Epidemiology and emerging infections

===Lecture Details===
Anton Peleg; Week 6 MED1022; Microbiology
===Lecture Content===
Epidemiology is study of causes, frequency, distribution and determinants of health and disease, morbidity, disability and mortality in human populations. Index is first case identified, but primary is case that first brings a disease to a population. Secondary is infected from primary, tertiary from secondary. Subclinical infections are relevant in epidemiology. 
Sporadic level of infection is occasional cases at regular intervals. Endemic is persistent occurrence with low to moderate level. Hyperendemic is persistently high level of occurrence. Epidemic is occurrence clearly in excess of expected level for a given time period. Pandemic is an epidemic over several continents/countries.
Chain of transmission is reservoir, portal of exit, agent, mode of transmission then portal of entry to susceptible host. An epidemic can occur from increases in reservoirs (animals, ineffective treatment for disease), new agents/increase in infectivity, increase in mode of transmission (more vectors, poor sanitation); new portals or immunosuppression.
An emerging infection is a new, re-emerging or drug resistant infection whos incidence has increased or threatens to increase. Factors in emerging infections are microbial adaptation and change, human susceptibility, population growth and density, urbanisation, crowding, breakdown of public health infrastructure, war/social dislocation and displacement of population, globalisation of travel, live/wild animal markets, intensified livestock production, misuse of antibiotics, changes to ecosystems, global climate change.
SARS has nonspecific presentation, incubation of 2-10 days; is a coronavirus.
Response to emerging infections is enhance surveillance and response, encourage applied research, strengthen public health infrastructure and training, develop and implement strategies for control, response strategies needed.
===Readings===