Olga Beh, doctor of veterinary medicine, pigbreeding consultant

Diseases of bacterial etiology are usually taken as secondary in comparison with viral, the preventive measures of which are paid more attention. At the same time, the problem of spreading respiratory diseases of bacterial origin become more and more up-to-date in Ukraine. One of them is hemophilic polyserositis or Glasser’s disease. The article concentrates on diagnosing and methods of its effective prevention.

Etiology and epizootology of Glasser’s disease

The causative agent of this disease is gram-negative bacillus Haemophilus parasuis.. At the present moment there are 15 serotypes that are differing in virulence. In Europe serotypes 4 and 5 are widespread.

Haemophilus parasuis is the part of normal microbial flora of nose and trachea of apparently healthy animals. Rarely the causative agent is isolated from lungs and tonsils not affected by inflammatory changes. It is present in general on farms with high health status.

Principally, the hemophilic polyserositis is the illness of growing piglets. But the disease can defeat fattening pigs; clinically it is shown in acute form. Usually it happens when the Glasser’s disease is accompanied by other pathogenic and opportunistic microorganisms. Thus, the amounts of sickness cases increase in households, positive on PRRS virus that is the strong immunosuppressant.

Pathogeny

Clinical signs can appear as in 3-4 weeks after weaning, so in inby fattening after contamination. This depends upon farm situation: immune status of livestock, diet quality, disinfection level and many other factors.

Disease outbreaks are often seen when piglets from other litters are put into groups of newly weaned animals. The main infection way is aerogenic, but the oral infesting is possible through the contaminated feed and water. The illness comes out in different season, mainly during severe cold.

Hemophilic disease is registered in the form of sporadic cases or small enzooties. At first it affects some weak piglets and after progress the number of sick animals grows quickly and can reach 75%. The specific epizootic peculiarity of hemophilic polyserositis is wide and long-term bacteria carrying and capability of passing together with other virulent diseases.

Glasser’s disease diagnostics

At the molecular diagnostic laboratory the PCR (polymerase chain reaction) method is used, with its help the DNA and RNA provocative are discovered as fingerprints of pathogen. According to research results, pathogenic is Haemophilus parasuis that is separated from irritated lungs exudation or fibrinous heart, and bacteria strip from nasal cavity or oral-pharyngeal lavage is mainly normal flora of animal and doesn’t have pathogenic qualities. To make a diagnosis it is possible to employ the service of postmortem and bacteriology laboratory and do the bacterial seeding of pathoanatomical substance. At the same time it’s possible to check the antibiotic sensitivity that assure effective treatment or prophylaxis.

If there is no possibility to send pathoanatomical substance (carcass or certain organs) to laboratory for bacterial seeding, one can use serologic testing method. It helps estimate the epizootic farm status/spreading of Haemophilus parasuis among livestock.

Full-scaled serological profile permits to estimate the colostrum antibody level of piglets in moment when they start to decrease, and also the infecting period.

Preventive efficiency of Glasser’s disease

All vaccines against Glasser’s disease are inactivated. The best result can be reached by vaccinating pigs twice. In such a way the long-term immune protection can be formed. While vaccinating for the first time in piglets’ organism are producing antibodies in sufficient number for protection but for the short period. When antigen is given secondly in organism the «memory cells» are already present, they promote fast reaction of immune system and production of bigger antibodies number.

Results

The majority of diseases have similar clinical aspects and pathoanatomical picture, that’s why for the effective prophylaxis it is necessary to put precise diagnosis. Laboratory studies are the instrument that essentially facilitate this task if use it properly. It is better to form vaccination schemes individually, taking into account the epizootic farm status and not only experience of farms that have the identical problem.

1. How long does the incubation period of Glasser’s disease last?
2. Why the hemophilic polyserositis is called the stress sickness?
3. How is it correctly to make prophylaxis of illness?
4. What is the epizootic situation of polyserositis in Ukraine?

You can find answers for these and other questions in the full version of the article in the magazine «Profitable Pig Production», № 4 (22) 2014