By Barry Whitworth, DVM
Your neighbor has a beautiful healthy hen that you want. She graciously gives her to you. After being in your flock for a few weeks, you notice a decrease in the number of eggs that you are getting. The birds are not eating as well, and you are hearing some coughing and sneezing. What is going on?
The above scenario would be an easy way that Mycoplasma could be introduced into the flock. Mycoplasmas are very small organisms that can be transmitted easily. The major species of Mycoplasma that are seen in chickens and turkeys are M. gallisepticum, M. meleagridis M. synoviae, and M. iowae.
The organisms are host specific, which means that chickens with Mycoplasma do not infect other animals. The disease causes economic losses due to condemnation of carcasses, reduced feed efficiency, decreased egg production and an increase in treatment and prevention cost.
Mycoplasma is passed from one bird to the other birds by vertical or horizontal transmission. Vertical transmission occurs when an infected hen passes the bacteria to the chick through the egg. Horizontal transmission can occur two ways, either by direct or indirect means.
Direct transmission occurs when an infected bird passes the organism directly to a susceptible bird. This usually occurs when the susceptible bird comes in contact with respiratory, nasal or ocular secretions from an infected bird.
Indirect transmissions occur when a producer accidentally contaminates the environment with the bacteria. This could happen when a producer visits a poultry auction, a show or a neighbor’s farm and does not practice good hygiene before having contact with his or her own flock. Borrowing poultry equipment from a neighbor is also a good way to introduce the bacteria into the flock.
Mycoplasma gallisepticum, which is sometimes called Chronic Respiratory Disease (CRD), is considered the most pathogenic and economically important mycoplasma found in the poultry industry. M. gallisepticum infections typically result in a respiratory infection. The most common clinical signs are difficult breathing, coughing and nasal discharge.
Most birds lose weight due to decrease feed consumption. In hens, egg production declines. The eyes may be inflamed (conjunctivitis). In turkeys, the head may swell due to sinus infections. With other Mycoplasma species, the joints may be infected. The hock and foot are the more common areas that swell. Death and sickness rates increase with environmental stresses (cold stress, heat stress, dust, ammonia, etc.). Also, if Mycoplasma is combined with other organisms such as E. coli, New Castle virus, or Infectious bronchitis virus, the severity and duration of the disease is worse.
Pick up the March issue to learn more!