PMID- 11821139
OWN - NLM
STAT- MEDLINE
DCOM- 20020314
LR  - 20191105
IS  - 0167-5877 (Print)
IS  - 0167-5877 (Linking)
VI  - 53
IP  - 1-2
DP  - 2002 Feb 14
TI  - Risk factors for infection of sow herds with porcine reproductive and respiratory 
      syndrome (PRRS) virus.
PG  - 83-101
AB  - In 1992, the porcine reproductive and respiratory syndrome virus (PRRSV) of 
      European type (PRRSV-EU) was introduced in Denmark. By 1996, the virus had spread 
      to approximately 25% of the Danish herds. In January 1996, a modified-live 
      vaccine based on the American type of the virus (PRRSV-US) was used in 
      replacement boars for Danish artificial insemination (AI) centres and from July 
      1996, the vaccine was used in PRRSV-EU infected herds for prevention of disease. 
      Soon after vaccine introduction, PRRSV non-infected herds experienced outbreaks 
      of disease due to infection with PRRSV-US. In this study, we investigated the 
      risk factors (biosecurity level, animals, exposure from PRRSV-US-infected 
      neighbour herds, semen, herd size, pig density and herd density) for infection 
      with PRRSV-US in a cohort of 1071 sow herds; we used a nested case-control study. 
      The retrospective observation period lasted from June 1996 (when they all were 
      non-infected) to October 1997. Seventy-three non-vaccinated, closed sow herds 
      became infected with the vaccine strain during this period. Each case herd was 
      matched with two control herds from the cohort (controls had not been infected at 
      the time of infection in the case herds). The data were analysed using a 
      Cox-regression model. The hazard of infection increased significantly with 
      exposure from PRRSV-US-infected neighbouring herds, purchase of animals from 
      herds incubating PRRSV-US infection, increasing herd size and purchase of semen 
      from boars at PRRSV-US-infected AI centres. The results are consistent with the 
      modified-live vaccine strain spread to other herds by trade with animals and 
      semen and by neighbour (area) transmission. We suggest that virus spread by 
      aerosols was a frequent mode of transmission.
FAU - Mortensen, Sten
AU  - Mortensen S
AD  - Department of Animal Science and Animal Health, Royal Veterinary and Agricultural 
      University, Frederiksberg C, Denmark. stm@fdir.dk
FAU - Stryhn, Henrik
AU  - Stryhn H
FAU - Sogaard, Rikke
AU  - Sogaard R
FAU - Boklund, Anette
AU  - Boklund A
FAU - Stark, Katharina D C
AU  - Stark KD
FAU - Christensen, Jette
AU  - Christensen J
FAU - Willeberg, Preben
AU  - Willeberg P
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - Netherlands
TA  - Prev Vet Med
JT  - Preventive veterinary medicine
JID - 8217463
RN  - 0 (Viral Vaccines)
SB  - IM
MH  - Animal Husbandry
MH  - Animals
MH  - Case-Control Studies
MH  - Cohort Studies
MH  - Denmark/epidemiology
MH  - Disease Transmission, Infectious/*veterinary
MH  - Enzyme-Linked Immunosorbent Assay/veterinary
MH  - Female
MH  - Insemination, Artificial/veterinary
MH  - Male
MH  - Porcine Reproductive and Respiratory Syndrome/epidemiology/etiology/*transmission
MH  - Porcine respiratory and reproductive syndrome 
      virus/classification/immunology/*isolation & purification
MH  - Proportional Hazards Models
MH  - Retrospective Studies
MH  - Risk Factors
MH  - Semen/virology
MH  - Swine
MH  - Viral Vaccines
MH  - Virus Shedding
EDAT- 2002/02/01 10:00
MHDA- 2002/03/15 10:01
CRDT- 2002/02/01 10:00
PHST- 2002/02/01 10:00 [pubmed]
PHST- 2002/03/15 10:01 [medline]
PHST- 2002/02/01 10:00 [entrez]
AID - S0167587701002604 [pii]
AID - 10.1016/s0167-5877(01)00260-4 [doi]
PST - ppublish
SO  - Prev Vet Med. 2002 Feb 14;53(1-2):83-101. doi: 10.1016/s0167-5877(01)00260-4.