Naturally co-infected boars with both porcine reproductive and respiratory syndrome virus and porcine circovirus type 2.

In this study, the humoral response against porcine reproductive and respiratory syndrome virus (PRRSV) and porcine circovirus type 2 (PCV2), the presence of the virus in semen and serum and the genetic characteristics of the virus detected in 15 boars from a commercial farm were analysed. The results showed that 53% of the boars presented anti-PRRSV antibodies and 100% presented anti-PCV2 antibodies. Porcine reproductive and respiratory syndrome virus was detected in 43% of the boars and 73% were positive to PCV2. The complete ORF5 gene of PRRSV of 14 samples and a fragment of the ORF2 gene of PCV2 of 22 samples were sequenced. Porcine reproductive and respiratory syndrome virus analysis revealed <92% identity in viruses from semen and serum of two boars, whereas in the rest of the boars the identity was >97.5%. As for PCV2, two boars presented an identity <95% in serum and semen and the rest had an identity >96%. The results showed that PRRSV- and PCV2-naturally infected boars can be found, and at least two different strains of viruses from semen and serum can be detected.

Seroprevalence and risk factors for swine influenza zoonotic transmission in swine workers from northwestern Mexico.

A cross-sectional study was conducted to evaluate the transmission of swine influenza through occupational exposure and to assess some risk factors for zoonotic transmission in workers from commercial farms in Mexico. Seroprevalence to swine influenza subtypes was determined by hemagglutinin inhibition assay and was higher in exposed (E), in comparison with unexposed (UE) participants (P<0.05). Percentages of seropositivity between UE and E were 28.57% and 19.35% to A/NewCaledonia/20/99 (H1N1), 68.25% and 33.87% to A/Panama/2001/99-like (H3N2), 1.58% and 12.9% to A/Sw/England/163266/87 (H3N2), respectively. No antibodies were detected against A/Sw/Wisconsin/238/97 (H1N1) in the UE subjects, and only 3.22% were positive in the E group (P<0.05). A significant association between elevated antibody titres to swine influenza virus (SIV) H3N2 and the exposition to swine [OR 3.05, 95% (CI) 1.65-5.64] and to geographic location [OR 8.15, 95% (CI) 1.41-47.05] was found. Vaccination appeared as a protective factor [OR 0.05, 95% (CI) 0.01-0.52]. Farms with high number of breeding herd were associated with increased anti-SIV antibodies in the E group [OR 3.98, 95% (CI) 1.00-15.86]. These findings are relevant and support the evidence of zoonoses in swine farms and point out the need to implement preventive measures to diminish the occurrence of the disease and the potential emergence of pathogenic reassortant strains.

Avian influenza survey in migrating waterfowl in Sonora, Mexico.

A two-year survey was carried out on the occurrence of avian influenza in migrating birds in two estuaries of the Mexican state of Sonora, which is located within the Pacific flyway. Cloacal and oropharyngeal swabs were collected from 1262 birds, including 20 aquatic bird species from the Moroncarit and Tobari estuaries in Sonora, Mexico. Samples were tested for type A influenza (M), H5 Eurasian and North American subtypes (H5EA and H5NA respectively) and the H7 North American subtype (H7NA). Gene detection was determined by one-step real-time reverse transcription polymerase chain reaction (RRT-PCR). The results revealed that neither the highly pathogenic avian influenza virus H5 of Eurasian lineage nor H7NA were detected. The overall prevalence of avian influenza type A (M-positive) in the sampled birds was 3.6% with the vast majority in dabbling ducks (Anas species). Samples from two birds, one from a Redhead (Aythya americana) and another from a Northern Shoveler (Anas clypeata), were positive for the low-pathogenic H5 avian influenza virus of North American lineage. These findings represented documented evidence of the occurrence of avian influenza in wintering birds in the Mexican wetlands. This type of study contributes to the understanding of how viruses spread to new regions of North America and highlights the importance of surveillance for the early detection and control of potentially pathogenic strains, which could affect animal and human health.