2.1 Reportable disease surveillance

Effective surveillance is essential in tracking the trends in incidence and prevalence of diseases of known significance. It is also important for picking up emerging disease threats at local, national and global levels. Reportable disease surveillance captures data on an ongoing and continuous basis. For instance, this is the way surveillance is carried out on notifiable diseases. This is often done for the prevention and control of disease, where regular, frequent and timely information-gathering is considered necessary (Diallo et al., 2020).

Example 1: In the sub-Saharan African state of Ghana, the National Surveillance Unit, created in 1998, coordinates a surveillance system which gathers and reports on communicable disease data. The District Health Information Management System II (DHIMS2) – an internet-based system, established in 2011 – operates across Ghana’s ten administrative regions, focusing on infectious diseases and events of national significance. These include malaria, HIV/AIDS, tuberculosis, cholera, meningitis and pneumonia, among others. DHIMS2 collects disease data from out-patient, in-patient, general or community practitioners and laboratories, and ensures the communication of data from the administrative regions to national level. Health facility workers based in these clinical settings tally disease counts and events, which include suspected cases (for example, a clinical diagnosis of malaria), laboratory-confirmed cases (a laboratory sample confirmation is often used to back up a clinical diagnosis of disease) and deaths (death certificates will contain information on the cause of death and if a notifiable disease caused an individual’s death) at the end of every clinical session. Aggregated cases are then tallied weekly and monthly.

Weekly and monthly disease tally data are used to complete standardised reporting forms, which are submitted to the DHIMS2 system. If you wish, you can read more information about disease surveillance in Ghana [Tip: hold Ctrl and click a link to open it in a new tab. (Hide tip)] (Adokiya et al., 2015). Reports on disease incidence and prevalence based on these data are used in Ghana to inform planning and decision-making nationally in an effort to prevent and control the spread of disease. Over the period DHIMS2 has been operational, it has provided valuable information on the prevalence of disease of national importance in Ghana. Some examples are confirming malaria to be the most prevalent disease country-wide, prompting authorities to roll out effective malaria control interventions, tracing an increase in the incidence of pneumonia in the paediatric population and confirming the impact of the national meningitis vaccination programme through observation of a reduction in reportable cases over time.

Example 2: In the UK, for animal health, there is a statutory surveillance obligation (mandated by the state or country) on veterinary practices in the United Kingdom. It is thus a legal requirement in the UK to notify government authorities of suspected or confirmed cases of diseases such as Foot and Mouth Disease (FMD) and rabies. Here, as in the above example of DHIMS2, the kind of data this system gathers can be a clinical diagnosis of disease (suspected or confirmed) in an animal, a laboratory sample showing the presence of a pathogen known to cause a reportable disease, or an event such as a death of an animal where a reportable disease is the suspected leading cause.

In the event of a notifiable disease (for example, rabies), veterinarians in the UK are required to contact the Animal and Plant Health Agency (APHA). This agency in turn mobilises an investigation team as necessary and collects, analyses and reports on overall trends of these notifiable diseases in animals. The APHA acts as the central investigation and surveillance platform. This surveillance information aids decision-making to improve animal health and welfare and plan interventions to prevent and control known and emerging animal diseases (British Veterinary Association, 2021).