Public Health and Microbiology


Vasanthi Thevanesam
Emeritus Professor
Department of Microbiology, Faculty of Medicine,
University of  Peradeniya


Public Health is defined as ‘the science of protecting the safety and improving the health of communities through education, policy making and research for disease and injury prevention’. Microbes have been seen as a major threat to public health throughout the ages. Although there have been many advances in the control of infections in the past 200 years, the safety and health of the world population continues to be threatened by the microbial population.

Many infectious diseases such as plague, diphtheria, small pox and poliomyelitis which caused fear and panic in past centuries have been eradicated or their impact reduced using vaccines, improved detection and/or use of effective antimicrobials. However, even as the burden of these diseases lessened, viral infections such as the Human Immunodeficiency virus, dengue and Influenza, many bacterial(tuberculosis, leptospirosis, cholera, meningococcal infections among others), fungal (cryptococcosis, invasive candidiasis, mould in buildings) and parasitic infections (malaria, cryptosporidia, intestinal parasites to name a few) continue to challenge the health of human populations throughout the world. Additional threats to public health which need recognition and appropriate action are emerging infections (SARS), occupational exposures to infective agents and the use of microbes in biowarfare.

The role of microbes in what was considered non-infective (non-communicable) disease was established with the discovery Helicobacter pylorias a cause of peptic ulcer. Since then, Hepatitis B has been recognized as a cause of hepatocellular carcinoma and more recently, papillomavirus, of cervical carcinoma, one of the commonest malignancies in women throughout the world. The recognition of the human microbiome – what was previously referred to as the normal flora – opens up a whole new avenue of exploration of the role of human microbiota in human health and disease. The human microbiome project, initiated in 2007, has led to investigation of the role of the human microbiota in many chronic non-communicable diseases includingobesity, diabetes mellitus, and atherosclerosis. The public health implications if a causative link can be proven are enormous!

The development of laboratory services to meet public health needs is a necessity in modern healthcare. Public health microbiology laboratory (PHML) services meet public health needs of local communities, cities and provinces and finally nationwide. Ideally, they should consist of a network of laboratories and network partners covering the required area with systems to ensure communication between all stakeholders and decision makers in meeting infectious disease threats. It is therefore very important that those who initiate testing including clinical, environmental, veterinary, and agricultural laboratories as well as other governmental, non-private, or private laboratories that perform laboratory testing of public health significanceand those who use the results should participate in the PHML system.
Functions of PHMLs include the capability of providing accurate and precise data required for the detection, prevention and control of infectious, communicable diseases in a timely manner. PHMLs also play a vital role in recognition of outbreaks. As noted above, all laboratories in the PHML network should be networked efficiently so that an unusual number of requests for a particular microbe or an increasing number of positive results in a particular locality is recognized and used to trigger a public health response. Resources for rapid identification of causative organisms need to be developed and made accessible to both state and private sector laboratories. Monitoring of low incidence and/or high-risk diseases, such as antibiotic-resistant tuberculosis, influenza, dengue and rabies is also an important function of the PHML services. The PHML service should alsoprovide expertise, reference and resources in microbiological testing to the entire laboratory network in the country, particularly by verifying results, confirming atypical test results, providing reference services and supporting the diagnosis and surveillance for unusual and emerging pathogens. Data analysis with detection of trends and sentinel events is another function of the PHML service.

Clinical diagnostic laboratory services are primarily used to provide diagnostics for individual patients (human or animal) presenting with an infectious disease. These services use laboratory methods ranging from microscopy to sophisticated modern techniques, depending on the clinical need and availability of the required resources. However, Public Health Laboratories are needed to monitor the environment (water soil etc.) and food sources which serve a preventive strategy. PHMLs can exist as a single central entity or different services can be provided by different laboratories serving as Reference Laboratories as occurs in the USA and UK.

Microbiologists can serve the public health needs of the country by envisioning and contributing to the expansion of the Public Health Laboratory services in Sri Lanka to service public health needs related to infectious diseases in the 21st century.