Use of ivermectin for the management of scabies in a nursing home

ARTICLE

Human scabies is a common contagious disorder found in almost all parts of the world. In western countries, there has been an upsurge in the elderly in nursing homes and other long stay care facilities [1]. Control of a scabies epidemic can only be achieved by treatment of the entire population at risk, associated with other procedures such as parasitic documentation of the disease, staff education, recognition of crusted scabies cases, schedule of treatment time and coordination of therapy [2].

Topical treatment such as lindane and permethrin have been shown to be effective for scabies [3]. Nevertheless, careful application of a topical agent for treatment of a whole population is difficult and time consuming. Ivermectin initially used for treatment of animal parasitic infections has been used extensively as an antiparasitic agent in humans, particularly to control onchocerciasis [4]. Several studies have reported a good efficacy of ivermectin for the treatment of scabies in humans [5-8].

In this study we report the use of ivermectin for the treatment of an outbreak of scabies in a nursing home.

Patients and methods

In June 1995 several residents of a nursing home near Lyon, France complained of pruritus and scabies was microscopically demonstrated in two patients by skin scraping. The nursing home is a three level building with a total of 129 beds (24, 66 and 39 beds at levels 1, 2 and 3 respectively). In July 1995 all residents of levels 1 and 2 were treated with topical application of 1% lindane (Scabecid^®). This anti-scabies treatment was associated with careful disinfection of bedding and furniture.

In February 1996, a reappearance of pruritus in several residents and three staff members was noted. We were consulted by the medical staff of this nursing home for parasitological confirmation and therapeutic advice for a suspected new scabies outbreak. For each of the 129 residents and the three symptomatic staff members a cutaneous examination was conducted and the distribution and severity of lesions were plotted on a body diagram. The presence and degree of pruritus were also recorded and underlying disease(s) and maintenance therapy for other conditions were noted. In patients with clinical signs of scabies, skin scrapings were performed and microscopically examined, in our laboratory, for scabies mites, eggs and/or fecal pellets. Information for staff members was given by the occupational physician in charge of the nursing home.

Ivermectin was obtained for compassionate use from Merk Sharp and Dhome-Chibret (Paris, France). All residents, symptomatic or not, were given orally 12 mg of ivermectin (Mectizan^®). The treatment was administered the 27th of February for levels 2 and 3 (104 patients) and the 28th February for level 1 (24 patients). For these two days, residents were asked to stay at their own level. A second dose of ivermectin (12 mg) was administered to all residents 14 days after the initial therapy. In addition to oral treatment with ivermectin, clothes were disinfected with lindane powder before washing. Furniture, bedding and non-washable clothes were disinfected with a pyrethrinoid powder (A-Par^®). Patients were followed-up for seven weeks after the initial treatment and the presence of pruritus and/or cutaneous lesions was recorded.

It was proposed that all staff members and their families be treated, at home, either with oral ivermectin or with topical medications. Treatment was associated with disinfection of clothes and bedding. Other subjects who were in contact with patients were treated only if they were symptomatic. Scabicides were provided, by the institution, at no cost to staff members and their families.

Results

One patient with Down's syndrome had hyperkeratotic cutaneous lesions and had been treated at least three times for scabies over the past 12 months. This patient was transferred to an infectious diseases department to insure proper isolation and treatment. The 128 remaining patients (mean age 86 years) were examined clinically. Forty-two patients (33% of the population) had pruritus and/or cutaneous lesions. Typical burrows were noted in 19% of the cases. In more than half of the cases, cutaneous lesions were not typical of scabies. Papular rash was noted in 29% and vesicular rash in 12% of the cases. Cutaneous lesions affected the upper limbs in 81% of the patients, the trunk in 26% and the lower limbs in 17%. Generalized lesions were seen in 17% of the cases. Skin scrapings were performed in 22 patients and scabies mites or their by-products were present in seven patients. Itching decreased a few days after initial treatment and skin lesions improved within seven days in the majority of the cases. In only one case was a failure noted, with reappearance of itching four weeks after the initial therapy and microscopical demonstration of scabies at the seven-week follow-up. This patient was treated again with oral ivermectin. No new cases of scabies were diagnosed in residents or staff members during the follow-up period. Three patients died during the follow-up period; two were over 90 years old and one had a colon carcinoma.

