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What Else Did my Cat Bring Home?


Romeo, who was infected twice with toxoplasmosis after eating a mouse


Photo Credit: © Jennifer Yarchever
Cats love to chase (and sometimes kill) mice. That's a given, and something that most people do not find too alarming. In fact, people in many countries still utilize "barn cats" to dispatch unwanted rodents - a win-win situation for all parties (except the rodents). The cats have plenty of food available, and the farmer is assured of grain bins undisturbed by hungry mice. A perfect scenario, eh?

Almost. In addition to barn cats, many suburban indoor-outdoor kitties will occasionally bring home a small kill to proudly display, which we humans (depending on our constitutions) might or might not allow him to eat. If not, we might be tempted to just pick it up by the tail and dispose of it in the trash container, or down the toilet. The problem is that, depending on the region, those little mice may be loaded with a variety of "nasties," that neither you nor your cats want to encounter. Romeo, the cat pictured here, was infected with toxoplasmosis twice, after catching and eating mice. The toxoplasmosis led to uvitis, which in turn led to glaucoma. Romeo is now an indoors-only cat as a result of this chain of events. Although most cats are exposed to toxoplasmosis at one time or another, the usual reaction is mild. However, Romeo's experience underscores the potential deadliness of this organism. Another case in point:

The Dreaded Hantavirus

In May of 1993, a new hantavirus, Hantavirus Pulmonary Syndrome (HPS) was identified in New Mexico, after forty-two people were infected, with eleven fatalities. Since that time, the new strain has been discovered in other parts of the U.S., with various rodents, including the common house mouse (Mus musculus) acting as hosts, and the incidence of disease in humans has become widespread. Several other hantaviruses that affect humans exist worldwide, and have been found responsible for outbreaks of hantavirus among animal caretakers and laboratory workers in Korea, China, Japan, Scandinavia, the U.K., France, the Netherlands, Belgium, and the former Soviet Union.1

Although HPS can be transmitted to humans by handling infected mice, inhalence of the aerosols produced directly from the saliva or excreta of the animal is the most virulent means of transfer, if not the most common. For these reasons, it is wise to wear not only rubber gloves when handling a mouse your brave hunter brings in, but also a mask, and to thoroughly scrub any surface area the mouse may contacted with a disinfectant.

Symptoms of HPS in Humans Early symptoms of HPS are very similar to those of other respiratory illnesses, including pneumonia, and may consist of:

  • Headache
  • Gastrointestinal complaints
  • Fever
  • Myalgia (muscle pain)
  • Variable respiratory symptoms

The condition can quickly progress into acute respiratory distress and pulmonary edema. Since the incubation period for HPS is from one to three weeks, early symptoms of this nature should be reported to your physician if you have had contact with a rodent during that time frame.

The Center for Disease Control (CDC) is investigating whether other animals that prey on rodents may be carriers. The UCSB Office of Research said, "The impetus for this research is a 1987 study suggesting that cats, which tested positive for two other hantaviruses-the Hantaan and Seoul types-may help transmit the virus to humans in China." However, the CDC has stated unequivocally that cats are not carriers of the hantaviruses that cause HPS in the United States, nor can it be transferred from one person to another. Although results are inconclusive as yet, virologists also think most non rodent carriers are "dead-end" hosts, which means they are unlikely to infect people. Unfortunately, cats do not get off quite as easily with the next zoonose we'll discuss.

1 Institutional Animal Care and Use Committee

Next > Toxoplasmosis: not just for pregnant people

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