Pruritic bug infestations are a common problem among school-age children, Albert C. Yan, MD, said at a pediatric dermatology meeting sponsored by Rady Children’s Hospital-San Diego and UC San Diego School of Medicine.
There are four basic bug infestations – cutaneous larva migrans, carpet beetle dermatitis, scabies, and lice – and it is essential for you to be able to recognize and treat these appropriately. You also need to know resistance patterns, and how to counsel patient on full treatment protocol.
Cutaneous larva migrans typically present with a skin rash on the feet or thighs of children and young adults who walk around barefoot. The organism invades through the skin of the foot and creates serpiginous patterns. Ancylostoma braziliense is the most common species to cause this rash. The parasite is usually trapped by the basement membrane and rarely penetrates to visceral organs. However, rarely it can present in the oral mucosa when contaminated products are placed in the mouth, which is why Dr. Yan tells his own kids “not to eat things off the ground.” The treatment for this infection includes ivermectin, albendazole, or thiabendazole.
Carpet beetle dermatitis presents in children with a history of spending lots of time on a carpet, presenting with nondescript itchy patches on skin areas that were in contact with the carpet. Carpet beetle dermatitis is becoming more common on the east coast. Patients can actually find these beetles, which have tiger-striped coloring and have little prickly hairs that stick out of them, in their carpets. The beetles do not bite; rather, the rash is a reaction from exposure to insect blood or the larval hairs. The adult beetles tend to feed on carpet fabrics, wool, grains of food products, animal material, or nectar and pollen in flowers. The treatment is to get rid of the beetles. To rid the house of the beetles, it is recommended to vacuum, remove contaminated food sources, freeze stuffed animals for 10-14 days, and have an exterminator visit the home. Bringing in fresh cut flowers from the garden without rinsing them may bring the beetles into the house.
Scabies tends to be an itchy, widespread dermatosis. It is associated with extensive small skin papules scattered across the body with linear or curvilinear burrows, and tends to present from the elbows or knees distally, and especially in webbed areas, such as between the fingers. Keeping these geographic locations in mind makes it easier to differentiate scabies from hand dermatitis and eczema, said Dr. Yan, chief of pediatric dermatology at Children’s Hospital of Philadelphia and professor of pediatrics and dermatology at the University of Pennsylvania, Philadelphia.
To help diagnose this infestation, scrape the lesion and visualize the mite, the scybala or mite feces, or the oval eggs under the microscope.
The treatment is a “permethrin party.” Luckily, the scabies mite has very little documented resistance to permethrin 5% cream. However, with recurrent treatment, resistance starts to develop, he said. Proper administration is critical in controlling the infestation. For an adult, use 3 ounces or one tube, and for a child, use about 1.5 ounces for a child or one-half a tube. Apply it to the skin from neck down, leave it on for 8 hours overnight. Treat the patient and family members or close contacts. Repeat this application in 1 week. Oral ivermectin is effective and is useful in older kids who may not adhere to the permethrin.
A commonly encountered problem is apparent treatment failure. The scabies may be identified, treated, and then they appear to recur. Some patients have persistent postscabetic itch – the patients are still itchy afterward, but the lesions look excoriated and different than the original scabies lesions. The patient does not need retreatment, Dr. Yan emphasized. Rather, use topical corticosteroids or antihistamines to treat the itch.
Another explanation is improper use of medication – for instance, only certain parts of the skin were treated or all family members had not been treated. In this case, everyone needs to be retreated, he said. Reinfection is possible, but resistance is unlikely. Patients with scabies sometimes develop scabetic nodules or hypersensitivity nodules. Often, these are leftover areas of inflammation that can remain for up to 1 year. Dr. Yan recommends treating these areas with low-dose topical steroids.
The last phenomena presents with recurrent crops of pustules in the acral area, which is acropustulosis of infancy or postscabetic pustulosis. This is a variant of acropustulosis of infancy, in that it is more likely to involve the torso than is traditional acropustulosis and tends to be cyclical in that it reappears every few weeks.
Head lice are an “easy” diagnosis, and Dr. Yan describes finding the actual lice on a patient’s head as “very satisfying.” They are usually found behind ears, on the posterior aspect of the head, and on the neck. Head lice are very common, affecting approximately 6-12 million people per year, and $100 million is spent annually on treating these infestations. It is more common in 3- to 12-year-old girls, usually more prevalent with longer hair, and is spread primarily through direct contact. Live nits are 1-2 mm from scalp, hatch about 1 week later, live for 1 month, then reproduce, while the original nits die off. The lice cannot survive more than 1-2 days off the human body. Infestations tend to be cyclical throughout the year, with an increased number of cases at the end of school year or during the summer.
Recently, the Journal of Medical Entomology published study findings in which head lice genetics were assessed, raising the concern about the development of “super lice.” However, this information has not yet brought treatment changes.
The conventional treatments include Nix, Rid, Triple X, but there can be a fair amount of resistance with these OTC treatment. Other options include mayonnaise and olive oil, however, not much data support the efficacy of this treatment. There are three prescription medications available: benzyl alcohol lotion, spinosad topical suspension, and ivermectin lotion. Start with these treatments quickly when dealing with lice that are resistant. Oral ivermectin also is effective. Dr. Yan concluded his lecture with discussion of other techniques that have been Food and Drug Administration–cleared, such as blowing drying them off the head, if one is okay with them landing in the office!
Dr. Yan reported no relevant financial disclosures.
