Influenza A viruses are likely highly prevalent in South African swine farms.

Mohamed E El Zowalaty,Mariette F Ducatez,Anfal Abdelgadir,Emily S Bailey,Gregory C Gray,Laura K Borkenhagen

doi:10.1111/tbed.14255

Abstract

Growth in pork production during the last decade in South Africa has escalated the risk of zoonotic pathogen emergence. This cross-sectional study was conducted to evaluate evidence for transmission of influenza A virus between pigs and swine workers. Between February and October 2018, samples from swine workers and pigs were collected from three farms in KwaZulu-Natal Province, South Africa. Workers nasal washes and serum samples, and swine oral secretion samples (rope sampling method) were studied for evidence of swine influenza A virus infection using molecular and serological methods. Among 84 human nasal washes and 51 swine oral secretion specimens, 44 (52.4%) and 6 (11.8%) had molecular evidence of influenza A virus. Microneutralization assays with enrolled workers' sera against swine H1N1 and H3N2 viruses revealed a high prevalence of elevated antibodies. Multivariate risk factor analysis showed that male workers from the age-group quartile 23-32 years, who self-reported a recent history of exposure to someone with influenza disease and seldom use of personal protective equipment were at highest risk of molecular detection of influenza A virus. These pilot study data suggest that influenza A viruses are likely highly prevalent in South African swine farms. South Africa would benefit from periodic surveillance for novel influenza viruses in swine farms as well as education and seasonal influenza vaccine programmes for swine workers.

Highlights

Evidence continues to mount that pigs may play important roles in amplifying and generating novel viruses, some of which are zoonotic (Krueger & Gray, 2013; Mena et al, 2016; Pepin et al, 2021; Pickering et al, 2021; Smith et al, 2011; Wardeh et al, 2021)
It is recognized that multiple novel influenza A viruses have emerged from pigs and pigs were at least associated with the new influenza A virus strains causing the 1918 (H1N1),1957 (H2N2),1968 (H3N2) and 2009 (H1N1) pandemics (Crosby 2003; Easterday, 2003; Krueger & Gray, 2013; Scholtissek et al, 1978)
Between 22 February and 16 October 2018, a total of 87 swine workers were enrolled and 51 swine oral secretion samples were collected in this pilot study from three South African swine farms (Figure 1)

Summary

Introduction

Evidence continues to mount that pigs may play important roles in amplifying and generating novel viruses, some of which are zoonotic (Krueger & Gray, 2013; Mena et al, 2016; Pepin et al, 2021; Pickering et al, 2021; Smith et al, 2011; Wardeh et al, 2021) With their close association to humans, other mammals and birds, pigs are key reservoirs for respiratory viruses but they may serve as a host for novel virus generation Surveillance for emerging and re-emerging viruses among pigs remains sparse, especially in Africa

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