Non-Oscar Winning Parasites
Sophia Linton, MSc Candidate, Translational Medicine
At the March 5, Medical Grand Rounds, the Department of Medicine was fortunate to host Dr. Thomas Herzinger, a Professor and world-renowned Dermatologist here at Queen's University. Dr. Herzinger opened our eyes to the colorful and clinically relevant world of dermatology, specifically parasitic infections.
A parasite is an organism that lives on or in a host organism and gets its food from or at the expense of its host. Parasitic infections cause a tremendous burden of disease in both the tropics and subtropics as well as in more temperate climates. Dr. Herzinger prefaced his talk by stating that many parasitic diseases suffer from a lack of attention by the public health community, yet they affect over 1 billion people—one-sixth of the world’s population—particularly in rural areas of developing countries.
Dr. Herzinger hosted his very own award ceremony for "non-Oscar winning parasites," with seven nominees up for “Best Parasite”. Honorable mentions were given to Trombiculidae (chiggers), Pediculus humanus corporis (body louse) and Pthirus pubis (pubic louse), which can all be treated easily with pediculicides. Fleas, specifically Yersinia pestis, were not forgotten for their role as the causative agent in the Plague. Today, modern antibiotics are effective in treating the plague. However, without immediate treatment, the disease can cause serious illness or death.
Three parasites were left in the running for the "bug statuette": head lice, scabies and bed bugs.
Head lice are roughly 2–3 mm long and infest the head and neck by attaching their eggs to the base of the hair shaft. Head lice infestation, or pediculosis, is typically spread by close person-to-person contact. In Canada, pediculosis is most common among preschool- and elementary school-age children and their household members and caretakers. Dr. Herzinger emphasized that getting head lice is not related to the cleanliness of the person or their environment and can be easily treated with over the counter and prescription medications. The head louse's popularity among the younger generation was awarded a third-place finish at the "Academy Awards."
Scabies is an infestation of the skin by the human itch mite. The scabies mite is typically spread by direct, prolonged; skin-to-skin contact with a person who has scabies. There are two basic diagnostic methods to identify scabies infection: skin scrapings and scabioscopy. Dr. Herzinger explained that both methods require special equipment and expertise that may not be readily available to every physician faced with the challenge of diagnosing scabies. In response, he adapted the technique of Superficial Cyanoacrylate Biopsy (SCAB) as an alternative method for mite identification in scabies. Here, a small drop of cyanoacrylate glue is applied to a glass slide, which is immediately pressed on the skin lesion. After 30 seconds, the slide is swiftly detached, and examined with a conventional microscope. Under the microscope, the mites are discernable as tiny dark oval dots. Perhaps, the "Academy's" vested interest in scabies had a hand in its second-place finish. However, the global impact of scabies in institutions such as nursing homes, extended-care facilities, and prisons is undeniable.
And the non-Oscar goes to … bed bugs! These parasites are found across the globe and feed solely on the blood of people and animals while they sleep. Although the presence of bed bugs has traditionally been seen as a problem in developing countries, it has become rampant in parts of the United States, Canada, the United Kingdom, and other parts of Europe. Bed bugs have been found in five-star hotels and resorts, and their presence is not determined by the cleanliness of the living conditions where they are located. The good news is that bed bugs do not transmit disease. The “Academy” recognizing its resurgence, effect on property loss, expense, and inconvenience awarded it “Best Parasite.”
Dr. Herzinger emphasized that it isn't easy to disentangle the relative importance of economic, environmental, and behavioral factors since they frequently co-exist in these cases. He urges dermatologists to take this into account when diagnosing and treating cutaneous parasitic infections in the clinic and to be considerate of the lifestyle changes required to treat these patients. Dr. Herzinger believes it is especially important to recognize the role of primary care physicians in diagnosing parasitic infections, as most cases can be diagnosed and treated without a dermatologist.
It was a pleasure to hear from Dr. Herzinger at the Medical Grand Rounds. On behalf of the TMED graduate students, we thank him for his time and invaluable introduction to the world of parasites.