Monitoring, surveillance and investigation of health threats are vital capabilities for an effective health system. The International Health Regulations require countries to maintain an integrated, national system for public health surveillance and response and set out the core capabilities that countries are required to achieve. Public health laws typically establish a list of “notifiable diseases” and other conditions that health care providers, hospitals and/or laboratories are required to report to the relevant local or national public health authority. Notifiable diseases generally include infectious diseases that can quickly spread throughout communities and regions via water, food, contact with animals, mosquitoes, airborne droplets or through sexual contact and other forms of human interaction. Rare and new events may not be included in regular, clinical and laboratory-based surveillance systems. Also, outbreaks of serious or contagious diseases require immediate investigation so that appropriate public health measures including isolation and contact tracing can be implemented. A significant degree of stigma may be attached to some diseases. Notifiable disease legislation should require the protection of personal information, and clearly define any exceptions. Concerns about discrimination and breach of privacy may be addressed by requiring certain diseases to be reported on an anonymous or de-identified basis.