Factor Responsible for Emergence and Reemergence of Infections Diseases

  Following are some important factors thought to be responsible for the development of new diseases and the reemergence of older diseases.
(i) Evolution of new microbial strains and the development of resistance to antibiotics and other antimicrobial drugs. Examples are : penicillin-resistant Streptococcus pneumoniae, Vancomycin-resistant enterococci, and Staphylococcus aureus resistant to methicillin.
(ii) Modern medicine such as Immunosuppression.
(iii) Population-growth, shifts of population from one part to the other (demographic) and fast urbanization.