Professionals in the medical field understand quite clearly what is meant by the terms ‘epidemiology’ and ‘surveillance’, but usually have difficulty in defining them. Practically speaking, these two terms can be usefully employed to describe the role of the NICD to provide data and information on the status of communicable diseases in the country. This is the bread-and-butter occupation of a public health institution like the NICD. Its activities cover the wide array of infectious agents: viral, bacterial, fungal and parasitic. This information and data are crucial for guiding public health authorities, nationally and internationally, and informing both the medical profession and the general public.

Some 60 years ago Alexander D. Langmuir, widely regarded as the father of modern communicable diseases surveillance and epidemiology, defined what is encompassed by the discipline of disease surveillance:

More recently, the pandemic of Covid-19, the ongoing threat of viral haemorrhagic fevers and the burden of HIV/AIDS and TB have underlined the critical value of a well-run, scientifically informed surveillance programme. The success of communicable diseases surveillance, as is the case with surveillance for exposure to noxious chemicals, is crucially dependent on the timeliness of being alerted to the earliest signals of an impending outbreak. For example, surveillance of wastewater to detect the circulation of pathogenic organisms, such as SARS-CoV-2, or surveillance of acute flaccid paralysis (AFP) (the typical clinical sign of polio), have been shown to be effective tools for the early detection of impending outbreaks. Prompt responses to effect control measures need to be initiated as early as possible before an outbreak erupts in a population.