Adenovirus / Atadenovirus In Bearded Dragons

We have updated this article after discovering new information regarding Atadenovirus in bearded dragons. We’ll be the first to admit when we got something wrong, and it turns out, we’ve been looking at old information and more studies have recently come to light.

It should be noted that our original article was based on older research which suggested a link between dead baby bearded dragons and Adenovirus^[3]. Nevertheless, new research seems to be indicating that Atadenovirus is not the death sentence we thought it was and in fact something else (presently unknown) must be at play.

What Is Atadenovirus In Bearded Dragons?

It used to be thought that Atadenovirus in bearded dragons was a relatively rare – although highly contagious virus with a very high mortality rate. Whilst it is true that it is still believed to be highly infectious, it’s mortality rate, according to the latest research, appears to be very very low indeed. And it appears to be far more common than previously thought too.

Indeed, research from Hokkaido University in Japan suggests that around 57% of bearded dragons tested had active Atadenovirus infections. The number of infected individuals was higher in females than males, but was NOT higher in sick animals versus those with no symptoms^[1].

Another study, involving wild bearded dragons sampled from Australia suggested that 1 in 5 bearded dragons, across the different species, were carriers of Atadenovirus with no ill effects (except for one of the test subjects). The study in 2019 suggests that Bearded Dragons are in fact natural carriers of Atadenovirus[²]. It’s hard to think that a virus with such an allegedly high mortality rate would be so prevalent.

And finally (for us, for now) a separate study looked for the antibodies against Atadenoviruses in various reptiles, including bearded dragons, and concluded that most reptiles have antibodies against Adenoviruses. This included captive and wild caught species. This suggests they’ve all been exposed to Adenoviruses and fought off the infection. The study also posed the question for further research wondering if the Adenoviruses were as species specific as previously thought^[4].

Agamid Atadenovirus, or lizard Atadenovirus is one of the members of the Atadenovirus family, which itself is a member of the much larger, Adenovirus family. Adenoviruses are medium sized viruses that do not have any outer enclosing layer of lipids and they contain a double stranded DNA genome. They’ve gained their name because they were initially discovered in the adenoids of humans.

Throughout the family, their pathologic effects range from mild respiratory infections to severe organ failure in immunocompromised individuals. Human adenoviruses are one of the causes for the common cold – although adenoviruses can cause some nasty illnesses in susceptible people, such as viral pneumonia or other lower respiratory infections. But it’s worth noting that in otherwise healthy people, the symptoms are usually mild, and common.

Atadenovirus Symptoms

So, given what we’ve said above, what are the symptoms of Atadenovirus? Well, our conclusion from the latest research is that there often isn’t any. And given that the prevalence of Atadenovirus in sick animals was the same as it was in healthy ones^[1], is the cause of the illness actually down to Atadenovirus at all? It seems unlikely.

So what did people used to think the symptoms of Atadenovirus were?

Symptoms previously assigned to Atadenovirus included;

• Weight loss
• Diarrhoea
• Weakness / Lethargy / Depression
• Failure to thrive
• Stargazing – where the dragon continually stretches its neck upwards to “gaze at the stars”
• Flipping onto their back randomly

With the exception of the last two symptoms, the others are of course common across many different sick bearded dragon symptoms.

The latter two used to be ascribed to late stage, and usually fatal, Atadenovirus infection.

Our interpretation of the latest research is that Atadenovirus infection is an unlikely cause. However, it is important to note that more research is needed into Atadenovirus itself and, since it seems unlikely that these neurological symptoms are caused by Atadenovirus then more research is urgently needed to determine what the cause of these might be.

If it’s a contagion, then we may not be aware what contagion it is. But in many cases it may be tumours or something similar that hasn’t been discovered because a post mortem was never performed once one received the answer that the dragon died as an Atadenovirus positive dragon.

People used to assign these symptoms to Atadenovirus – in particular the ‘stargazing’ and ‘flipping onto their back’. This is clearly not true any more. Many bearded dragons with Atadenovirus display no symptoms at all. And of the remaining test subjects in the Japanese study, they all had respiratory infection symptoms, not neurological symptoms – which would be more consistent with human type adenovirus infection too.

