Q.Name the causative pathogens of typhoid fever, pneumonia, the common cold and ringworm.

Typhoid fever is a systemic bacterial infection caused by Salmonella typhi, a rod-shaped bacterium transmitted through the faecal–oral route, chiefly via water and food contaminated by the faeces or urine of an infected person or an asymptomatic carrier. Because transmission is so tightly linked to sanitation, typhoid is treated in this chapter as the classic example of a hygiene-dependent infectious disease, connecting directly to the Public Health section.

Symptoms. The disease produces a sustained, step-ladder pattern of high fever, general weakness and fatigue, headache, abdominal pain and discomfort, and disturbed bowel habit (constipation in some patients, diarrhoea in others). Untreated, severe cases can progress to serious intestinal complications.

Prophylaxis. Prevention rests on breaking the faecal–oral transmission chain: ensuring a safe, treated drinking-water supply, proper sewage and waste disposal, thorough food hygiene (washing and adequately cooking food, avoiding contaminated raw produce), personal hand hygiene, and vaccination with the typhoid vaccine for individuals at higher risk of exposure, such as those travelling to or living in areas with poor sanitation.

Exam-focused takeaway: know the causative organism (Salmonella typhi), the transmission route (faecal–oral, via contaminated food/water), and that prevention is fundamentally a sanitation-and-hygiene problem — the same public-health principle that applies to amoebiasis and ascariasis elsewhere in this chapter. …