Mycoplasma hyopneumoniae

Mycoplasma | in pigs

What is it and what causes it?

Mycoplasma is one of the main causes of pneumonia in pigs. It is a bacterial species that occurs worldwide and is endemic on many farms. Usually, pneumonia, also called enzootic pneumonia, is caused by the subspecies Mycoplasma hyopneumoniae. Other species also occur in pigs, for example, M. hyosynoviae and M. hyorhinis. M. hyopneumoniae spreads across the farm through direct contact between pigs (sow to piglet, piglet to piglet), or indirectly through aerosols. Through the air, the bacteria can travel distances of more than 2.5 kilometers. The bacterium paves the way for other respiratory germs, such as the PRRS virus, because it damages the cilia in the anterior airways. This greatly weakens the lungs' defenses. M. hyopneumoniae together with the PRRS virus causes the basis for the condition PRDC (porcine respiratory disease complex) in pigs. In this type of combination infection, the severity of disease symptoms increases greatly.

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Which animal?

Pig

Which organ system?

Respiratory system

How to recognize it.

With an infection of M. hyopneumoniae in a naive population, a large outbreak can occur affecting pigs of all ages. The pigs begin to eat less, have a slight fever, cough and are stuffy. The severity of the symptoms is determined primarily by the pathogenic potential of the Mycoplasma germ. The barn climate and the occurrence of the PRDC complex also determine the severity of the infection. Many pigs become ill, but mortality is usually low. Most symptoms are seen among weaned piglets and meat pigs.

In a more chronic form, only coughing and growth retardation are often seen. The cough is a typical loud, dry cough that can last up to 50 days and is easily triggered after a startle. Secondary infections often occur. Depending on the secondary pathogen, post-mortem examination may find extensive pneumonia of the upper lung lobes, with bloody or festering exudate and connective tissue. Typically, accumulations of white blood cells (also called "cuffs") around the small bronchi and blood vessels in the lungs are visible under the microscope.

What other symptoms are there?

Pigs can also be carriers without developing symptoms of disease. Often a mild pneumonia is then not noticed until the slaughter line.

What are the risk factors?

Mixing and pooling of litters is an important risk factor. Consequently, most infections occur after weaning and at layover to the fattening pig house. Suboptimal barn climate and high stall occupancy are also risk factors.

What does this disease mean for the farmer and the farm?

Mycoplasma infections cause growth retardation and increased feed conversion. Drug costs will also increase.

How can you prevent the disease?

Because many farms in the United Kingdom are infected, many purchased pigs will carry M. hyopneumoniae. Farm management is therefore an important factor in limiting the damage. Many management measures offer a good preventive effect: good adaptation and quarantine period of purchased gilts, good climatic conditions, preventing overcrowding, not mixing litters and groups of piglets, and a strict all-in all-out system where empty departments are cleaned and disinfected in between. In addition, vaccination against Mycoplasma can be done. Several vaccines are available, which are effective if administered well in advance of infection. Vaccinating infected farms greatly reduces the economic damage on the farm and reduces the risk of lung infections in fattening pigs. Vaccinating sows ensures that piglets receive more antibodies through colostrum, protecting them from infection longer. However, they must be vaccinated at a later age.

How can you treat the disease?

M. hyopneumoniae can be treated with antibiotics. This reduces clinical symptoms and the risk of secondary infections. However, resistance to certain agents is known. Preventive measures are strongly preferred.

Alternative names

Enzootic pneumoniae

Search terms

Mycoplasma, M. hyopneumoniae, M. hyosynoviae, enzootic pneumonia, M. hyo

Sources

Animal Health Service "Mycoplasma," accessed Feb. 9, 2021.

de Jong, Anno, et al. "Antimicrobial susceptibility monitoring of Mycoplasma hyopneumoniae isolated from seven European countries during 2015–2016." Veterinary Microbiology 253 (2021): 108973.

Locquet, Laurent. "Bestrijding van Mycoplasma hyopneumoniae met nadruk op vaccinatie." Fac. Diergeneeskunde, Universiteit Gent.

Thacker, Eileen L. "Diagnosis of Mycoplasma hyopneumoniae." Journal of Swine Health and Production 12.5 (2004): 252-254.

Thacker, Eileen L., et al. "Mycoplasma hyopneumoniae potentiation of porcine reproductive and respiratory syndrome virus-induced pneumonia." Journal of clinical microbiology 37.3 (1999): 620-627.

Vangroenweghe, F. A. C. J., et al. "Mycoplasma hyopneumoniae infections in peri-weaned and post-weaned pigs in Belgium and The Netherlands: Prevalence and associations with climatic conditions." The Veterinary Journal 205.1 (2015): 93-97.

Yeske, Paul, et al. "Survival analysis of two Mycoplasma hyopneumoniae eradication methods." Preventive veterinary medicine 174 (2020): 104811.

Zoetis "Mycoplasma", accessed Feb. 10, 2021.