Common Complications of Typhoid Fever Intestinal bleeding or perforation Sepsis Myocarditis Meningitis Osteomyelitis Pneumonia Pancreatitis Delirium, psychosis Schematic Diagram of Typhoid Fever Predisposing Factors: Precipitating Factors: Age: Infants and youths/ elderly Improper food handling and sanitation Prevalent in temperate climates Contaminated water supply High incidence in fall Living in overcrowded areas/ poor housing Poor hygiene/ hand washing Low gastric acidity (Use of antacids) Ingestion of food or water contaminated with Salmonella typhi The bacteria adheres and invades the gut wall of the gastrointestinal tract It enters the distal ileum (Peyer patches) S.typhi has a Vi capsular antigen that avoids neutrophil- based inflammation. It induces host macrophages to attract more macrophages. The bacteria co-opt the macrophage’s cellular machinery for their own reproduction which is carried through the mesenteric lymph nodes. It enters the thoracic duct then the lymphatic system and then through the tissues of the liver, spleen, bone marrow, and lymph nodes. The bacteria continue to multiply until it reached a critical density (1,000,000 to cause an infection). It then induces apoptosis of the macrophages and leaking into the blood stream (bacteremia) and to the rest of the body. TYPHOID FEVER The gallbladder is infected through extension of infection of bacteria or via bacteremia. S.typhi reinvades the gastrointestinal tract as well as the Peyer’s patches The bacteria that does The bacteria that remained not re- infect the host is present in the system of the host shed into the stool pauses and continuos to multiply which makes the host as “carrier” for a long time.