Quantitative investigation of population persistence and recurrent outbreaks of bovine respiratory syncytial virus on dairy farms.
OBJECTIVE
To determine if transmission of virus among seropositive cattle is a plausible mechanism for the permanent presence of bovine respiratory syncytial virus (BRSV) in dairy herds, and how likely, with the scenario for persistence, there will be only 1 clinical outbreak of BRSV per year.


METHODS
Build a stochastic model, parameter estimation from serologic data on BRSV, and interpret the estimated parameter values from the model analysis.


METHODS
Monthly data on the prevalence of antibodies directed against BRSV in sera from all cattle in 6 dairy herds.


METHODS
Parameter estimation applying general linear models, model analysis using calculation of the reproduction ratio for simplified models, and Monte-Carlo simulation for the whole model.


RESULTS
Persistence of BRSV by transmission among seropositive cattle given estimated parameter values would be accompanied by frequent extinctions (once every 10 to 50 years) and long infectious periods in seropositive cattle (100 days). Moreover, in the model, a single clinical outbreak among seronegative cattle only occurred with external forcing.


CONCLUSIONS
From these data, transmission among seropositive cattle is not a plausible mechanism for persistence of BRSV in dairy herds.
De Jong
M C
MC
Department of Pathobiology and Epidemiology, Institute for Animal Science and Health, Lelystad, The Netherlands.
van der Poel
W H
WH
Kramps
J A
JA
Brand
A
A
van Oirschot
J T
JT
D000818:Animals; D000914:Antibodies, Viral / Q000032:analysis / Q000276:immunology; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology*; D003612:Dairying; D004196:Disease Outbreaks / Q000706:statistics & numerical data / Q000662:veterinary*; D005260:Female; D015994:Incidence; D008954:Models, Biological; D015233:Models, Statistical; D015995:Prevalence; D012008:Recurrence; D018357:Respiratory Syncytial Virus Infections / Q000453:epidemiology / Q000662:veterinary*; D018112:Respiratory Syncytial Virus, Bovine / Q000276:immunology; D013269:Stochastic Processes
D000914:Antibodies, Viral