Mycoplasma is a genus of bacteria that lack a cell wall. It is currently considered the smallest known cell. Infections in reptiles caused by various species of mycoplasma are commonly called mycoplasmosis, which is an upper respiratory tract disease (URTD) in turtles and tortoises, a tracheal and pneumonia disease in Burmese pythons, and an arthritis disease in alligators and crocodiles. Turtles and tortoises are most commonly infected with Mycoplasma in captivity and that will be the main focus here.
Mycoplasma has been shown to infect a number of different species of reptiles:
- Mycoplasma agassizii has been shown to be one cause of significant URTD in California desert tortoises (Gopherus agassizii) and Florida gopher tortoises (Gopherus polyphemus).
- A different species from California desert tortoises, M. testudineum, is also associated with URTD.
- An unnamed Mycoplasma spp. has been found in association with URTD in Eastern box turtles (Terrapene carolina).
- M. crocodyli is associated with polyarthritis in Nile crocodiles (Crocodylus niloticus).
- M. alligatoris has been shown to cause pneumonia, polyserositis, and polyarthritis in American alligators (Alligator mississippiensis) and broad-nosed caiman (Caiman latirostris), but did not cause disease in Siamese crocodiles (Crocodylus siamensis).
- A second unnamed Mycoplasma species has been associated with proliferative tracheitis and pneumonia in a Burmese python (Python molurus bivittatus).
Mycoplasma disease may be seen at all ages in reptiles but is more common in adult males of some tortoise species. M. agassizii is widespread in North American G. agassizii and G. polyphemus populations. There are no reports of it being a seasonal disease, but in animals that bromate/hibernate, clinical disease is often seen following brumation/hibernation.
The most typical cause of nasal discharge in captive turtles and tortoises is URTD, or mycoplasmosis. Common signs include a nasal discharge of a clear serous-to-thick bubbling of mucus to mix of mucus and pus. A similar discharge from the eyes and swollen eyelids.
Clinical signs may appear within one to two weeks of being exposed to the mycoplasma bacteria. Mycoplasma is spread directly via nasal discharge and is quite contagious as tortoises often greet one another nose to nose. Many tortoises are chronically infected. Infected tortoises often do not want to eat, are lethargic, have lost weight or feel light, and have clogged nostrils or a clear, bubbling nasal discharge. Chronic cases can have erosion and deformation of the nostrils and beak; hatchlings can have enlarged and distorted snouts that may affect the ability to eat. Sometimes a nasal discharge is not apparent during a veterinarian’s clinical examination, but pushing the tortoise's head straight back into its shell will often produce it. Other common signs for mycoplasmosis include nonspecific illness, difficulty breathing, and swollen joints.
There is no known risk of infection to humans from reptile Mycoplasma, so you don’t have to worry about people.
Affected Reptiles
Mycoplasma has been identified as a disease-causing agent in many different species. The most commonly diagnosed groups of reptiles are alligators and crocodiles, and turtles and tortoises. There have been uncommon reports in Burmese pythons of disease caused by Mycoplasma. It is likely that all turtles and tortoises have the potential to be infected with Mycoplasma.
Diagnosis
Your veterinarian will start with a detailed history, husbandry review and physical examination. Often the physical signs of a runny nose and swollen eyes, especially in tortoises, will suggest infection with mycoplasma. A complete blood count (there is often a high white blood cell count), a chemistry profile, and a set of X-rays may be suggested to assess the overall health. X-rays can be especially helpful to see if there are other causes for the nasal discharge or lack of appetite, such as a colon obstruction from gravel, sand or other objects; or tumors or bladder stones.
Several diagnostic options are available that your veterinarian can discuss with you. Because Mycoplasma bacteria lack a cell wall, they do not live for long outside of the animal’s body; samples for diagnosis must be obtained directly from the animal. Culture, similar to other bacterial infections, can be attempted but turtle and tortoise Mycoplasma culture is extremely difficult due to a number of factors.
Another method is a PCR diagnosis from a nasal flush, which may require anesthesia, or a nasal swab. A negative flush doesn't necessarily mean the tortoise doesn't have Mycoplasma, it just wasn't in that sample. Serology is the test of choice for Mycoplasma infections in other species and ELISA testing has been validated for desert and gopher tortoises to detect anti-Mycoplasma antibodies. The disadvantage of ELISA is that it only detects antibodies that documents exposure but not necessarily infection. Nonetheless, this is an important screening test when bringing in turtles and tortoises to a closed collection. This type of test requires a blood sample.
If all of these tests are negative but your veterinarian still suspects a Mycoplasma infection, you can discuss the option of treating for this disease anyway.
Treatment
The goal of treatment is for infected reptile to able to function normally. However, Mycoplasma spp. are difficult to completely eradicate, and the possibility of having a carrier after treatment is significant.
Treatments of mycoplasmosis in turtles and tortoises usually are a combination of long-term antibiotic injections and flushing of the nasal passage and choana (the slit in the top of the mouth) with a solution containing antibiotics, steroids and saline. Treatment length is often for a long period (45-60 days) and so it is important to get to all the follow-up appointments. Patients should be rechecked every two months for the first year to see if the disease has returned.
Severely underweight animals or those that are not eating benefit from a feeding tube. Untreated patients develop chronic disease and may accumulate solid cellular debris or thick mucus in the nasal sinuses, leading to weight loss and slow decline.
Husbandry should be reviewed and the proper temperatures, diet and lighting should be instituted in the overall treatment plan. In general, any turtle or tortoise that has had mycoplasmosis should not be hibernated; a high percentage of these animals get the disease again after hibernation or brumation.
Prevention/Prognosis
The goal is not to allow the disease to enter the collection. Quarantine monitoring is critical: all turtles and tortoises with nasal discharge should be looked at by a veterinarian and be tested for mycoplasmosis before they join the collection.
Mycoplasma spp. are easily inactivated or killed by common household disinfectants and by drying up. Cage and cleaning utensils should be cleaned with an appropriate disinfectant, such as 0.15 percent bleach and rinsed with clean water. Mycoplasma-positive tortoises should be isolated from Mycoplasma-negative tortoises as the disease is extremely contagious and the possibility of carrier status even after treatment should be remembered; discuss with your veterinarian the implications of this to the rest of the collection.
In captivity, tortoises that receive proper treatment and husbandry can survive indefinitely with mycoplasmosis.