A cross-sectional study of swine influenza in intensive and extensive farms in the northeastern region of the state of São Paulo, Brazil

Abstract

Swine influenza (SI) is a seasonal infectious disease highly important to the world pig industry. Loss of daily weight gain, increased costs for the prevention and treatment of secondary infections are the main economic losses associated with the presence of this disease. However, some epidemiological features of SI remain quite unclear. This study focused on assessing the prevalence of swine influenza virus (SIV) infection in intensive and extensive pig herds and associating risk factors. A set of 601 blood samples of five intensive farrow-to-finish farms and 361 blood samples from 56 extensive farms were analyzed using an indirect ELISA kit CIVTEST SUIS INFLUENZA®, Hipra (Amer, Spain), in order to detect anti-SIV antibodies. In total, 24.13 % of samples from intensive herds were positive, while no positive samples were detected in extensive rearing herds. Sow and weaning piglets had the highest prevalence values. In the intensive rearing system, occurrence of reproductive disorders and exposure to recently introduced animals were positively associated with the disease occurrence in swine herds. The findings highlight the importance of sows in the epidemiology of the disease and bring information about risk factors involved in the occurrence of swine influenza in intensive herds.

Serological surveillance and factors associated with influenza A virus in backyard pigs in Southern Brazil

“…Here, our study demonstrated exposure of backyard pig populations to IAV with a mean seroprevalence estimated in 5.3% in 2012 and 2.3% in 2014, in which mostly H1N1pdm09 was detected and very few other subtype coinfections were found. This result corroborates a previous study performed in Guatemala, where a high percentage of the pandemic H1 was detected in backyard pig farms, but exposure to swine-origin IAVs from other H1 clades was only found in commercial pig farms showed 24% of seropositive pigs in holdings with intensive production system (Almeida et al, 2017). Similarly, a seroprevalence of 1% was found in backyard pig samples collected in post-pandemic period in Peru (Tinoco et al, 2016).…”

“…Although it was not possible to collect other biological samples for virus isolation and sequencing to address the genetic background of the circulating IAVs, our results highlight the susceptibility of backyard pig populations to H1N1pdm09, H1N2 and H3N2 viruses. A recent serological study performed in Southeast region in Brazil did not detect IAV seropositivity in pigs from extensive farm system, like the present backyard holdings, but showed 24% of seropositive pigs in holdings with intensive production system (Almeida et al, ). Similarly, a seroprevalence of 1% was found in backyard pig samples collected in post‐pandemic period in Peru (Tinoco et al, ).…”

“…In Latin America, recent reports showed IAV seroprevalence and evidence of transmission from human into pigs (Bravo-Vasquez et al, 2017;Dibarbora et al, 2017;Gonzalez-Reiche et al, 2017;Tinoco et al, 2016). Information regarding IAV seroprevalence (Almeida et al, 2017) and/or virus characterization from backyard pig population in Brazil is still scarce, and it is unknown which IAV subtypes circulate in these pig populations, as well the risk of inter-species transmission.…”

Prevalence, distribution and risk factors of farmer reported swine influenza infection in Guangdong Province, China

“…The husbandry and biosecurity practices adopted by local farms indicate several potential pathways for the introduction of SI into the surveyed farms. For example, live pig movement between pig farms is considered a high-risk practice (Brown, 2000;Almeida et al, 2017) with 57% of the visited farms having introduced live pigs in the year preceding the survey. Approximately one-third (35%) of the farms that introduced pigs in the preceding year did not always quarantine these introduced stock, and of those who did adopt some form of quarantine, half of them only used visual inspection for signs of clinical disease.…”

Limited awareness of animal influenza prevention and control among Dai Lue smallholder farmers in Southwest China

“…Animal influenza is a considerable threat to livestock health, production and welfare (Almeida et al 2017;Vaarst et al 2007). Epidemics also result in human and economic losses, especially in agriculture, public health and tourism.…”