This research has examined the jurisprudence and legal aspects of the civil liability of individuals who are the cause of transmitting infectious and dangerous diseases to others and analyzes the conditions that cause the fall or removal of this liability. The main basis of civil liability in this context is the proof of the element of fault (negligence or recklessness) in Iranian judicial practice. In the case of knowledge or failure to detect the disease, liability remains established. From the perspective of Islamic jurisprudence, the removal of liability is based on the failure to establish one of the elements of causation (intention, quasi-intention, or error based on negligence). The research method is analytical and descriptive and conducted with a library method. In conclusion, the removal of the civil liability of the carrier in both legal and jurisprudential systems is subject to the proof of one of two cases: 1) absolute ignorance, unexamined and resulting from the lack of any means of awareness; or 2) the realization of a classic factor such as the Cairo force or the failure to prove a definitive causal relationship. This study has emphasized the need for a precise distinction between negligence and absolute ignorance in determining liability. Based on the findings of the present study, liability can be considered for a carrier of a disease who suspects or even doubts that the disease will be transmitted to others due to the probable importance (killing others) and considering the possibility of invoking damage against him. Also, transmission of the disease from a carrier with intent to act (even without intent to result) is considered liability, but from a carrier without intent to act, it is considered non-liability.