This episode of "This Week in Parasitism" (TWIP) delves into a listener case involving three family members who discovered small, dark, mobile objects embedded in their skin after extensive hiking across Scotland and the Northeastern United States. The hosts and listeners overwhelmingly identify the parasites as various species of ticks. The discussion covers the diverse tick species prevalent in the visited geographic locations, the diseases they can transmit (including Lyme disease, anaplasmosis, babesiosis, and alpha-gal syndrome), proper tick removal techniques, the crucial timing for disease transmission, and appropriate testing and prophylactic treatments. The hosts emphasize patient education on tick checks and the nuances of diagnostic testing. The episode concludes with a "hero" segment honoring Dr. Lawrence Tetley, a pioneering microscopist specializing in parasites, and introduces a new case about a summer camp parasite check.
Exploring Ectoparasites Without Borders: A Tick Infestation Case Study
0:00 Introduction to TWIP 263: The podcast, "This Week in Parasitism" (TWIP), begins, introducing hosts Vincent Racaniello, Daniel Griffin, and Christina Naula.
0:27 Case Introduction – The "Ectoparasites Without Borders" Case: Daniel Griffin reveals the ongoing case: a mother, daughter, and son found small, dark, poppy seed-sized objects embedded in their skin, some mobile, after significant travel.
2:20 Travel History: The family's recent travels included a remote island off Scotland (Harris and Lewis), mainland Scotland (Loch Ness, Cairngorms), Long Island, and Cape Cod, with extensive hiking in grassy and wooded areas.
4:46 Key Questions: The hosts pose questions for listeners: What are these objects? Is the travel history relevant? Are there timing issues? How should they be removed, and is testing or treatment indicated?
5:20 Listener Responses - Ticks Identified: Listeners unanimously identify the objects as ticks, with many specifying different species like Ixodes ricinus (sheep tick), Ixodes scapularis (blacklegged tick), and Dermacentor variabilis (American dog tick).
5:52 Tick Identification and Removal: Suggestions for identification include looking for eight legs with a magnifying glass. Removal advice focuses on using fine-tipped tweezers to grasp the tick close to the skin and pulling upward steadily, avoiding squeezing.
6:06 Associated Diseases & Risks: Listeners detail potential diseases such as Lyme disease, anaplasmosis, babesiosis, Rocky Mountain spotted fever, tularemia, tick paralysis, and alpha-gal syndrome (meat allergy). The importance of monitoring for symptoms like a bullseye rash is highlighted.
16:21 Timing and Transmission: It's noted that disease transmission (e.g., Lyme disease) typically requires the tick to be attached for 36-48 hours. The timing of discovery after a weekend of hiking could mean some ticks were attached long enough for transmission.
17:29 Post-Removal Protocol: Recommendations include cleaning the bite area, saving removed ticks for identification/testing (submerged in alcohol or in a bag), consulting a healthcare provider, and monitoring for symptoms for 30 days.
21:35 Prophylactic Treatment: A single dose of doxycycline (200mg for adults) may be indicated for Lyme disease prophylaxis if specific criteria (endemic area, Ixodes scapularis tick, >36 hours attachment, within 72 hours of removal) are met.
36:45 Host Discussion & Confirmation: The hosts confirm the consensus that the objects were ticks. Christina discusses the incidence of Lyme disease and tick-borne encephalitis in Scotland, noting lower risk compared to the US East Coast.
40:35 Geographic Relevance & Different Pathogens: Daniel emphasizes that different geographic areas host different tick species and associated pathogens, making travel history crucial. He mentions apps like "Tickr" for tick identification.
41:20 Timing of Transmission & Prophylaxis Nuances: Daniel explains the delay in Lyme disease transmission (pathogen migration) and notes that the 36-48 hour window for doxycycline prophylaxis primarily applies to Lyme, not necessarily other tick-borne diseases. He raises concerns about over-prescribing doxycycline and potential resistance.
43:59 Diagnostic Testing Advice: He advises against "knee-jerk" serology immediately after a bite, as IgG takes 3 weeks to turn positive. PCR testing can be done during the acute period, especially for severely ill patients, considering co-infections.
45:45 Case Outcome: The family successfully removed all ticks, and no one developed any health problems. The ticks were likely picked up in Cape Cod due to crawling under a log.
46:22 Book Giveaway: Angelica from Sweden is the lucky winner of a copy of "Parasitic Diseases."
47:49 Hero of the Week – Dr. Lawrence Tetley: Christina honors Dr. Lawrence Tetley, a recently deceased pioneering microscopist at the University of Glasgow, who specialized in electron microscopy of parasites (especially trypanosomes) and contributed significantly to understanding cell biology of parasites.
53:01 New Case for Next Episode: Daniel introduces a new case about a summer camp parasite check, where two children are asked to step aside for an identified concern (likely head lice).
54:48 Limerick: David shares a clever limerick about parasitic identification.