Discussion

In this study, scabies was recognized several weeks after the beginning of the outbreak. This time delay is often seen in institutions [2, 9] and can be related to atypical lesions of scabies in elderly patients. In our series typical burrows were noted in only 19% of the cases. Absence of typical lesions and small numbers of parasites in the cornified layer could explain the low number of patients in which skin scrapings were positive (7 out of 22). A recent report suggests that incident light microscopy which allows observation of large body areas with sufficient magnification could be an accurate diagnostic method for patients with atypical disease [10].

Patients with hyperkeratotic scabies, such as individuals with Down's syndrome, are known to be index cases for large hospital outbreaks [2]. In the present study a resident with Down's syndrome presented severe scabies and was suspected to be a major source of contamination for other residents and staff members. This patient was therefore transferred to a hospital ward for isolation and treatment before the therapeutic strategy for the outbreak was initiated. After parasitological confirmation of the scabies diagnosis, an information session was held by the occupational physician to inform staff members about the disease and patient care procedures that minimize the risk of transmission of mites. A planning for the medical treatment of patients and practical procedures for environmental disinfection (Table I) was made [2, 9].

Although mites do not survive off the host for more than 48 hours [1], environmental disinfection decreases the risk of reinfection from the environment during the treatment period.

In our study the treatment scheme was effective with only one relapse during the follow-up period. Ivermectin has been used extensively for several years for onchocerciasis and other parasitic diseases [4]. During a double blind placebo controlled study of ivermectin for onchocerciasis in Sierra-Leone, it was shown that administration of 100-200 µg/kg of ivermectin did not reduce significantly Sarcoptes scabiei infestation [11]. Subsequently, two randomized studies have compared a 100 µg/kg single dose of ivermectin versus topical application of benzyl benzoate [8] and a 200 µg/ml single dose of ivermectin versus placebo [7] for common scabies. In these two studies, 70 and 74% of the patients treated with ivermectin were cured, respectively. In 1995, Meinking et al. [5] successfully treated 11 immunocompetent and 11 HIV positive patients with a single dose of 200 µg/kg. One hundred percent of the immunocompetent patients and 73% of the HIV positive patients were cured. Other reports have shown the efficacy of ivermectin in crusted scabies [12-20] which is a condition difficult to treat with topical medications.

Treatment failure has been reported in cases of crusted scabies [21-23] but recurrence of scabies has been related to probable reinfection [23]. Ivermectin has also been used in institutions to control scabies epidemics with a good efficacy [6, 24]. In our series, among the 128 patients treated with ivermectin, three died during the seven week follow-up period. A report has suggested an excess of mortality in 47 patients treated with a 150-200 µg/kg single dose of ivermectin in a long-term care facilities when compared with 47 patients matched for age and sex [25]. Nevertheless, patients were not matched for concomitant illnesses [26] and subsequent reports did not confirm this finding even in elderly patients [23, 27, 28].

Control of a scabies outbreak in a nursing home depends on the treatment of all persons at risk simultaneously to avoid reinfestation. Application of topical anti-scabies treatment to a large number of patients at the same time is difficult. Oral administration of ivermectin is a safe and effective therapy and offers a good alternative for management of scabies on a large scale.

CONCLUSION

Acknowledgements

We thank Mrs. Perrin and the nursing and medical staff of the nursing home involved for their invaluable help. We are grateful to Dr. P. Gaxotte from Merk Sharp and Dohme-Chibret for supplying the ivermectin tablets.

REFERENCES

1. Burgess I. Sarcoptes scabiei and scabies. Adv Parasitol 1994; 33: 235-92.

2. Estes SA, Estes J. Therapy of scabies: nursing homes, hospitals, and the homeless. Semin Dermatol 1993; 12: 26-33.

3. Brown S, Becher J, Brady W. Treatment of ectoparasitic infections: review of the English-language literature, 1982-1992. Clin Infect Dis 1995; 20 (suppl. 1): S104-9.

4. Campbell WC. Ivermectin as an antiparasitic agent for use in humans. Annu Rev Microbiol 1991; 45: 445-74.

5. Meinking TL, Taplin D, Hermida JL, Pardo R, Kerdel FA. The treatment of scabies with ivermectin. N Engl J Med 1995; 333: 26-30.

