Friday Faculty Focus: Paul Davis
February 22nd, 2019
Dr. Paul Davis is currently involved in researching toxoplasmosis gondii, one of the most common parasitic infections of humans and other warm-blooded animals. Dr. Davis and I recently discussed the dangers this rather common and often misunderstood microbial parasite presents to all of us.
Dr. Paul Davis: Most of us don’t really understand some of the microorganisms that inhabit us as human beings. Our colon is filled with microbes, our skin is covered in microbes and we’re only now beginning to learn of some of the effects, often positive effects of having these microbes in us or on us. This is a parasite that inhabits the brain of about one-third of all adult Americans. We’re trying to understand a little more about what it is that does.
We know that when you become infected with this parasite, there doesn’t seem to be any acute difficulty. What that means is that if you become infected you maybe get a fever that will last for a few days and then that fever clears.
New research by colleagues around the world suggest that infection by this parasite might have some subtle effects. It might change our risk taking behavior. It might change our susceptibility to certain neurological or psychiatric diseases. As this data is now starting to emerge, I think our interest in discovering a vaccine, of which there is none; or some drugs that can treat this disease, for which there isn’t any that really penetrate the brain well.
Dr. Davis expanded on what changes to risk taking behavior might mean:
Davis: It’s not well delineated where the possible changes might be. In mouse models we’ve seen the biggest change that’s been done by others were infected mice (that) are no longer afraid of their predator, their natural predator, the cat. What we find is that, naturally, cats will eat mice, therefore mice tend to run away from cats. In infected mice, we find that they’re no longer scared of cats. The cat can eat them, because they’re not running away, and then the parasite ends up infecting the cat. It turns out that the cat is the definitive host, it’s the host in which the parasite most likes to live. By changing the behavior of a mouse, it can actually get into its preferred host faster.
We think that’s what’s happening in that predation model. Whether we’re being affected in the same way that mice are being affected: that’s an open question.
Dr. Davis also noted the connection between Toxoplasma Gondii and sexually transmitted diseases such as HIV and AIDS.
Davis: One of the things that we see in the clinic is that individuals who progress to AIDS often have opportunistic infections that can really affect their health and toxoplasma gondii is one of the most prevalent and one of the most dangerous. This is a parasite that people get from eating undercooked meat or being exposed to an infected cat. What happens is the parasite migrates to the brain and other tissues in the body. If the immune system goes offline, if it becomes reduced such in the case of AIDS patients. That can lead to tissue degradation near the sites of where they’ve insisted.
On another health related subject, research out of Baylor University has found that a type of mosquito that transmits malaria has been found in Ethiopia for the first time, which would be a new region of people to be exposed to the disease.
Davis: Malaria has been prevalent in many parts of the world over history. The United States drove it out through a combination of mosquito control and trying to control the disease itself in individuals. As the vector, the mosquito spreads to different areas. We’re going to see Malaria, as well as a number of other mosquito-born diseases continue to spread. Some of that’s affected by climate change, because the mosquito has new areas that it can go into; some of that is affected by drug resistance. As we lose the ability to treat some of these diseases with current drugs that we have.
Scientists are currently looking at new ways on how best to control mosquitos. Dr. Davis speculated on what might happ