Week 2 - Control Of Communicabke Disease Control - HS

Question 1

Why is infectious disease Important?

Answer 1

• it’s a global burden
• UK priorities :
  Health care associated infections - impact on health service delivery
  Antibiotic resistance
  New and emerging infections

Question 2

Chain of infection

Answer 2

Infectious agent -> Host > portal of entry -> mode of transmission -> reservoir/environment

Question 3

BInfectious agent/ pathogen has to be …

Answer 3

• ability to reproduce
• survival (incl environment )
• Ability to spread
• infectivity ( ability to cause infection also consider colonisation without infection )
• pathogenicity (severity of the illness

Question 4

Reservoir/environment has to be …

Answer 4

• exposures - don’t forget relationship as a host issue
• animals as reservoirs
• other humans
• water systems
• environmental contamination

Question 5

What kinds of modes of transmission are available?

Answer 5

1- respiratory spread
: droplet (3 feet)
: airborne(suspended particles)
: plus aerosolisation of water

2- ingestion 
  : direct consumption 
  : hand to mouth 
  : contamination from people (person to person spread) 
  : contamination from environment 
3- blood borne 

4- sexual contact

Question 6

The different portal of entries

Answer 6

• mouth
• nose
• ear
• genital tract
• skin ( breakdown of barrier )

Question 7

What host factors make them suspectible to infection from organisms ?

Answer 7

• chronic illness
• nutrition
• age (the very young and the very old )
• immunity (immune conditions ; chemotherapy; transplant etc)
• lifestyle factors ( drugs, alcohol, sex , occupation , poverty, leisure activities )

Question 8

Example of an outbreak of an Infectious disease

Answer 8

Measles outbreak in a prison

Question 9

How did measles outbreak occur

Answer 9

: infectious agent (IA)
- measles is highly infectious (15 mins in the same room )
:Reservoir/environment (E)
- humans only ; crowded enclosed institution , lack of isolation facilities , the dinner queue
: mode of transmission (MOT)
- droplet spread , cough , sneezes
: portal of entry (POE)
- respiratory tract
: host (H)
- young adults most UK born but some non UK born , chaotic lifestyles not sure if immunised with MMR at birth ( no health records available)

Question 10

How did it get controlled ?

Answer 10

Mass vaccination

Question 11

Difficulties faces in controlling measles outbreak

Answer 11

• long incubation period
• consent
• identification of new cases
• isolation of cases
• vaccination ( who pays and who does it in this setting )

Question 12

Legionnaires disease outbreak in Stoke

Answer 12

:IA
- legionella
: E
- survives in amoebic sludge in water systems and can grow at certain temps
: MOT
- droplet or aerosois (showers, sprays, fountains, car washes , air conditioning , hot tubs etc )
: POE
- respiratory
: Host
- generally older people are vulnerable to infection with pre existing respiratory conditions

Question 13

Food poisoning outbreak - E.coli in Germany

Answer 13

\:IA
- E.Coli (usually O157) VTEC is ....
- high mortality and morbidity , haemolytic Uralemic syndrome 
\: E
- cattle guts, other animal reservoirs, soil survival 
\: MOT 
- ingestion ,person to person spread 
\: POE
- GI tract 
\:H
- babies and young children aged 5

Question 14

Gonorrhoea outbreak in England

Answer 14

\:IA
- gonorrhoea 
- high level antibiotic resistance - risk of untreatable infections 
\: E
- humans 
\: MOT 
- sexual contact 
\:POE
-genital  tract , pharynx 
\:H
- lifestyle risks , unprotected sex , number of patients , high risk MSN cohorts

Question 15

Surveillance

Answer 15

Systemic collection, collation and analysis of data and dissemination of the results so that appropriate control measure can be taken

Question 16

Measles outbreak

Answer 16

• NOIDS (notice of intent to deny)
• lab testing
• public health , follow up all contacts

Problems : rashes look very similar not everyone notifies , lab test is not routinely available, lab test takes Time to come back - issue in example of offenders not wanting to disclose illness .

Question 17

Legionnaires outbreak

Answer 17

• lab test
• NOID
• enhanced surveillance questionnaire
• monitoring

Problems - presenting illness may be easily diagnosed as something else , test may not be done , test is not that great , need to confirm at a reference lab , clinical may not remember to notify , ESQ relies on recall ( recall bias ) , diffcult to complete.

Question 18

Food poisoning outbreak

Answer 18

• NOIDS
• lab tests
• food complaints
• syndromic survelliance
• investigation if exceedances
• enhanced survelliance questionnaires
• outbreak specific questionnaires

Problems : mild cases don’t present, doctors don’t test. Recall bias for food eaten in the past , ingredients hard to identify , food distribution in the modern world is complex

Question 19

Gonorrhoea outbreak

Answer 19

• GUM reporting (quarterly only at best)
• relies on GUM notifying increases
• lab tests to confirm organism and antibiotic resistance
• reference lab to confirm
• whole genome sequencing
• enhanced survelliance

Problems : late identification , chaos of life , non attendance , non disclosure of partners , partners not being tested , sexual health promotion and target audiences , behaviour change diffcult

Question 20

Healthcare associated infections

Answer 20

• Norovirus (viral gastroenteritis ) , Burden on hospitals
• Carbapenemase producing organisms (CPO) - antibiotic resistance
• MERs -CoV - novel or emerging infections ; hospital as the point of amplification

Question 21

Carbapenemase producing organisms (CPO)

Answer 21

Carbapenems are a powerful group of broad spectrum beta lactams antibiotics . Last effective defence against infections caused by multi resistant bacteria, such as some Strains of klebsiella pneumoniae and escherichia coli

Resistance to CPO had emerged and beginning to spread . New antibiotics needed to counter bacteria with this resistance and hospitals need good infection control to prevent their spread.

Question 22

Control of HCAI

Answer 22

• hospital environmental hygiene ( incl isolation of cases )
• hand hygiene
• use of personal protective equipment (PPE)
• safe use and disposal of sharps and
• principles of asepsis