Facility-Based Routine Surveillance

In many countries, health workers are required to report on the number of individuals that come to their facility and are diagnosed with reportable diseases. These reportable diseases are usually diseases that have outbreak potential, such as cholera, polio, and measles, or diseases that are targets of national control programs, such as malaria and tetanus. Data on individual patients, which are recorded in patient registers, are used to calculate the number of cases of reportable diseases diagnosed by health facility staff over a certain period of time. These data are periodically reported to district authorities who compile and send them to higher administrative levels. This process of detecting and reporting information on diseases that bring patients to the health facility is known as passive surveillance.

Passive surveillance yields only limited data because many sick people do not visit a health facility and because those cases that do show up may not be correctly classified, recorded, or reported. If managers fail to fully understand and account for these limitations, they may incorrectly interpret trends and patterns of infectious diseases.

One way to overcome the limitations of passive surveillance and get a better picture of disease burden in the community is for health workers to visit health facilities and communities to seek out cases. This is known as active surveillance.

Since passive surveillance has limitations due to its lack of access to some groups within the population, active surveillance is often used to enhance the completeness of a passive surveillance system. Active surveillance is also more expensive than a passive system and requires considerable additional effort to organize. This means that active surveillance is usually conducted on a limited segment of the population and for only a brief period. Active surveillance is, therefore, used to gain targeted insight into a situation and not collect routine data over a long period of time.

Routine surveillance by health facilities, whether passive or active, is often hampered by the difficulty of making accurate diagnoses. health workers may lack the proper equipment or training for diagnosis in the health facility, and laboratory services are often not available to confirm clinical diagnoses.

In certain instances, health workers conduct case-based investigations to learn more about a specific illness pattern, for example, when there is a suspected case of a disease targeted for eradication, such as polio, or during suspected outbreaks of epidemic- prone diseases such as yellow fever. In case-based investigations, health workers record information such as the patient’s name, age, vaccination status, location, date of disease onset, suspected diagnosis, and laboratory results (when available).

Types of Surveillance 

Community-Based Surveillance

Sentinel Surveillance