Melissa Kaplan's
Herp Care Collection
Last updated January 1, 2014

Adenoviruses in Reptiles

©2000 Melissa Kaplan

There has been a growing problem with adenovirus in bearded dragons (Pogona vitticeps) over the past several years. At the end of this page are several links to more information on adenovirus and yellow fungus (Chrysosporium a. Nannizziopsis vriesii), another disease hitting beardeds particularly hard. See below for updated information on diagnosis and treatment

General Adenovirus Information
Adenovirus enteritis is a infectious virus of the small bowel caused by a dsDNA virus resulting in a secretory diarrhea.

In humans, it is the second most common cause of virus-induced enteritis (incidence 4-12%). Those at highest risk of infection are

• infants & young adults; most are under 2 years of age

• bone marrow recipients

The virus is not seasonal in nature - it can be contracted at any time of year. Routes of infection are:

• fecal-oral (direct transmission)

• respiratory droplets (environmental)

The virus can also be passed on vertically, that is, from parent to ova. In animals, this means the mother can pass it to her developing embryos, or the eggs can be infected when they are fertilized by an infected father, and when the eggs/neonates pass through the cloaca.

The incubation period is 8-10 days. Diarrhea is the most common symptoms in humans, with the virus found in stools for 7-14 days. About 50% of human patients have respiratory symptoms before the gastrointestinal symptoms start. In humans, mild fever, vomited and abdominal pain accompany the period of diarrhea, which can last for 10 days or so. During the first 4-5 days, no virus cells are shed.

The strain caused by the cramps and diarrhea can cause one part of the intestine to slide into another (intussusception), causing further discomfort and digestion problems.

Diagnosis is made by subjecting the feces to EM, latex agglutination, or monoclonal antibody based immune electron microscopy (EM) examination.

Treatment is supportive in nature: oral, subcutaneous or intracoelomic fluids.

Adenovirus in Reptiles
Per Juergen Schumacher, DVM, author of Viral Diseases, in Mader's Reptile Medicine & Surgery:

Adenovirus has been reported in a bearded dragon (Pogona barbatus), Rankin's dragons (Pogona henrylawsonii), and a savannah monitor (Varanus exanthematicus). The actual route of transmission was not known, but suspected to be direct (fecal-oral).

The bearded dragon exhibited recurring loss of appetite before dying. The Rankin's died soon after exhibiting limb paresis, loss of appetite, and lethargy. The monitor died suddenly with no prior signs of illness.

The post mortems found no gross abnormalities in the monitor and bearded; in the Rankin's, the lungs were congested and liver swollen and pale. Microscopic exam found multiple spots of necrotic tissue in the livers of all three species. Eosinophilic intranuclear bodies were found in the bearded's liver cells (hepatocytes). Basophilic inclusion bodies were found in the monitor's and Rankin's, and inclusion bodies were also found in the endothelial cells of the monitor. EM exam the viral particles were found in all the animals examined.

Diagnosis is made post mortem. [MK 2007 Note: See bolded paragraph above and new information below...]

There is no treatment for the adenovirus; antimicrobials can be given for secondary bacterial infections.

In the following section, under general guidelines for the collection and handling of specimens, Dr. Schumacher goes on to say:

In living reptiles, biopsies of skin, liver, oral mucosa, etc., can be collected and stored in formalin for histologic and electron microscopy exam. For direct viral detection, samples of urine, saliva or vesicular fluid (as from cysts or blisters) can be processed for negative staining EM. If the virus particles are present in sufficient number, these methods will work.

There have been reports of adenovirus in some bearded dragon breeders' collections. There has also recently been some discussion on the Pogona email list, with some members concerned that hatchlings who thrash and flail about when put in water for a bath or soak. Neurological signs (loss of coordination, spasms, tremors, intention tremors, falling down, etc.) are generally not signs of adenovirus infection. In the lizards behaving this way in bath, it is most likely that they are simply freaked out by the water. This is a common occurrence when green iguanas are introduced to baths for the first time, and it may take weeks or months for them to be completely comfortable in a bath. In the case of desert lizards such as bearded dragons, such a fear-related response is understandable. For information on bathing and how to help lizards acclimate, see the Bathing and Swimming: Not Just A Bathroom Activity article.

The most common cause of neuromotor problems in young bearded dragons can be caused by feeding them prey that is too large. For more information, see the following excerpt from the Feeding section in my Dragons Down Under: Inland Bearded Dragons article:

You must feed very small prey to baby bearded dragons. While the rule-of-thumb for feeding lizards says that it is generally safe to feed prey that is 2/3 the size of the lizard's head, this is not advisable with baby beardeds (0-4 months). When fed prey that is too large for them, serious physical problems often result: partial paralysis, seizures, ataxia (loss of motor control), inability to self-feed, gut impaction, even death. Start with feeding pin-head crickets and tiny, freshly molted worms, moving only slowly and gradually to larger sizes, phasing in day-old pinks when they are ready for them. Despite the fact that most stores sell animals that need them, most don't sell pin-heads, so you will have to order them directly from a cricket breeder; you can order mealworms from them at the same time.

Gut impactions, as from retained insect chitin, can cause loss of appetite, rapid weight loss, dehydration, lethargy, and ambulatory problems as the gut tries to move the mass along, food cannot be digested, the gut becomes infected and gassy from the food rotting, and pain and cramping set in. Loss of appetite, lethargy, dehydration are also the most common signs of a wide range of bacterial, parasitic, fungal, mycoplasmal, and viral illnesses. All avenues should be explored, and in the case of young bearded dragons (most of the survivors of which outgrow the neuromotor symptoms as they get older), great care must be taken when selecting the insects being fed out, making sure to feed small, newly molted ones.

Note that some viruses, such as the boid inclusion body disease, does cause ataxia and stargazing, two neuromotor signs.

Adenovirus and Yellow Fungus in Bearded Dragons

• Adenovirus in the Bearded Dragon, Pogona vitticeps. Proceedings of the ARAV, 1996, page 131.
  Mader, Douglas R. (ed.). 1996. Reptile Medicine and Surgery. WB Saunders, Philadelphia PA. ISBN 0-7216-5208-5

• Adenoviruses and Yellow Fungus (ReptileRooms)

• Bearded Dragon Diseases (Yahoo!Groups Email List)

• Yellow Fungus Research: Possible Cause & Effects

Updated Information on Testing

Adenovirus in Bearded Dragons (Daniel Wentz DVM)

Reptile Adenovirus PCR and Sequencing at University of Florida CVM (PDF)

PCR (Polymerase Chain Reaction) vs. EM (Electron Microscopy) Testing

Testing Labs:

     Veterinary Molecular Diagnostics, Inc.  Real-time PCR fecal test.
     Contact lab for requirements.

    University of Florida College of Veterinary Medicine Nested PCR fecal testing.
    Your vet must contact the UFCVM lab (352-392-4700 x 5775) to find out what and how to submit samples.

    University Illinois at Urbana-Champagne Vet School's Center for Microscopic Imaging EM test.

Sources

Adenovirus
Adenovirus enteritis
Adenoviruses
Common Diseases of Bearded Dragons, Part 3: Adenoviruses, Klingenberg
Detection and Confirmation of Reptilian Adenovirus Infection by In Situ Hybridization, Perkins, et al.
Infectious Diseases in Reptiles, Jacobson
The Big Picture Book of Viruses: Adenoviridae
AFIP Slide