introduction to virology and needlestick injuries

Question 1

how can viruses be classified

Answer 1

by host
according to disease or target organ
according to vector
genetic sequence and biophysical structure

Question 2

what does taxonomy describe

Answer 2

virus order
virus family
subfamily
type species
morphology
genetic material
envelope - has a role in virus transmission

Question 3

how to differentiate between bacterial and viral causes of infection

Answer 3

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

Question 4

what is the purpose of diagnosing viral infection

Answer 4

medical - patient management
epidemiological
intra-hospital infection prevention and control
academic (research)

Question 5

4 advanced molecular diagnostic testing techniques

Answer 5

nucleic acid-based technologies
next generation sequencing
monoclonal antibodies
enzyme immune assays

Question 6

example of rapid viral diagnostic test and impact - POCT

Answer 6

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

Question 7

methods for detecting virus infections

Answer 7

detection of viral antigens
detection of nucleic acids
electron microscopy
virus culture
histopathology staining
serology testing - presence of virus specific antibodies

Question 8

what is enzyme immunoassay

Answer 8

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

Question 9

what is detection of viral pathogens dependent on?

Answer 9

1. obtaining an adequate specimen from the appropriate site
2. proper timing of specimen collection relative to onset of symptoms
3. timely processing of the sample

Question 10

what should be considered to notifying about a disease

Answer 10

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

Question 11

examples of notifiable viral infections

Answer 11

acute poliomyelitis
acute Hep A and B
measles
MERS
mumps
rabies
rubella
SARS CoV-2
viral haemorrhagic fever
yellow fever

Question 12

what is a needlestick injury

Answer 12

incident in which the blood of a pateint comes into contact with the blood of a healthcare worker