Text book Flashcards
1
Q
what is surveillance
A
ongoing collection of data to detect changes in trend or distribution in order to initiate investigative or control measures
2
Q
purposes of surveillance
A
impact of disease - extent and limits, vulnerable groups, natural history, severity, complications
detection of changes - early warning, forecasting, outbreak detection
monitoring effectiveness of preventative and control measures
highlighting priorities
basis for costing studies
etiological clues
3
Q
what will affect changes in the number of cases reported in a surveillance system?
A
true change in incidence - seasonal patterns
a new lab diagnostic method
increasing interest in disease
someone making special effort to increase numbers diagnosed
change in personnel
economic effects - lab not able to afford tests
lab failing to report
4
Q
examples of public health interventions for which surveillance is essential
A
effects of mass vaccination on infection
effects of introduction of sanitation and clean water supplies on diarrhoeal disease
controlling an epidemic of salmonella by withdrawing contaminated food
monitoring the effect of legionnaire’s disease of a law requiring regular maintenance of water cooling towers
5
Q
what is sentinel surveillance
A
a form of sample surveillance - e.g. using GP practices
6
Q
example of when active surveillance was used
A
to eradicate small pox
7
Q
when is completeness of reporting important?
A
less common but important conditions conditions for which public health measures are necessary highly contagious infections very rare diseases serious infections
8
Q
do you have to negatively report in active surveillance
A
yes
9
Q
what is enhanced surveillance
A
where certain regions have to perform active surveillance
10
Q
how would you conduct disease surveillance - measures
A
mortality, morbidity, outbreaks, laboratory
11
Q
how would you conduct drug utilization surveillance - measures
A
therapeutic, diagnostic, prophylactic
12
Q
how would you conduct vaccine surveillance - measures
A
utilisation and efficacy
side effects
13
Q
important features of a successful surveillance system
A
importance of disease under surveillance timeliness representativeness consistency completeness accuracy
14
Q
4 steps in running a surveillance system
A
collection
analysis
interpretation
response
15
Q
sources of surveillance data
A
death
hospital admissions
morbidity systems
asymptomatic - serological surveillance
16
Q
if there was a tsunami which diseases would you put under surveillance
A
cholera, typhoid, dysentery, measles, malaria, dengue fever, japanese encephalitis, hep A and E, tetanus, wound infections
17
Q
diseases which would benefit from international surveillance
A
legionnaires, E coli, salmonella, influenza, cholera, SAES, hep A, meningococcal infection
18
Q
who is legionnaires more common in
A
over 50 smokers males heavy drinks those with chronic conditions/immunosuppressed common in late summer and autumn
19
Q
what promotes the growth of legionella
A
stagnant water
temps between 20 and 50 degrees
ph between 5 and 8.5
20
Q
main aims and objectives in investigating outbreak of legionnaires
A
aim: identify source quickly so it can be removed immediately or rendered safe
objective: identify as many linked cases as possible, use relevant info from all known cases to identify a common source of exposure
confirm source microbiologically by taking sample
ensure that appropriate hygiene measures used
draw up guidelines for hygienic management of water systems
21
Q
how to diagnose legionella pneumophilia
A
urine test or specimen of sputum or blood
22
Q
why would you institute national surveillance for a disease?
A
can prevent cases
serious and potentially fatal
easily and accurately confirmed by a lab
not common enough to make surveillance a burden
23
Q
example of an international surveillance system
A
WHO global outbreak alert and response network
24
Q
two factors basic to success of a mass immunisation programme
A
vaccine efficacy
vaccine uptake
25
ten principles of a field investigation
1) determine if its an outbreak
2) confirm diagnosis
3) define a case, conduct case finding
4) collect info on cases
5) analyse data epidemiologically: time, place, person, exposure
6) interpret
7) test hypothesis with an analytical study
8) draw appropriate conclusions
9) prepare a written report
10) execute control and prevention measures
26
what would you ask in a questionnaire to collect info on outbreak
```
demographic data
details of illness
burden of illness
exposure details
details of secondary cases
```
27
why do a case control rather than cohort in outbreak?
difficult to get two groups together
quicker
can look at various exposures
28
why is a cohort study more powerful in an outbreak?
can calculate food specific attack rate, relative risk and attributable risk
however need to know how many exposed and how many not exposed
case control gives you food specific preference rate
29
role of the outbreak control team
```
epidemiology
communication
specimens
prevention
reports
```
30
functions of epidemiologist
ensure a systematic epidemiological investigation of the outbreak
supervise case finding
identify risk factors, analyse and interpret the data
identify interventions
work with others to implement control measures that prevent further exposure and infection
31
what does an outbreak management team do
in national or international outbreaks, act as a higher tier responsible for OCT. Agree a plan of action for the epidemiological and microbiological investigation and control measures, commit the appropriate amount of resources to the OCT and decide on a communication strategy
32
essential details of outbreak data and information
```
accuracy
consistency
freedom from bias
confidentiality
security
accessibility
```
33
```
Hep A:
how much for infection
spread
incubation period
when are patients infectious
```
small dose for infection
faecal-oral
15-40 days with median of 28 days
infectious when asymptomatic - common in young
organism hardy and can survive in water, surfaces and at freezing temperatures
34
what are the stages in the implementation of a vaccine strategy?
how severe is the infection?
how good is the vaccine?
how do we use it?
how well is it doing?
