Prevalence of …. % is considered as an epidemic of trachoma and indication for staing chemoprophylaxis.
**Core Concept**
Trachoma is a leading cause of preventable blindness worldwide, caused by chronic infection with Chlamydia trachomatis. The World Health Organization (WHO) has established criteria for defining the prevalence of trachoma that necessitates public health intervention.
**Why the Correct Answer is Right**
The WHO defines an epidemic of trachoma as a prevalence of trachoma of 10% or more among children aged 1-9 years in a community. This is based on the fact that trachoma is primarily a childhood disease, and high prevalence among this age group indicates an outbreak. The decision to initiate chemoprophylaxis is also guided by the presence of other indicators of trachoma endemicity, such as increased conjunctival scarring.
**Why Each Wrong Option is Incorrect**
**Option A:** 5% prevalence is considered a threshold for public health action, but it is not the specific percentage that defines an epidemic of trachoma.
**Option B:** Prevalence among adults is not a reliable indicator of trachoma endemicity, as this disease primarily affects children.
**Option C:** Prevalence of 1% is not sufficient to warrant public health intervention, as this is considered a low level of endemicity.
**Clinical Pearl / High-Yield Fact**
The SAFE strategy (Surgery for trichiasis, Antibiotics, Facial cleanliness, and Environmental improvement) is a comprehensive approach to controlling trachoma, and chemoprophylaxis is an essential component of this strategy.
**Correct Answer: D. 10%**