Seroprevalence and risk factors of swine influenza in Spain

Simon-Grifé, Meritxell; Martín‐Valls, Gerard; Vilar, M.J.; García‐Bocanegra, Ignacio; Mora, M. Marcela; Martín, Maria Carmen; Mateu, Enric; Casal, Jordi Domènech

doi:10.1016/j.vetmic.2010.10.015

Cited by 49 publications

(75 citation statements)

References 17 publications

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“…However, the information collected on health status may be biased by the ability of the collector to observe respiratory signs at the time of sampling. In terms of IAV detection by age, higher risk of IAV infection observed in juvenile pigs is in agreement with other studies 34, 35. As for virus exposure, only a number of seropositive animals were detected in 2011, and expectedly, most of the samples were from sows.…”

Section: Discussionsupporting

confidence: 91%

Origin, distribution, and potential risk factors associated with influenza A virus in swine in two production systems in Guatemala

Gonzalez‐Reiche

Ramírez

Müller

et al. 2017

Influenza Resp Viruses

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BackgroundGuatemala is the country with the largest swine production in Central America; however, evidence of influenza A virus (IAV) in pigs has not been clearly delineated.ObjectivesIn this study, we analyzed the presence and spatial distribution of IAV in commercial and backyard swine populations.MethodsSamples from two nationwide surveys conducted in 2010 and 2011 were tested using virological (rRT‐PCR and virus isolation) and serological (ELISA and hemagglutination inhibition) assays to detect IAV.ResultsInfluenza A virus was detected in 15.7% of the sampled pigs (30.6% of herds) in 2010 and in 11.7% (24.2% of herds) in 2011. The percentage of seropositive pigs was 10.6% (16.1% of herds) and 1.4% (3.1% of herds) for each year, respectively. Three pandemic H1N1 and one seasonal human‐like H3N2 viruses were isolated. Antibodies against viruses from different genetic clusters were detected. No reassortant strains with swine viruses were detected. The H3N2 virus was closely related to human viruses that circulated in Central America in 2010, distinct to the most recent human seasonal vaccine lineages. Spatial clusters of rRT‐PCR positive herds were detected each year by scan statistics.ConclusionsOur results demonstrate circulation of IAV throughout Guatemala and identify commercial farms, animal health status, and age as potential risk factors associated with IAV infection and exposure. Detection of human‐origin viruses in pigs suggests a role for humans in the molecular epidemiology of IAV in swine in Guatemala and evidences gaps in local animal and human surveillance.

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Section: Discussionsupporting

confidence: 91%

Origin, distribution, and potential risk factors associated with influenza A virus in swine in two production systems in Guatemala

Gonzalez‐Reiche

Ramírez

Müller

et al. 2017

Influenza Resp Viruses

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“…Persistence IAV infection in swine farms has been recently described in Spain and North American [7,9,34]. The farm under study in this report has shown persistent IAV infection since its first detection in 2008.…”

Section: Discussionmentioning

confidence: 64%

“…The subsequent spillover of such virus back into pigs, had led to more intensive swine influenza surveillance efforts worldwide, particularly in commercial swine operations [1,8]. Several studies have suggested that influenza infection is far more common than suggested by confirmed clinical outbreaks [3,6,7,9]. IAV persistence in endemically infected herds is not well understood [7].…”

Section: Introductionmentioning

confidence: 99%

Two years of surveillance of influenza a virus infection in a swine herd. Results of virological, serological and pathological studies

Cappuccio

Dibárbora

Lozada

et al. 2017

Comparative Immunology, Microbiology and Infectious Diseases

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Swine farms provide a dynamic environment for the evolution of influenza A viruses (IAVs). The present report shows the results of a surveillance effort of IAV infection in one commercial swine farm in Argentina. Two cross-sectional serological and virological studies (n=480) were carried out in 2011 and 2012. Virus shedding was detected in nasal samples from pigs from ages 7, 21 and 42-days old. More than 90% of sows and gilts but less than 40% of 21-days old piglets had antibodies against IAV. In addition, IAV was detected in 8/17 nasal swabs and 10/15 lung samples taken from necropsied pigs. A subset of these samples was further processed for virus isolation resulting in 6 viruses of the H1N2 subtype (δ2 cluster). Pathological studies revealed an association between suppurative bronchopneumonia and necrotizing bronchiolitis with IAV positive samples. Statistical analyses showed that the degree of lesions in bronchi, bronchiole, and alveoli was higher in lungs positive to IAV. The results of this study depict the relevance of continuing long-term active surveillance of IAV in swine populations to establish IAV evolution relevant to swine and humans.

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“…A survey of Spanish swine farms during 2008-2009 found a seroprevalence of 75.4 per cent to at least one of three strains of influenza (H1N1, H1N2 and H3N2) [17]. These results were broken down by age, with seropositivity among younger fattening pigs (11-20 weeks of age, a closer match to animals included in our study) measured to be 53.1 per cent, while that among older cows was 89.9 per cent.…”

Section: (A) Epidemiology Of Swine Influenzamentioning

confidence: 99%

“…In the week before slaughter, pigs are exposed to increased population mixing in trucks and holding pens, as well as 'transport stress' that may affect immunity to infection [15,16]. During their earlier life on the farms, infection risk will be influenced by animal density, facility design and biosecurity [17]. We investigate how these risks of exposure to influenza have changed over the past decade in Chinese swine, by using our inference framework to estimate older exposures (corresponding to time spent on the farm) and recent exposures (corresponding to transport and holding just before slaughter).…”

Section: Introductionmentioning

confidence: 99%

Inferring patterns of influenza transmission in swine from multiple streams of surveillance data

et al. 2013

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Swine populations are known to be an important source of new human strains of influenza A, including those responsible for global pandemics. Yet our knowledge of the epidemiology of influenza in swine is dismayingly poor, as highlighted by the emergence of the 2009 pandemic strain and the paucity of data describing its origins. Here, we analyse a unique dataset arising from surveillance of swine influenza at a Hong Kong abattoir from 1998 to 2010. We introduce a state–space model that estimates disease exposure histories by joint inference from multiple modes of surveillance, integrating both virological and serological data. We find that an observed decrease in virus isolation rates is not due to a reduction in the regional prevalence of influenza. Instead, a more likely explanation is increased infection of swine in production farms, creating greater immunity to disease early in life. Consistent with this, we find that the weekly risk of exposure on farms equals or exceeds the exposure risk during transport to slaughter. We discuss potential causes for these patterns, including competition between influenza strains and shifts in the Chinese pork industry, and suggest opportunities to improve knowledge and reduce prevalence of influenza in the region.

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Seroprevalence and risk factors of swine influenza in Spain

Cited by 49 publications

References 17 publications

Origin, distribution, and potential risk factors associated with influenza A virus in swine in two production systems in Guatemala

Origin, distribution, and potential risk factors associated with influenza A virus in swine in two production systems in Guatemala

Two years of surveillance of influenza a virus infection in a swine herd. Results of virological, serological and pathological studies

Inferring patterns of influenza transmission in swine from multiple streams of surveillance data

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