Introduction of a pathogen by the bite of a mosquito that fails to illicit disease symptoms (at any point in time) could be of value to provide some degree of immunity against future potential invasion of the same pathogen. This would largely depend on the nature of the pathogen. The degree of immunity acquired would likely be negligible for most if not all mosquito borne diseases. One can also gain some immunity from the specific proteins in the saliva of the bite by specific mosquito species. This could also result in greater hypersensitivity!

I am also thinking of it. Mosquito bites do expose humans to small amounts of saliva and other compounds that can trigger an immune response. Research has shown that repeated exposure to mosquito bites can lead to immune tolerance or even immunity to certain mosquito-borne diseases. Designing experiments to investigate this further, such as comparing immune responses in individuals with varying levels of mosquito exposure, could provide valuable insights into this potential natural immunization method.