Prevalence of trachoma in Aboriginal communities in the Katherine Region of the Northern Territory in 2007

To the Editor: Trachoma, caused by the bacterium Chlamydia trachomatis, is the leading cause of infectious blindness worldwide.1 In Australia, the burden of disease falls almost exclusively on the Aboriginal population.2 However, there has been little consistent data collection on the prevalence of trachoma in recent years in Australia.3,4 Furthermore, despite Australian Government recommendations for biennial screening of people aged 40–54 years and annual screening of people aged ≥ 55 years in areas where trachoma is or has been endemic,5 very little screening of older people for trachomatous trichiasis has been conducted.2,4

We report on the first large-scale population study in 30 years of the current prevalence of active and cicatricial trachoma in the Northern Territory Aboriginal population. We conducted a standardised clinical screening study of five Aboriginal communities in the Katherine Region of the NT over a 5-week period in 2007.

A representative sampling frame of those believed to be currently living in each community was constructed using the medical clinic patient list, the council housing list and the local knowledge of Aboriginal Health Workers seconded from the clinics to assist with the project. All people in each community were invited to undergo a clinical eye examination for trachoma. The parameters of the World Health Organization simplified grading scheme6 were used to determine prevalence of the five signs of trachoma: tarsal conjunctival follicles, intense inflammation, tarsal scarring, trichiasis and corneal opacity.

A total of 1316 people (85.2% of the total estimated population), including 415 children aged under 10 years, were screened for trachoma. Across the five communities, active trachoma (assessed as the presence of either follicles or inflammation in one or both eyes) was at an endemic level (> 10%). The prevalences of active trachoma, scarring and trichiasis in different age groups are summarised in the Box. The overall rate of active trachoma in children under 10 years of age was 19.8% (95% CI, 16.0%–23.9%) (n = 82), and two communities had hyperendemic prevalence of trachoma (> 20%) in this age group. The youngest child observed with active trachoma was just over 1 year old.

The prevalence of scarring in people aged 20 years and over was 32% (95% CI, 28.3%–35.9%) (n = 193). The youngest person identified with scarring was 7 years old. Six people (2.3% of all people aged 40 years and over) were identified with trichiasis requiring urgent ophthalmological attention. Across the population, this placed the prevalence of unoperated trichiasis at more than four times the acceptable threshold set by the WHO. A seventh person had had trichiasis surgery.

That trachoma is still hyperendemic in Aboriginal communities more than 30 years after the National Trachoma and Eye Health Program first identified the extent of trachoma is unconscionable. Urgent and sustained public health and clinical interventions are required, with greater commitment from politicians and health policymakers, if Australia is to join the ranks of other developed nations in eradicating endemic trachoma. The guidelines for trachoma control developed by the Communicable Diseases Network Australia5 need to be resourced appropriately and implemented.

Prevalence of active trachoma, scarring and trichiasis in five Aboriginal communities in the Northern Territory in 2007, by age group*

TFI = active trachoma (follicles [TF] and/or inflammation [TI]). TS = trachomatous scarring. TT = trachomatous trichiasis. * Vertical bars indicate 95% CIs.