Original article
Essential oil of Australian lemon myrtle (Backhousia citriodora) in the treatment of molluscum contagiosum in children

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Abstract

Molluscum contagiosum is a common viral illness of childhood and is increasingly found as a sexually transmitted disease in sexually active young adults. Current treatment options are invasive, requiring tissue destruction and attendant discomfort. Thirty-one children (mean age 4.6 ± 2.1 years) with the diagnosis of molluscum contagiosum (mean length of time with condition 8.6 ± 5.3 months) were treated with once daily topical application of a 10% solution (v/v) of essential oil of Australian lemon myrtle (Backhousia citriodora) or vehicle (olive oil). At the end of 21 days, there was greater than 90% reduction in the number of lesions in 9/16 children treated with lemon myrtle oil, while 0/16 children met the same criteria for improvement in the vehicle group (P < 0.05). No adverse events were reported.

Introduction

Molluscum contagiosum is a common contagious viral disease of childhood occurring worldwide, with an estimated prevalence in the US of approximately 1/200 children under age 10 [1], [2]. Molluscum occurs predominantly in pre-adolescent children, but occurs also in sexually active adults, participants in sports with skin-to-skin contact, and in those with impaired cellular immunity such as HIV positive individuals [2]. Its exact prevalence in the adult population is unknown but the incidence of sexual transmission is rapidly increasing [3].

Molluscum contagiosum virus (MCV) causes characteristic pearly, flesh-colored, dome-shaped papules with central unbilication [4]. It is a double stranded DNA poxvirus that has been sequenced [6], and like variola virus (small pox), has no animal reservoir but is specific to humans [2]. Cell debris and virus accumulate in the crater-like central ostium [2], [4], and infection is spread principally by skin contact. In immunocompetent patients the illness is self-limited and MCV infection does not recur [4]. However like other members of the poxvirus family, MCV exhibits an ability to avoid host defense mechanisms, and it is not unusual for lesions to persist and spread.

The general recommendation for treatment is expectant management [1], [4], with spontaneous resolution generally occurring in 12–30 months. However, lesions may spread to the face or cover extensive portions of the body, prompting the desire for treatment. Treatment options largely depend upon tissue destruction and include curettage, cryotherapy, CO2 laser, electrodessication, or application of caustics such as trichloroacetic acid, podophyllotoxin, or cantharadin [5], [6]. Recently, topical immune modulators such as imiquimod have been used with some success [7]. However, all current treatment options involve some degree of pain, discomfort, or irritation to the patient with accompanying distress to the parents of small children. In addition, treatments that rely on tissue destruction may increase the risk of infection and scarring [1], [2], [4], [5]. Thus, the need exists for a safe, painless, effective, rapid treatment option.

The essential oil (steam distillate) from the Australian lemon myrtle (Backhousia citriodora) has been reported to exhibit antibacterial actions in vitro [9], [10] with low cytotoxicity [10]. After anecdotal reports suggested efficacy against molluscum, we tested a topical application of a 10% (v/v) solution of essential oil of B. citriodora in the treatment of children with molluscum contagiosum.

Section snippets

Study protocol

Thirty-one children (mean age 4.6 ± 3.1 years) with molluscum contagiosum were enrolled from four outpatient clinics in Boise, ID, USA between 17 February 2001 and 29 July 2001. Children were otherwise healthy without major disease, at or above the 50th percentile for height and weight, and had met all age-appropriate developmental milestones. Mean length of time with the diagnosis of molluscum was 8.6 ± 5.3 months (Fig. 1 ). Detailed written informed consent was obtained from the parents, and

Results

In the MLE treated group, one child was lost to follow-up, six had reductions in the number of lesions but did not meet the 90% criterion, five had total resolution of all lesions, and four had reductions in the number of lesions greater than 90% at the end of 21 days. In the vehicle treated group, three children withdrew as the parents perceived worsening of the molluscum and sought other treatment, 0/16 met the 90% reduction criterion, and 12 had no change or an increase in lesion number. A

Discussion

MCV is a cytoplasmically replicating virus possessing a complex genome encoding approximately 182 proteins [6], and exhibits genetic heterogeneity with several strain reported [8]. The genetic makeup of the MCV in this study is unknown. Furthermore, it is unclear if genetic heterogeneity contributed to the differential effects observed, with some strains being sensitive to MLE application while others were not.

The speed of action of MLE and a lack of generalized inflammation associated with its

Acknowledgments

This work was supported by intramural funding from the Center for Biomedical Research, Inc.

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