Head Lice: Prevalence in Schoolchildren and Insecticide Resistance

Abstract

Several small case studies have shown a therapeutic response for oral cotrimoxazole22xShashindran, C.H. et al. Br. J. Dermatol. 1978; 98: 699Crossref | PubMedSee all References22, oral and topical ivermectin23xGlaziou, P. et al. Trop. Med. Parasitol. 1994; 45: 253–254PubMedSee all References, 24xYoussef, M.Y. et al. Am. J. Trop. Med. Hyg. 1995; 53: 652–653PubMedSee all References, topical crotamiton25xKaracic, I. and Yawalkar, S.J. Int. J. Dermatol. 1982; 21: 611–613Crossref | PubMedSee all References25, and topical 1% copper oleate shampoo26xIannantuono, R.F. et al. Adv. Ther. 1997; 14: 134–139See all References26. We have also assessed the novel flea adulticides, fipronil and imidicloprid, and found them to be 97 and 100% effective in vitro against head and body lice (unpublished). Alternative carbamates such as propoxur or alternative organophosphates such as temephos27xMazzarri, M.B. and Georghiou, G.P. J. Am. Mosq. Control Assoc. 1995; 11: 315–322PubMedSee all References27 may be unaffected by the resistance mechanism against malathion. All these agents may have a place in the control of head lice. If a new agent is introduced into the human market, it is likely that head lice will eventually develop resistance. To reduce chronic use, and so slow the development of resistance, an option would be to have all insecticides available by prescription only. Strategies should be used to keep head lice levels to a socially acceptable minimum level. Strategies such as educational campaigns by community nurses, doctors and school teachers should promote head lice eradication. Although it is doubtful whether regular combing will cure a head lice infestation, it is likely to reduce the numbers of lice carried and should be promoted as the first line of treatment before insecticides. Children who fail to clear their infestations should be targeted by school nurses for treatment. All family members and classmates should be assessed for asymptomatic carriage. Ideally, all schoolchildren should be at separate desks during lessons to reduce transmission of head lice. Given the national rise in the prevalence of head lice and in insecticide sales, it is likely that the resistance phenomenon we have observed in Bristol and Bath is nationwide, and will require national changes in attitudes towards the treatment and surveillance of this ectoparasite.