Weighing serological evidence of human exposure to animal influenza viruses − a literature review

Abstract

Assessing influenza A virus strains circulating in animals and their potential to cross the species barrier and cause human infections is important to improve human influenza surveillance and preparedness. We reviewed studies describing serological evidence of human exposure to animal influenza viruses. Comparing serological data is difficult due to a lack of standardisation in study designs and in laboratory methods used in published reports. Therefore, we designed a scoring system to assess and weigh specificity of obtained serology results in the selected articles. Many studies report reliable evidence of antibodies to swine influenza viruses among persons occupationally exposed to pigs. Most avian influenza studies target H5, H7 and H9 subtypes and most serological evidence of human exposure to avian influenza viruses is reported for these subtypes. Avian influenza studies receiving a low grade in this review often reported higher seroprevalences in humans compared with studies with a high grade. Official surveillance systems mainly focus on avian H5 and H7 viruses. Swine influenza viruses and avian subtypes other than H5 and H7 (emphasising H9) should be additionally included in official surveillance systems. Surveillance efforts should also be directed towards understudied geographical areas, such as Africa and South America.

Protective Measures for Humans against Avian Influenza A(H5N8) Outbreaks in 22 European Union/European Economic Area Countries and Israel, 2016–17

“…However, challenges remain and efforts toward a One Health approach should be continued. Serosurveys in epidemiologic studies to follow up exposed cohorts and identify possible transmission events might better describe the risk for transmission and help reduce uncertainty when assessing the risk for those newly emerging viruses, despite known limitations regarding subtype specificity of serologic testing ( 33 , 34 ). Despite a wide diversity in the recommendations for use of PPE and of antiviral prophylaxis for exposed persons, we found no evidence of bird-to-human transmission of infection.…”

Serological evidence for exposure to avian influenza viruses within poultry workers in southern China

“…We chose to use multiplex microarray-based serological profiling to allow assessment of antibodies to a range of viruses that had circulated in the region. Most serological studies uses hemagglutination inhibition or virus neutralization assays that are more difficult to standardize (Van Kerkhove et al, 2012) and are using a limited number of (mean of 1.4, range 1-4) strains per influenza virus H subtype for the detection of antibodies [all grade A and B studies testing for avian influenza virus subtype H5, H7 or H9 antibodies in Sikkema et al (2016)]. A drawback of PA is that it detects all binding antibodies, and therefore, there is no described correlation, including a cut-off value, for being protected to infection.…”

High Risk of Influenza Virus Infection Among Swine Workers: Examining a Dynamic Cohort in China

“…Still, there are relatively few robust, prospective studies examining the risk of zoonotic transmission of swine IAVs to swine workers [10]. Even fewer studies have captured the incidences of asymptomatic swine influenza virus (SIV) infections among humans through routine surveillance [11,12].…”