Influenza A virus infection of healthy piglets in an abattoir in Brazil: animal-human interface and risk for interspecies transmission

Abstract

Asymptomatic influenza virus infections in pigs are frequent and the lack of measures for controlling viral spread facilitates the circulation of different virus strains between pigs. The goal of this study was to demonstrate the circulation of influenza A virus strains among asymptomatic piglets in an abattoir in Brazil and discuss the potential public health impacts. Tracheal samples (n = 330) were collected from asymptomatic animals by a veterinarian that also performed visual lung tissue examinations. No slaughtered animals presented with any noticeable macroscopic signs of influenza infection following examination of lung tissues. Samples were then analysed by reverse transcription-polymerase chain reaction that resulted in the identification of 30 (9%) influenza A positive samples. The presence of asymptomatic pig infections suggested that these animals could facilitate virus dissemination and act as a source of infection for the herd, thereby enabling the emergence of influenza outbreaks associated with significant economic losses. Furthermore, the continuous exposure of the farm and abattoir workers to the virus increases the risk for interspecies transmission. Monitoring measures of swine influenza virus infections and vaccination and monitoring of employees for influenza infection should also be considered. In addition regulatory agencies should consider the public health ramifications regarding the potential zoonotic viral transmission between humans and pigs.

Molecular detection of influenza A(H1N1)pdm09 viruses with M genes from human pandemic strains among Nigerian pigs, 2013–2015: implications and associated risk factors

“…Nonetheless, H1N1pdm09 was observed to have circulated among these pigs during both years of the study. This is also similar to previous results obtained from studies in Nigeria [20,42], Togo, also in West Africa [16], and Brazil [43] during which influenza viruses were detected among apparently healthy pigs. This underscores the importance of strict adherence to measures which reduce interspecies transmission of influenza viruses at the human-swine interface.…”

“…This is similar to the findings of Amorim et al . who reported that continuous exposure of abattoir workers to pigs in Brazil increased the risk for interspecies transmission of influenza A virus [43]. Second, because of very dismal levels of personal and environmental hygiene observed at the abattoir, viruses shed by abattoir workers during the symptomatic phase of influenza could readily infect these pigs.…”

Environmental Role in Influenza Virus Outbreaks

“…Therefore, it is speculated that IAV infectious aerosols originated in pig farms could be transported downwind (167). Similar studies conducted in Brazil have also identified that 9% of asymptomatic piglet tracheal samples showed IAV positivity in RT-PCR (168). Hence, continuous exposure of farm animals or humans to the aerosols generated in-farm could potentiate zoonotic IAV transmission to human caretakers.…”

Zoonoses Occupationally Acquired By Abattoir Workers

“…Rajão and co-workers [42] reported 38.3% positive human serum samples in serological survey. Continuous exposure of the abattoir workers to animals suffering from subclinical influenza virus infections provided an environment conducive to the occurrence of interspecies infections and the emergence of new potentially pathogenic viral variants [43]. Pregnant women are at greater risks of acquiring swine flu.…”