Thrips mistaken for headlice or Ekban Syndrome.
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Animals↗
Biomedical subjects
Terri L Meinking
Publications and source records attributed to Terri L Meinking.
Clinical update on resistance and treatment of Pediculosis capitis.
The anatomy and physiology of head lice make them extremely adaptable to their human hosts but also difficult to eradicate. Their coloring and small size make them difficult to see, and the larvae, or nymphs, have multiple exoskeletons for protection. When exposed to pediculicides, a nymph can shed its outer exoskeleton and receive only a sublethal dose. Through natural selection, head lice have developed resistance to commonly used pediculicides, making it increasingly difficult to eliminate infestations. Other contributors to resistance include changes in formulations of pediculicides and improper use. Over the last 20 years, the efficacy of pyrethrins has declined because of necessary safety changes in formulations and unintentional effects of new packaging on chemical components of these products. Pediculicides designed to be applied to wet hair may become too diluted to produce the desired effect. Patients also may use too little product to conserve costs. The combination of decreased product efficacy and exposure of head lice to diluted or insufficient amounts of pediculicides has reduced their effectiveness substantially. Studies comparing the current efficacy of several over-the-counter and prescription pediculicides with effectiveness in the 1980s has shown that OVIDE (malathion) Lotion, 0.5% is the only product that has retained its efficacy over time. The efficacy of over-the-counter pyrethrin products had declined significantly, and lindane, another prescription product, was least effective of all products tested both in the 1980s and in more recent studies. In addition to retaining its efficacy, malathion 0.5% also is effective when applied for only 20 minutes. The shorter application time is safer for children and also decreases the likelihood that residual product remains in the hair, further contributing to resistance.
Animals↗
Faculty discussion: definitive management of head lice in the era of pediculicide resistance.
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Animals↗
Ivermectin.
Ivermectin is a potent antiparasitic drug and the first commercially available member of a new class of drugs (macrocyclic lactones) that has been approved for human use. Ivermectin has already proven to be highly effective in the elimination of river blindness as a public health burden. Side effects have been minor, and patient acceptance is good. Promising results in off-label applications for ectoparasitic infestations are increasingly important as resistance to topical therapy becomes more prevalent Ivermectin represents an advance in the therapeutic armamentarium and should be considered in appropriate cases.
Antiparasitic Agents↗
Comparative in vitro pediculicidal efficacy of treatments in a resistant head lice population in the United States.
OBJECTIVE: To compare the pediculicidal activity of 5 head lice products available in the United States on head lice from south Florida. DESIGN: In vitro pediculicidal product comparison. SETTING: Lice Source Services, Inc, located in Plantation, Fla, a clinic for the treatment and grooming of individuals with pediculosis capitis. PARTICIPANTS: Head lice were collected from healthy clients with Pediculus capitis that came to Lice Source Services, Inc, to seek their services. INTERVENTIONS: Within 2 to 6 hours of capture, lice were placed in continuous direct contact with the pediculicide products and observed at regular intervals. Results were compared with findings of a recent study of a treatment-sensitive population of head lice conducted in Panama. MAIN OUTCOME MEASURE: Percentage of lice dead at regular observation intervals between 5 minutes and 3 hours of continuous exposure to the pediculicides. RESULTS: Two prescription products, Ovide lotion (0.5% malathion) and 1% lindane shampoo, were ranked in the same order as in 2 previous studies (first and last, respectively). The order of effectiveness from most to least effective was as follows: Ovide lotion, A-200 shampoo (a natural pyrethrin product synergized with piperonyl butoxide), undiluted Nix (1% permethrin), diluted Nix, RID (a natural pyrethrin product synergized with piperonyl butoxide), and 1% lindane shampoo. CONCLUSIONS: There were statistically significant differences in the efficacy of all the products when compared with the results found in the recent study in Panama, except for Ovide lotion. Of those tested, Ovide was the only pediculicide in the United States that had not become less effective. The difference in efficacy of 1% lindane, Nix, and pyrethrins between the Panama and Florida studies supports the argument that some head lice in the United States have become resistant to these treatments.
