Which disease is caused by direct skin penetration of helminth larvae?

The disease caused by direct skin penetration of helminth larvae is indeed schistosomiasis. This disease is primarily caused by parasitic flatworms known as schistosomes. The lifecycle of these parasites involves a freshwater environment where they release their cercariae, which are the larval form capable of penetrating the skin of humans who come into contact with infested water.

When a person swims or bathes in contaminated water, the cercariae can quickly penetrate the skin, leading to their entry into the bloodstream. Once inside the body, the schistosomes migrate through various tissues and eventually settle in the blood vessels, where they mature into adult worms, causing a range of health issues, including gastrointestinal and genitourinary symptoms.

Understanding that cercariae are the form that directly enters through the skin is crucial in recognizing how schistosomiasis spreads, distinguishing it from other helminth-related diseases that may require different forms of transmission. Other options listed involve different transmission mechanisms or life cycles that do not primarily involve skin penetration by larvae.