35
characteristics of ideal vaccine
```
100% efficacy
no side effects
non painful route
free cost
100% stable at all temperatures
```
36
reasons for choosing a selective rather than mass vaccination strategy
rare disease
diseases more common in certain groups
threat of a serious infection being imported
the cost of the vaccine
37
example of selective immunisation
```
rabies
tick borne encephalitis
typhoid
hep B
influenza
```
38
advantages and disadvantages of selective immunisation
adv: less waste, fewer side effects, more efficient
dish: not always possible to target groups, difficult to predict who needs it, herd immunisation can't be achieved
39
options of mass immunisation programme
containment
elimination
eradication
40
what effects vaccine efficacy
```
wrong age of patient
wrong site
vaccine deterioration
reconstituted vaccine not made up correctly or used within recommended period
immunological status of patient
change in prevalent organism
```
41
factors affecting uptake of vaccine
efficiency and cost. social perception.
42
aim of influenza surveillance?
provide timely info on morbidity and morality associated with influenza. effective early warning system so plans can be put in place to alert GPs, hospitals etc. info on components of vaccine for following year. impact on population can be measured.
43
what info would you use if you conducted surveillance of influenza?
mortality
morbidity
lab findings
serological studies
44
what cause of death would you analyse in trying to assess mortality from influenza?
deaths from influenza, pneumonia, bronchitis, all respiratory diseases, coronary heart disease and total morality during influenza epidemic.
45
why might influenza not be a notifiable disease?
difficulty in making diagnosis
could overwhelm surveillance system during epidemic
little urgent action
morbidity can be measured by other methods which have higher specificity
46
how do you think serological studies can help in influenza surveillance?
assess clinical susceptibility and hence usefulness of vaccine
likely impact of a new variant assessed
unravel the history of influenza
47
what sort of vaccine is influenza
killed vaccine
48
```
SARS: what sort of virus
symptoms
incubation
transmission
management
```
coronavirus
high fever, cough, SOB and leading to pneumonia and acute respiratory distress syndrome
2-10 days (mean =5)
droplet and direct contact with bodily fluids
intense surveillance
information, education and travel advice to general public, contingency planning, collaboration with government and other agencies, international collaboration
49
what does respiratory syncytial virus result in in young children
and when is it common
bronchiolitis and pneumonia
| in winter
50
common cause of TB in humans
mycobacterium tuberculosis
51
TB:
transmission
diagnosis
respiratory route - droplets lodge in lung
acid fast bacilli - culture and smear,
tuberculin skin test
52
M. bovis - how is it transmitted
swallowing and creating primary focus in intestinal wall
53
important triggering factors for TB
```
immunosuppression
age and sex
poor nutrition
poverty
low socio economic status
overcrowding
occupation
ethnicity
travel/migration
gastrectomy
pregnancy
exposure to animals
```
54
what has caused a resurgence of TB even in some high and middle income countries
displacement and migration
HIV infection
poverty - poor housing, over crowdedness, homelessness, poor nutrition
political will and priorities and conflict - disruption in health infrastructure
TB drug resistance
55
useful sources of data for TB surveillance
notification system
enhanced surveillance - need completeness
laboratory back up - accurate diagnosis
death certification
56
what info would you want to collect from each TB case
```
age and sex
type of TB
infectivity
details of organism
drug resistance
basic clinical details - previous TB
relevant occupational and social info
outcome
```
57
list of methods to control TB
BCG
surveillance for case finding and action on cases
outbreak investigation
chemotherapy of cases with disease
chemoprophylaxis of infection
improving social conditions
58
strategy to increase compliance with TB therapy
DOTS (otherwise encourages drug resistance)
government commitment to sustained TB control
detection of TB cases through sputum smear microscopy in people with symptoms
regular and uninterrupted supply of TB drugs
6-8 months of regular supervised treatment
reporting systems to monitor treatment progress and programme performance
59
common cause of short incubation period GE infections
staph aureus and bacillus cereus - vomiting
60
what is it from staph aureus that causes the vomiting?
enterotoxin
61
where do you find bacillus cereus
rice - destroyed by boiling as forms spores
62
causes of medium incubation period GE infections
```
salmonella/shigella/E.coli (6-72h)
vibrio cholerae (12h-5 days)
```
63
symptoms of salmonella
fever, diarrhoea and abdominal pain
64
difficulty swallowing and speaking after vomiting and diarrhoea, cause?
clostidrium botulinum
65
why do the symptoms from botulinum appear later? (longer incubation period?)
