Pathophysiology Of Typhoid Fever 5o6i1m

Typhoid fever, also known simply as typhoid, is a common worldwide bacterial disease transmitted by the ingestion of food or water contaminated with the feces of an infected person, which contain the bacterium Salmonella enterica enterica, serovar Typhi.

The pathophysiology of typhoid fever is complex and occurs through several stages. Once, the bacteria (Salmonella typhi), survives the acidity of the stomach, it reaches the intestine and invades the Peyer`s patches of the intestinal wall. Peyer`s patches are the clusters of cell primarily composed of Macrophages are specialized cells that are essential to kill any bacteria. But, Salmonella Typhi is unaffected by these macrophages but, start survive within the macrophage itself. Salmonella Typhi alters its structure to resist destruction and allow them to exist within the macrophage. This renders them resistant to damage by Polymorphonuclear leukocytes (PMN or PML) and the immune response. So, during this asymptomatic incubation period of 7-14 days, the bacteria spread via the lymphatics while inside the macrophages. This gives them access to the reticuloendothelial system and then to the different organs throughout the body such as the liver, spleen, gallbladder, and bone marrow. The organism is a Gram-negative short bacillus that is motile due to its peritrichous flagella. The bacterium grows best at 37 °C/99 °F – human body temperature. The first week of symptomatic period is characterized by progressive elevation of temperature. In the second week, the victim may experience abdominal pain, spleen enlargement and notice Rose spots on his skin. The third week is more intense as the bacteria start causing necrosis of the Peyer`s patches of the intestine which leads to perforation and bleeding. This is the terminal stage, if, left untreated, death is imminent. Precipitating factors -salmonella typhi -poor hygiene -unsanitary food preparations -contaminated food and water Predisposing factors -age -gender -culture -nationality -genetics Etiologic factors 1. Salmonella typhi (Typhoid Fever) - Most common and more severe form 2. Salmonella paratyphi (Paratyphoid Fever)

- Much more mild than Typhoid Fever

PATHOPHYSIOLOGY OF TYPHOID FEVER Precipitating factors -salmonella typhi -poor hygiene -unsanitary food preparations -contaminated food and water

Ingestion of contaminated food and water with salmonella typhi

Salmonella typhi survives the acidity of the stomach

Predisposing factors -age -gender -culture -nationality -genetics

First week: elevation of the body temperature

Second week: abdominal pain, spleen enlargement and rose spots

Invades the Peyer’s patches of the intestinal wall Third week: necrosis of the Peyer’s Patches

Macrophages in the intestines engulf salmonella typhi and survive within it

Bacteria spread through lymphatics and access reticuloendothelial system, liver, spleen, gall bladder and bone marrow

leads to perforation, bleeding

if left untreated, death is imminent