Frequency of Detection and Prevalence Factors Associated with Common Respiratory Pathogens in Equids with Acute Onset of Fever and/or Respiratory Signs (2008–2021)

Abstract

A voluntary biosurveillance program was established in 2008 in order to determine the shedding frequency and prevalence factors for common respiratory pathogens associated with acute onset of fever and/or respiratory signs in equids from the USA. Over a period of 13 years, a total of 10,296 equids were enrolled in the program and nasal secretions were analyzed for the qPCR detection of equine influenza virus (EIV), equine herpesvirus-1 (EHV-1), EHV-4, equine rhinitis A and B virus (ERVs), and Streptococcus equi subspecies equi (S. equi). Single infections with respiratory pathogens were detected in 21.1% of the submissions with EIV (6.8%) and EHV-4 (6.6%) as the two most prevalent viruses, followed by S. equi (4.7%), ERVs (2.3%), and EHV-1 (0.7%). Multiple pathogens were detected in 274 horses (2.7%) and no respiratory pathogens in 7836 horses (76.2%). Specific prevalence factors were determined for each of the six respiratory pathogen groups; most differences were associated with age, breed, and use of the horses, while the clinical signs were fairly consistent between viral and bacterial respiratory infections. Monitoring the frequency of detection of common respiratory pathogens is important in order to gain a better understanding of their epidemiology and to implement management practices aimed at controlling disease spread.

Neuropathogenic Equid Herpesvirus 1 involving in horse respiratory disease outbreak, north Xinjiang, China, 2021-2023

“…Many investigations showed that comparing with neuropathogenic strains (G2254), non-neuropathogenic strains (A2254) were the predominant genotype affecting primarily horses with respiratory disease [14,18]. Recently, four studies in Europe and the USA revealed a new EHV-1 DNA polymerase (ORF30) genotype C2254/H752 which was then associated with respiratory signs outbreak [9,12,13,15]. Whereas, in this study, neuropathogenic strains were detected in samples collected of horses with respiratory problem.…”

“…Several previous studies had shown that major viral respiratory pathogens considered were: equine in uenza virus (EIV), EHV-1, EHV-4, equine rhinitis viruses A (ERAV) and B (ERBV), and equine arteritis virus (EAV) [11][12][13]. One previously published report had been showed that H3N8 equine in uenza virus was pathogen for respiratory disease of China horse population [23].…”

“…Previous studies have shown that the nucleotide (adenine (A), guanine (G) or cytosine (C)) at position 2254 of ORF30 was strongly associated with the occurrence of EHV-1 neurological diseases [6][7][8][9][10][11][12][13][14][15][16][17][18][19]. For instance, most of the viruses recovered from abortion cases worldwide contained A at this position (asparagine (N) at position 752 of the protein) and belonged to non-neuropathogenic strains (associated with non-neurological conditions) [13].…”

“…Equid herpesviruses 1 (EHV-1) is one of members of of the Alphaherpesvirinae subfamily, genus Varicellovirus, and an important viral pathogen of the horse population as it frequently caused respiratory problems, abortion as well as both ocular and neurological diseases in horses [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. As such, it can have a signi cant impact not only on equine health but also on the overall equine industry around the world [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20].…”

Equine Influenza Virus: An Old Known Enemy in the Americas

“…Currently, Florida Clade 1 is endemic in the United States, and the reports associated with Clade 2 belong to imported horses [ 82 ]. A prevalence of 9.3% was reported in horses with acute respiratory clinical signs in a study conducted from 2010 to 2013 [ 50 ], and recently, a rt-qPCR frequency of 6,8% was reported in a voluntary sampling of 10,296 equids with acute onset of fever and/or respiratory signs for rostral nasal secretions in the country between 2008 and 2021 [ 83 ]. Phylogenetic analyses of EIV H3N8 strains from 2012 to 2017 based on the HA gene have shown that H3N8 strains from the US underwent antigenic drift and fixed multiple substitutions accumulated in the HA gene [ 84 ] and that the H3N8 FC1 North American lineage was the major source of globally dominant EIV variants and spread to other global regions [ 85 ].…”