Leprosy
- Progressive infection caused by Mycobacterium leprae
- Affects peripheral nerves and skin
- Development of granulomas in skin, respiratory tract and nerves.
- Results in inability to feel pain, skin lesions
- The disease has two polar forms
- Tuberculoid leprosy
- Dry, scaly skin lesions and damage to peripheral nerves
- Lepromatous leprosy
- Skin thickening, sheets of foamy histiocytes full of bacilli (unlike the well-formed granulomas of tuberculoid leprosy)
Remember: leprosy has two polar forms set by the immune response. Tuberculoid (strong Th1): few dry, anaesthetic skin patches, well-formed granulomas, nerve damage, very few bacilli. Lepromatous (weak Th1 response): thickened nodular skin (leonine face), sheets of foamy macrophages (lepra cells) full of acid-fast bacilli.
Typhoid enteritis
- Caused by Salmonella typhi (spread by contaminated drinking water)
- Symptoms include high fever, weakness, abdominal pain, diarrhea or constipation and headaches
- Some people develop a rash
- Pathophysiology
- Bacterial proteins are transferred to enterocytes and M cells in the intestine triggering inflammatory response with recruitment of macrophages and lymphocytes and mucosal damage
Remember: in typhoid the Peyer patches of the terminal ileum swell into plateau-like elevations and then ulcerate, giving oval ulcers along the long axis of the bowel that can bleed or perforate. Microscopically the infiltrate is of macrophages ("typhoid cells") and lymphocytes, with few neutrophils.