The avian haemophili.

Area of Science:

• Veterinary Microbiology
• Avian Pathology

Background:

• Four taxa accommodate avian haemophili: Haemophilus paragallinarum, Pasteurella avium, Pasteurella volantium, and Pasteurella species A.
• These bacteria require V factor but not X factor for in vitro growth.
• Recent studies have clarified phenotypic properties for differentiating these taxa.

Purpose of the Study:

• To review the current understanding of avian haemophili taxa.
• To highlight unanswered questions regarding Haemophilus paragallinarum pathogenicity and virulence.
• To identify research needs for antigens inducing protective immunity.

Main Methods:

• Literature review of phenotypic and serological properties of avian haemophili.
• Analysis of current knowledge gaps in H. paragallinarum pathogenesis.
• Identification of areas for future research in vaccine development.

Main Results:

• Established taxa for avian haemophili include H. paragallinarum and formerly H. avium (now P. avium, P. volantium, and P. species A).
• H. paragallinarum is the causative agent of infectious coryza in chickens.
• Significant knowledge gaps exist regarding H. paragallinarum virulence and protective immunity.

Conclusions:

• Further investigation into H. paragallinarum pathogenicity and virulence mechanisms is crucial.
• Identifying antigens for protective immunity is essential for effective vaccine development against infectious coryza.
• Continued research on avian haemophili is needed for better disease control.