The mass treatment of trachoma is undertaken if the prevalence in community is –

**Core Concept**
Trachoma is a leading cause of preventable blindness worldwide, primarily affecting children in areas with inadequate access to clean water and sanitation. The World Health Organization (WHO) recommends mass treatment of trachoma in communities with a high prevalence of the disease.

**Why the Correct Answer is Right**
Mass treatment of trachoma is recommended in communities where the prevalence of trachoma among children aged 1-9 years is 10% or higher. This high prevalence threshold is based on the fact that trachoma is highly infectious and spreads rapidly in areas with poor sanitation and hygiene. The goal of mass treatment is to reduce the prevalence of trachoma to 5% or less, thereby preventing the spread of the disease and reducing the risk of blindness.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the WHO recommends mass treatment for a prevalence of 10% or higher, not lower.
**Option B:** This option is incorrect because the prevalence threshold for mass treatment is based on the prevalence among children aged 1-9 years, not the general population.
**Option C:** This option is incorrect because the prevalence threshold for mass treatment is 10% or higher, not 5% or higher.

**Clinical Pearl / High-Yield Fact**
The SAFE strategy (Surgery for trichiasis, Antibiotics, Facial cleanliness, and Environmental improvement) is the recommended approach for controlling trachoma, and mass treatment is an essential component of this strategy.

**Correct Answer: C. 10% or higher.