Academic journal article Bulletin of the World Health Organization

Efficacy of Oral Azithromycin versus Topical Tetracycline in Mass Treatment of Endemic Trachoma

Academic journal article Bulletin of the World Health Organization

Efficacy of Oral Azithromycin versus Topical Tetracycline in Mass Treatment of Endemic Trachoma

Article excerpt

Voit page 639 le resume en francais. En la pagina 639 figura un resumen en espanol.

Introduction

Trachoma is caused by the recurrent, chronic infection of the eye with Chlamydia trachomatis serotypes A, B, Ba or C, and progresses from inflammation to conjunctival scarring, lid deformities, corneal abrasion and visual impairment. It is the most common infectious cause of blindness, and is responsible for an estimated 15% of global blindness (1). Active trachoma affects an estimated 150 million people (2), and about 5.5 million are blind as a consequence of the disease. Blinding trachoma mainly occurs in rural, resource-poor areas of Africa and Asia (for a review of risk factors see Mabey et al. (3)). The importance of within-household transmission is supported by epidemiological observations (4, 5) and by serotyping and genotyping results (6-8).

International efforts to control the disease are based on the SAFE strategy which combines Surgery, Antibiotics, Facial cleanliness and Environmental improvement. The Global Elimination of Trachoma as a disease of public health importance by 2020 (GET 2020) is currently the overall goal in trachoma control efforts (9). Active trachoma is routinely treated with tetracycline eye ointment applied daily for 6 weeks. However, topical treatment is not practical for mass treatment since the ointment is difficult and uncomfortable to apply, it blurs the vision, and it must be performed daily over an extended period of time.

Systemic antibiotics tested in randomized controlled trials have shown some efficacy against active trachoma but carried a high risk of adverse side-effects. Treatment with sulfonamides (trisulfapyrimidine (10) and sulfamethoxypyridazine (11) given over 3 weeks, and sulfadimethoxine (12) administered over 5 months), which were evaluated in the 1960s, all have the major drawback of causing systemic complications. The subsequently tested oral tetracyclines, doxycycline (13, 14) and minocycline (15), administered for periods up to 1 year, may cause adverse effects in children and fetuses. Under field conditions the cost of delivery of intensive, supervised topical or multidose oral therapy to rural populations is prohibitive.

Systemic azithromycin is highly effective as a single-dose therapy for genital C. trachomatis infection (9, 16), and appears to offer a novel alternative for trachoma control. It has a half-life in tissue of 23 days (17) and a good safety profile in all age groups. A trial in the Gambia established that a single dose of azithromycin (20 mg/kg) was as effective as six weeks of twice-daily topical tetracycline (18); but reinfection is common when only individual cases are treated, and 40% of subjects were reinfected 6 months after treatment. In a study on dosage schedules involving Egyptian children with active trachoma, Dawson et al. (19) found that the prevalence of both severe trachoma and C. trachomatis infection was similar after 1-6 doses of oral azithromycin or 30 days of topical tetracycline. Tabbara et al. (20) reported comparable efficacy with only a single dose of azithromycin.

There is some experience in mass or selective mass treatment using topical and oral compounds. Vertical control programmes in Saudi Arabia in the 1960s and late 1980s and in Tunisia in the 1980s combined topical mass treatment with hygiene promotion and eyelid surgery (9). Recent intervention studies in the United Republic of Tanzania assessed topical mass treatment and face washing (21). Tetracycline regimens have been shown to be effective primarily in highly exposed school-children (13). Resnikoff et al. (22) tested oral minocycline in selective mass treatment. Mass treatment has generally, in the absence of improvements in living standards, been accompanied by substantial treatment failures and a short-lived treatment response. The latest recommendation from WHO is that all children should be treated in communities where more than 20% of children show signs of active trachoma. …

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