Sirenomelia is a rare congenital disorder characterized by the fusion of the lower limbs, often referred to as "mermaid syndrome." It is important to note that Sirenomelia is not contagious. It is a developmental abnormality that occurs during fetal development. The exact cause of Sirenomelia is still unknown, but it is believed to be a result of vascular abnormalities. Sirenomelia is not caused by any infectious agent and cannot be transmitted from person to person.