Final answer:
Swimming or wading in water where blood flukes are present poses the risk of contracting Schistosomiasis due to the transmission of parasitic larvae that can penetrate the skin and cause organ damage. Option d is correct.
Step-by-step explanation:
It is hazardous to swim or wade in fresh-water lakes or rivers where blood flukes are prevalent due to the high risk of transmission of Schistosomiasis, which is an infectious disease caused by parasitic flatworms called schistosomes. When humans make contact with contaminated water, the cercariae (larvae of the fluke) penetrate the skin.
The parasites then migrate through the human body, settling in the veins and leading to organ damage and chronic illness. The transmission cycle is sustained when infected individuals excrete eggs through urine or feces into bodies of water, which then infect freshwater snails, continuing the lifecycle of the parasite.
High-risk groups for Schistosomiasis include children, farmers, fishermen, and individuals using contaminated water for household chores.