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Table 2 Parameters used to estimate the effects of different exclusion policies

From: Evaluation of the impact of shigellosis exclusion policies in childcare settings upon detection of a shigellosis outbreak

Parameter

Value

Range

Source

Shedding duration (days)

 Treatment scenario Aa

3.6

1–5

[3, 4]

 Treatment scenario Bb

5.6

3–7

[3, 4]

 Treatment scenario C

31

17–41

[5, 6]

 Treatment scenario D

11

4–31

[5, 6, 8]

Symptom duration

 Treatment scenario A

3.6

1–5

[3, 4]

 Treatment scenario B

5.6

3–7

[3, 4]c

 Treatment scenario C

10d

1–41

[3, 7]

 Treatment scenario De

5

1–30

[3, 4]

Days between doing test and receiving results from convalescent test (PCR)f

2

1–6

Expert opinion

Days between doing test and receiving results from convalescent test (Culture)f

3

2–7

Expert opinion

Duration of antimicrobial treatment (days)

5

 

[9]

Attack rate (%)g

25

 

[10, 11, 16, 17]

Test sensitivity PCR (%)h

96

94–98

[18]

Test sensitivity, stool culture (%)

52

44–72

[19, 20]

Test specificity, PCR or stool culture (%)i

95

90–99

[18, 20]

  1. Notes
  2. Different treatments: A. Immediate, effective treatment; B. Effective treatment after diagnosis; C. Ineffective treatment; D. No treatment
  3. aWe assumed that duration of fecal shedding of shigellae for patients treated with an appropriate antibiotic is similar to the duration of shigellosis symptoms
  4. bSame assumption for the duration of fecal shedding of shigellae as for scenario A plus two days, which correspond to the assumed interval between starting treatment immediately after seeking care (Treatment A), and starting treatment after doing the test and receiving diagnosis (Treatment B)
  5. cThe symptom duration was estimated as scenario A plus two days
  6. dThe mean value of symptom duration for scenario C was assumed
  7. eThe upper bound of symptom duration for scenario D was based on data from State Health Departments and PulseNet outbreak 1407MLJ16–2
  8. fAssumption based on the information provided by State Health Departments. For PCR tests, the lower bound for the time elapsed between receiving results from the first and second test is one day if the health department initiates the request. The upper bound was defined as six days if there are delays or a weekend between laboratory tests. One day was added for culture tests
  9. gHoffman et al. [10] estimated an overall attack rate of 25% in a Denver child-care servicing 18 months to 6 years old. The other references are used for suggested ranges in Additional file 2: Appendix B
  10. hProportion of tests from patients with shigellosis that show positive results (true positive rate)
  11. iProportion of tests from patients without shigellosis that show negative results (true negative rate). We assumed that the lower bound and median value of the test specificity were 90 and 95%
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BMC Infectious Diseases

ISSN: 1471-2334

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