All are true about Yaws except
**Core Concept**
Yaws is a chronic tropical disease caused by the bacterium *Treponema pallidum subspecies pertenue*. It is a non-venereal treponematosis, primarily affecting children in tropical regions. The disease is characterized by a primary lesion, followed by secondary and tertiary stages.
**Why the Correct Answer is Right**
The primary stage of Yaws is marked by the appearance of a painless, solitary lesion, often on the skin or mucous membranes. This lesion contains spirochetes and is highly infectious. The bacteria then enter the bloodstream, causing the secondary stage, which can involve multiple lesions on the skin, bones, and joints. The tertiary stage, which can occur years after the initial infection, affects the heart, eyes, and bones.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because while Yaws is indeed a tropical disease, it is not transmitted through vectors like mosquitoes or ticks. The disease is primarily spread through skin-to-skin contact with an infected person.
**Option B:** This option is incorrect because Yaws is not a sexually transmitted disease. It is a non-venereal treponematosis, primarily affecting children.
**Option C:** This option is incorrect because Yaws is not caused by the same bacterium as syphilis. While both diseases are caused by *Treponema pallidum*, they are different subspecies.
**Clinical Pearl / High-Yield Fact**
The classic treatment for Yaws is a single dose of penicillin, which is highly effective in eradicating the disease. It is essential to diagnose and treat Yaws early to prevent long-term complications.
**Correct Answer: B. Yaws is not a sexually transmitted disease.