Treatment and management of lice

Treatment should be tailed to the individual. A plan should use a pediculicide that will be effective in killing both the eggs(nits) and the adults. Patients should be aware of their intimate contact. This contact should be avoided until both individuals have been treated and follow-up care has been administered. In addition, contact points around the home need examination to prevent spreading of cases.

One treatment is permethrin 1% creme rinse (2 ox bottle) that costs about $7.67. It should be applied to effected areas and then washed off after about 10 minutes. Another treatment option is Lindane 1% shampoo, costing between $3.00-$14.72. This option shouldn’t be used first since it can be toxic. Only use the lindane if alternative treatments aren’t tolerated. Pyrethrins with piperonyl butoxide is another treatment to apply to affected areas and then to wash off after10 minutes of use. Shampoo and mousse are other low cost treatments to lice.

When decontaminated the household, all bedding, towels and clothing should be washed. If initial application of medicine does not work apply again in 3-7 days after 1st application. Eyelashes that need treatment should be treated via application of occlusive ointment such as petroleum jelly twice a day for 10 days. For the treatment of Pthirus pubis one may use 0.5% malathion, 0.5-1% carbaryl and 0.2% phenothrin.

Since 2000, there have been no new treatment trials published concerning the treatment of Pthirus pubis. However, there were three randomized clinical treatment trials assessing the treatment of head lice. In one comparative trial conducted in Florida, 0.5% malathion compared to 1% permethrin demonstrated a clearance rate of 98% with malathion compared to 55% with permethrin. Permethrin coupled with oral TMP/SMX enhanced the efficacy of therapy with permethrin. Combining did not improve clearance in response to therapy with permethrin. One study assessed both in vitro susceptibility of lice and in vivo response to topical lice treatment in children in Bath and Bristol, England. Both cohorts of children had lice that demonstrated a decreased mortality rate in response to permethrin and malathion. Children in Bath were treated with malathion with a 36% cure at 48-72 hours. Children in Bristol were treated with permethrin and had a 13% cure at 48-72 hours. The sample size of this stdy was only 30 children, bit it suggests the presence of dual resistance to permethrin and malathion in these cohorts.

Additional in vitro evaluations were performed y Pollack et al. who sampled head lice from children in Massachusetts, Idaho, and Malaysian Borneo. They found that among lice in the United States, the morality was 50% in response to treatment with permethrin. The mortality rate was unaltered by increasing concentrations of drug. Conversely, the lice from Malaysia had a 37% mortality rate at the lowest concentrations of permethrin. Their fataility increased linearly with increasing permethrin concentrations to a maximum mortality rate of about 95%. This study used different evaluations times for the U.S. and malaysian lice because of baseline differences in survival times. Regardless, this study suggests possible emergence of drug resistance in the U.S. head lice. The concern raised by these results is amplified by another in vitro analysis demonstrating that lice with permethrin resistance also have resistance to smithrin and a newer agent for treatment, deltamethrin. The emergence of drug resistance in head lice throughout the world is concerning but the implications for the treatment of Pthirus pubis are unclear. A case of pubic lice resistant to pyrethrins in vitro was reported but the patient demonstrated clinical clearance with 5% permethrin. Since 1996, there have not been any studies in English language documenting significant treatment failure in the management of Pthirus pubis.

The use of 1% gamma benzene hexachloride (lindanse) has several disadvantages and is no longer recommended as a first or second line of therapy. It can be absorbed percutaneously when applied to severely excoriated skin. Case reports have alluded to mild signs and symptoms of neurotoxicity when it has been ingested, applied too frequently, not washed off as directed, or used on massively excoriated skin. In one study, 90% of a single dose was found in the urine in a badly excoriated patient in 5 days following the treatment. No other studies, however, have shown blood, tissue, and urine levels. Nonetheless, blood dyscrasias such as aplastic anemia and leukopenia have been described after use of lindane in agriculture and against ectoparasites in animals and humans, lindase is reportedly cytotoxic in vitro for human hoematopoietic progenitor cells. In particular, lindane use should be avoided in small children, pregnant women, and individuals with massive excoriations or multiple lesions over the scrotum.

Itching is an important feature of all lice infestion. The first treatment with a pediculicide may be effective for killing both the adult lice and the eggs, but the itching may continue because of an allergic reaction and/or irritation. The possibility of postreatment pruritus should be discussed with the patient; a mild topical antipruritic/anti-inflammatory cream or ointment may need to be prescribed. The patient should be revaluated 4-7 days after initial treatment. Attention to these considerations is crucial, since it often prevents excessive pediculicide use and may prevent parasitophobia and feelings of “Being unclean.”

Unlike the other forms of louse infestations, the lesions caused by body lice are the main focus of treatment. Antipruritics and antibiotics (for secondary infections) are used to treat the skin lesions. Ivermectin, a synthetic derivative of a macrocyclic lactone, has been used for various parasitic infestations. Recently, the drug (3 doses of 12 mg each, given at 7-day intervals) greatly reduced the number of body lice infesting a population of homeless men. Such treatment may be effective in limiting the viability of body lice in patients living in an institution or routinely returning to a treatment center or shelter. Depending on the geographic location of the infested individual and his or her contact with other similarly infested individuals, the physician should consider the possibility of louse-borne disease and notify the appropriate public health authorities if such disease occurs. Louse eggs that are laid on clothing (especially in seams) may be destroyed by pressing with a hot iron. Washing clothes in hot water and dry cleaning will kill lice and nits as in other forms of louse infestation. Lice have been killed in infested clothing with various pesticide treatments (10% DDT, 1% malathion, and 1% permethrin powders). Infested furniture, mattresses, and box springs should be discarded or fumigated to destroy lice and nits. Infested materials sealed in plastic bags may be used safely after 4 weeks.

(Back to background and history of pubic lice or crabs from¬†”treatment and management of lice”)
 
References:

David Schlossberg, ed. 2008. Clinical Infectious Disease. New York. Cambridge University Press. ISBN-10: 0-521-87112-3, ISBN-13: 978-0-521-87112-9. STAT!Ref Online Electronic Medical Library. http://online.statref.com/document.aspx?fxid=388&docid=153. 9/15/2012 12:11:52 PM CDT (UTC -05:00).

King K. Homes, P. Frederick Sparling, Walter E. Stamm et al. Sexually Transmitted Diseases, 4th Edition.