introduction to virology and needlestick injuries Flashcards
how can viruses be classified
by host
according to disease or target organ
according to vector
genetic sequence and biophysical structure
what does taxonomy describe
virus order
virus family
subfamily
type species
morphology
genetic material
envelope - has a role in virus transmission
how to differentiate between bacterial and viral causes of infection
secondary bacterial infection symptoms persist longer than the expected 10 days
fever is higher than in viral infection
CRP - rise of CRP indicates bacterial
FBC - neutrophils associated with bacterial, lymphocytes and monocytes associated with viral
BC - pinpoints bacterial infection
PCR - can detect both by amplifying DNA sample for better analysis
CSF cell count - lymphocytes=virus, neutrophils=bacterial
what is the purpose of diagnosing viral infection
medical - patient management
epidemiological
intra-hospital infection prevention and control
academic (research)
4 advanced molecular diagnostic testing techniques
nucleic acid-based technologies
next generation sequencing
monoclonal antibodies
enzyme immune assays
example of rapid viral diagnostic test and impact - POCT
by bedside
tests for influenza A, influenza B, and RSV
PCR based
20 mins from start to finish
treatment - prophylaxis - patient admission - patients isolation - patients discharge
diagnosis important for public health
methods for detecting virus infections
detection of viral antigens
detection of nucleic acids
electron microscopy
virus culture
histopathology staining
serology testing - presence of virus specific antibodies
what is enzyme immunoassay
applied for detection of antibodies against viruses or viral antigens
several versions of enzyme
‘capture’ specific antibody for viral antigen is bound to surface of plastic wells
when sample is added, viral antigen present in sample binds to the capture antibody
when second antibody with enzyme label is added there is a colour change
what is detection of viral pathogens dependent on?
- obtaining an adequate specimen from the appropriate site
- proper timing of specimen collection relative to onset of symptoms
- timely processing of the sample
what should be considered to notifying about a disease
nature of suspected infection
ease of spread
the ways in which the spread of the infection can be prevented or controlled
the patient circumstances
urgent cases should be reported by phone within 24 hours
examples of notifiable viral infections
acute poliomyelitis
acute Hep A and B
measles
MERS
mumps
rabies
rubella
SARS CoV-2
viral haemorrhagic fever
yellow fever
what is a needlestick injury
incident in which the blood of a pateint comes into contact with the blood of a healthcare worker
