This episode of This Week in Parasitism (TWiP) begins with a discussion on the current state of US public health, focusing on the detrimental effects of funding cuts to organizations like USAID, NIH, and the CDC. The hosts and guest Chuck Knirsch express concern over the impact on global health initiatives and disease surveillance. The main scientific segment is a critical review of a paper investigating the link between schistosome infection, behavior, and the gut-brain axis in a mouse model. The study found that infected mice exhibited increased anxiety, enhanced short-term memory, and impaired spatial learning. While the infection also caused significant shifts in the gut microbiome, the hosts conclude that the paper does not establish a causal link and that further experiments, such as fecal transplants, are needed. The latter half of the episode is a heartfelt tribute to the late Dr. Dickson Despommier, a co-founder of the podcast. The hosts reminisce about his charismatic personality, his influential teaching career, his research on Trichinella, his passion for vertical farming, and his foundational role in establishing the MicrobeTV network.
Exploring Schistosomes, Behavior, and a Tribute to a Mentor
1:04 Public Health Under Threat: The episode opens with a discussion about significant funding cuts to US public health institutions like USAID and the NIH. Guest Chuck Knirsch highlights the catastrophic impact, such as donated drugs and vaccines being stuck in ports, and the dismantling of early warning systems for emerging diseases in low-income countries.
8:50 Paper Discussion: Schistosomes and Behavior: The hosts begin their review of a paper from PLOS Neglected Tropical Diseases titled, "Does schistosome infection affect behavior through the gut-brain axis?" The study uses a mouse model to investigate the connection.
14:41 Mouse Model and Behavioral Tests: The study infected female mice with Schistosoma mansoni and performed a series of behavioral tests to measure anxiety, memory, and learning, including the open field test, novel object task, and Morris water maze.
25:01 Increased Anxiety in Infected Mice: In the open field test, schistosome-infected mice spent significantly more time in the outer boundaries of the arena, a behavior interpreted as a sign of increased anxiety and fear compared to uninfected mice.
26:33 Altered Memory Retention: The novel object task revealed that infected mice had enhanced memory retention one hour after exposure to an object, but this effect disappeared after 24 hours. The hosts discuss the potential evolutionary implications of this short-term memory enhancement.
32:04 Impaired Spatial Learning: The Morris water maze task, designed to test spatial memory, suggested that infected mice had more difficulty remembering the location of a hidden platform, forcing them to swim a greater distance to find it.
34:06 Questioning the Microbiome Link: While the infection clearly altered the gut microbiome of the mice, the study's authors and the TWiP hosts conclude there is no direct evidence of a causal link between these microbiome changes and the observed behavioral shifts. They suggest a fecal transplant experiment would be a critical next step to establish causality.
43:49 Tribute to Dr. Dickson Despommier: The conversation shifts to a celebration of the life and career of the late Dr. Dickson Despommier, a mentor and co-founder of the TWiP podcast.
46:37 A Multifaceted Career: The hosts share memories of Dickson's major contributions, including his foundational research on how Trichinella parasites create a "nurse cell" in muscle, his later-career passion for developing vertical farming, and his legendary status as a multiple-time "Teacher of the Year" award winner at Columbia University.
55:05 Founding Father of MicrobeTV Podcasts: Vincent Racaniello recounts starting This Week in Virology (TWiV) and then TWiP with Dickson, who he chose for his eloquence, enthusiasm, and broad knowledge. They credit Dickson with bringing Dr. Daniel Griffin onto the podcast, revitalizing the show with a clinical perspective.