Salmonellosis and Chronic Infections

Frequently asked questions

What are the clinical and morphological forms of leprosy and their features?

Three main clinical and morphological forms of leprosy are distinguished: tuberculoid, lepromatous, and borderline (undifferentiated).

• Tuberculoid form — characterized by a relatively benign course in individuals with good immunity. Features mildly pigmented macules with sharp margins and reduced sensitivity, early involvement of peripheral nerves, trophic ulcers, muscle atrophy, contractures, and potential bone resorption. Epithelioid cell granulomas form; mycobacteria are detected rarely or in smaller numbers than in the lepromatous form. In nerve trunks, tuberculoid granulomas are usually large and frequently undergo caseous necrosis with the development of a nerve abscess.
• Lepromatous form — a severe generalized variant occurring with a significant decrease in host resistance. Skin, nasal and oropharyngeal mucous membranes, anterior chamber of the eye, peripheral nerves, reticuloendothelial system, adrenal glands, and testes are affected. Skin lesions present as confluent reddish-brown infiltrates, predominantly on the face and distal extremities; loss of eyebrows and eyelashes and the formation of "leonine facies" (facies leonina) can occur. Granulomas contain foamy Virchow lepra cells with mycobacteria.
• Undifferentiated form — occupies an intermediate position, developing in individuals with unstable immunity. Characterized by granulomas in the skin and mucous membranes consisting of epithelioid and giant cells surrounded by a lymphocytic rim, as well as peripheral nerve involvement. Transformation into lepromatous or tuberculoid types is possible.

What are the clinical and morphological forms of salmonellosis?

Four main clinical and morphological forms of salmonellosis are distinguished.

• Gastrointestinal form (toxic) — proceeds with the development of acute gastroenteritis, including gastritis, gastroenteritis, and gastroenterocolitis variants.
• Generalized form (septic) — develops against the background of immunodeficiency resembling septicopyemia with the formation of an intestinal septic focus and metastatic abscesses. Includes typhoid-like and septicopyemic variants.
• Typhoid-like form — characterized by changes similar to the typhoid-paratyphoid group, but less pronounced.
• Bacteriocarriage (subclinical form) — subdivided into acute, chronic, and transient pathogen shedding without clinical manifestations.

What is the morphological characteristic of skin lesions in anthrax?

In the cutaneous form of anthrax, an anthrax carbuncle forms or acute diffuse serous-hemorrhagic inflammation develops. Macroscopically, the carbuncle presents as a black-colored eschar with a hard crust, surrounded by a purplish infiltrate and extensive tissue edema containing numerous pathogens. Microscopically, an exudate poor in cellular elements is observed, while necrosis extends deep into the dermis and subcutaneous adipose tissue. Regional serous-hemorrhagic lymphangitis and lymphadenitis join the primary effect. After 2–4 weeks, the eschar sloughs off, forming an ulcer, which subsequently heals into a dense white scar.

What local changes in the gastrointestinal tract are characteristic of the intestinal form of salmonellosis?

For intestinal lesions in salmonellosis, catarrhal or catarrhal-ulcerative gastroenteritis, gastroenterocolitis, and terminal ileitis are described. The intestinal wall is infiltrated by neutrophils, lymphocytes, small numbers of eosinophils, and plasma cells. Hyperplasia and ulceration of Peyer's patches are observed in the lymphoid apparatus of the intestine. Mesenteric lymphadenitis develops in the mesenteric lymph nodes: initially, the nodes are enlarged and hyperemic, with proliferation of monocytes and reticular cells; subsequently, specific granulomas may form, followed by necrosis of the granulomas, their organization, and petrification.

What is the main difference between the tuberculoid granuloma in leprosy and true tuberculosis?

Dermal leprous granulomas typically lack characteristic caseous necrosis, although it may occur in affected nerve trunks.

What are Virchow cells?

These are large foamy macrophages found in the lepromatous form of leprosy, whose cytoplasm is densely packed with mycobacteria.

Why is urinary bladder schistosomiasis extremely dangerous?

Confluent granulomas form around schistosome eggs in the bladder wall, followed by ulceration; this process is a precancerous condition.

What causes the development of elephantiasis in filariasis?

Filariae cause inflammation and sclerosis of the lymphatic vessels, leading to a complete blockade of lymphatic drainage and massive tissue edema (lymphedema).