Lecture 2.1 - An Infection Model

Introduction: ◦Epidemic - widespread disease within a community ◦Pandemic - an epidemic which has spread beyond borders The infection model ◦The patient (age, immune status, comorbidities) ◦The pathogen (bacteria, virus, fungus, parasite) ◦Mechanism of infection (contig...

Introduction: ◦Epidemic - widespread disease within a community ◦Pandemic - an epidemic which has spread beyond borders The infection model ◦The patient (age, immune status, comorbidities) ◦The pathogen (bacteria, virus, fungus, parasite) ◦Mechanism of infection (contiguous (direct) spread, inoculation, haematogenous, ingestion, inhalation, vector, vertical transmission) ◦Process of infection (attachment, interaction with host defences, host damage) ◦Management of the patient (history, examination, investigations, specific and supportive treatment) ◦Patient outcome (cure, disability, chronic infection, death) Pathogen class: Patient factors: Mechanism of infection: Pathogen-host interaction:  Management: Investigations: ◦To identify the actual infecting agent: ‣ For bacteria: microbiology on specimen for example swab, sputum sample, lavage, urine sample, stool sample or blood culture. Detection of antigens or nucleic acid (PCR) ‣ For viruses: Antigen detection, viral nucleic acid detection (PCR) ‣ Other investigations: blood tests for example, full blood count (FBC), C reactive protein (CRP), liver and kidney function tests. Imaging (X- ray, ultrasound, CT scan, MRI scan) Treatment: Outcome: Infection prevention: ◦Hospital: ‣ Prevent spread to other patients and staff as well as visitors ‣ Common hospital infections? - MRSA, UTIs etc ‣ Source? ◦Community: ‣ Herd immunity ‣ Vaccination (anti-vaccination debate) ◦Public health