A case / control study was carried out in France in 2001 and 2002 aiming at the identification of risk factors for PMWS occurrence in farrow-to-finish farms. This survey involved 149 farms located in the main pig-producing areas of the country. Three groups of farms were selected according to their currentor past-PMWS status. The latter was defined using a combination of inclusion criteria. The cases (n=59) were defined as farms where typical PMWS was currently running and if possible since less than two years. The control farms were of two types: type 1 (n=55) had no history of PMWS whereas type 2 (n=35) had been typically concerned and had been able to properly recover with a mortality rate being now close to the one before PMWS outbreak. A questionnaire was filled in with the farmer during the visit to the farm and blood samples were taken from different categories of pigs including sows of different parities and growing pigs. The dynamic of PCV-2 infection was clearly modified in cases farms with a higher within-herd seroprevalence for 13 week-old pigs. Risk factors were mainly related to co-infectious agents (PRRSv and Parvovirus), rearing and hygiene conditions and the vaccination scheme against the Parvovirus.

Concomitant infections by different influenza A virus subtypes within pig farms increase the risk of new reassortant virus emergence. The aims of this study were to characterize the epidemiology of recurrent swine influenza virus infections and identify their main determinants. A follow-up study was carried out in 3 selected farms known to be affected by repeated influenza infections. Three batches of pigs were followed within each farm from birth to slaughter through a representative sample of 40 piglets per batch. Piglets were monitored individually on a monthly basis for serology and clinical parameters. When a flu outbreak occurred, daily virological and clinical investigations were carried out for two weeks. Influenza outbreaks, confirmed by influenza A virus detection, were reported at least once in each batch. These outbreaks occurred at a constant age within farms and were correlated with an increased frequency of sneezing and coughing fits. H1N1 and H1N2 viruses from European enzootic subtypes and reassortants between viruses from these lineages were consecutively and sometimes simultaneously identified depending on the batch, suggesting virus co-circulations at the farm, batch and sometimes individual levels. The estimated reproduction ratio R of influenza outbreaks ranged between 2.5 [1.9-2.9] and 6.9 [4.1-10.5] according to the age at infection-time and serological status of infected piglets. Duration of shedding was influenced by the age at infection time, the serological status of the dam and mingling practices. An impaired humoral response was identified in piglets infected at a time when they still presented maternally-derived antibodies.

The porcine circovirus type 2 (PCV-2) is associated with several diseases including reproductive failure. This syndrome has been experimentally reproduced twice with two PCV-2 isolates representative of each major PCV-2 genogroup, i.e. PCV-2a and PCV-2b (Cariolet et al., 2002; Rose et al., 2007). In these two previous studies, the sows were infected by intra-uterine inoculation at insemination with 10(4.3) and 10(3.18) TCID(50) of PCV-2a and PCV-2b, respectively, corresponding to 1.2 × 10(11) and 3 × 10(10) genome copies, respectively. The aim of this present study was to quantify viral shedding in semen from specific-pathogen-free (SPF) boars infected with isolates from the two major PCV-2 genogroups a and b. We studied the transmission of the PCV-2 virus through contaminated semen to SPF sows and their offspring. The four inoculated boars developed sub-clinical PCV-2 infections and PCV-2 genomes were occasionally detected in semen after nasal infection of boars, with up to 1.2 × 10(6)copies/mL in the sperm-rich fraction. When PCV-2-contaminated semen was inoculated in SPF sows at artificial insemination, the sows and their offspring did not show any signs of PCV-2 infection or PCV-2 antibodies or genomes. In the present study, sows were inoculated with a maximal dose of 1.7 × 10(7) viral genome copies, which is lower than the genomic loads (i.e. 1.2 × 10(11) and 3 × 10(10) genome copies) that have been shown to induce reproductive troubles in intra-uterine inoculated sows. Our results together with the previous experiment findings suggest that PCV-2-induced reproductive disorders depend on the infectious dose inoculated to sows by the intra-uterine route.

