Surveillance of communicable diseases
One of the most important tasks of the Public Health Agency of Sweden is to continuously follow the epidemiological situation concerning communicable diseases and especially those stated in the Communicable Diseases Act.
The notifiable diseases must be reported in accordance with Swedish law. A report is filed by the laboratories and the doctor treating the patient or performing the autopsy to the county council's County Medical Officer and to the Public Health Agency of Sweden via an electronic system called SmiNet.
Other forms of surveillance
The Public Health Agency of Sweden conducts several other forms of surveillance, in addition to analysing the reported cases of notifiable diseases.
Voluntary laboratory reporting
Certain infections are very significant but are spread to so many people that it would be unreasonable for the healthcare services to report individual cases. These infections are not covered by the Communicable Diseases Act, but are instead surveyed via different voluntary reporting systems. These systems supplement the reports received in accordance with the law. Within the framework of voluntary laboratory reporting, laboratories currently report laboratory confirmed cases of caliciviruses, Clostridium difficile, and respiratory syncytial virus (RSV). The Public Health Agency of Sweden presents the results of the voluntary laboratory reporting in special weekly reports, which for caliciviruses also includes the results from other surveillance systems.
Sentinel surveillance means that only a selection of doctors or clinics report on the prevalence of a disease. Sentinel surveillance is only used in Sweden to sample incidences of influenza. Through sampling you can get indications of how many people with influenza symptoms actually have influenza. The Public Health Agency of Sweden can also monitor what different influenza strains are circulating and whether vaccines and antivirals are effective, or whether resistance has developed.
The Public Health Agency of Sweden uses different types of syndromic surveillance to supplement the traditional disease surveillance. Given the fact that the majority of people who become ill do not need to seek medical attention, it is hard to know how many people among the population have a certain illness. The traditional reporting systems only captures those who seek medical attention. We therefore underestimate the proportion of the population that is actually affected. For example, in order to predict and handle an epidemic in the best way possible, the health services and society need to get rapid indications to determine the extent of spread. This is done, for instance, by examining visitor statistics from the county councils' website for medical information "Vårdguiden 1177".