What are Adenoviruses?
Adenoviruses, as noted above, are viral organisms which cause various diseases including hepatic and gastrointestinal diseases in various species of snakes, lizards and crocodiles. It is not, however, zoonotic in nature, meaning that it doesn’t pass from animal to human or vice versa. The method of transmission is not known but fecal/oral route is suspected. This virus has been considered causative in diseases like gastroenteritis, hepatitis, nephritis, pneumonia and even encephalitis.
Adenoviruses, which are viral organisms that cause infections, are from the family of adenoviridae and commonly cause hepatic (liver) and gastrointestinal (GI) disease and other diseases in snakes as well as other animals.
Symptoms of Adenoviruses in Reptiles
Adenoviruses are a fairly common malady among snakes and lizards. The symptoms of adenovirus in snakes are vague and subtle, but you might notice these in your captive pet snake:
- Lethargy or laziness
- Weight loss (with anorexia)
- Head tilt
- Opisthotonus - A tense spasm in which the body arches upward while being supported by head and heels (or tail)
- Sudden death
As you can see, many of the symptoms affect the central nervous system and are neurologically related as well as hepatic and gastrointestinal. Though vague and subtle, some of these symptoms are serious and could result in death.
The only types of adenoviruses which exist are those adenoviruses (and there are many) which are specific to the species of reptile in which they are found. For example, some of them are more specific to lizards, while others are primarily found in snakes and still others in crocodiles. While the primary sites of damage found in snakes from the adenoviruses are the liver and gastrointestinal system, evidence of the viruses have been found in cells in the myocardium and endocardium (heart), kidneys and brain.
Causes of Adenoviruses in Reptiles
The transmission of adenoviruses is not known for certain but is suspected to be fecal/oral direct contact from contaminated or infected animals. The host animal can have a genetic predisposition for the adenovirus and can pass the organism in its feces and through oral fluids such as those exchanged in fight wounds and breeding. It is felt that the genetic predisposition is also passed via DNA and RNA to offspring. The virus, once transmitted begins to cause damage to various organs and systems like the liver, gastrointestinal system, heart, kidneys, central nervous system and brain.
Diagnosis of Adenoviruses in Reptiles
Diagnosis of adenoviruses can be challenging for your veterinary professional as the signs and symptoms are vague at best sometimes and can mimic other diseases, as well as nutritional disorders. Your vet will need a complete history from you and will need to do a thorough physical examination. He will also need tissue samples and blood tests to isolate the organism causing the disease process. Sometimes, in the case of a large breeding group, it has been suggested that sacrificing one of the reptiles who is sick so that the pathological assessments can be made on the various tissue types may be advantageous in the long run for the rest of the brood. The diagnosis will be obtained essentially from the pathological review and PCR (Polymerase Chain Reaction) testing of the tissue and blood samples provided from the sick snake(s), though some of the tissue samples needed may be difficult or less efficient to obtain from a living patient. Isolation of the adenovirus may be available in the future through evaluation of the feces of the diseased animal.
Treatment of Adenoviruses in Reptiles
There is no specific treatment for adenoviruses, though fluids, supportive care and medications to treat the gastrointestinal issues and the secondary bacterial infections that can accompany the disease are generally the treatment recommendations. Since not enough is known about how the disease is transmitted, where it comes from and the length of its life cycle, it is important to isolate any sick captive pet snakes from your remaining pet population. It is also important to maintain strict handling standards for anyone involved in their care. Washing your hands after handling the sick snake will help to protect other animals in your care. Separate the sick snake from your breeding stock so that it can’t reproduce the virus in its offspring. Another thing to remember is that, though adenoviruses are not zoonotic in that they don’t pass to humans, these viruses can be passed to other animal species, making the extra care and steps for handling vitally important for the prevention of further infections and the maintenance of the health of the remaining animal species in your environment.
Recovery of Adenoviruses in Reptiles
Adenoviruses can be fatal to your captive pet snake. This is especially true of the younger snakes who are more susceptible to serious damage to their young, still-developing bodily systems. For those snakes who are recovered, it is recommended that you keep them quarantined for a period of at least three months. Since there is no treatment for adenoviruses and there is simply not enough information on adenoviruses in regard to the life cycle and the length of time it takes for the virus to shed after the animal is recovered, it is not recommended to sell or trade an animal who has been previously afflicted. It is also recommended that PCR testing be done on any new arrivals to your environment and, those animals who test positive, should be kept quarantined for 3 to 6 months before introducing them into your environment. Maintenance of strict handling precautions, separation/quarantine steps and the PCR testing should help to reduce the number of animals who ultimately become infected with adenoviruses.