Question

A male student that attends a 4 year College majoring in Arts and music felt sick for a day with diarrhea he took some medication and felt fine. 8 days later he had a second round of diarrhea this time it was much worse and lasted most of the day. Again with somewhat more medication he was fine. 5 days later he had a 3rd round of diarrhea that was much worse and included vomiting. He was bed ridden the next day his symptoms continued with fever.

Explain the pathogenesis of typhoid fever disease .3. What is the virulence factor and how would you treat this disease? 4. How would the immune system deal with this case and why?Why Doctors could only treat the symptoms before and not the disease and why death may result from it?

Answer 1

The typhoid fever is caused by the bacteria called Salmonella typhi. This is a foodborne bacteria which can survive the acidic stomach to gain entry into the intestine. it colonizes the intestine and also gains entry into the bloodstream. The organism can enter the body via contaminated water or food. The most common entry of salmonella is via uncocked meat or chicken, sprouts and vegetables.

The bacteria produce the Vi toxin and Invasive toxins which help in colonization and entry into the blood. these are exotoxins which are secreted via vehicles. These toxins are active only against mammalian cells.
The main host defence against salmonella occurs in neutrophils followed by mononuclear cells. The cells produce cytokines such as TNF alpha, Il-1, Il-2 .etc. These cytokines activate other immune cells including T4 cells. The dendritic cells and B cells are involved in the development of T-cell mediated immunity to salmonella. The interaction of B and T cells develops antibodies against the bacteria and help in its clearance using macrophages.
The interaction of bacteria with epithelial cells also generates a large number of chemokines which guide and recruit the polymorphonuclear cells across the intestinal epithelium.
Typhoid causes diarrhoea and vomiting which cause excessive fluid loss from the body. These symptoms have to be treated first otherwise the patient will die due to dehydration. The death is inevitable in case the symptoms are not treated. The organism can also notoriously cause chronic illness due to unhygienic lifestyle.