One of the ways of controlling Schistosomiasis is by

Step 1: Analyze the question The question asks for a method of controlling Schistosomiasis (also called bilharzia).

Step 2: Explain the concept Schistosomiasis is caused by a blood fluke, Schistosoma (e.g., S. haematobium, S. mansoni). Its life cycle involves:

• Eggs are passed out in urine or faeces of an infected person into fresh water.
• Eggs hatch into larvae (miracidia), which infect freshwater snails, the intermediate host (Bulinus and Biomphalaria).
• Inside the snail, the parasite develops into cercariae, which swim in the water.
• Cercariae penetrate the skin of people who wade, bathe, wash or swim in the contaminated water.

Since the snail is an essential link in the cycle, breaking that link controls the disease. Water weeds provide the snails with food, shelter and a place to lay eggs, so removing them also reduces snail populations.

Step 3: Evaluate the options

• A. Destroying water snails and water weeds: Correct. It removes the intermediate host and its habitat.
• B. Clearing bushes around the house: This helps control vectors like mosquitoes (malaria) or tsetse flies (sleeping sickness), but not schistosomiasis.
• C. Washing hands after using the toilet: This prevents faecal-oral diseases like cholera, typhoid and dysentery. Schistosomiasis is contracted through skin penetration, not by ingestion.
• D. Washing fruits before eating: This also prevents ingestion-related infections, not schistosomiasis.

Step 4: Answer The correct option is A.

Tip: Link each disease to its transmission route:

• Schistosomiasis → water snail + skin contact with water
• Malaria → Anopheles mosquito
• Cholera/typhoid → contaminated food and water (ingestion)
• Sleeping sickness → tsetse fly

If you see "snail" in the question or options, think schistosomiasis straight away. Other control measures include avoiding bathing in stagnant streams, using treated or piped water, and treating infected persons.