toxin doesn't act primarily on the intestine - has to be absorbed into the bloodstream and then transmitted to the nerve/muscle junction before symptoms of paralysis appear
66
how is shigella most likely to spread?
case to case transmission - only 1-100 organisms
| in crowded institutions with poor facilities - refugee camps, psych hospitals
67
what are the 4 groups of mechanisms of E.coli
enteropathogenic
enterohaemorrhagic
enteroinvasive
enterotoxigenic
68
complication of e coli
haemolytic uraemia syndrome - haemolysis, thrombocytopenia purport and renal failure
69
most common cause of GE globally
norovirus
70
what type of outbreak would you expect norovirus to cause?
point source
continuing source
case to case
71
why is case to case transmission of norovirus more common than hep A?
norovirus even more infectious, more stable in environment, more resistant to disinfection, potential for spread greater because vomit infectious, antigenic diversity in norovirus
72
causes of long incubation period GE infections (>48 hours)
campylobacters, listeria monocytogenes, giardia lamblia
73
campylobacter symptoms
diarrhoea with blood and mucus, abdominal colic and fever - can get septicaemia and guillain barre syndrome
74
common cause of diarrhoea under 5
rota virus
75
ways of avoiding food poisoning
cook food thoroughly
do not leave moist cooked foods in a warm environment for a long length of time
avoid cross contamination of raw to cooked food
reheat pre cooked food thoroughly and consume straight away
careful cooling bulk foods
avoid eating certain raw foods
wash hands before preparing salads
defrost food thoroughly before cooking
76
```
hep A:
transmission
how is it destroyed
incubation period
who is more susceptible
```
faecal oral
heating high temperatures
15-40 days
children - more likely to be asymptomatic
77
which immunoglobulins appear quickly then time after?
IgM quickly
| IgG after
78
diagnosis of Hep A
HAV IgM in blood, saliva or urine - up to 4-6 months
79
why would you run a surveillance system for hep A in your country?
to detect outbreaks, through trends and natural variations in incidence. Changes in age distribution and geographical location. foods contaminated can occasionally cause large outbreaks.
80
who should have prophylactic hep A vaccination
frequent or long term travellers
staff and residents of schools for people with developmental problems
staff working in day care centres
those working with raw sewage
lab workers handling the virus
other groups with prolonged hep A infection
injection drug users
81
how is hep B spread
blood borne - skin puncture or across mucous membranes
parenteral exposure to infected blood or body fluids
sexual contact with an infected person
mother to child transmission
horizontal person to person contact
82
what do you have to have to be a hep B carrier
6 months or more of HBsAg - low risk
| those high risk carriers have HBeAg or HBVDNA in their blood
83
objectives of surveillance of Hep B
estimate incidence of Hep B
estimate prevalence
build an estimate of burden
identify outbreak and main modes of transmission
identify changes in epidemiology of infection
choose and monitor control strategies
84
why is there a large proportion of unknowns with hep B in most countries
the incubation period for hep B is 2 to 6 months so infection could have occurred long time before
disease is highly infectious
most of the routes of transmission can cause stigma
risk information not reported by clinician
85
if you were to screen routinely for hep B, which populations would you choose
blood donors, women in antenatal period, health care workers, those intending to train for health care work
certain professions
86
who would you give hep B vaccine to
babies of HBsAg positive mothers
injecting drug users
those who change sexual partners regularly
close family contacts of cases
frequent blood product recipients
patients with chronic renal failure requiring dialysis
health care workers and students
prisoners
frequent travellers to high endemic countries
those living or working in residential institutions
87
why are STIs of public health importance?
```
occur worldwide
high impact on mortality
impact on morbidity
communicable but can be hidden
effects mainly young adults
direct health care costs, indirect, cost in terms of chronic disease and infertility
no vaccines
they interact to facilitate transmission of each other
```
88
what do you ask in enhanced surveillance for STIs
number of sexual partners
use of sex workers
hetero/home sex behaviours
previous STIs/HIV testing
89
why is surveillance of HIV more complicated?
```
initial infection asymptomatic
stigma and discrimination
mobility of young adults
fear/irrational reactions
different risk groups
rapidly changing trends
wide variation in prevalence
effect of resistance to anti virals
testing invasive and may be barriers
strict confidentiality necessary
quality control on specimens important
```
90
methods of STI and HIV surveillance
case reporting
unlinked anonymous surveys
screening results
behavioural surveillance
91
main clinical sights of hospital acquired infections
```
blood
urinary tract
resp tract
skin/wound/surgical site
GI tract
```
92
factors which will influence whether a HAI will occur
host - age, sex, and health status of patient
agent - virulence of organism and site of inoculation
environment - general hygiene and cleanliness of patient surroundings, cleanliness of apparatus and facilities for hand washing etc
93
what sources of data for HAI surveillance are available
case notes, microbiology reports, clinical diagnoses and antibiotic records
94
why are HAIs likely to increase
increasing vulnerable patients
antibiotic resistance
new infections
new technologies