It’s possible that the reason these symptoms were assigned to Atadenovirus is due to the article published in 2002 in the Journal Of Veterinary Diagnostic Investigation where the death of 30 (of 200) baby bearded dragons was assigned to Atadenovirus^[3]. The article itself does state though that the co-infection of Coccidia along with Atadenovirus could have been the cause. We’re still left wondering to this day.

Atadenovirus In Bearded Dragons, Prevention

Atadenovirus is spread in infected faeces between reptiles. Many different reptiles can be infected including water dragons, bearded dragons, chameleons, geckos, monitor lizards, turtles and tortoises and even snakes.

It is highly contagious among species and of course, being a virus, it’s incredibly small and you won’t be able to see it.

Given that we currently don’t seem to fully understand Atadenovirus infection, it’s probably wise to do everything we can to minimize the risk of transmission between reptiles in any case.

Hand Hygiene

If you mingle with multiple reptiles (whether for work or lesiure) you should always practice excellent hand hygiene. Wash your hands with soap and water regularly and always after handling a reptile before handling another reptile or touching any other surface. Wash hands in warm soapy water for 20 to 30 seconds at a minimum and ensure you cover all fingers, thumbs and backs of hands and wrists.

Quarantine

When bringing a new reptile into your house or into your bearded dragon’s environment, quarantine them first. Of course, we don’t recommend cohabiting bearded dragons with any other reptile, including other bearded dragons. But any newcomer should be quarantined in a completely separate room for a month or so before being trusted to be a non-carrier. If the newcomer displays any symptoms of illness then it may be a good idea to contact your reptile specialist vet for advise.

Atadenovirus Treatment

Given that we now believe that the symptoms previously ascribed to Atadenovirus are probably in fact not symptoms we would have to suggest that a trip to the Reptile Vet is going to be necessary.

But be aware, they may test for Atadenovirus and may well determine that the symptoms are due to its infection. We would suggest you respectfully and politely point to the latest research as they may not be aware of it themselves. Then, we would think that further tests would be warranted to ensure your bearded dragon gets the best treatment possible.

If your bearded dragon is experiencing seizures, stargazing or flipping on their back – symptoms that were previously ascribed to fatal Atadenovirus – they still need an urgent vet consult. But Atadenovirus probably is not the cause but merely a coincident finding.

And as with any of the illnesses experienced by bearded dragons, it’s wise to ensure your husbandry is up to scratch before suspecting any sinister pathogens for the cause 🙂

Thanks to Tracy Saltmarsh for providing the inspiration for us to go digging further and find the latest research for ourselves.

References

1: Akabane, Yoshihito; Oba, Mami; Hata, Keisuke; Ochiai, Hideharu; Katayama, Yukie; Omatsu, Tsutomu; Okumura, Atsushi; Okumura, Maho; Madarame, Hiroo; Mizutani, Tetsuya – Prevalence of Agamid adenoviruses of the bearded dragons (Pogona vitticeps) in Japan – Japanese Journal of Veterinary Research, 68(1), 47-53. February 2020. http://doi.org/10.14943/jjvr.68.1.43

2: Timothy H Hyndman, Jonathon G Howard, Robert JT Doneley – Adenoviruses in free-ranging Australian bearded dragons (Pogona spp.) – Veterinary Microbiology, Volume 234 pp74-76. July 2019. https://doi.org/10.1016/j.vetmic.2019.05.014

3: Dae Young Kim, Mark A. Mitchell, Rudy W. Bauer, Rob Poston, Doo-Youn Cho – An Outbreak of Adenoviral Infection in Inland Bearded Dragons (Pogona Vitticeps) Coinfected with Dependovirus and Coccidial Protozoa (Isospora Sp.) – Journal Of Veterinary Diagnostic Investigation, Volume 14 issue 4 pp332-334. July 1 2002. https://doi.org/10.1177%2F104063870201400411

4: Inna Ball, Sabine Öfner, Richard S. Funk, Chris Griffin, Ulf Riede, Jens Möhring, Rachel E. Marschang – Prevalence of neutralising antibodies against adenoviruses in lizards and snakes – The Veterinary Journal, Volume 202 issue 1 pp176 181. October 2014. https://doi.org/10.1016/j.tvjl.2014.07.027