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Glässer's Disease: lateral recumbency
"The bacterium is ubiquitous, found throughout the world and is present even in high health herds."
Glässers Disease is caused by Glasser Disease. H. parasuis is endemic in the majority of pig herds and is frequently isolated from the nasal cavities of healthy pigs.
Introduction of H. parasuis in a naÃ¯ve herd through mixing pigs of different origins, may lead to high rates of morbidity and mortality. However, vigilant observation of the herd and early treatment of pigs can greatly decrease the mortality.
Glasser Disease is a small, rod-shaped Gram-negative bacterium. This bacillus was originally isolated from pigs in 1910 by K. GlÃ¤sser and was later identified in the laboratory in 1931 by Lewis and Shope, who originally named it Haemophilus influenzae suis due to similarities to human H. influenzae. It was later found to have different properties and was thereafter known as H. parasuis. At least fifteen different serotypes have been identified.
The bacterium is ubiquitous, found throughout the world, and is present even in healthy herds. This bacterium is a normal resident of swine respiratory tracts and is passed to piglets through interaction with the sow after birth. It generally colonizes the upper respiratory tract of piglets by 60 days of age. Piglets at this time are still protected by maternal antibodies received through colostrum, and this passive immunity, in most scenarios, holds H. parasuis colonization in check until the pigletsâ€™ own immunity develops around 7-8 weeks of age to protect against infection. (Swine Disease Manual, 4th Ed). However, several environmental factors can lead to an upset in the balance between immunity and colonization of this bacterium, leading to disease. Such environmental factors include fluctuations in room temperature, inadequate ventilation, or stress in the piglets caused by early weaning, transportation, or the presence of other pathogens in addition to H. parasuis. In naÃ¯ve populations, the bacterium may cause severe disease on its own but can also be the cause of secondary bacterial infections in other diseases, particularly enzootic pneumonia (M. hyopneumoniae). Interaction with other diseases, such as PRRS virus and Postweaning Multisystemic Wasting Disease can lead to increased susceptibility.
H. parasuis first colonizes the nasal mucosa and causes the destruction of nasal epithelial cells. The bacteria then may spread to the lungs and possibly other system organs if entry into the blood occurs. In the lung, the more virulent strains of H. parasuis are able to survive clearance by the macrophages of the lungs in nÃ¤ive or immune-compromised pigs. The bacteria invade the endothelial cells, inducing apoptosis of these cells and causing the production of cytokines, including IL-6 and IL-8, which induce inflammation and are believed to be the phenomenon that allows the passage of bacterial cells into the blood of the infected animal. Once in the bloodstream, the bacteria are free to infect other areas of the body, such as the brain and other areas covered by serous membranes, which leads to the clinical signs seen with Glässer’s disease.
In the majority of H. parasuis endemic herds, piglets usually have a strong maternal immunity until 6 to 10 weeks of age. As a result, the effects of infection in weaned piglets tend to be minimal. If, however, maternal immunity wears off before infection or establishment of the pigletsâ€™ own immune protection, piglets may develop severe disease. Outbreaks of disease are sometimes experienced in suckling pigs, particularly in gilt herds. Clinical signs of this disease are mostly observed in piglets between the ages of 4 and 8 weeks. Disease may also be found in adult pigs that originate from nÃ¤ive herds after introduction to a new herd, although this is rare due to the ubiquitous nature of this bacterium. The incubation period of this disease ranges from 1 - 5 days after infection.
- The onset of GlÃ¤sserâ€™s disease is rapid and can lead to sudden death in less than 2 days after the development of symptoms. H. parasuis attacks joint surfaces and the smooth membranes around the intestines, lungs, heart, and brain. In young growing pigs, meningitis or middle ear infections are common together with pneumonia, pericarditis, peritonitis, and pleurisy.
- Sudden death
- High fever (106 deg. F)
- Heavy breathing
- Swollen joints with lameness on affected limbs
- Lateral recumbency (lying on side)
- Posterior paresis (weakness in hind limbs)
- Less common: rhinitis (runny nose), conjunctivitis (swelling and redness of tissues around the eyes), and blue discoloration of extremities
- Pigs that survive the initial acute phase of infection may develop chronic disease. Common clinical signs include a rough hair coat, decreased growth rate, chronic lameness, and/or sudden death from chronic conditions such as pericarditis.
A diagnosis of Glässer’s disease is confirmed by clinical signs, post-mortem examination, isolation of the organism, and PCR identification. This disease induces lesions and other tissue damage that can be observed at necropsy. The disease causes fibrin deposits on serous membranes, such as the meninges and lining of the intestinal tract. Fibrinous blood clots may be seen in the kidneys, liver, and pulmonary capillaries. There may also be an increased amount of fluid, containing both blood and serous fluids, in the thoracic and abdominal cavities. Fibrin deposits can be observed on the serous membranes of the body including the pleura, pericardium, peritoneum, and meninges. However, the clinical signs and findings at necropsy can also be found with other similar pathogens, so these observations will not lead to a definitive diagnosis. Isolation of the organism can be incredibly difficult due to the bacteriaâ€™s fastidious nature, making it difficult to culture. PCR is the most specific method for detecting this bacterium and can differentiate between different strains that may or may not be virulent.
- Actinobacillus suis
- Porcine pleuropneumonia
- Mulberry heart disease
- Streptococcal meningitis
- Streptococcal septicaemias
Treatment and Prevention
IIdeally, antibiotic treatment should begin before clinical disease is apparent, which requires frequent inspection of any pigs at risk.
H. parasuishas a wide antibiotic sensitivity including amoxycillin, ampicillin, oxytetracycline, sulphonamides, penicillin and ceftiofur.
Management control and prevention
- The lactating and creep rations and/or water can be medicated with antibiotics; however, individual treatments will be more effective, since affected pigs may not want to eat or drink.
- Vaccination with inactivated vaccines based on Glasser Disease serotypes.
- Maternal antibodies and interaction with the sow are important for immunity in piglets. Proper husbandry and management can keep H. parasuis from causing infection.