Gov. Code 835, which imposes liability on governmental entities for dangerous conditions of their property, does not impose liability for injury that may be caused by conditions of the property to someone who never came in contact with it.  Here, plaintiff claimed that the unsanitary conditions of a downtown police station caused Wong, a policeman, to catch typhus.  Plaintiff, who lived with Wong, caught typhus from him without ever venturing near the police station.  In this situation, the case holds, Gov. Code 835 does not impose liability on the city.  Moreover, the city is immune under Gov. Code 855.4 which immunizes governmental entities from liability for an injury resulting from the decision to perform or not to perform any act to promote the public health of the community by preventing disease or controlling the communication of disease within the community if the decision is discretionary.