Dermatology Weekly

The flea bite is a problem for a variety of populations — from those in natural disaster scenarios to pet owners. Dr. Vincent DeLeo talks with Dr. Dirk M. Elston about cat fleas and other issues in environmental dermatology. Dr. Elston discusses vector-borne diseases, including endemic typhus and cat-scratch disease, caused by organisms transmitted by fleas, as well as interventions to remove fleas and treat their bites. Dr. Elston also gets personal and talks about how he got interested in bugs following his time in the military.

We also bring you the latest in dermatology news and research.

1. States pass record number of laws to reel in drug prices

Measures include authorizing imported prescription drugs, screening for excessive price increases by drug companies, and establishing oversight boards to set drug prices.

2. Peanut allergy pill gets thumbs-up from FDA advisory panel

The approval of Palforzia is on condition that a black-box warning and medication guide are included in the packaging.

3. Dr. Henry W. Lim takes a closer look at new data on sunscreens.

Things you will learn in this episode:

• All fleas are vectors for disease in humans. “You see dog fleas on cats, and cat fleas on dogs,” Dr. Elston explains. “You’ll see poultry fleas on dogs, especially in the Carolinas. But there are certain fleas that historically have been the ones that carry most disease.”
• Cat fleas (Ctenocephalides felis) can carry endemic typhus and are typically found in south Texas and southern California. Oriental rat fleas are a vector for disease in other parts of the United States, including areas of California and the Southwest.
• One of the clues for identifying endemic typhus would be a small rickettsial or black depressed eschar at the site of the original bite.
• Flea bites — presenting as papular, vesicular, intensely pruritic— tend to occur on the lower parts of the body. “The fact that they’re grouped on the lower extremity, the papular vesicular or bolus quality does suggest the possibility of fleas,” reports Dr. Elston.
• For houses or abodes that have long been unoccupied (e.g., 2-3 years), new owners walking on the floorboards may rapidly activate the pupae living in them.
• Flea treatments for animals include fipronil, which is applied on the animal’s neck and spreads like an oil over its body. Oral agents containing ivermectin for heart worm and fleas; however, ivermectin can be fatal for some animals, such as collie dogs.
• Disease depends on the type of vector. “If you have the organism transmitted by a louse, you’re likely to get endocarditis,” Dr. Elston explains. “Whereas if it’s a flea, you are more likely to get cat-scratch disease rather than sepsis and endocarditis.”
• Long-term therapy with macrolides is a mainstay treatment of cat scratch disease.
• Children with cat-scratch disease who present with systemic disease, including neurologic disease, should be managed together with an infectious disease specialist.

Guests: Dirk M. Elston, MD (Medical University of South Carolina, Charleston); Henry W. Lim, MD (Henry Ford Medical Center, Detroit)

Show notes by Jason Orszt, Melissa Sears, and Elizabeth Mechcatie.

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