By Kate Narita My biggest aha moments in life have happened when I’ve become aware of an implicit bias that a few months earlier I would have told…
Do you think cleaning the cat litter box is an annoying chore that you have to complete every day? What if I told you that scooping the litter incorrectly could endanger your life? It is possible that your sweet and innocent cat is harboring a parasite called Toxoplasma gondii (Toxoplasma) that can be passed to humans through contact with cat feces. In most cases of human infection, the parasite lies asleep in the brain. However, in individuals with impaired immune systems, Toxoplasma can cause lots of problems for its human host such as damage to the eyes, brain, and other organs. Toxoplasma can also impact pregnant mothers and their fetuses, and infants that are born to mothers who were infected with Toxoplasma during pregnancy can suffer from severe eye and/or brain damage. Shockingly, it is estimated that 1/3 of people around the world are infected with Toxoplasma and do not even know it.
Dr. Bill Sullivan is the Showalter Professor of Pharmacology and Toxicology at the Indiana University School of Medicine. His lab studies Toxoplasma gondii and how the parasite can lay dormant in the brain in a stage of development called a cyst. Dr. Sullivan was first introduced to Toxoplasma while he was doing his PhD work at the University of Pennsylvania. Toxoplasmosis, the manifestation of disease caused by the parasite, was one of the major killers of HIV patients early in the AIDS epidemic. He says this clinical relevance drew him into the parasite, “I was able to merge my love of microbiology and cellular biology with the projects I have been doing with Toxoplasma.”
When asked about some of his favorite research developments he laughed and said “every paper is kind of like your child and it’s hard to pick favorites.” But, if he had to decide on just one paper, there is a recent study out of his lab that excited many other people in the field. It focused on the drug guanabenz, which is an old drug that used to be used to treat high blood pressure. Guanabenz is not commonly used today due to the discovery of more effective blood pressure medications, however, his group discovered that this drug could be repurposed as an antiparasitic agent that works well against toxoplasmosis and malaria. What makes this drug particularly exciting is that his lab has found that it can reduce the brain cyst count in mouse models of Toxoplasma infection. Former MD/PhD student, Dr. Jennifer Martynowicz, studied the effect of guanabenz on the behavioral changes associated with Toxoplasma infection in mice. Mice infected with Toxoplasma lose their fear of cats and are attracted to the smell of cat urine among other things. This is because Toxoplasma needs to be inside of a cat to sexually reproduce. Dr. Martynowicz hypothesized that if they could remove enough cysts from the brain, they could also reverse these behavioral changes. In one mouse model, Dr. Martynowicz saw brain cyst numbers go down by 80% and saw the behavior of the mice return to normal. However, additional experiments showed that the restoration of normal behavior was linked to the fact that guanabenz was also reducing inflammation in the brain. This “shattered the dogma of the field” because it moved the blame of the behavioral changes from the parasite itself to the immune response of the host. As ground-breaking as this is, Dr. Sullivan stresses that just because this phenomenon is observed in mice does not mean it will also occur in humans. He states that “It would be premature to say that this happens in people,” but he believes that this research may eventually lead to better treatments for Toxoplasma infection.
Toxoplasma is out there and it is easy to get infected with it. Currently, there is no cure for Toxoplasmainfection, so prevention is the best medicine. He believes that “with very simple and straightforward behavioral changes you can avoid catching this thing.” Since many people become infected with Toxoplasma through contact with cat fecal material, it is incredibly important to wash your hands after scooping the litter box or after gardening outdoors. If you are immunocompromised or pregnant, it is recommended that you wear gloves while performing these activities as well. The parasite is also transmitted through undercooked meat. For more resources on Toxoplasma, please visit the CDC website.
Although his lab mainly focuses on Toxoplasma, Dr. Sullivan believes that there are shared challenges certain pathogens face that could be exploited to develop new therapies. He is the founder of the Biology of Intracellular Pathogens (BIP) group that meets once a week to discuss advances in research in the fields of parasitic organisms such as Toxoplasma and Plasmodium (which causes malaria), but also intracellular bacterial organisms like Chlamydia. This group allows its members to see what is happening in other fields and apply those research advances to what they are doing with their own pathogen. I myself study Plasmodium, which is a parasite that is related to Toxoplasma, and I am also a member of BIP. I enjoy learning about the research being conducted by my colleagues and seeing the great strides that are being made in our field. BIP is not the only place where Dr. Sullivan blends different ideas together. He has published a book called Pleased to Meet Me: Genes, Germs, and the Curious Forces That Make Us Who We Are, which talks about the interaction of commensal organisms living in our bodies and how they can affect different aspects of our everyday lives from behavior to food preferences. Through his book he is able to connect with the public and teach them about science. He shared a story with me about an interaction he had with a woman at one of his book signings. She approached Dr. Sullivan and told him reading his book changed her life. Her sister had been cut off from the rest of her family due to her ongoing issues with addiction, and reading the chapter in Pleased to Meet Me that explained addiction allowed her and the rest of her family to better understand why her sister was struggling so much, and this encouraged them to reach out to her to reconnect. Dr. Sullivan said this interaction “moved him to tears” and reaffirmed to him why he does science communication work.
Given his background in infectious diseases, Dr. Sullivan felt an obligation to speak to the public about COVID-19 when the pandemic began. “I know a lot more about viruses and antivirals than the average person, so I thought it was kind of our obligation to go out there and inform and educate the public about COVID-19 and the various treatments that were popping up,” he stated. He has written several articles breaking down complicated scientific topics into smaller, more digestible pieces. Some examples of his work are linked here and here. Dr. Sullivan believes that a lot of vaccine hesitancy and inability to get the pandemic under control is due in part to inadequate science communication. “There is really no reason we shouldn’t have had better control of COVID-19 one hundred years after the last plague of this scale. The urgent need for better education and scientific literacy inspired me to get out there and put a voice of expertise into the mix of all the disinformation and lies.”
Given that public mistrust of scientists is at an all-time high it is now more important than ever for us to communicate effectively and clearly with non-scientists. We have an obligation as experts in our fields to communicate our work with those it directly impacts. I believe we can all take a page out of Dr. Sullivan’s book on how to be advocates for science in the public eye.
Elizabeth Fusco is a graduate student at the Indiana University School of Medicine. Her research investigates how the gut microbiome impacts the functionality of the immune system in response to Plasmodium infection. In particular, Elizabeth is interested in exploring how the gut microbiome affects memory cell populations in Plasmodium infection. In the future, she hopes to pursue a career in science communication and education. You can connect with Elizabeth on Twitter at @elizabeth_fus