Pediculosis and scabies are caused by ectoparasites; patients usually present with itching. Head and pubic lice infestations are diagnosed by the visualization of insects or viable nits (eggs). Primary treatment is topically administered 1 percent permethrin. Malathion is one alternative for treatment failures. The importance of environmental measures to prevent infestation is a matter of controversy. Pubic lice are treated the same as head lice, but this finding should prompt evaluation for other sexually transmitted diseases. Body lice infestation should be suspected when symptoms of generalized itching occur in persons who do not change or wash their clothing or bedding regularly; lice may be found in the seams of their clothing. Topically administered permethrin may help to eradicate body lice, but personal hygiene measures are essential for successful treatment. Classic scabies in adults can be recognized by a pruritic, papular rash with excoriations; in infants, small children, and the immunocompromised, the rash may include vesicles, pustules, or nodules. Primary treatment for scabies is permethrin cream, and environmental measures are important to prevent recurrent infestation. Generalized crusted scabies is best treated with oral ivermectin.

Oral ivermectin is an effective and cost-comparable alternative to topical agents in the treatment of scabies infection. It may be particularly useful in the treatment of severely crusted scabies lesions in immunocompromised patients or when topical therapy has failed. Oral dosing may be more convenient in institutional outbreaks and in the treatment of mentally impaired patients. Ivermectin has been used extensively and safely in the treatment of other parasitic infections, but the U.S. Food and Drug Administration has not approved the drug for the treatment of scabies infection. The safety of oral ivermectin in pregnant and lactating women and young children has yet to be established.

The regulatory effect of amino acids on the production of thaxtomin A, a phytotoxin produced by Streptomyces scabies, was investigated. Tryptophan had an important inhibitory effect on the toxin biosynthesis in all five strains of S. scabies tested. Two other aromatic amino acids (tyrosine and phenylalanine) also inhibited thaxtomin A biosynthesis, while aliphatic amino acids did not cause an important decline in thaxtomin A production. Methylation of tryptophan prevented or reduced the inhibitory effect on thaxtomin A biosynthesis. In spite of the inhibitory action of tryptophan and phenylalanine on thaxtomin A production, incorporation of these radiolabeled molecules into thaxtomin A confirmed that they are metabolic precursors for the biosynthesis of the phytotoxin.

We report the case of an 80-year-old patient who had intense pruritus which did not respond to a 3-month treatment with topical corticosteroids. On dermoscopy examination of the excoriations, we found the typical dermoscopic aspect of the scabies mite at a distance. Dermoscopy allows identifying a triangular structure which corresponds to the anterior section of the mite including the mouth part and the 2 pairs of front legs. This aspect has been described as resembling a jetliner with its trail, a delta glider or a spermatozoid. Traditional diagnostic methods for scabies failed in this case because the mites were at a distance from the burrows. This was due to the fact that the reaction to the mite was less pronounced and the diagnosis is frequently missed. Dermoscopy is a useful tool for the diagnosis of scabies either as a diagnostic test or to guide the traditional diagnostic tests.

The challenge for nurses in hospital and community settings is to recognise scabies, deal with it appropriately and to help educate those who are most vulnerable.