LO: Explain the link between scientific accuracy in pathogen detection, appropriate test selection and viral disease management
Clinical virology laboratory - leading component of microbiology department that provides significant benefits to patient care
Purpose of diagnosing viral infection:
Medical (therapeutic) - patient management
Epidemiological (public health)
Intra-hospital infection prevention and control
Academic (research)
Effective antiviral medications for a number of viral infections are now widely used
Enzyme immunoassay (EIA)
Detection of antibodies against viruses or viral antigens
Capture antibody specific for the viral antigen is bound to the surface of wells
When sample added - viral antigen present in th sample binds to the capture antibody
When second antibody is added - colour change
Test selection
Necessitates excellent and frequent communication between hospital and primary care clinicians and virologists for optimal use of diagnostic tests
Detection of viral pathogens
Obtaining an adequate specimen from the appropriate site
Proper timing of specimen collection relative to onset of symptoms
Timely processing of the sample
Viral disease management
Viral shedding begins shortly before the symptoms occur
Peaks rapidly after the onset of symptoms
Declines steadily as infection resolves
Samples should be collected as soon as possible after onset of symptoms
Rapid diagnosis important for treatment start
Seological response sometimes lengthy (IgM/IgG)
LO: Be able to list the infective notifiable disease
All registered medical practitioners in the UK have a statutory duty to notify the local Health Protection Team (HPT), part of UKHSA of suspected cases of certain infectious diseases
Any infection which presents significant harm to human health
All virology and microbiology laboratories in England performing a primary diagnostic role must notify HPT when notifiable organism is confirmed
When to notify
Nature of infection
Ease of spread
Ways in which spread can be prevented/controlled
Patient circumstances
Urgent cases reported by phone within 24 hours
Examples
Measles
Mumps
Rabies
Rubella
SARS-CoV-2
Yellow fever
LO: Know what pathogen needlestick injuries may transmit and means to manage those
Needlestick injuries
Incident in which blood of a patient comes into contact with the blood of a health care worker
Percutaneous injury - needles, sharp instruments, bone fragments, significant bites which break the skin
Exposure of broken skin - abrasions, cuts, eczema
Exposure of mucous membranes including eyes and mouths
Blood borne viruses (BBV)
Viruses which can be present in blood or other body fluids and have high potential for transmission to another person by direct contact with blood/susceptible fluids
Hepatitis B (HBV) 30%, Hepatitis C (HCV) 3% and Human Immunodeficiency Virus (HIV) 0.3%
Recipient - individual exposed to the possibility of acquiring a blood borne infection
Source - individual who was the source of the blood/body fluid, which made contact with recipient
Post exposure prophylaxis (PEP) - treatment advised and supplied to the recipient following a risk assessment from a high risk exposure incident
Infectious material
Blood
Amniotic fluid, vaginal secretions, semen, breast milk, CSF, synovial fluid
Non-infectious: urine, vomit, saliva and faeces that are not visibly blood stained
Management
flowchart TD
A[Immediate management]
B[Facilitate investigation of the source]
C{Time of incident}
D[A&E assessment]
E[Contact workplace health and wellbeing]
Incident --> A
A --> C
A --> B
C -->|17:00-8:30 and weekends and bank holidays|D
C --> |8:30-17:00 weekdays|E
Immediate management:
Wash/cleanse/cover
Inform person in charge of ward/department
A&E assessment:
Staff member attend with details of source
Consent
Must be obtained from source patient for blood tests to be undertaken using appropriate patient consent form
Blood sample should be collected in a plain orange-topped tube (clotted blood sample)
Hepatitis B surface antigen (HBsAG) test
Hepatitis C antibodies (Anti-HCV) test
If source has a risk factor for HCV: Hepatitis C RNA test also (purple topped bottle)
HIV-1/2 antibodies and HIV-1 antigen test
Drugs for post-exposure prophylaxis (PEP)
Tenofovir disoproxil 245mg/emtricitabine 200mg and raltegravir 1200mg once daily
PEP should be initiated ASAP - preferably within 24 hours but can be up to 72 hours
Exposure to HBC/HCV
Check immunisation status
Booster dose of HBV or HBIG
HCV - no PEP
Follow-up key to making sure any transmission is detected
