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Table 2 Results and parameterization of the stochastic model with Swiss national survey data on BoHV-1. Detailed information on BoHV-1 surveys conducted or planned from 2002–2007 in Swiss cattle and pre-survey probability of freedom estimates using deterministic and stochastic model approaches. Sample sizes of previous surveys in the stochastic model: (SSS) standard sample size calculation or (RBS) sample size calculation as described by Eq. 8.

From: A stochastic simulation model to determine the sample size of repeated national surveys to document freedom from bovine herpesvirus 1 (BoHV-1) infection

Input values

2002

2003

2004

2005

2006 a)

2007 a)

Population size (number of cattle herds)

50,591

48,231

48,790

46,574

46,574

46,300

Allowed threshold herd level prevalence

0.001

0.001

0.001

0.002b)

0.002

0.002

Number of positive herds detected in previous survey

0

1

0

0

1

0

Sample size of previous survey RBS

632

2400

2274

2828

1430

1550

Sample size of previous survey SSS

4650

4650

4650

2325

2325

2325

n direct imports from BoHV-1-free countries

c)

c)

c)

155

976

552

n indirect imports from BoHV-1-infected countries

500d)

8 e)

496

1145

388

658

n indirect imports, national eradication of BoHV-1 accomplished but not officially free

    

344

680

Remaining pre-SPF from the last survey, deterministic model [1]

0.8910

0.9094

0.8371

0.8947

0.8201

0.8618

Remaining pre-SPF from the last survey, stochastic model f) (RBS)

0.9516

0.4958

0.7826

0.9740

0.5866

0.8320

Remaining pre-SPF from the last survey, (RBS) and bin. detection probability of 0.8

0.9856

0.6406

0.872

0.9936

0.7312

0.9336

Remaining pre-SPF from the last survey, stochastic model (SSS)

0.9516

0.8106

0.9516

0.9958

0.8104

0.9514

  1. a) planned surveys that are not carried out yet or analysis not completed
  2. b) adaptation of Swiss regulation to European animal disease surveillance regulation
  3. c) Swiss regulation on cattle import changed in July 2004, specific distinction between animal imports originating from EU countries officially free or not free from certain diseases
  4. d) due e) qualitative risk-assessment only. The import number was adjusted to n = 500 for the model input to obtain comparable results with the qualitative estimate
  5. e) import stop due to foot and mouth disease outbreaks in Europe 2001
  6. f) the stochastic model developed and investigated in this publication