Causes Of Infectious Diseases

The term "disease" refers to conditions that impair normal tissue function. However, there are fundamentally different causes for each of these diseases. An infectious disease is a disease that is caused by the invasion of a host by agents whose activities harm the host's tissues (that is, they cause disease) and can be transmitted to other individuals (that is, they are infectious).

Infectious diseases, being one of the main causes of death worldwide, account for approximately one-half of all deaths in tropical countries. Death from infectious diseases ranked 5th in 1981, has become the 3rd leading cause of death, with an increase 58%, in 1992 (Venkataswamy et al., 2010). In industrialized nations, despite the progress made in the understanding

In the human history, numerous infectious diseases have emerged and re-emerged. The emerging infectious diseases and their basic causes present a threat to the stability of the nations worldwide. Thus, the preparedness for the known and unknown infectious diseases will be a top priority for our public health systems (Gupta et al., 2012).

Infectious diseases are caused due to a complex interaction between the pathogen (that is, disease causing agent or infectious agent), host and the environment. There are five major types of infectious agents: bacteria, viruses, fungi, protozoa, and helminths. In addition, a new class of infectious agents, the prions, has recently been recognized.

Man is in constant contact with a large number of different bacteria which temporarily or permanently inhabit his body creating temporary or permanent community. Relations which are thus established are various and very complex, from those positive to those whose consequences for man are extremely negative. Oftenly, both on and in man’s body, bacteria which have the ability to cause an infection are present. This ability of pathogenic bacteria to establish disease is reflected in possession of certain pathogenicity factors: toxins, surface structures and enzymes. These established complex relations’ income depends on host’s characteristics as well as on pathogen’s characteristics.( Olgica Stefanović, Ivana Radojević, Sava Vasić

Foodborne disease can be defined as any disease of an infectious or toxic nature caused by the consumption of food or water. The global burden of foodborne disease is currently unknown but the World Health Organization (WHO) has responded to this data gap by launching a new initiative to provide better estimates. In 2005 it was reported that 1.8 million people died from diarrheal diseases largely due to contaminated food and water. The scientific investigations/reports on outbreak of foodborne diseases in India for the 29 (1980–2009) years indicated that a total of 37 outbreaks involving 3,485 persons have been affected due to food poisoning. Of the 10 pathogens tracked by FoodNet (a reporting system used by public health agencies in US), Salmonella, Campylobacter, and Shigella were found responsible formost cases of foodborne illnesses and Salmonella causes 31% of food related deaths. (R. V. Sudershan et al.