Distribution and genetic characterization of Enterovirus G and Sapelovirus A in six Spanish swine herds.

The prevalence of Enterovirus G (EV-G) and Sapelovirus A (PSV-1) was investigated in Spanish swine herds by means of cross-sectional studies. Faecal samples from clinically healthy pigs were collected from six farms, and analysed by RT-PCR. The results indicated a high prevalence of EV-G detected in nearly all the animals older than 3 weeks of age. Otherwise, PSV-1 was only detected in 3-week-old piglets from one of the farms. Genetic analyses performed in the VP1 region of the EV-G indicated circulation of diverse strains in the same farm, related to genotypes G1, G2, G3, G4, G6, G9, G12, G13 and G14. Moreover, co-infection of several PSV-1 variants in the same animal was evident, typical of viral quasispecies. Evolutionary pressure analysis indicated that microevolution of PSV-1 seems to be driven by negative selection. This study gives further insights in the epidemiology of EV-G and PSV-1.

Biosecurity practices in Spanish pig herds: perceptions of farmers and veterinarians of the most important biosecurity measures.

One hundred Spanish pig farms were surveyed to determine the biosecurity measures currently applied, as reported by farmers, and to investigate the importance awarded by farmers and veterinarians to each of these measures. Data was gathered by means of a questionnaire administered to farmers and veterinarians. Biosecurity measures were reported based on two scenarios: in the presence and in the absence of a highly contagious disease. Multiple-correspondence and two-step cluster analyses were performed to investigate the effect of farm type on the biosecurity level. Farmers awarded significantly higher scores to their farms' level of biosecurity than the veterinarians servicing said farms. According to the farmers and veterinarians, the most important biosecurity measures were those aimed at minimising the risk of disease introduction by visits and vehicles. Biosecurity practices seeking to reduce the risk of disease introduction by breeding stock were not applied on a considerable number of farms. The findings also revealed that medium-sized to large farms located in high pig density regions reported higher biosecurity measures than small herds located in low pig density areas.

Seroprevalence and risk factors of swine influenza in Spain.

Swine influenza is caused by type A influenza virus. Pigs can be infected by both avian and human influenza viruses; therefore, the influenza virus infection in pigs is considered an important public health concern. The aims of present study were to asses the seroprevalence of swine influenza subtypes in Spain and explore the risk factors associated with the spread of those infections. Serum samples from 2151 pigs of 98 randomly selected farms were analyzed by an indirect ELISA for detection of antibodies against nucleoprotein A of influenza viruses and by the hemagglutination inhibition (HI) using H1N1, H1N2 and H3N2 swine influenza viruses (SIV) as antigens. Data gathered in questionnaires filled for each farm were used to explore risk factors associated with swine influenza. For that purpose, data were analyzed using the generalized estimating equations method and, in parallel by means of a logistic regression. By ELISA, 92 farms (93.9%; CI(95%): 89.1-98.7%) had at least one positive animal and, in total, 1340/2151 animals (62.3%; CI(95%): 60.2-64.3%) were seropositive. A total of 1622 animals (75.4%; CI(95%): 73.6-77.2%) were positive in at least one of the HI tests. Of the 98 farms, 91 (92.9%; CI(95%): 87.7-98.1%) had H1N1 seropositive animals; 63 (64.3%; CI(95%): 54.6-73.9%) had H1N2 seropositive pigs and 91 (92.9%; CI(95%): 87.7-98.1%) were positive to H3N2. Mixed infections were detected in 88 farms (89.8; CI(95%): 83.7-95.9%). Three risk factors were associated with seroprevalences of SIV: increased replacement rates in pregnancy units and, for fatteners, existence of open partitions between pens and uncontrolled entrance to the farm.

Seroprevalence and risk factors associated with Toxoplasma gondii infection in pig farms from Catalonia, north-eastern Spain.

Seroprevalence and associated risk factors for Toxoplasma gondii infection in pigs were analyzed in 1202 sera samples, including sows and pigs of three, seven, 11, 15 and 20 weeks of age, from 23 farms in Catalonia, north-eastern Spain. Antibodies were tested by the modified agglutination test (MAT) at titers > or =1:25. Antibodies to T. gondii were found in 228 samples (19.0%; 95% CI: 16.8-21.2). The individual prevalence in animals higher than 7 weeks of age was 22.8% (174/762; 95% CI: 16.6-29.0) and the within-farm prevalence ranged from 7.1% to 36.4%. Statistically significant differences were found among age classes. The risk factors significantly associated with T. gondii seroprevalence were the presence of cats, percentage of mortality at weaning and the presence of outdoor facilities in the farms. The seroprevalence observed in the present study indicates widespread exposure to T. gondii among domestic pigs in Catalonia, which may have important implications for public health.

Duration of maternally derived antibodies in Toxoplasma gondii naturally infected piglets.

A longitudinal study was performed to analyze the dynamics of Toxoplasma gondii antibodies in naturally infected piglets from 1 to 25 weeks of age. Seventy-three piglets from 20 seronegative sows (modified agglutination test, MAT <1:25) and 20 naturally infected T. gondii seropositive sows (MAT >or=1:25) were analyzed at 1, 3, 6, 9, 12, 15, 18, 22 and 25 weeks of age. Twenty-six of the 73 piglets analyzed (35.6%; CI 95%: 25.5-45.7) were seropositive at some point during the study. Seroprevalence in piglets at 1 and 3 weeks of age was significantly higher in animals born from seropositive sows (P<0.001 and P=0.02, respectively) as an indication of maternally derived antibodies. The longest persistence (up to 6 weeks of age) was observed in piglets whose dam had high T. gondii antibody level (MAT >or=1:500), while persistence of maternally derived antibodies in the piglets born from sows with low antibody titers (maximum 1:50) was shorter and lasted only up to 3 weeks of age, when the piglets were weaned. The risk of horizontal transmission in piglets increased with age and was higher in piglets during the finishing period. The present results indicate that the decline of T. gondii maternally derived antibodies in naturally infected piglets is associated with the titers of their dams.