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Published on: October 2, 2018
Mycoplasmas: Brain invaders?
Rubén S Rosales1, Roberto Puleio2, Guido R Loria2
1Instituto Universitario de Sanidad Animal y Seguridad Alimentaria, Universidad de Las Palmas de Gran Canaria, C/Trasmontaña s/n, Arucas, 35416, Gran Canaria, Spain.
Abstract:
Mycoplasmas of humans and animals are usually associated with respiratory, autoimmune, genital and joint diseases. Human mycoplasmas have also been known to affect the brain. Severe central nervous system (CNS) diseases, such as encephalitis, have been linked to Mycoplasma pneumoniae and ureaplasma infections. Less well known is the sheep and goat pathogen, Mycoplasma agalactiae, which has been found in large quantities in the brain where it may be responsible for non-purulent encephalitis as well as ataxia in young animals. Experimental intra-mammary infections of sheep with this mycoplasma have resulted in histopathological changes in the CNS. The cattle pathogen, M. bovis, has been reported occasionally in the brains of calves and adult cattle showing a range of histopathological lesions including abscesses and fibrinous meningitis. Two avian pathogens, M. gallisepticum and M. synoviae have been isolated from the brains of poultry showing meningeal vasculitis and encephalitis. There have been no reported detections of two other avian pathogens, M. meleagridis or M. iowae in the CNS. Over the last few decades, mycoplasmas have been isolated from the brains of sea mammals dying in large numbers in the North Sea although it was concluded that their role may be secondary to underlying viral disease. Finally, evidence has been advanced that certain Spiroplasma species may have a role in the development of the transmissible spongiform encephalopathies (TSE). Invasion of the brain by mycoplasmas may be as a result of direct entry following damage to the inner ear as seen with M. bovis or across the blood brain barrier by mechanisms as yet uncertain.
Insights
Mycoplasmas, bacteria lacking cell walls, can infect the central nervous system (CNS) in various animals and humans. This review highlights their role in causing neurological diseases like encephalitis and ataxia.
Area of Science:
- Veterinary Neurology
- Infectious Diseases
- Microbiology
Background:
- Mycoplasmas are known pathogens causing respiratory, autoimmune, genital, and joint diseases in humans and animals.
- Certain Mycoplasma species, including Mycoplasma pneumoniae, have been implicated in severe human central nervous system (CNS) diseases like encephalitis.
- Less common Mycoplasma species are increasingly recognized for their neuroinvasive potential across diverse hosts.
Purpose of the Study:
- To review the current understanding of Mycoplasma species' involvement in CNS diseases across various animal species and humans.
- To consolidate evidence linking specific Mycoplasmas to neurological conditions such as encephalitis, ataxia, and meningitis.
- To explore potential mechanisms of Mycoplasma brain invasion and their contribution to neuropathology.
Main Methods:
- Literature review of scientific publications detailing Mycoplasma isolation and identification from CNS tissues.
- Analysis of histopathological findings and clinical signs associated with Mycoplasma CNS infections in different animal models and human cases.
- Examination of experimental studies investigating Mycoplasma pathogenesis and neuroinvasion routes.
Main Results:
- Mycoplasma agalactiae, M. bovis, M. gallisepticum, and M. synoviae are identified as significant Mycoplasma pathogens affecting the CNS in sheep, cattle, and poultry, respectively.
- Evidence suggests Mycoplasma species can cause non-purulent encephalitis, ataxia, abscesses, and meningitis.
- Mycoplasma CNS infections have also been reported in marine mammals, and Spiroplasma species are investigated for a role in transmissible spongiform encephalopathies (TSEs).
Conclusions:
- Mycoplasmas represent an underappreciated group of neurotropic pathogens with significant implications for animal and potentially human health.
- Further research is needed to elucidate the precise mechanisms of Mycoplasma entry into the CNS and their pathogenic roles.
- Understanding Mycoplasma neurotropism is crucial for accurate diagnosis, treatment, and prevention of neurological diseases.
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