Certain pathogens can invade the intestinal mucosa without causing diarrhea. One well-known example is the bacterium Campylobacter jejuni in some cases, as well as Yersinia enterocolitica, which can lead to intestinal invasion without necessarily resulting in diarrhea.
Additionally, some viruses, such as Norovirus, can cause gastrointestinal symptoms without diarrhea in particular cases.
Specific infections may depend on the individual's overall health, immune response, and other factors, so clinical presentations can vary. Always consult with a healthcare professional for accurate diagnosis and information.