Parasitic skin infestations II, scabies, pediculosis, spider bites: unapproved treatments

Facts, fiction, and figures of the Sarcoptes scabiei infection

Today scabies, an ectoparasitic skin disease caused by the mite Sarcoptes scabiei variety hominis, is estimated to infect over 300 million humans worldwide. Scabies most frequently occurs among children and young adults. Outbreaks in child care facilities and schools are common. Scabies affects all socioeconomic classes and races. Students presenting with a possible outbreak of scabies in the school setting must be referred by the school nurse to a medical provider for diagnosis and treatment because scabies is highly contagious and can be spread by skin contact. This article will provide school nurses with the history, etiology, mode of transmission, symptoms, and the recommended treatment of a S. scabiei infection. Implications for school nursing practice will be discussed.

The Scourge of Sarcoptes: Oral Ivermectin for Scabies

OBJECTIVE

To review the use of the oral antiparasitic ivermectin in the treatment of scabies, with an emphasis on its use in the elderly and in long-term care settings.

DATA SOURCE

A MEDLINE/PUBMED search was conducted to identify pertinent studies, case reports, letters, and reviews in the English language. All articles published from 1980 to October 2003 were reviewed. Additional references were obtained from the bibliographies of these articles.

STUDY SELECTION

All studies evaluating ivermectin in the context of scabies mite infestation.

DATA SYNTHESIS

The semisynthetic macrocyclic lactone ivermectin has been available since the early 1980s as a broad-spectrum antiparasitic agent in animals and humans. This agent, which works by suppressing motor nerve conduction leading to parasite paralysis and death, was first used in ectoparasitic diseases (i.e., those caused by lice and mites) shortly after commercial introduction. A large body of literature, mainly uncontrolled case reports and series, has since evolved. However, these reports and results of the small number of placebo- and/or active-controlled studies have demonstrated the favorable response of both classic and crusted scabies to single- and multiple-dose oral ivermectin. Adverse reactions to the drug are uncommon, with the exception of a transient, new onset, or mild increase in existing pruritus soon after drug ingestion, which is thought to be a hypersensitivity reaction to dead mites and/or their products.

CONCLUSION

Oral ivermectin may prove to be a time- and labor-saving alternative to topical scabicide treatments, especially in the institutional setting where labor shortages make the management of scabies outbreaks a true challenge. However, the use of this agent does not change the need to decontaminate the environment (clothing, bedding, bed clothes, and, in selected cases, floors and walls) in order to truncate an outbreak and prevent reinfestation.

Clinical features and associated morbidity of scabies in a rural community in Alagoas, Brazil

OBJECTIVE

To describe the clinical characteristics of scabies and the associated morbidity in an impoverished rural community in northeast Brazil.

METHOD

A door-to-door survey was made to examine twice the population of an endemic area; first at the end of the rainy season, and a second time in the dry season 4 months later.

RESULTS

In total, 2005 individuals were examined. The overall prevalence of scabies was 9.8% (95% CI 8.5-11.2). Predilection sites with similar relative frequencies in all age groups were the abdomen (83.7%) and the inguinal area/inner part of the thighs (66.3%). Hands, feet, genitals and the scalp/neck/face were significantly more often affected in children <7 years (all P < 0.03). Fifty-five per cent of the patients showed scabies lesions simultaneously at > or = 12 distinct topographic areas. Papular lesions were most commonly found, followed by papular-crusted lesions. Vesicles were significantly more often observed in children (P = 0.04). Sixty-four per cent of the patients had three or more types of lesions. Local lymphadenopathy was present in 53.6% and superinfection in 36.7% of the cases. The number of topographic areas affected, as well as the proportion of superinfected lesions, was inversely correlated with age (rho = -0.22, P = 0.002 and rho = -0.358, P < 0.05, respectively). The quantity of skin surface infested, the proportion of superinfected lesions and the presence of a superinfected lesion distal to an enlarged lymphnode were predictors of lymphadenopathy. Seventy-two per cent of the patients suffered from sleep disorders, mainly because of itching.

CONCLUSION

Scabies is associated with considerable morbidity in this endemic community. Predilection sites, clinical presentation, quantity of skin surface affected and proportion of secondary infected lesions show a dichotomy between children and adults.

Scabies, pediculosis, bedbugs, and stinkbugs: uncommon presentations

Parasitic agents determine some of the most common skin disorders. Although well known, they could present different manifestations or be modified by individual or external factors that make their diagnosis or treatment difficult. This review will discuss some of the most prevalent parasitic infections, scabies, and pediculosis and also mention reactions determined by contact with certain insects that, although rarely found, could induce important skin reactions.

The life-threatening complications of dermatologic therapies

Dermatologists use a variety of systemic drugs, some of which can cause severe adverse reactions and even fatalities. Ivermectin, a well-tolerated drug, can cause severe neurological side effects, whereas metronidazole, in high cumulative doses, has been associated with convulsions and rarely with hepatotoxicity. Dapsone is associated with frequent hematologic side effects, such as methemoglobinemia, hemolysis, and anemia. Although hepatotoxicity is rare and usually mild and reversible with the new antifungal agents, severe cutaneous reactions (such as toxic epidermal necrolysis, Stevens-Johnson syndrome, and anaphylaxis) have been reported. Even a relatively safe drug such as acyclovir has been reported to be the cause of renal failure and neurotoxicity. Retinoids can cause not so benign "benign" intracranial hypertension. Methotrexate can cause not only liver toxicity, but also myelosuppression and pancytopenia, which may be acute and life threatening. Nephrotoxicity is a well-recognized side effect of cyclosporine, whereas thrombotic thrombocytopenic purpura, which is associated with high morbidity and mortality, is less well known. Dermatologists should be familiar with these and other severe adverse reactions of the most popular and most used systemic medications of our trade.

