The answer to 'are flea dangerous' is yes, fleas can be dangerous to both humans and pets. Fleas are small insects that feed on the blood of their hosts, and their bites can cause itching, irritation, and even allergic reactions in some people. In addition, fleas can transmit diseases, such as the bubonic plague, murine typhus, and cat-scratch disease.
Fleas can also be a serious problem for pets, as they can cause skin irritation, hair loss, and even anemia in severe cases. Pets can also inadvertently bring fleas into the home, where they can quickly multiply and become a nuisance for the entire household.