***Entry gate of infection*** is an infectious agent that enters the body and leads to the onset of the infectious process. The distribution of the infectious agent throughout the body and the development of the disease depend on the entrance gate of infection. The number of entrance gates of infectious agents in one organism can be varied. The entrance gates are often the mucous membranes of the respiratory tract and gastrointestinal tract. Some types of pathogens require penetration through one entrance, others through several. An example of the first case is the influenza virus, which penetrates through the upper respiratory tract; the second is the measles virus, which can penetrate the skin. Some pathogens (bacteria) can penetrate internal organs from undamaged places in the body through the lymphatic system, while others have the property of rapidly multiplying inside the body. All of them cause different diseases, since pathogenicity and toxicity have varying degrees. Entry points for infection can include wounds or punctures, as well as more varied entry points such as sharks. But such entrance gates are less common for infectious contamination.