Pathophysio Typhoid Fever Jps Jun 9

PHATOPHYSIOLOGY  Invasion of the blood stream occurs through the upper intestinal tract and the organisms localize in the reticulo indothelial system, with hyperplasia and hypertrophy of the lymph nodes and follicles and enlargement of the spleen and liver.  The bacteria then re-invade the blood from the foci and multiply in different organs, particularly the gall bladder, from where they are discharged into the intestines.  They then penetrate the lymphoid tissue of the small intestines and proximal colon, especially the Payer’s patches and there are areas of focal necrosis and ulceration.  A prominent microscopic finding is erythrophagocytosis and scattered infiltrates if lymphocytes and plasma cells in and about these foci.  Characteristically, there is absence polymorphonuclear leukocytes.  Hemorrhage and perforation due to extension of the lesions may occur, although these are rare in children.  Symptoms are due to the systemic effects of endotoxin and other bacterial products. The organism enters the body via the GIT, it invades the walls of the GIT, leading to bacteremia which localizes in mesenteric lymph nodes, in the masses of lymphatic tissue in the mucous membrane of the intestinal wall (Payer’s Patches), and in small, solitary lymph follicles in the ileum and colon, ulceration of the intestines may ensure. 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 Payer`s patches of the intestinal wall.Payer`s patches are the clusters of cell primarily composed of Macrophages are specialised cells that are essential to kill any bacteria. But, Salmonella Typhi is unaffected by these macrophages but, start survive within the macrophage itself. So , during this asymptomatic incubation period of

7-14 days, the bacteria spread throughout the reticuloendothelial system of liver,spleen,gallbladder,and bone marrow. The first week of symptomatic period is characterized by progressive elevationof 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 Payer`s patches of the intestine which leads to perforation and bleeding.This is the terminal stage,if, left untreated, death is imminent.

THYPHOID FEVER

Salmonella Typhosa / Typhi

Contaminated food / water, feces, fingers, fomites and flies

GIT invading small intestine mucosa

Transverse the intestinal lymphatics, Mesenteric

Payer’s Patches (lower ileum)

Lymph flow

Thoracic Duct

Blood Stream

Etiologic Agent in the Blood Circulation

Bacteremia – secondary to the infection of liver, spleen, bone marrow and Lymph nodes

In the liver and kidneys, the focal necrosis of parenchymal cells at the site of colonization lymphoid tissue hypertrophy and hyperplasia