5 Signs Your Cat Is Messing With Your Brain

You've probably heard of the infamous parasite Toxoplasma gondii and its possible role in the amicable nature of cat-human relations, but how do you know if you've been infected? There's good news and bad news on the subject: The good news is that in healthy adults, the physical signs of toxoplasmosis are often nonexistent, and if they do manifest, they're totally mild. The bad news is that since the infection is virtually symptomless, you could be infected right now and never realize it until you find yourself living in a decrepit house at the end of the lane, surrounded by dozens of cats — and even then, you'd still have to get tested to actually find out.

Admittedly, there are far worse diseases out there, but T. gondii works in super creepy ways. It can only sexually reproduce inside cat intestines, which means the parasite spends much of its life cycle convincing host mammals to let themselves be eaten by cats. Because nature is terrifying sometimes, T. gondii does this by taking up residence inside the host's brain and tinkering around.

In mammals like mice and rats, this manifests in an attraction to the smell of feline urine and slower reflexes. In people, things look a little different — research indicates that people who have been infected with T. gondii have higher rates of mental illnesses like schizophrenia and obsessive compulsive disorder, and latent toxoplasmosis has even been associated with a higher risk for car accidents. There's not enough evidence to make any concrete claims linking toxoplasmosis and an obsession with cats, but the disease has become nicknamed the "crazy cat lady syndrome" anyway. (Although it's a term that we might want to think about retiring; "crazy" is one of many mental health phrases we use carelessly in a way that makes light of mental illness.)

Even the staunchest cat lover (that is, myself) can get a little alarmed at the thought that their beloved kitty has gifted them with a parasite that burrows into their brain cells. Unfortunately for your peace of mind, toxoplasmosis is incredibly common; according to the Centers for Disease Control, an estimated 60 million people are infected in the United States alone.

So how do you know if you have toxoplasmosis? According to the Mayo Clinic, there can be "extremely serious complications" for infants and people with weakened immune systems, but as mentioned above, most healthy people never develop symptoms. Furthermore, the only way to find out whether you have it is to get tested by a doctor. On the other hand, some healthy people do show mild symptoms common to most infections — let's look at five below. (But again, be wary of self-diagnosing — head to a doctor instead.)

1. Body Aches

The CDC writes on its website that "some people who have toxoplasmosis may feel as if they have the 'flu' with... muscle aches and pains that last for a month or more."

2. Swollen Lymph Nodes

Swollen lymph nodes are a common reaction in many infections; usually, they swell up in the neck, armpits, or groin. The CDC notes that swollen lymph nodes are a common symptom of toxoplasmosis.

3. Fever

According to the Mayo Clinic, fever may result from an infection of toxoplasmosis; again, many signs mimic those of the flu.

4. Fatigue

Finally, the Mayo Clinic writes that fatigue is common in healthy adults who develop toxoplasmosis symptoms.

5. More Advanced Symptoms

Although most people don't need treatment for the disease, adults with compromised immune systems — people with HIV/AIDS, for example, or those who have recently undergone an organ transplant — may develop more severe symptoms. According to the Mayo Clinic, these can include the following signs:

• Headache
• Confusion
• Poor coordination
• Seizures
• Lung problems that may resemble tuberculosis or Pneumocystis jiroveci pneumonia, a common opportunistic infection that occurs in people with AIDS
• Blurred vision caused by severe inflammation of your retina (ocular toxoplasmosis)

Unless your immune system is already weak, though, chances are fairly high that you'll never even realize you have a literal parasitic roommate upstairs.

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