Infective stage to man of the parasite that causes haematuria isAMiracidiumBRediaCMicrofilariaDCercaria

Break Down the Problem

1. Identify the types of parasites mentioned in the question.
2. Determine which stage of these parasites is infective to humans and causes haematuria.

Relevant Concepts

• Miracidium: The larval stage of trematodes (flukes) that typically infects a snail.
• Redia: A developmental stage of some digenetic trematodes that evolves from a miracidium inside the snail host.
• Microfilaria: The larval stage of filarial worms in the bloodstream.
• Cercaria: The free-swimming larval stage of trematodes that emerges from the snail and can penetrate the skin of the definitive host.

Analysis and Detail

• Haematuria refers to the presence of blood in urine and is commonly associated with certain parasitic infections.
• The parasites that typically cause haematuria include schistosomes, which are a type of trematode. The infective stage for humans is the cercaria, which penetrates human skin and can lead to infections such as schistosomiasis, causing symptoms including haematuria.

Verify and Summarize

Having considered the life cycle of the parasites and the specific stage responsible for causing haematuria, the infective stage of the parasite that causes this condition in humans is indeed the cercaria.

Final Answer

The infective stage to humans of the parasite that causes haematuria is Cercaria (D).