Avian-like H1N1 and reassortant H3N2 and H1N2 influenza A viruses with a human-like haemagglutinin have been co-circulating in swine in Europe for more than a decade. We aimed to examine the infection dynamics of the three swine influenza virus (SIV) lineages at the farm level, and to identify possible regional and seasonal variations in their circulation. Sera were collected from six successive generations of fattening pigs (2006–2008) in a total 80 farrow-to-finish herds in Belgium, Italy, France and Spain and examined for antibodies against the three SIVs in haemagglutination inhibition tests. Overall, in all regions and periods, 9.7% of all farms were negative for SIV, 49% were infected with one subtype, 38% with two subtypes and 3.9% with all three SIVs. We found serological evidence for the circulation of all three subtypes in Belgium, Italy and Spain, while only infections with H1N1 and H1N2 SIVs were detected in France. Despite temporary changes in the circulation of H1N2 in Belgium and in Spain, there was no true seasonal variation. The exact combination of subtypes on the same farm differed in each of the sampling periods. On the other hand, 21 farms were found to be consistently infected with the same SIV subtype throughout the study. This can either be explained by the persistence of the virus in a farm, or by the periodical re-introduction of SIVs of the same subtype.

Herd-level factors associated with European H1N1 or H1N2 swine influenza virus (SIV) infections were assessed by mean of a cross-sectional study carried out in 125 herds in France. Serum samples from 15 fattening pigs in each herd were tested by haemagglutination inhibition. Data related to herd characteristics, biosecurity, management and housing conditions were collected by questionnaire during the farm visit. Climatic conditions in the post-weaning and fattening rooms, where the sampled pigs were housed, were measured over 20 h. Factors associated with H1N1 or H1N2 sero-positive status of the herd were identified by logistic regressions for binary outcome. For both subtypes, the odds for a herd to be SIV sero-positive increased if there were more than two pig herds in the vicinity (OR = 3.2, 95% confidence interval (95% CI): 1.4–7.6, p < 0.01 and OR = 3.5, 95% CI: 1.5–8.1 p < 0.01 for H1N1 and H1N2 respectively). Different factors were specifically associated with either H1N1 or H1N2 SIV infections. The odds for a herd to be H1N1 sero-positive were significantly increased by having a large number of pigs per pen in the post-weaning room (OR = 3.2, 95% CI: 1.2–8.6, p = 0.02), temperature setpoints below 25 °C (OR = 2.6, 95% CI: 1.1–6.4, p = 0.03) and below 24 °C (OR = 2.6, 95% CI: 1.1–6.1, p = 0.03) for the heating device in the farrowing room and the ventilation controller, respectively, and moving the pigs to the fattening facility via a room housing older pigs (OR = 3.3, 95% CI: 1.1–9.6, p = 0.03). A H1N2 sero-positive status was associated with a brief down period in the farrowing room (OR = 2.6, 95% CI: 1.1–6.3, p = 0.03), small floor area per pig in the post-weaning pen (OR = 2.9, 95% CI: 1.2–7.0, p = 0.02), large-sized fattening room (OR = 2.5, 95% CI: 1.1–5.9, p = 0.03), lack of all-in all-out management in the fattening room (OR = 2.4, 95% CI: 1.0–5.8, p = 0.04) and a temperature range of less than 5 °C controlling ventilation in the fattening facilities (OR = 3.2, 95% CI: 1.4–7.4, p < 0.01). Factors related to external and internal biosecurity and to the control of inside climatic conditions should be considered together when implementing programmes to better control SIV infections.

The words hygiene, sanitation, dirtiness and cleanliness, are all commonly used by the general public. Cleanliness refers to the avoidance of dirt, whereas hygiene can have a broader meaning. In animal farming, particularly when livestock are raised in total confinement, cleanliness is of utmost importance in health maintenance, even though it is not the sole factor. This chapter reviews the relationships between cleanliness and disease with special focus on multifactorial health disorders for which the immediate environment imposed on the animals is a major determinant. Building cleanliness and animal cleanliness are closely correlated. Therefore more attention has been paid to evaluating and maintaining animal cleanliness than to building cleanliness 'per se'. Cleanliness is affected by the design of the buildings, especially the floor, and the internal equipment, as well as by their usage. The cleaning-disinfection process is of pivotal importance when raising livestock and must not be ranked as a 'minor chore'. It needs to be considered in the context of herd management and correct husbandry with emphasis placed on its role in reducing the microbial load and pathogen transmission. The efficacy of the cleaning-disinfection process can be assessed by laboratory investigations.

