Modern approaches in the diagnosis of avian Pasteurellosis

Abstract

Studies carried out in many countries of the world demonstrate considerable variability in the virulence properties of pasteurellosis. The variety of antigenicity and toxicity serovars of the pathogen determines a number of specific features of display of poultry pasteurellosis, especially in associated infections when several causative agents of infectious diseases of bacterial and/or viral etiology circulate in one farm. In mixed infections, birds show a variety of clinical signs, most notably a respiratory syndrome characterized by respiratory involvement (sinusitis, conjunctivitis, laryngitis, tracheitis, bronchitis, pneumonia, and aerosacculitis) and tissue swelling in the suborbital sinuses, intermandibular spaces, and ear flaps.This situation makes it difficult to timely and promptly conduct effective therapeutic and anti-epizootic measures. However, it is necessary to identify the etiology of the disease as soon as possible, methodically and comprehensively, taking into account epizootic data, clinical signs, pathological anatomical changes and with obligatory confirmation by laboratory tests.At present time laboratory methods for diagnostics of avian pasteurellosis are regulated by Methodical instructions (MI) on laboratory diagnostics of pasteurellosis of animals and birds approved by the Chief Veterinary Department on August 20, 1992 № 22-7/82.According to the approved MI, the laboratory diagnosis of avian pasteurellosis includes microscopy of smears and fingerprints, isolation of pasteurella cultures and their identification, and, if necessary, bioassaying.It should be noted that the laboratory diagnosis of pasteurellosis according to the MI is a laborious and time-consuming process.Apart from the methods described in the MI, the serological method - enzyme immunoassay (ELISA) and molecular biological method - polymerase chain reaction (PCR) are currently widely and successfully used in laboratory practice for diagnosis of avian pasteurellosis, which are not reflected in the approved MI, but allow relatively simple and rapid reliable results.