6. Marty P, Gari-Toussaint M, Le Fichoux Y, Gaxotte P. Efficacy of ivermectin in the treatment of an epidemic of sarcoptic scabies. Ann Trop Med Parasitol 1994; 88: 453.

7. Macotela-Ruiz E, Pena-Gonzalez G. Tratamiento de la escabiasis con ivermectin por vía oral. Gac Med Mex 1993; 129: 201-5.

8. Glaziou P, Cartel JL, Alzieu P, Briot C, Moulia-Pelat JP, Martin PM. Comparison of ivermectin and benzyl benzoate for treatment of scabies. Trop Med Parasitol 1993; 44: 331-2.

9. Juranek DD, Currier RW, Millikan LE. "Scabies control in institutions." In: Orkin M, Maibach HI. Cutaneous infestations and insect bites. M. Dekker Inc., New York, 1984: 139-56.

10. Brunetti B, Vitiello A, Delfino S. Findings in vivo of Sarcoptes scabiei with incident light microscopy. Eur J Dermatol 1998; 8: 266-7.

11. Dunne CL, Malone CJ, Whitworth JA. A field study of the effects of ivermectin on ectoparasites of man. Trans R Soc Trop Med Hyg 1991; 85: 550-1.

12. Aubin F, Humbert P. Ivermectin for crusted (Norwegian) scabies. N Engl J Med 1995; 332: 612.

13. Cordoliani F, Vasseur E, Baccard M, Fournier S, Feuilhade de
Chauvin M, Tancrede E, et al. Ivermectin-responsive crusted scabies in HTLV1 carrier. Dermatology 1996; 192: 351-2.

14. Corbett EL, Crossley I, Holton J, Levell N, Miller R, De Cock KM. Crusted ("Norwegian") scabies in a specialist HIV unit: successful use of ivermectin and failure to prevent nosocomial transmission. Genitourin Med 1996; 72: 115-7.

15. DelGiudice P, Carles M, Couppie P, Bernard E, Lacour JP, Marty P, et al. Successful treatment of crusted (Norwegian) scabies with ivermectin in two patients with human immunodeficiency virus infection. Br J Dermatol 1996; 135: 494-5.

16. Dourmishev AL, Serafimova DK, Dourmishev LA, Mualla MA, Papaharalambous V, Malchevsky T. Crusted scabies of the scalp in dermatomyositis patients: three cases treated with oral ivermectin. Int J Dermatol 1998; 37: 231-4.

17. Jaramillo-Ayerbe F, Berrio-Munoz J. Ivermectin for crusted Norwegian scabies induced by use of topical steroids. Arch Dermatol 1998; 134: 143-5.

18. Huffam SE, Currie BJ. Ivermectin for Sarcoptes scabiei hyperinfestation. Int J Infect Dis 1998; 2: 152-4.

19. Guggisberg D, de Viragh PA, Constantin C, Panizzon RG. Norwegian scabies in a patient with acquired immunodeficiency syndrome. Dermatology 1998; 197: 306-8.

20. Pellizzer G, Betto P, Manfrin V, Benedetti P, De Lalla F. Ivermectin treatment of AIDS-related, crusted scabies. Eur J Dermatol 1996; 5: 396.

21. Currie BJ, Connors CM, Krause VL. Scabies programs in aboriginal communities. Med J Aust 1994; 161: 636-7.

22. Currie BJ, Maguire GP, Wood YK. Ivermectin and crusted (Norwegian) scabies. Med J Aust 1995; 163: 559-60.

23. Currie B, Huffam S, Ob D, Walton S. Ivermectin for scabies. Lancet 1997; 350: 1551.

24. Sullivan JR, Watt G, Barker B. Successful use of ivermectin in the treatment of endemic scabies in a nursing home. Australas J Dermatol 1997; 38: 137-40.

25. Barkwell R, Shields S. Deaths associated with ivermectin treatment of scabies. Lancet 1997; 349: 1144-5.

26. Coyne PE, Addiss DG. Deaths associated with ivermectin for scabies. Lancet 1997; 350: 215-6.

27. Diazgranados JA, Costa JL. Deaths after ivermectin treatment. Lancet 1997; 349: 1698.

28. Reintjes R, Hoek C. Deaths associated with ivermectin for scabies. Lancet 1997; 350: 215.