Diseases

Learn More About a Disease

Glasser's disease

Glässer disease is caused by a small Gram-negative bacterium from the Pasteurellaceae family, Haemophilis parasuis. It is a nasal colonizer that is particularly fragile because it survives only a few hours at ambient temperature.1 Because the bacterium is usually present in the nasal cavities, its passage from the snout into the bloodstream requires a period of weakening and stress in the animal.  This bacterium causes a severe systemic disease characterized by polyserositis, arthritis and fibrinous meningitis. Glässer disease is currently considered a disease with increasing economic impact around the world.

Clinical Signs +

In farms or in pigs that have never been in contact with the bacterium, Glässer disease appears rapidly, a few days after exposure to Haemophilus parasuis. Clinical signs include high fever, listlessness and anorexia.  Depending on the location of the inflammatory lesions, other clinical signs may also be present, including abdominal breathing, dyspnea, severe coughing, thoracic and abdominal pain, swollen joints (especially the carpus and tarsus), lameness, trembling, lack of coordination, lateral decubitus and cyanosis. Death rates can reach 10%. Chronic infections can cause a lowering in performance, with thin pigs of no economic value that show coughing, dyspnea, weight loss, lameness and a rough coat. Primary macroscopic lesions identified during necropsy take the form of serofibrinous (early stage) to fibrinopurulent (final stage) exudate on one or more serous membranes (especially the pericardium, peritoneum, and pleura) and in the joints and meninges.

In addition to causing a systemic disease, Haemophilus parasuis also contributes to the development of porcine respiratory disease.2

Diagnosis +

Diagnosis of disease associated with Haemophilus parasuis is usually based on the farm's history, clinical signs, anatomopathological necropsy results and isolation of the bacterium. However, non-virulent strains and early colonization of upper respiratory tracts in healthy pigs can sometimes complicate diagnosis. Though the causative bacterium is not easy to isolate, this method remains the most reliable method of diagnosis. However, isolating Haemophilus parasuis can be a challenge for analytical labs: the bacterium is easily masked by other, faster growing bacteria, and Haemophilus quickly becomes non-viable in the samples themselves. Diagnosis can also be altered by the fact that the animals have received antibiotics. Retrospective analysis of samples sent to diagnostic laboratories indicates that the true incidence of the disease may be up to ten times higher than the reported incidence, in part due to the impossibility of confirming the presence of Haemophilus parasuis in the samples provided. As such, the diagnosis of H. parasuis infections remains a real challenge for many veterinarians, but the success rate can be considerably improved through rigorous sampling procedures.3

Treatment +

Eliminating Haemophilus parasuis from a farm may not be desirable because the introduction of new reproductive animals, or the mixing of naive pigs, never exposed to the bacterium, with pigs carrying Haemophilus parasuis, can trigger severe disease throughout the farm, causing considerable financial losses. H. parasuis infections can be controlled through antibiotherapy. Antibiotics should be administered parenterally at first appearance of clinical signs, and all pigs in the affected group should be treated, not just those that present clinical signs.  Most strains of H. parasuis are sensitive to most antibiotics. However, with reasonable use of antibiotics in the treatment of Glässer disease, the susceptibility pattern of clinical isolates of Haemophilus parasuis should be systematically monitored before treatment.

Consult your veterinarian before administering antibiotics and vaccines to animals. Your veterinarian is the best source of recommendations that are truly adapted to your farm.1

Prevention +

Haemophilus parasuis infection can be controlled through vaccination, as long as vaccination programs adequately address two essential issues: the diversity of serotypes and the timing of vaccination. Furthermore, infection control measures for H. parasuis must also take into account the isolation and acclimatization periods for piglets newly introduced to the farm, and other farming practices, in order to reduce or eliminate other pathogenic agents, control weaning ages and restrict the flow of animals (batch farrowing), eliminate the mixing of pigs at all production steps, etc.5

REFERENCES:

1 Maladies d’élevage des porcs, Second Edition, Guy Pierre Martineau

2 Møller, K., Andersen, L.V., Christen, G. & Filian, M. (1993). Optimization of the detection of NAD dependent Pasteurellaceae from the respiratory tract of slaughterhouse pigs. Veterinary Microbiology 36, 261-271.

3 Oliveira, S. & Pijoan, C. (2004). Haemophilus parasuis: new trends on diagnosis, epidemiology and control. Veterinary Microbiology 99, 1-12.

4 Oliveira, S. (2004). Improving rates of success in isolating Haemophilus parasuis from clinical samples. Journal of Swine Health and Production 12, 308-309.

5 Rapp-Gabrielson, V., Kocus, G., Clark, J. & Stephen, K. (1997). Haemophilus parasuis: immunity in swine after vaccination. Veterinary Medicine 92, 83-90.