Pathogenesis and Disease Flashcards
Q: Define pathogenesis.
A: Pathogenesis is the capacity of a parasite to cause disease.
Q: Define disease in relation to parasitic infections.
A: Disease is a condition where a parasite causes harm to its host, resulting in symptoms or physiological dysfunction, ranging from mild to severe.
Q: What is virulence?
A: Virulence is the degree of harm a parasite causes to its host, balancing the fitness cost of virulence to the parasite and the host’s resistance.
Q: What are three factors that affect the likelihood of disease from a parasitic infection?
A: 1) Status of host defenses, 2) Number of parasites present, and 3) Pathogenicity of the parasites.
Q: What is the threshold of disease in parasitic infections?
A: The number of parasites required to cause detectable signs and symptoms in a host.
Q: How can parasite-induced pathology serve as an adaptation?
A: Pathology can enhance transmission, like Yersinia pestis, which forms a blocking mass in fleas, causing them to feed more often and spread the bacteria.
Q: Give an example of parasite-induced pathology that has no adaptive value.
A: Liver flukes causing cholangiocarcinoma through mechanical damage and inflammation, which harms the host but does not benefit the parasite.
Q: Name the main categories of parasite-induced pathology.
A: 1) Trauma to cells, tissues, and organs, 2) Changes in cellular growth patterns, 3) Interference with nutrient acquisition, 4) Toxins, 5) Host immune response.
Q: What type of pathology is caused by Taenia solium in hydatid disease?
A: Direct trauma through the growth of cysts, which damages adjacent liver tissue.
Q: What are flask-shaped lesions, and how are they formed?
A: Flask-shaped lesions are formed in invasive amoebiasis when Entamoeba histolytica breaches the intestinal mucosa, leading to necrosis and tissue destruction.
Q: Define hypertrophy and provide an example caused by parasites.
A: Hypertrophy is the enlargement of organ or tissue cells; Leishmania causes monocytes to become hypertrophic.
Q: What is hyperplasia and how can it benefit parasites?
A: Hyperplasia is an increase in cell number; it can benefit parasites like Fasciola hepatica, which induces bile duct hyperplasia to feed on epithelial cells.
Q: Define metaplasia and provide a parasitic example.
A: Metaplasia is a change from one cell type to another; Trichinella larvae cause muscle cells to transform into “nurse cells” that protect the parasite.
Q: What is neoplasia, and what are its characteristics?
A: Neoplasia is uncontrolled cell growth, potentially leading to benign or malignant tumors, often irreversible and can disrupt normal cell function.
Q: Name two parasites associated with neoplastic growth in hosts.
A: Liver flukes (linked to cholangiocarcinoma) and Spirocera lupi (can cause esophageal sarcomas in dogs).
