Health protection Flashcards
Information needed to notify communicable disease
Severity: Morbidity, fatality, etc..
Transmissibility: Potential, route, sources, infectiousness
Contacts: Susceptibility/resistance among contacts, number, nature
Control measures: That would prevent transmission, availability/evidence
Special circumstances: e.g. age, pregnancy, occupation that increase risk of case
Definition of incubation period
Time between inoculation and becoming symptomatic
Latent period
Time between inoculation and becoming infectious
Caution if latent < incubation –> infective while asymptomatic
Infectious period
Time during which patient is capable of infecting others
Pathogenicity definition
Ability of organism to cause disease
Virulence definition
Severity of illness caused by organism
Interventions to reduce person-person transmission
Reduce infectiousness: Treatment, hygiene
Limit contact: Quarantine, isolation, advice
Reduce susceptibility of contacts: PPE, PEP, immunisation, Tracing/screening
Interventions to reduce indirect transmission
Source decontamination
Vector source control
Zoonotic animal cull/movement ban
Source shutdown (restaurant, factory)
Presentation of CO poisoning
Nausea, vomiting, confusion
Lethargy, flu-like symptoms
Headache, dizziness, syncope
Tachypnoea, metabolic acidosis, respiratory failure
Normal carboxyhaemoglobin concentration
1-3% in non-smokers
5-10% in smokers
Information to collect for suspected CO poisoning
New appliances?
CO alarm?
Who else at home? esp. pregnant, extremes of age, heart conditions
Any communal areas they have been in recently?
Actions to take for CO poisoning
100% O2 until asymptomatic and normal COHb levels
Contact local Health Protection Team
Advise not to use new appliances + contact HSE/Gase Emergency Helpline
F/U at 1-2months
Rationale for post-exposure chemoprophylaxis in meningococcal disease
Eradication of carriage of invasive meningococcal strain
At-risk period for secondary cases of meningococcal disease
7 days is highest risk period
Chemoprophylaxis should be given within 24h
Definition of close contact for antibiotic prophylaxis in meningococcal disease
Prolonged contact during preceiding 7d
Boy/girlfriend
Household contacts, shared dormitory, shared kitchen
Contact with large-droplet respiratory secretions within 24h (incl healthcare workers)
Vaccination guidance after meningococcal case
Close contacts: Vaccination unless serogroup-immunised within preceding 12mo OR MenB case
Give full recommended vaccination to case if not already immunised (don’t re-immunise)
Meningococcal cases requiring public health action
Clinical: Septicaemia, mengingitis, other invasive disease
AND
Lab: G-ve diplococci OR N. meningiditis organisms or DNA from sterile site
OR
evidence of bacterial infection and N. meningiditis likely source (PH/microbiologist advice)
Timings for measles symptoms
7-21d (typically 10-12d) incubation period
2-4d prodromal phase: fever, cough, conjunctivitis
7d maculopapular, nonitchy rash
Infectious period for measles
4d before and after rash onset
Extremely infectious (respiratory droplets)
Ideal samples for measles testing
Oral fluid is ideal sample
Mouth viral swab if not possible
Serum IgM/IgG to assess contact immunisations status
Factors increasing risk/likelihood of measles
Recent international mass gathering
Epi link to confirmed measles case or visit to area with known circulation
Not fully immunised
Local community with low vaccination rate
Adolescents/young adults (fewer similar disease presentations)
Individual info to be collected for notifying measles
Travel Hx - incl. GP/A&E visits
Vaccination Hx
Epi link to outbreaks
Ethnic/cultural background (Esp if low vacc community)
Signs, symptoms, lab results
Which contacts should be traced following measles case?
Household contacts
>15min in closed, confined space (e.g. classroom)
Face-to-face contact of any length
Priority groups for measles contact tracing?
- Immunocompromised
- Pregnant or infant <12mo
- Healthcare workers
- Healthy contacts
Post-exposure treatment for measles contacts
MMR vaccination and serum IgG testing
Consider IgG for immunocompromised individuals
Presentation of O157 E. Coli
Mild non-bloody diarrhoea
Bloody diarrhoea
HUS (ESP <5YO)
Incubation period for O157 E. Coli
3-4 days
Sources of O157 E. Coli
Faeco-oral transmission from infected animal excreta:
- Water: drinking/vegetables
- Meat: during slaughter, if not properly cooked; contact with other raw meat
- Direct: E.g. farms, petting zoos
- Human-human: esp in nurseries, primary schools due to prolonged contact, immature immune systems, poor personal hygiene
Indications for faecal culture in acute diarrhoea (bloody or non-bloody)
- Vulnerable: <16y, >60y, pregnant, frail, immunocomp
- Recent travel abroad
- Bio plausible contact to O157/ part of outbreak
- Severe/protracted illness
What to avoid in O157 management
Antibiotics - higher risk of HUS
Anti-motility, opioids, NSAIDs
Active vs passive surveillance
Passive: Relies on routine data collection, cheap but incomplete coverage
Active: Surveillance team reaches out to labs/clinicians/patients to collect data e.g. during outbreaks
Sentinel surveillance
Centres with high probability of seeing cases identify and notify the disease as routine to pick up trends
Enhanced surveillance
Collection of additional info if disease suspected (e.g. TB routine info not enough)
Definition of epidemic
Occurence of illness/health-behaviour in a population in excess of normal expectancy
Interchangeable with outbreak
Pandemic = global epidemic
Case fatality definition
Proportion of cases that are fatal within a given time period
Definition of cluster
Cases in a similar time/place where an epidemiological link is possible but unconfirmed
Basic reproduction number
Average number of secondary cases from a single index case in a totally susceptible population
Affected by: Rate of contact, probability of transmission, duration of infectious period
Effective reproduction number (R)
Average number of 2ry cases in a population with a mixture of susceptible/unsusceptible individuals
R= R0x where x is the fraction of the population that is susceptible
Herd immunity threshold
Proportion of population that needs to beimmunised to make disease stable in population (i.e. R=1)
1- 1/R0
Attack rate
Number of new cases/population at risk
within specified time
Secondary attack rate
Number of cases among contacts/Number of contacts
Within one incubation period
Point source epidemic curve
All cases appear within one incubation period
e.g. food poisoning at wedding
Continuous source epidemic curve
Abrupt start within one incubation period
Continuous source = prolonged, high level of cases
Propagated epidemic curve
Waves occuring within average incubation period - increasing until susceptible population falls or intervention measures succeed
