Infection, Immunity and epidemiology скачать в хорошем качестве

Infection, Immunity and epidemiology

Infection and immunity Infection Infectious (transmissible) disease Organism Bugs Host Clinical features Carrier Immunity Probability of exposure leading to infection Virulence of organism Number of organisms Immune defences Humans and bacteria Skin, mouth and vagina (mucous membranes), GI tract Internal tissues are sterile Relationships Commensalism, mutualism or parasitic relationship Commensalism – organisms which live with us but normally cause no harm, (commensal flora) Mutual bacteria derive benefit from us and we from them, e.g. some coliforms produce vitamin K Parasitic relationship the infecting organism benefits to the host’s detriment Pathogenic microorganisms Pathogens - virulent bacteria or viruses which usually cause disease if present Commensal organisms can become pathogenic, opportunistic pathogens Opportunistic microorganisms Often of low pathogenicity but may cause infections in certain circumstances Reduced host defences Local and systemic infection Inflammation Conjunctivitis Boils Abscess Osteomyelitis Cellulitis Balanitis Systemic Epidemiology Causes, incidence, distribution and control of disease Endemic Epidemic Pandemic Mortality rate Morbidity Incidence Prevalence