Communicable diseases: surveillance and control Flashcards Preview

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Flashcards in Communicable diseases: surveillance and control Deck (56)
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1
Q

What do you need to do to stop an infection?

A

need to remove any element of the chain of infection to prevent a susceptible host acquiring an infection

2
Q

What is the agent in influenza?

A

Orthomyoxviridase (RNA viruses) - types A, B, C

Classical respiration/systemic illness, complications frequent

3
Q

What is the epidemiology of influenza?

A

Winter epidemics in temperate regions

3-30K excess deaths in the UK

4
Q

What is the reservoir for influenza?

A

human, pig, avian

5
Q

Who is susceptible to influenza?

A

Universal until immunity acquired to specific subtype

6
Q

What is the incubation and period of communicability for influenza?

A

Incubation: 7-67 hours (median is 34 for type A)

Highly infectious for 1 day before symptoms to 1-2 days after (very low after 7 days)

7
Q

What are the means of preventing/treating of influenza within its chain of infection?

A

1) Infectious agent: Rapid diagnosis and identification
2) Reservoir: Immunisation, specific anti-viral meds
3) Portal of exit: Respiratory hygiene
4) Mode of transmission: Isolation, hand washing, respiratory hygiene, environmental cleaning
5) Portal of entry: Infection control - Personal protective equipment (PPE)
6) Susceptible host: Immunisation, antiviral chemoprophylaxis, public health management of outbreaks

8
Q

What are the different modes of transmission?

A

Direct = directly from reservoir to host

  • contact with skin/mucous membrane/blood or other bodily fluids
  • droplet spread (respiratory route)
  • transfer of faecal contamination to mouth (faecal oral route)

Indirect

  • Vehicle borne- inanimate material or object (fomites), contaminated food or water (faecal oral route), contaminated sharps (blood borne route)
  • Vector borne-mechanical or biological

Airborne
- dissemination of microbiological aerosols (<5micrometers)

9
Q

What is different about measles compared to flu?

A

Measles is an entirely human condition

10
Q

What is the agent for measles?

A

Paramyxovirus (RNA virus)

Rash and systemic illness, significant complications occur

11
Q

What is the epidemiology for measles?

A

Now rare in developed countries

12
Q

What is the reservoir for measles?

A

Human only

13
Q

Who is susceptible to measles?

A

Universal until immunity acquired

14
Q

What are the modes of transmission for measles?

A

Direct contact with respiratory secretions/droplets

15
Q

What is the incubation and period of communicability fo measles?

A

Incubation 7-18 days (typically 1 day)

Highly infectious just before rash and for 4 days after

16
Q

What are the means of preventing/treating of measles within its chain of infection?

A

1) Infectious agent: rapid diagnosis and reporting
2) Reservoir: Immunisation, healthcare employment screening
3) Portal of exit: respiratory hygiene
4) Modes of transmission: isolation, hand washing, respiratory hygiene
5) Portal of entry: Infection control PPE
6) Susceptible host: Immunisation, immunoglobin, public health management of outbreak

17
Q

What is the “green book” from PHE?

A

Schedule for vaccine preventable infections -changes over time

18
Q

What are our routine childhood immunisation programmes?

A
  • Diptheria, tetanus, pertussis, influenza B, pneumococcal, rotavirus, men C, men B, measles, mumps, rubella, influenza
19
Q

What are our routine adulthood immunisation programmes?

A

HPV, tetanus, diphtheria, polio, men A,C,W,Y

20
Q

What are some other immunisation programmes?

A

flu, pneumococcal, shingles

21
Q

What are the selective immunisation programmes?

A

Hep B -babies born to infected mothers
BCG -high prevalence areas or family link to high prevalence countries
Influenza - pregnant women
Pertussis - pregnant women

22
Q

What are the immunisation programmes for individuals with underlying medical conditions?

A

Splenic dysfunction or complement disorders - men A, B, C W, Y, pneumococcal, Hib, influenza)
Cochlear implants - pneumococcal
Diabetes and chronic respiratory/cardiovascular/neurologial disease - pneumococcal, influenza
Chronic kidney disease - pneumococcal, influenza, hep B
Chronic liver disease - Pneumococcal, influenza, hep A and hep B
Immunosuppression - pneumococcal, influenza
haemophilia - hep A and B

23
Q

What is the agent for HIV?

A

Rotavirus, HIV 1 and HIV2

Acute seroconversion illness, progressing to AIDS if left untreated

24
Q

What is the epidemiology for HIV?

A

variable according to risk groups (related to transmission) - increasing

25
Q

What is the reservoir for HIV?

A

human only

26
Q

Who is susceptible to HIV?

A

Universal

27
Q

What are the modes of transmission for HIV?

A

via exposure to blood, issues, semen, mucous membranes

vertical transmission

28
Q

What is the incubation and period of communicability for HIV?

A

Nucleic acid sequences detectable 1-4 weeks after exposure

infectivity relates to viral load and co-morbidity

29
Q

What are the means of preventing/treating of HIV within its chain of infection?

A

Infectious agent / Reservoir: active case finding, specific antiviral meds, treatment of other STIs
Portal of exit: screening of blood and organ donation
Mode of transmission: Safer sex practice, harm minimisation approaches for injecting drug use, antenatal screening programme
Susceptible host: post-exposure, pre-exposure prophylaxis (PrEP), treatment of other STIs

30
Q

What is the agent for salmonellae (non-typhoid)?

