All of the following statements about ‘yaws’ are true except –
**Core Concept**
Yaws is a tropical disease caused by the bacterium *Treponema pallidum subspecies pertenue*, which is closely related to the bacterium that causes syphilis. It primarily affects children and is characterized by a skin lesion, which can progress to more severe forms of the disease if left untreated.
**Why the Correct Answer is Right**
Yaws is transmitted through skin-to-skin contact with an infected person, usually through minor injuries or cuts in the skin. The disease typically starts with a painless skin lesion, often on the feet or legs, which can be confused with other skin conditions. If left untreated, yaws can progress to more severe forms, including secondary yaws, which involves the lymph nodes, bones, and joints.
**Why Each Wrong Option is Incorrect**
**Option A:** Yaws is not transmitted through mosquito bites, unlike other tropical diseases such as dengue fever and Zika virus. Yaws is primarily spread through direct skin-to-skin contact with an infected person.
**Option B:** While yaws can affect the skin, bones, and joints, it is not typically associated with the central nervous system like neurosyphilis in syphilis.
**Option C:** Yaws is not a sexually transmitted disease; it primarily affects children and is transmitted through skin-to-skin contact.
**Option D:** Untreated yaws can lead to severe forms of the disease, including cardiovascular syphilis and gummatous syphilis in syphilis, but it is not typically associated with these complications.
**Clinical Pearl / High-Yield Fact**
Yaws is often confused with other tropical diseases, such as leprosy and cutaneous anthrax, due to its similar skin lesions. However, yaws typically affects children and is characterized by a painless skin lesion that can progress to more severe forms if left untreated.
**Correct Answer:** C. Yaws is not a sexually transmitted disease; it primarily affects children and is transmitted through skin-to-skin contact.