Name the causative agent of typhoid. Explain its mode of transmission, symptoms and preventive measures. Mention the body organ that gets affected in severe cases. [1+2+2+2+1]

Causative Agent of Typhoid

Typhoid fever is caused by the bacterium Salmonella Typhi, a Gram-negative, non-motile, facultative anaerobic bacillus belonging to the Enterobacteriaceae family. It is a human-specific pathogen, meaning it does not infect animals and spreads exclusively among humans.

---

Mode of Transmission

Typhoid spreads primarily through the fecal-oral route via:

1. Contaminated Food and Water:
   • Consumption of food or water contaminated with feces from an infected person.
   • Common in areas with poor sanitation and unsafe drinking water.
2. Person-to-Person Contact:
   • Poor hygiene practices (e.g., not washing hands after using the toilet or before handling food).
   • Close contact with an infected individual, especially in crowded or unsanitary conditions.
3. Carriers:
   • Some individuals become chronic carriers (e.g., Typhoid Mary, a famous historical case) and can spread the disease for years without showing symptoms.

---

Symptoms

Typhoid fever has a gradual onset and progresses through distinct stages:

Early Symptoms (1–3 weeks after infection)

• High fever (up to 40–41°C) with a sustained pattern (remains elevated for days).
• Headache, weakness, and fatigue.
• Loss of appetite and abdominal discomfort.
• Relative bradycardia (slow pulse rate despite high fever).

Later Symptoms (2–4 weeks)

• Rose spots: Small, pinkish-red spots (2–4 mm) on the abdomen and chest (visible in ~30% of cases).
• Diarrhea or constipation (sometimes bloody stools).
• Abdominal pain (often in the right upper quadrant).
• Enlarged liver and spleen (hepatosplenomegaly).
• Delirium or confusion in severe cases.

---

Preventive Measures

Prevention focuses on breaking the transmission cycle through:

1. Sanitation and Hygiene

• Safe drinking water: Boil water or use filtered/purified water.
• Proper sewage disposal: Prevent fecal contamination of water sources.
• Handwashing: Wash hands with soap and clean water, especially before eating and after using the toilet.

2. Vaccination

• Oral Ty21a vaccine: Live, attenuated strain (given in 3–4 doses).
• Injectable Vi polysaccharide vaccine: Provides ~50–70% protection for 2–3 years.
• Recommended for: Travelers to endemic areas, healthcare workers, and high-risk populations.

3. Food Safety

• Avoid raw or undercooked food (e.g., street food, unpeeled fruits).
• Store food properly to prevent contamination.
• Cook food thoroughly (especially seafood and poultry).

4. Public Health Measures

• Isolation of confirmed cases to prevent spread.
• Health education on typhoid risks and prevention.
• Monitoring of water sources in endemic regions.

---

Body Organ Affected in Severe Cases

In untreated or severe cases, typhoid can lead to:

• Intestinal perforation (especially in the ileum, the last part of the small intestine).
• This perforation can cause peritonitis (inflammation of the abdominal lining), a life-threatening condition requiring emergency surgery.

Other complications include:

• Hemorrhage (bleeding from the gastrointestinal tract).
• Septicemia (bacteria entering the bloodstream).
• Metastatic infections (e.g., osteomyelitis, endocarditis).

---

Typhoid remains a significant public health concern in Nepal, particularly in regions with poor sanitation and limited access to clean water. Early diagnosis (via Widal test or blood culture) and treatment with antibiotics (e.g., ciprofloxacin, azithromycin) are critical to prevent complications. Public health campaigns emphasizing hygiene and vaccination are essential for control.