A

Salmonella enterica subspecies/serovars

Gastroenteritis (severe), systemic illness, extra-intestinal complications

31
Q

What is the epidemiology for salmonellae (non-typhoid)?

A

common worldwide

32
Q

What is the reservoir for salmonellae (non-typhoid)?

A

Many animals can be infected or acts as carriers

33
Q

Who is susceptible to salmonellae (non-typhoid)?

A

Universal (partial immunity to related servers may be acquired)

34
Q

What is the mode of transmission for salmonellae (non-typhoid)?

A

Ingestion of the organism

35
Q

What is the incubation and period of communicability for salmonellae (non-typhoid)?

A

Incubation 4 hours to 5 days (typically 12-48 hours)

Infective dose 10to power of 3 - 10 to the power of 5

36
Q

What are the means of preventing/treating of salmonellae enteritis within its chain of infection?

A

1) Infectious agent: rapid diagnosis and identification
2) Reservoir: immunising egg laying flocks, good practice in animal husbandry, abattoir and food chain occupation, good health practice
3) Mode of transmission: good practice in food prep and handling, isolation of cases, excursion of cases, enteric infection control precautions
4) susceptible host: public health management of outbreaks

37
Q

What are the stages of statutory notification of infectious disease?

A

1) surveillance system
2) Legal duty for ‘registered medical practitioners’
3) Statutory basis for notification
4) Registered medical practitioners requirements

38
Q

What is involved in the surveillance system?

A
  • identify outbreaks
  • evaluate current control measures
  • provide info to plan health services
  • identify changes to epidemiology/risk group
  • trigger for local public health action
39
Q

What acts are involved in the statuary basis for notification?

A

Health protection regulation 2010
Public health act 1984
Primary purpose - to enable the prompt investigation, risk assessment, and response to cases of infectious diseases

40
Q

What are the responsibilities of registered medical practitioners?

A

“notifiy the proper officer of the local authority in which the patient resides when they have reasonable grounds for suscepting that the patient has…”

  • notifiable disease
  • an infection that (could) present significant harm to human health
  • contaminated in a manner that could present signifiant harm to human health
41
Q

What are the common / occasional / unusual / rare notifications for infectious diseases?

A

Common
- food poisoning, TB, mumps, scarlet fever

Occasional
- measles, whooping cough

Unusual
- Acute infectious hepatitis, Typhoid and paratyphoid fever, rubella, meningitis and meningococcal septicaemia

Rare
- tetanus, polio, cholera, rabies, viral harmorrhagic fever

42
Q

What is the agent for hepatitis A?

A

picomavirus (RNA)

Wide range - from asymptomatic to fulminant hepatitis

43
Q

What is the epidemiology for hepatitis A?

A

Decreasing in developed countries, common elsewhere

44
Q

What is the reservoir for hepatitis A?

A

Humans

45
Q

Who is susceptible for hepatitis A?

A

universal until immunity is acquired

46
Q

What is the mode of transmission for hepatitis A?

A

Faecal oral route (ingestion), sexual and percutaneous transmission reported

47
Q

What is the incubation and period of communicability for hepatitis A?

A

Incubation 15-50 days (mean 28 days)

Infectious from 2 weeks before symptoms to 1 week after adults

48
Q

What are the means of preventing/treating of hepatitis A within its chain of infection?

A

1) Infectious agents: rapid diagnosis and reporting
2) Reservoir: Appropriate sewerage and sanitation facilities, water treatment processes
3) Modes of transmission: isolation of cases, exclusion of cases, enteric infection control, good practice in food handling and prep, safer sex, reduction in IV drug use
4) Susceptible host: Immunisation (occupation, travel, vulnerable cases), post exposure prophylaxis, public health management of outbreaks

49
Q

What is hepatitis A like in <5year olds?

A

generally asymptomatic

50
Q

What are the elements of the epidemiological framework?

A

Host- susceptibility, likelihood of exposure, response to agent
Agent- infectivity, pathogenicity, virulence
Environment - extrinsic factors affecting the agent and likelihood of exposure (social life, social behaviours)

51
Q

In terms of the host, what helps to ensure they are safe, more likely to suffer and more likely to suffer severely from Hepatitis A?

A

Safe- past infection, immunisation
More likely to suffer- Travel, IV drug use, sex, occupation
More severe suffering- immune status, liver disease, older age

52
Q

What are the severe symptoms of E. coli O157?

A

mild diarrhoea to severe haemorrhage colitis (related to age)
haemolytic uraemia syndrome
serious complications in up to 10% - case fatality 1-5%

53
Q

What is the infective dose of E. coli O157?

A

Excretion continues for up to a week (longer in young children)
Incubation period typically 3-4 days (range from 2 -10 days)- very easy to catch

54
Q

Where does E.Coli O157 live?

A

Cattle (<1% to 16%), sheep, deer, goats (also wild rabbits, pets and birds)

55
Q

What are the modes of transmission of E.Coli O157?

A

Many routes of transmission
- inadequately cooked meat, cross contamination
Direct contact with animals - poor animal husbandry, inadequate hand washing
Environmental- water, farmland, manure used for vegetables, salad, fruit

56
Q

What is the agent for E.Coli O157?

A

Gram -ve enterococcus