Parasites In Cat Poop, Public Health Menace?

Dr E Fuller Torrey, medical director at the Storey Research Institute, warns that cat feces may be the source of an enormous, unnoticed public health problem.

Every year, Torrey says, cats in the USA alone produce 1.2 million tons of feces. This cat scat harbors eggs of a parasite called Toxoplasma gondii. Even where cats don't leave visible traces of toileting, each square foot of the ground in urban yards and parks tested in a sampling of locations over the United States, a recent study found, contains from 4 to 434 oocytes, parasite eggs with a tough coating that keeps them viable for several years. 

It only takes one oocyte to cause an infection with the disease called toxoplasmosis, and every single square foot of ground in urban areas offers, on average, 400 opportunities for cats, and humans, to pick up this parasitic disease. Controlling cat poop, Dr Torrey says, needs to be a much higher priority for public health officials all over the world where cats are kept as pets, and especially in the United States.

What is toxoplasmosis?

Toxoplasmosis is an infection with the parasite Toxoplasmo gondii. a single-celled organism called a protozoan that establishes itself inside human cells.  About one in every three people around the world have a toxoplasmosis infection, usually after exposure to cat litter at some point in life, typically in childhood. It is also possible to be born with the infection. 

What are the symptoms of toxoplasmosis?

The first case of toxoplasmosis was identified in 1923 in an infant who suffered swelling of the brain (hydrocephalus), loss of vision, and seizures. Usually, however, the symptoms of the infection are much less severe. There can be swelling of the lymph nodes, usually less than 3 cm (less than about 1-1/4 inch), and the nodes are typically not tender. There can be a sore throat, mild abdominal pain, and irritation of the retina. Unless there is some kind of someone has a compromised immune system, even these symptoms are of only short duration.

When the immune system is compromised, however, toxoplasmosis can cause severe symptoms. In non-AIDS compromise of the immune system, toxoplasmosis results in neurological symptoms about 50 percent of the time. There may be seizures, and paralysis on one side of the body, similar to stroke. 

In people who have HIV or AIDS, the symptoms of infection are even more severe. There can be movement disorders, "cerebellar signs" (difficulty standing or sitting, tendency to fall backwards, among other problems with movement), profound weakness, alterations of vision, and psychiatric problems.

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And in children who are born with the infection, about 70 percent will have no problems at all, but about 30 percent will experience some degree of vision or hearing loss if they do not get timely treatment. 

Toxoplasmosis is sometimes referred to as "crazy cat lady syndrome," and it actually is associated in some cases with eccentric behavior.

How To Avoid Toxoplasmosis And Keep Your Cat

Some people who are at special risk for toxoplasmosis, especially people who have had organ transplants and have to be put on immune rejection drugs, simply cannot keep cats. The risk of contracting toxoplasmosis is simply too high with a cat in the house or even in the yard.

But what if you just don't want to risk toxoplasmosis, and you can't imagine giving up the family cat? Here is what you need to know and do to minimize the risk of infection.

• No breed of cat that is more or less likely to be infected with the parasite. Most cats carry it.
• Infection with toxoplasmosis is much more common in Western Europe than in the USA. One study found that 63 percent of French people are infected with the parasite, compared to about 30 percent of Americans.
• Country cats are more likely to be infected with toxoplasmosis than city cats, because they eat more mice and rats. If your cat is a good "mouser," it is more likely to get the parasite from the rodents it eats.
• Avoid contact with cat feces. Wear gloves when changing the litter box, but even if you do, pet owners should wash their hards when they're done with this task. Vacuum around the litter box regularly. Don't walk barefoot in the yard if your cats have ever defecated there — the eggs of the parasite can survive for years in the soil, long after any evidence of feces has weathered away, even after cat poop has been picked up and put in the trash.
• Wear gloves when working with soil in the garden or in flower beds. If there is a chance that a visiting cat has relieved itself in your yard or flower bed, parasites may have been deposited into the soil.
• Wash hands thoroughly after handling eggs (chickens can also get infected with the parasite) or raw meat (as can farm animals). Don't eat raw meat, and make sure blood from raw meat does not contaminate other foodstuffs.
• Wash fruits and vegetables, especially fruits and vegetables that come from your garden, the gardens of your friends and neighbors, or organic farms. The inherent quality of these fruits and vegetables is usually higher than anything you can get at the supermarket, but contamination is more likely, too.

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Treatment for toxoplasmosis usually is not necessary if there are no symptoms, except in children under the age of five, in whom it is important to prevent vision and hearing loss. People who have AIDS or HIV are usually given aggressive treatment for the parasite if their CD4+ (T-cell) counts fall below 100. Babies who are born with the infection need to be followed closely to make sure hearing and vision are normal and there are no developmental delays, usually through the age of six. Visiting the doctor as often as once a week for routine blood work may be necessary.