhoods routinely come in contact.

It turns out, said Tilzer, that while there are several flea species common in Southern California, the variety that transmits typhus is the same type that is attracted to cats. Both 1984 and 1985 were severe flea years, though 1986 does not appear to be as bad--though some cats (not to mention their owners) in the affected neighborhoods might disagree.

Importance of Flea Control

Tilzer and other experts agreed the typhus situation underscores the importance of flea control, a fundamental part of any effective program to avoid pet-related illnesses of many different kinds. Controlling fleas, concluded Tilzer and a research team from UC Davis and the University of Oregon that published a review of pet-related illness in a major journal last year, depends on these basic strategies:

- Control on the animal. Good techniques, the experts agreed, include using flea dip on the animal every two weeks during flea season. Flea shampoos are generally ineffective, the article published in the New England Journal of Medicine last October noted. Flea powders and sprays can be used between dips; flea collars are somewhat effective, but do not constitute an alternative to more aggressive means of flea control on animals.

Because flea collars contain the same basic chemicals as most dips, sprays and powders, however, combination use of those items and flea collars can be toxic to animals.

- Control in the animal’s environment. This can include both inside the house and in yard areas. Tilzer cautioned that people who live where there is heavy vegetation in and around yards--especially large amounts of ivy, a major habitat for flea-infested tree rats--could include yard clearance as part of a good flea-control program. Some flea bombs are available for exterior use, as well.

Pet food should not be left outdoors because possums, skunks, raccoons and other creatures may be attracted to it. Openings that could permit an animal the size of a possum to get under a house should be eliminated. Fruit that falls from trees should be removed and pet foods should be stored in containers that resist animals.

Inside the house, aerosol flea bombs can be used. The bombs penetrate into nooks and crannies inaccessible to aerosol sprays, which are reasonably effective on furniture and floor coverings like rugs. Frequent, thorough vacuuming is also helpful.

Ticks are also a concern; while tick collars are not terribly effective, they can be used in areas where there are large concentrations of ticks. Ticks, which can transmit Rocky Mountain spotted fever from dogs to humans, should be gently removed with tweezers or the fingers. Regular checking for ticks is the best approach because a tick must be attached to a pet or human for 12 hours before it can transmit the fever virus. Hands should be washed thoroughly after removing ticks.

Dr. James Miller of the UC Davis School of Veterinary Medicine said that while he was not aware of any statewide or regional problem with murine typhus, flea control is an essential part--though far from the only component--of the effective strategy by which any pet owner can minimize the risk of acquiring some disease from his or her animal. Miller was one of four authors of the review of pet-human health problems published last year.

Miller noted that fleas are the culprit in one of the most feared of all pet-related illnesses, plague, which can be--though it rarely is--transmitted to humans by cats. Though various forms of plague decimated Europe several hundred years ago, plague today is comparatively easy to treat with modern antibiotics.

A cat bitten by a plague-infested flea reacts differently from a dog, in which the illness is generally mild. Cats, however, are susceptible to much more severe plague infection.

“I think in general, the key is sanitation practices,” Miller said in a telephone interview. “Excrement--particularly bowel movements--ought to be cleaned up on a routine basis.” He and other experts agreed that local pooper-scooper laws requiring pet owners to retrieve droppings of their animals are an excellent public-health resource.

Of the animal-born illnesses that can potentially affect humans, most rely on parasites that can be found in feces or blood of animals. Included is a wide variety of worm parasites.

Bacterial infections are also numerous and they include leptospirosis, commonly associated with urban stray dogs but occasionally found in pets, too. The resulting disease in humans--after contact with urine, feces, blood or animal tissue--includes fever, headache and the possibility of neurological damage. Salmonella can be transmitted by pets, though this is thought to be infrequent.

The range of problems also includes disorders like cat-scratch disease, first identified in 1950 but still of unknown cause. It is mostly confined to children and involves development of skin lesions near the site of a scratch or bite inflicted by a cat. The disorder is not serious.

Miller and other experts on animal-related disease agreed that perhaps the most controversial, potential health problem tied directly to sanitation concerns is the risk to pregnant women of contracting toxoplasmosis, which is carried by microorganisms common to a variety of animals. Members of the cat family, however, are the most significant potential hosts.

