The diseases caused by water-borne pathogens include

Step 1: Analyze the question The question asks which pair of diseases is caused by pathogens spread through water (water-borne diseases).

Step 2: Key concept Water-borne diseases are caused by pathogens that enter the body through contaminated drinking water or food washed in it. Common examples are:

• Cholera (Vibrio cholerae, a bacterium)
• Typhoid fever (Salmonella typhi, a bacterium)
• Dysentery, hepatitis A, guinea worm, bilharzia (schistosomiasis)

Step 3: Check each option

• A. Gonorrhoea and poliomyelitis: Gonorrhoea is a sexually transmitted infection. Polio spreads mainly by the faecal-oral route and can be water-linked, but gonorrhoea is clearly not water-borne. ✗
• B. Typhoid and syphilis: Typhoid is water-borne, but syphilis is a sexually transmitted disease. ✗
• C. Tuberculosis and cholera: Cholera is water-borne, but tuberculosis is airborne (droplet infection). ✗
• D. Typhoid and cholera: Both are caused by bacteria spread through contaminated water. ✓

Step 4: Answer

Tip: Sort diseases by how they spread:

• Water/food-borne: cholera, typhoid, dysentery
• Airborne: tuberculosis, influenza, measles
• Sexually transmitted: gonorrhoea, syphilis, HIV
• Vector-borne: malaria (mosquito), sleeping sickness (tsetse fly)

If an option pairs one water-borne disease with an STI or airborne disease, eliminate it right away.