Mycoplasma are a genus of bacteria distinguished by their lack of a cell wall. This structural difference means they are unaffected by many common antibiotics, which target cell wall synthesis. Given that various Mycoplasma species cause diseases in a wide range of hosts, a common concern arises about the potential for transmission from chickens to people. This analysis clarifies the specific risks associated with poultry-related Mycoplasma strains and human health.
Mycoplasma Infections in Poultry
Two species, Mycoplasma gallisepticum (MG) and Mycoplasma synoviae (MS), are primarily responsible for clinical disease in domestic poultry like chickens and turkeys. MG is commonly associated with Chronic Respiratory Disease (CRD), leading to symptoms such as coughing, sneezing, and nasal discharge. MS infections may cause similar mild respiratory signs but are also a known cause of infectious synovitis, presenting as lameness and swollen joints. Both infections significantly impact production, causing reduced egg yield and hatchability. Transmission occurs horizontally through direct bird-to-bird contact and aerosols, and vertically when the bacteria are passed from an infected hen directly into her hatching egg.
Mycoplasma Infections in Humans
The Mycoplasma species that cause illness in humans are distinct from those that affect poultry. The most common human pathogen is Mycoplasma pneumoniae, responsible for respiratory tract infections often called “walking pneumonia.” Symptoms typically include a persistent dry cough, fever, and headache. Another species, Mycoplasma genitalium, is primarily associated with sexually transmitted infections. These human-specific strains are spread almost exclusively from person-to-person via respiratory droplets and generally do not originate from avian hosts.
The Specific Risk of Zoonotic Transmission
The risk of contracting Mycoplasma infections from chickens, specifically the avian strains M. gallisepticum and M. synoviae, is considered extremely low for the vast majority of people. This low risk is due to host specificity, where a pathogen is highly adapted to the unique biological environment of a single host species. Avian Mycoplasma strains lack the necessary genetic and molecular machinery to successfully colonize, replicate, and cause systemic disease within the human body. The human immune system and physiological environment are not conducive to the proliferation of these avian bacteria. Theoretical risk exists primarily for individuals who are severely immunocompromised or who have pre-existing respiratory conditions; however, for the general public, the primary health concern remains the human-adapted strains like M. pneumoniae.
Safe Handling and Biosecurity Practices
While the Mycoplasma risk from poultry is minimal, maintaining good biosecurity practices is important for preventing the transmission of other general pathogens. Hand washing is the single most effective step, requiring soap and running water immediately after handling chickens, eggs, or any equipment used in the coop. This action minimizes the risk of transferring bacteria like Salmonella or E. coli. Several other practices are recommended for general disease prevention:
- Use dedicated boots for the coop or utilize footbaths with disinfectant.
- Avoid snuggling or kissing poultry, as this brings the bird’s natural bacteria close to human mucous membranes.
- Limit visitor access to the poultry area.
- Control rodent populations within the flock environment.