Final answer:
Hypersensitivity refers to an excessive immune reaction to environmental substances, with Flea allergic dermatitis (FAD) being a specific example. Variations in flea infestation levels cause inconsistencies in the severity of symptoms in FAD, complicating the interpretation of related literature.
Step-by-step explanation:
The concept of hypersensitivity indicates an exaggerated immune response to what are usually harmless environmental substances. Hypersensitivities can manifest in various ways, such as eczema, anaphylaxis, and allergic asthma. One specific example of hypersensitivity is Flea allergic dermatitis (FAD), a condition primarily found in pets, caused by an allergic reaction to flea bites. In considering FAD, differences in the levels of flea infestation can make interpretation of literature challenging due to variations in the threshold for sensitization and allergic reaction among individual animals. These discrepancies can affect the presentation and severity of symptoms, resulting in inconsistent data and difficulty in establishing a clear relationship between fleas and the severity of dermatitis. This makes it hard to generalize results and apply findings universally.