Scientists are blaming a parasite considered common in the United States for changes in the brain that result in suicide attempts. The culprit is Toxoplasma gondii, the parasite responsible for toxoplasmosis. Since it's transmitted from cats to humans, these findings are of particular importance to individuals such as myself who frequently handle cats or live with them.
Among the lead researchers in the study was Lena Brundin, associate professor of experimental psychiatry at Michigan State University's College of Human Medicine. Results suggested that in patients with this parasite, the risk of attempting suicide is seven times more likely than in those without it, according to Medical News Today.
As many as one in five U.S. residents have the Toxoplasma gondii parasite. Scientists have considered it virtually harmless -- dormant in the bodies of most people, whose healthy immune systems keep it at bay. The Mayo Clinic says that while most individuals who contract the disease have no signs of it, toxoplasmosis can cause some very serious complications.
When there are signs of the disorder, they're usually flu-like symptoms. However, the disease can be fatal for those who are immunocompromised and disabling for children who have congenital cases. Pregnant women are considered at elevated risk. For patients who need treatment, the two most common drugs are pyrimethamine and sulfadiazine.
The Centers for Disease Control and Prevention (CDC) notes that toxoplasmosis is a leading cause of death linked to foodborne illness. It is one of five parasitic diseases on the CDC's Neglected Parasitic Infections list. Others include Chagas disease, cysticercosis, toxocariasis, and trichomoniasis. All are parasitic illnesses marked as public-health priorities.
Although earlier research suggested a link between Toxoplasma gondii and suicide attempts, the work of the Brundin team was the first to measure scores on a suicide assessment scale using subjects known to have the parasite. The scientists hope that the ability to identify people carrying it will help healthcare providers predict those at higher-than-average risk for attempting suicide.
Their results suggest a relationship between serotonin levels in the brain and depression. The researchers believe that inflammation from the parasite could trigger chemical changes in the brain, resulting in depression and sometimes in suicidal thoughts.
Since I am a cat rescuer and take medication to suppress my immune system, I have had to take extra precautions around the feral cats I handle, especially those recuperating from illness or injury. One of these cats recently tested positive for toxoplasmosis and giardia.
I had to be tested twice for both conditions once we isolated the dates of my exposure. While there was no evidence of giardia, I did show prior exposure to but not the presence of Toxoplasma gondii. The linking of this so-called "harmless" parasite to attempted suicide and chemical changes in the brain puts an even soberer spin on this experience.
Vonda J. Sines has published thousands of print and online health and medical articles. She specializes in diseases and other conditions that affect the quality of life.