Relationships between macroscopic lesions and Polymerase Chain Reaction (PCR) detection of Mycoplasma hyopneumoniae (Mhp), Pasteurella multocida (Pm), Actinobacillus pleuropneumoniae (App), Haemophilus parasuis (Hps) and Streptococcus suis (Ssuis) of the lungs of 3731 slaughter pigs from 125 herds were assessed in France. Pneumonia and pleuritis were the most frequent lesions (69.3% and 15% of the lungs, respectively). Mhp, Pm, App, Ssuis and Hps were detected in 69.3%, 36.9%, 20.7%, 6.4% and 0.99% of the lungs, respectively. Mhp and Pm were associated with pneumonia at both the pig and herd levels. Pleuritis was not associated with any pathogen at the pig level, but was associated with a high percentage of pigs PCR-positive for App at the herd level. Measures focused on control of Mhp, Pm and App should significantly reduce the occurrence of both pneumonia and pleuritis.

A cross-sectional study involving 143 farrow-to-finish herds was carried out to identify herd-level noninfectious factors associated with pneumonia and pleuritis in slaughter pigs. Data related to herd characteristics, biosecurity, management and housing conditions were collected by questionnaire during a farm visit. Climatic conditions were measured over 20 h in the post-weaning and finishing rooms where the slaughter pigs were kept. After these on-farm investigations, the finishing pigs were examined at slaughter for lung lesions. A sample of 30 randomly selected pigs per herd was scored for pneumonia and pleuritis. Herds were grouped into three categories according to their pneumonia median score (class 1: <= 0.5; class 2: 0.5 < score <= 3.75; class 3: >3.75). For pleuritis, a herd was deemed affected if at least one pig had a high pleuritis score (>= 3). A multinomial logistic regression model was used to identify factors associated with pneumonia classes 2 and 3. A logistic regression for binary outcome was used to identify risk factors for severe pleuritis. An interval of less than four weeks between successive batches (OR = 4.5, 95% confidence interval (95% CI): 1.5-13.6, p < 0.01), large finishing room size (OR = 4.3, 95% CI: 1.6-11.6, p < 0.01) and high mean CO2 concentration in the finishing room (OR = 4.2, 95%CI: 1.6-11.3, p < 0.01), significantly increased the odds for a herd to be in class 2 for pneumonia. The same risk factors were found for class 3 and, in addition, a direct fresh air inlet from outside or from the corridor in the post-weaning room vs an appropriate ceiling above the pigs (OR = 5.1, 95% CI: 1.4-18.8. p = 0.01). The risk for a herd to have at least one pig with a high pleuritis score was increased when the farrowing facilities were not disinsected (OR = 2.7, 95% CI: 1.2-5.8, p = 0.01), when tail docking was performed later than 1.5 days after birth (OR = 2.6, 95% CI: 1.2-5.7, p = 0.01) and if the piglets were castrated when more than 14 days old (OR = 2.7. 95%CI: 1.1-6.8, p = 0.03). A temperature range of less than 5 degrees C for the ventilation control rate in the farrowing room (OR = 2.7, 95% CI: 1.2-5.9, p = 0.01), a mean temperature in the finishing room below 23 degrees C (OR = 3.0, 95% CI: 1.3-6.8, p < 0.01) and large herd size (OR = 3.1, 95% CI: 1.4-6.9, p < 0.01) were also associated with increased risk of pleuritis. The factors affecting pneumonia and pleuritis seemed to be different. All rearing steps from farrowing to finishing must be taken into account in any health programme aimed at controlling pneumonia and pleuritis and lung health may be improved through several pathways, i.e. correcting managerial and hygienic factors, implementing an appropriate and well-functioning ventilation in order to offer favorable climatic conditions. (c) 2011 Elsevier B.V. All rights reserved.