Prevalence and seroepidemiology ofHaemophilus parasuisin Sichuan province, China

Abstract

Haemophilus parasuis, the causative agent of Glässer’s disease, has been reported as widespread, but little is known about its epidemiology in the Sichuan province of China. The goal of our research is to reveal the prevalence and distribution of H. parasuis in this area. Sampling and isolation were performed across Sichuan; isolates were processed using serotyping multiplex PCR (serotyping-mPCR) and agar gel diffusion (AGD) for confirmation of serovar identity. This study was carried out from January 2014 to May 2016 and 254 H. parasuis field strains were isolated from 576 clinical samples collected from pigs displaying clinical symptoms. The isolation frequency was 44.10%. Statistically very significant differences of infection incidence were found in three age groups (P < 0.01) and different seasons (P < 0.01). Serovars 5 (25.98%) and 4 (23.62%) were the most prevalent, however, non-typeable isolates accounted for nearly 7.87%. In terms of geographical distribution, serovars 5 and 4 were mostly prevalent in west and east Sichuan. The results confirmed that the combined approach was dependable and revealed the diversity and distribution of serovars in Sichuan province, which is vital for efforts aimed at developing vaccine candidates allowing for the prevention or control of H. parasuis outbreaks.

New Pathological Lesions Developed in Pigs by a “Non-virulent” Strain of Glaesserella parasuis

“…The recent occurrence of outbreaks of Glässer's disease with serovar 7 strains of G. parasuis in Chinese and Brazilian swine herds (4,5) raise the question whether there has been an increase in virulence in strains of this serovar. This could potentially be explained by acquisition of virulence factors from more virulent strains by horizontal genetic exchange, which would readily be achieved by the efficient natural transformation system present in these species (16,17).…”

“…A subsequent study involving intranasal challenge of highly susceptible piglets confirmed the inability of this strain to cause infection (3). However, there have been recent outbreaks of GD with SV7 in swine herds in China (4) and Brazil (5). In Australia, nasal samples obtained from pigs showing clinical signs typical of GD were positive for SV7 G. parasuis (6).…”

Polyamine Transport Protein PotD Protects Mice against Haemophilus parasuis and Elevates the Secretion of Pro-Inflammatory Cytokines of Macrophage via JNK–MAPK and NF–κB Signal Pathways through TLR4

“…Haemophilus parasuis, or Glaesserella parasuis (G. parasuis) according to the new taxonomic reclassification, is normally a benign swine commensal in upper respiratory tract but may cause severe vascular lesions and multiorgan dysfunction, eliciting serious economic losses annually worldwide [46,47]. Commercial bacterins are often used to vaccinate swine against H. parasuis, but the deficiency in crossreactivity makes sole-serotype inactivated vaccine an ineffective means of protection against this disease [48].…”

Epidemiology ofHaemophilus parasuisisolates from pigs in China using serotyping, antimicrobial susceptibility, biofilm formation and ERIC-PCR genotyping

“…Polymerase chain reaction technique is a rapid and specific method for the molecular serotyping, and had been used for H. parasuis serotyping ( Jia et al, 2017 ; Lacouture et al, 2017 ; Wang et al, 2017 ). Accurate serotype identification is critical for epidemiological investigations or vaccine selection in H. parasuis infections.…”

“…The disease is characterized by pneumonia, meningitis, arthritis, polyserositis, and septicemia. Outbreaks of Glässer’s disease have resulted in serious lethality and economic losses in the global swine industry ( Kim et al, 2002 ; Oliveira, Blackall & Pijoan, 2003 ; Palzer et al, 2015 ; Wang et al, 2017 ; Yu et al, 2012 ). There are 15 serovars of H. parasuis but also a large number of non-typeable (NT) isolates and these possess wide differences in virulence ( Kielstein & Rapp-Gabrielson, 1992 ).…”