Figure 1.

Main mucous membranes affected by the entry of Brucella through the oral and intranasal routes. When ingesting food contaminated with Brucella, the oral cavity is the first site of contact of the bacteria with the host, although it is very little time that remains there, in the oral cavity there are elements of the immune system belonging to MALT that should recognize the presence of Brucella and eliminate it. After the oral cavity Brucella could enter the gastrointestinal tract along with the alimentary bolus through the esophagus up to the stomach. In the stomach Brucella is apparently able to resist the pH of gastric juices, then enters the small intestine, where it will face physical and chemical barriers, as well as different cell lines and lymphoid tissue belonging to GALT. Following this route is likely to reach the large intestine and even that the bacteria was eliminated by feces, however unknown.