Virginia Aragón

Side effects of perinatal medications on the microbiota can be detrimental to animal health.

The recent development of PCR serotyping is a step forward that allows any laboratory to determine the serotype of the isolated H. parasuis strain.

Basic preventative measures of management should be included in the control of the disease, such as adequate temperature control of the barns, a complete all-in all-out hygiene and disinfection, and the avoidance of any mixing of animals from distinct sanitary origins.

The decrease in the contact time between the mother and her piglets, due to the common practice of early weaning, has led to the appearance of some piglets that are not completely colonised or that have not acquired a sufficient level of maternal antibodies. On mixing with other litters, these piglets are faced with distinct strains while lacking the necessary antibodies against the disease.

It is important to be able to identify the distinct circulating strains and to differentiate between the strains that are merely colonisers and those that have the capacity to produce disease. With this aim various methods of classification of strains or “typing” of H. parasuis have been developed.

When the clinical signs on the farm and the lesions observed in the piglets lead us to suspect that there is a Haemophilus parasuis infection we have to confirm this diagnosis in the laboratory

Haemophilus parasuis is present in all swine producing countries and its prevalence is close to 100% on conventional farms. However, only a percentage of these farms present pathologies associated to the infection.

The factors of virulence allow the pathogenic strains to survive inside the animal and cause the infection, while the non-virulent strains lack these factors and can only survive in the upper respiratory tract as colonisers.

On a conventional farm with no problems with Glässer’s disease, it is possible to isolate various strains of Haemophilus parasuis which colonise piglets while being in balance with the animal’s immunity without producing pathology.

H. parasuis is a gram-negative bacillus of small size, which belongs to the Pasteurellaceae family. The group characterized by fibrinous polyserositis and fibrinous arthritis became known as Glässer’s disease.