Write causative agent, two symptoms and mode of transmission of typhoid.

Answer: Causative agent: Salmonella typhi; transmitted through contaminated food and water.

• Causative agent: the bacterium Salmonella typhi.
• Symptoms (any two): sustained high fever (39–40 °C), weakness, headache, stomach pain, loss of appetite and constipation; in severe cases intestinal perforation and death may occur.
• Mode of transmission: the bacteria enter the small intestine through food and water contaminated with faeces of infected persons or carriers (faecal–oral route); houseflies help spread it. The disease is confirmed by the Widal test.