Adult↗
An observer-blinded study of 1% permethrin creme rinse with and without adjunctive combing in patients with head lice.
OBJECTIVES: To determine if NIX (Warner Lambert Healthcare, Morris Plains, NJ) 1% Permethrin Creme Rinse Lice Treatment (1% PLT) without combing will effectively treat >/=95% of patients on day 2 or on day 15; to determine whether combing influences efficacy. STUDY DESIGN: A randomized, observer-blinded study enrolled 95 infested adults and children. All patients were treated with 1% PLT on day 1 and, if still infested, on day 8. One third of households were randomized to the combing group and two thirds to the no-combing group. Efficacy was assessed by: (1) visual inspection on days 1, 2, 8, 9, and 15 and, (2) shampooing/straining on days 2, 9, and 15. The target efficacy was 95%. RESULTS: In the no-combing group, the lice-free rate was 83.1% on day 2 (95% CI, 71.0-91.6), 45.8% on day 8 (before second treatment) (95% CI, 32.7-59.2), 77.6% on day 9 (95% CI, 64.7-87.5), and 78.3% on day 15 (95% CI, 65.8-87.9). Adjunctive combing did not improve efficacy on any day. CONCLUSIONS: In this population, 1% PLT was significantly less than 95% effective and suggests resistance to 1% PLT. The failure of nit removal combing by nonprofessional caregivers to improve efficacy demonstrates the unreliability of combing as adjunctive treatment in this setting.
Adolescent↗
Changing paradigms in parasitic infections: common dermatological helminthic infections and cutaneous myiasis.
Parasitic diseases caused by helminths, or worms, account for billions of human infections worldwide. Although most human pathogens caused by these organisms are infrequent in the United States, skin manifestations of parasitic diseases are being seen much more frequently in dermatologists' offices due to the increase in immigration and travel. Helminths are notable for their complicated lifecycles often including consecutive developmental phases, in separate hosts or in a free-living state. These parasitic organisms are usually macroscopic, multicellular organisms, and do not breed within their mammalian hosts. Notably, many helminthic diseases present with dermatologic signs and symptoms including skin nodules, cysts, migratory skin lesions, and pruritus. In this section, we discuss cutaneous myiasis as well as the four most common nematode dermatologic conditions seen in the United States.
Animals↗
Efficacy of a reduced application time of Ovide lotion (0.5% malathion) compared to Nix creme rinse (1% permethrin) for the treatment of head lice.
Our objective was to conduct a randomized, investigator-blinded evaluation of the pediculicidal and ovicidal activity of a reduced application time (20 minutes) of Ovide (0.5% malathion) compared to Nix (1% permethrin) in a south Florida population infested with Pediculus humanus capitis. Either Ovide or Nix was applied according to the label instructions. However, Ovide application time was reduced to 20 minutes. At day 8, subjects with live lice were re-treated with the same product and procedure as on day 1. Ovicidal and pediculicidal efficacy were evaluated at days 8 and 15. A subject free of lice and viable eggs at day 15 was considered to be a treatment success. Percent efficacy was calculated using the number of subjects free of lice and viable eggs per total number of subjects treated. We found that a 20-minute application of Ovide was significantly more pediculicidal and ovicidal (98%) compared to Nix (55%) at day 15 (p < 0.0001). The percentage of Ovide subjects who required treatment at day 8 was half that of the Nix group. The reinfestation rate was 0% with Ovide and 33% with Nix. In conclusion, a 20-minute treatment with Ovide, instead of the approved 8- to 12-hour application, cured 40 of 41 subjects (98%), demonstrating superior efficacy to Nix. The poor efficacy of Nix confirms the resistance of head lice to permethrin in south Florida.
Adolescent↗