Cats can acquire toxoplasmosis parasites from eating raw meat--generally in the form of prey--and Miller and other experts urged cat owners to do as much as they can to prevent their cats from consuming prey animals. The experts acknowledged what many cat owners already know: Cats often defy all attempts at influence by humans.

Human infection with toxoplasmosis can occur in three ways--ingestion, in the course of eating raw or undercooked meats, of cysts formed around the parasite in a meat animal host; ingestion of spores for the disease brought on by handling cat feces, and transfer, across the placenta, of the infection from an infected mother to her unborn child.

Symptoms Often Mild

Even in infected humans, toxoplasmosis is often either completely asymptomatic or causes fever, headache or a generalized sick feeling that is so mild it is shrugged off or attributed to some other cause. The organism can settle in the eye, as well.

When the parasite is passed from mother to fetus, possibly severe birth defects can occur, including hydrocephalic offspring, liver and eye problems.

For that reason, said Miller and Dr. Bruce Max Feldmann, former director of the UC Berkeley pet clinic and now a veterinarian in private practice in Kensington, Calif., pregnant women are probably best advised not to change cat litter. However, both Miller and Feldmann agreed that the risk may be substantially minimized by changing litter daily because it takes three days for the toxoplasmosis spore in cat feces to become active and, if the litter is discarded daily, the disease cannot be transmitted.

Miller and Feldmann both said they believe that toxoplasmosis blamed on pet contact is often caused by a pregnant woman eating raw or undercooked meat.

Miller and the team that assembled last year’s article urged pregnant women to avoid contact with cat feces and to wear gloves when working outdoors--in a garden, for instance--where cat excrement may have been. A pregnant woman, especially, should wash her hands thoroughly any time she may have come in contact with any surface contaminated by cat feces. She should also wash her hands after handling raw meat.

“It depends on how conservative you want to be,” Feldmann said. “Cats only pass toxoplasmosis when they are sick, so if you have a well cat, the chances are almost zero. But if you want to play it safe, she (a pregnant woman living alone, for instance) could change the litter daily.

“But generally, it’s not the cat that pregnant women should be concerned with. It’s handling hamburger and sticking their fingers in their mouths, or not cooking meat well enough.” To neutralize toxoplasmosis organisms in meat, it must be heated through to at least 150 degrees Fahrenheit.

Small Percentage of Problems

“I think that, on the whole, pet-associated illnesses are fairly infrequent,” said Dr. Allen Mathies Jr., a pediatrician with expertise in infectious disease and the head of Huntington Memorial Hospital in Pasadena. Like other doctors, Mathies said his experience in practice is that, considering the number of pets and the number of children there are, problems are few even though children are almost inevitably inclined to occasionally touch items contaminated by pets and then stick their fingers in their mouths.

“You do see occasional animal infection. But I think I’ve seen four cases of dog tapeworm in young children, for instance, and you put that into the perspective of saying that’s 20 years of practicing medicine in Los Angeles. Pets are not generally hazardous to health.

“But you must deal with the pet recognizing that it does not practice the same degree of hygiene that human beings do and you must assume the responsibility.”

Dr. Paul Wehrle, a USC pediatrics expert, agreed with several other physicians who cautioned that, of all pet-related health problems, animal bites are, by far, the most significant, followed by the risks of exposure to rabies. Wehrle said that in Southern California, bats are a frequent source of rabies infection, with foxes and skunks also involved. Dogs and cats can acquire rabies from any of these wild creatures.

Experts believe there are about a half-million animal-bite cases a year in the United States, with only about half the victims seeking medical care. Dogs are responsible for from 80% to 90% of the bites, but cat bites are more toxic to humans than dog bites because bacteria in cats’ mouths are more potentially toxic. However, Wehrle emphasized that the most dangerous of all bites for people in terms of infection s the bite of another human being.

“But the practical risks,” Wehrle said, “must be very small.

“Indeed, because there are millions of dogs and cats out there living in very close contact with (adults and) children, we do not see that many problems.”