Inhibition of acetylcholinesterase by Tea Tree oil

Pediculosis is a widespread condition reported in schoolchildren. Treatment most commonly involves the physical removal of nits using fine-toothcombs and the chemical treatment of adult lice and eggs with topical preparations. The active constituents of these preparations frequently exert their effects through inhibition of acetylcholinesterase (AChE, EC 3.1.1.7). Increasing resistance to many preparations has led to the search for more effective treatments. Tea Tree oil, otherwise known as Melaleuca oil, has been added to several preparations as an alternative treatment of head lice infestations. In this study two major constituents of Tea Tree oil, 1,8-cineole and terpinen-4-ol, were shown to inhibit acetylcholinesterase at IC50 values (inhibitor concentrations required to give 50% inhibition) of 0.04 and 10.30 mM, respectively. Four samples of Tea Tree oil tested (Tisserand, Body Treats, Main Camp and Irish Health Culture Association Pure Undiluted) showed anticholinesterase activity at IC50 values of 0.05, 0.10, 0.08 and 0.11 microL mL(-1), respectively. The results supported the hypothesis that the insecticidal activity of Tea Tree oil was attributable, in part, to the anticholinesterase activity of Tea Tree oil.

Sexually transmitted diseases in men

Sexually transmitted diseases are the most common infectious diseases in the United States. Physicians, nurses, and other health care providers are uncomfortable discussing sexual issues with their clients. Therefore many health care needs are not addressed, and many opportunities for education aimed at preventing STDs are missed. In the periodic health history, the health care provider must elicit information about sexual practices (vaginal,oral, or anal intercourse), sexual orientation (heterosexual, homosexual, or bisexual), sexual risk behaviors (ie, unprotected intercourse with multiple partners), contraceptive use (particularly condoms), and prior STDs. Based on this information, the health care practitioner moves to more specific questions regarding sexual health. The health care practitioner asks about sores on the penis, dripping or discharge from the penis, staining of the underwear, testicular pain, and scrotal swelling. For the client who engages in oral sex, the health care practitioner asks about sore throat. For the client who engages in anal intercourse ask about diarrhea, rectal bleeding, anal itching, and pain. Probe the desire phase, the arousal phase (erection), and the ejaculation phase. Ask about the desire for fatherhood and concerns about fatherhood. An important part of health care is prevention. Culturally specific and sensitive information should be available for patients. Patient education should not consist of simply handing a brochure to a man. Using the brochure as a guide for including all the necessary information and ascertaining the man's understanding may be a very effective method of patient education. For men who are at increased risk for STDs or who present with symptoms of STDs, offering diagnostic testing is necessary. Men who have multiple sexual partners especially need diagnostic testing and prevention counseling. The CDC recommends annual HIV and hepatitis C testing for men who have sex with men and other men who have increased risk for contracting HIV. Another important consideration at the periodic screening examination is the vaccinations that are to be recommended. Men who have sex with men should receive hepatitis A and hepatitis B vaccine. Additionally, it is recommended that all adolescents should receive hepatitis B vaccine.

Ectoparasites--the underestimated realm

CONTEXT

Ectoparasitoses (infestations with parasites that live on or in the skin) can cause considerable morbidity. Whereas pediculosis and scabies are ubiquitous, cutaneous larva migrans and tungiasis (sand-flea disease) occur mainly in hot climates. The prevalence of ectoparasitoses in the general population is usually low, but can be high in vulnerable groups. Scientific knowledge on how to deal best with parasitic skin diseases in different settings is scanty, and evidence-based measures for control are not available. For head lice and scabies the situation is daunting, because resistance of Pediculus humanus capitis and Sarcoptes scabiei to insecticides is spreading and unpredictable.

STARTING POINT

J Hunter and S Barker reported different patterns of resistance in schoolchildren in Brisbane, Australia: full resistance to malathion, permethrin, and pyrethrum in two schools, whereas head lice were susceptible to malathion and, to a lesser extent, to pyrethrums in three other schools (Parasitol Res 2003; 90: 476-78). K Yoon and colleagues found different resistance patterns in the USA and Ecuador (Arch Dermatol 2003; 139: 994-1000). Head lice from Florida were less susceptible to permethrin than those from Texas, and parasites from Ecuador were susceptible to both insecticides tested. WHERE NEXT? The occurrence of resistant pediculosis and scabies is expected to increase numerically and geographically. Clinicoepidemiological studies are urgently needed to identify the factors which govern the emergence and spread of strains of P humanus capitis and S scabiei that are resistant to insecticide or acaricide. Oral treatment with ivermectin could substitute for topically applied compounds, particularly in resource-poor communities where polyparasitism is common. A better understanding of local epidemiology is required to develop control measures. This knowledge has to be applied in combination with environmental sanitation, health education, and culturally acceptable interventions that are affordable by the underprivileged.