Cats, toxoplasma & madness (again)

There have been a few more recent articles on cats and madness. (Another issue you can trust Opinion Dominion to follow for you.)

This article from the New York Times is mainly a look at research about how toxoplasma gondii spreads and works. It is a pretty weird infection:

Once Toxoplasma enters a host, it spreads quickly. Within hours it can be detected in the heart and other organs. It is even able to infect the brain, which is protected from most pathogens by a tight barrier.

Antonio Barragan ...[was] puzzled at first about how Toxoplasma managed this swift journey.

"When we looked for parasites in the blood, we found very few that were just swimming around," said Barragan, an associate professor. But the scientists observed many of the parasites inside immune cells known as dendritic cells.

Barragan was intrigued. Dendritic cells, common in the gut, often come into contact with pathogens. They respond by crawling to the lymph nodes or the spleen, where they communicate with other immune cells.

"That led us to think, what if this parasite is directing these cells to move and to disseminate through the body?" Barragan said. He and his colleagues put dendritic cells in a dish and injected them with Toxoplasma. They noticed that the parasites triggered a peculiar change: the dendritic cells became hyperactive, crawling for an entire day.

Erk.

Also, as noted on the web in many places, studies indicate that the infection in rats makes them lose their fear of cats. How this happens is very odd:

Scientists at Stanford University recently followed up on these experiments, studying rats and mice. "They actually show a mild attraction to the cat odor," said Ajai Vyas, a Stanford neurobiologist. "It's not just the loss of an old behavior. A new behavior is being induced."

Vyas and his colleagues found that Toxoplasma's effects were precisely aimed at cat odor. The rats were still afraid of dog odor but not of rabbit odor. They could also acquire new fearful responses. "Only the innate fear to the cat was different, which was very surprising," he said.

How Toxoplasma incites this change is a mystery. It is possible that the parasite alters the production of certain neurotransmitters. "But I don't know how some global change could have such a specific effect," Vyas said.

This article is a summary of research going on about schizophrenia and infections, with this comment on studies looking at the possible treatment for toxoplasma (and other infections) for those suffering schizophrenia symptoms:

...we are conducting several double-blind treatment trials that involve the use of adjunctive antibiotics and antiviral medications in persons with schizophrenia and bipolar illness. To date, these medications show some promise in patients with recent-onset disease. The results are less remarkable in persons with long-standing illness. In the future, it might even be possible to develop a vaccine to protect children against possible infections that contribute to these 2 mental illnesses.

Even with what is known today, in clinical settings, some patients who present initially with symptoms suggestive of schizophrenia or bipolar disorder could instead be in the initial stages of viral encephalitis. Some physicians would argue that patients with first-admission psychosis should have a lumbar puncture and CSF analysis, adding other studies as appropriate if indicated by an increase in CSF protein or lymphocytes.

If you feel you are going mad, maybe this should be suggested to your doctor. Just don't mention that you read it on a blog.