From tuberculosis,malaria,polio to the less–publicised Chikungunya and Leishmaniasis,diseases continue to inflict humankind.As the world battles 'arch enemies' like AIDS and cancers, newer foes like SARS, anthrax,West Nile, avian influenza, etc. have been raising their ugly heads (some being deadly bio–terrorism tools!).Even chronic ailments related to heart,metabolism,etc,and behavioural,neurological and psychological disorders are major health issues that concern all nations, whether developed or developing. In response, action needs to be taken. But here, the health of populations at large is in question,and thus,service of 'individual–centric' doctors is limited.It calls for an elite band of 'populationcentric'professionals called epidemiologists.

Epidemiology is widely recognised as a diagnostic and management tool of public health . Earlier it was just the 'study of epidemics' but current–day health scenarios have broadened the definition and scope in epidemiology. The draft outline of the World Health Report 2006 of World Health Organization (WHO) mentions epidemiology as an important field that will be responsible for shaping the future of health work.

Dr Fawad Khan, from United Kingdom, is an epidemiologist and an orthopedic surgeon, in Middle East division of the World Health Organization (WHO). He laments, "Epidemiologists are scarce world over. And most people do not know what they do. Secondly, people do not understand the concept of public health . There should be awareness that in medical field there are not only physicians or surgeons but also public health workers which include epidemiologists."

Trends, actions and events (like lifestyle, economic and cultural status, foreign aid to a nation, wars, natural disasters, etc) constantly affect the health of a population. It is imperative, thus, that some surveillance is in place which can identify these factors and see to it that action can be taken as and when called for. That is the role of epidemiologists. The WHO report cites the significance of epidemiologists in control and prevention of diseases during the tsunami outbreak in Thailand, and also their role in surveillance of SARS in China, Hong Kong (China), Philippines and Vietnam.

1. Historical study: The rise and fall of diseases

2.Community diagnosis, community health : Burdens of disease, surveys

3. Workings of health services: Need, demand and supply, quality of care

4. Individual chances and risks: Prediction, risk scoring

5. Identifying syndromes: Clustering of symptoms and signs

6. Completing the clinical picture: Icebergs of disease, normal and abnormal

7. Search for causes: Secular and geographic variation, individual susceptibility, multifactorial causation

The west is relatively diseasefree due to work of epidemiologists. Shailee Tanna, a Canadian medical student, informs,"In Canada, aside from research, resources and money have been invested in studying and developing prevention and control programs for diseases such as the West Nile disease and the SARS. Due to this, SARS has been effectively controlled since after the epidemic in 2003, and so has the West Nile virus."

We also need to understand that epidemiological research has profound influence on 'routine' clinical practice of doctors. It gives validation for treatments or practices, and helps conceptualise new ones.

In India, there is a shortage of field trained epidemiologists in the public health system. It is estimated that the country requires minimum of 1000 trained epidemiologists (one per district). Shruti Priya, faculty at Institute of Science, Mumbai, observes,"In India, epidemiology is still in a developing stage and needs lots of efforts to get ahead."

However, the demand for trained epidemiologists is increasing with the Integrated Disease Surveillance Project being implemented in the country.

Dr Manoj Murhekar, deputy director, National Institute of Epidemiology (NIE) states, "Undergraduate medical students are taught a little about epidemiology. Very few courses in the country teach it exclusively. Most MBBS graduates who want to pursue epidemiology, do MD in Preventive and Social Medicine or Community Medicine. Career options are aplenty in research, or in state/central public health sectors and NGO's." Internationally, one can could try for organisations like WHO and UNICEF, or health centres and research universities.