Surveillance and monitoring of disease

Monitoring of the epidemiological patterns (animal, place, time) of diseases and pathogens within populations provides a vital system for the identification of changes in disease status within this population (whether this relates to all animals worldwide, or those within a single country, region, village or farm). For this reason, most countries have systems in place for the intermittent collection and collation of data relating to disease. Monitoring of production levels also provides a method of informing farmers about the productivity of their animals. These processes can be described as monitoring systems.

Surveillance differs conceptually from monitoring as it is an ongoing, systematic process for the collection, analysis and interpretation of data. As a result of surveillance activities, results can be disseminated in order to inform which future actions are to be taken. Despite these differences, similar systems of data collection are often used in both monitoring and surveillance.

Epidemiologists have a large role to play in surveillance strategies, as they involve the continual collection, storage, analysis and interpretation of data. It is important to ensure that selection of animals for testing, the testing procedure used, the method of data storage and the analysis and interpretation are all appropriate, and if errors or biases are present, that these are identified.

An example of a surveillance campaign currently in place is that for infection with the bacteria Brucella abortus in Great Britain. All animals imported from countries without 'Official Brucellosis Free' status are tested for the pathogen upon entry, and all animals within Britain are tested routinely for the pathogen, using milk or blood tests. If positive animals are detected, appropriate action is taken to ensure that the country remains free from infection.