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Haemophilus parasuis is a commensal organism of the upper respiratory tract of pigs. Under specific conditions (intensive production, movement of pigs, high density, presence of immunosuppressive pathogens [PCV2, PRRSV] in the herd, etc.) this pathogen can invade and cause severe systemic diseases, characterized by fibrinous polyserositis, arthritis, pericarditis and meningitis. Clinical symptoms of this disease (Glässer’s disease) are highly variable; often virulent strains participate as microorganisms secondary to porcine respiratory disease complex. Fifteen serovars of H. parasuis have been described by now. Individual serovars differ in virulence. Serovars 1, 5, 10, 12, 13 and 14 belong to the most virulent ones. Several strains can be found on one farm and even within a single pig. Therefore, it is important to determine the specific strain responsible for the clinical outbreak. Culture detection of the causative agent, particularly from the brain, joints and polyserositis is an essential diagnostic tool. Molecular-based methods have also been used for detecting the pathogen. Serological diagnosis of H. parasuis is inconsistent and inaccurate. The disease can be controlled by improving the swine husbandry and upgrading the level of animal hygiene and immunoprophylaxis. Commercial or autogenous (preferably) vaccines can be used for specific prophylaxis. For the production of autogenous vaccines, it is preferable to use isolates from pigs with lesions present in CNS. The clinical form of the disease can be treated with antibiotics (penicillin, amoxicillin and cephalosporin); however oral or parenteral administration of high doses of antibiotics is necessary. In herds endemically infected by virulent strain (strains), metaphylaxis based on medicated feed is recommend.
Haemophilus parasuis belongs to opportunistic microorganisms of undefined virulence. The purpose of the studies was to compare suitability of PCR/RFLP in our modification and ERIC PCR for epidemiological study of domestic strains of H. parasuis. The results were evaluated taking into account two different aspects: suitability of the tests for isolating the highest possible number of clone groups and subjective evaluation of the method judged with respect to the following criteria: difficulty, availability of equipment and reagents as well as time and cost of the study. The results obtained in the present study show that the two methods used for typing of H. parasuis had high discriminatory power. Taking into account this parameter it can be concluded that ERIC PCR is more suitable than PCR/RFLP. This justifies the use of ERIC PCR for routine epidemiological analyses of mentioned pathogen. Taking into account the complexity of method used, ERIC-PCR based on random amplification of DNA, proved to be comparable to PCR/RFLP. The last mentioned technique is relatively less expensive and labour-consuming, especially when diagnostic PCR method is used for the epidemiological studies.
The introduction of this review of literature contains basic data of Glässer’s disease occurring in swine and boar. This is followed by the characterization of the properties of Haemophilus (H.) parasuis and the pathogenesis. Information about at least 15 classified serovars, using immunodiffusion testing or passive hemagglutination, is given. Potentially pathoghenic strains belong to serovar: 1, 5, 10, 12, 13 and 14. However, this classification shows exceptions, indicating that not all strains of the mentioned serovars, even of serovar 5, are pathogenic. On the other side strains, not belonging to the so called pathogenic serovars, cause Glässer’s disease. The recent developments of genomic information and genetic manipulation systems have improved the selection of virulent H. parasuis strains, contributing to better understanding of the pathogenesis of H. parasuis infection. Some data are presented how the pathogen overcomes host immune responses, with participation of virulence factors coded by defined genes. The cited results, concerning genes and pathogenicity factors of H. parasuis contribute also to improvement of the efficacy of the vaccine against Glässer’s disease. Finally prevention and control of Glässer’s disease is presented.
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