What does an elevated number of eosinophils usually indicate?

An elevated number of eosinophils is commonly associated with allergic reactions and parasitic infections. Eosinophils are a type of white blood cell that plays a crucial role in the body's immune response, particularly in combating parasitic infections and mediating allergic responses. When the body encounters allergens, such as pollen or certain foods, or when it is infected by parasites like worms, eosinophil levels typically rise as part of the immune response.

This increase helps the body combat these challenges by releasing inflammatory mediators that are effective in targeting both allergens and parasites. Therefore, the correct answer highlights the specific roles eosinophils play in these conditions, making it clear why elevated levels point primarily to allergic reactions and parasitic infections.