Adenovirus - The First Step

Based on this study that was performed and published in 2002 -
http://cat.inist.fr/?aModele=afficheN&cpsidt=13822415

30 of 200 (a 15% mortality rate) hatchling dragons perished with clinical signs of weakness and lethargy. 6 with neurological signs were euthanized for necropsy and examination and were determined to have coccidia and viral particles consistent with adenovirus and dependovirus.
None of the apparently healthy dragons were documented as being examined.

Of the remaining 164 dragons that possibly survived - the probability is high that they also may have been infected with these 3 pathogens. We have to ask ourselves how many of these dragons could have survived to a ripe age and lived happy, normal lives with no clinical signs of these infections - as we know now in 2006 that this is likely the case.

If the number of surviving dragons in this case is even half, at 82, and they were able to reproduce - let us consider how contagious/resilient adenovirus is believed to be, how prolific bearded dragons are and the degree of exchange in the USA

Applying this information to the mid 90’s, based upon the first diagnosed/documented case in the USA which was over 10 years ago by Dr. Jacobson… ((Remember, this is the 1st diagnosed case - not the first dragon to have contracted adenovirus.)) the possibility of wide-spread infection is likely - with outbreaks of illness occurring in crowded conditions, stressed individuals or immunocompromised animals.

Adenovirus is not new. “Adenoviruses have been isolated from every species of mammals, birds and amphibians studied.”
http://www.virology-online.com/viruses/Adenoviruses.htm


Dr. Jacobson is leading the way in research related to adenoviruses in reptiles. In a 2004 study “Detection and Analysis of Six Lizard Adenoviruses by consensus Primer PCR Provides Further Evidence of a Reptilian Origin for the Atadenoviruses”
http://jvi.asm.org/cgi/content/full/78/23/13366 the first sequence information from the lizard adenoviruses was performed. The findings indicate a particular adenovirus that is found in bearded dragons - which belongs to the genus Atadenovirus.
In closing the study calls for “the need for additional sequences from more hosts.”

To the bearded dragon community, we believe this is where we all need to step up to the plate. Those who have had positive results through EM testing - please consider additional PCR testing with Dr. Jacobson - You have the fecal samples that are needed to further any research and possibly identify or discount additional strains of the adenovirus in the North American bearded dragon population. Identification is paramount - it is the first of many steps needed.

It is unrealistic to claim to have knowledge of something of which there is minimal, factual information available.

Rob & Vickie

Vicki,

The first study you cite, I believe was Susanne's dragons, the same ones that were a part of Dr Wentz's studies and report in 2002. I may be wrong, but that was the lab he was working with at the time and she had 200 dragons infected. The others were examined and followed up, as the went to Dr Wentz for research and all tested positive also.

Some did survive and live a fairly normal life, it is the father of those babies that lived another 4 years and was still shedding viral cells during that time. It that the case for all? No one knows, but it was for him and all the babies he produced. The mother died after laying several clutches in a row, which is another thing that is often seen with infected females. If you would like, I have some emails from her back at that time, some when the father died and she does not object to those being shared with others, so if you want, I will dig them up and forward them to you.

I think there is some confusion on when it was first documented in bearded dragons, it appears there is even confusion on that, based on what Bruce says he is told and quoting other vets. There are other cases of adneovirus documented in the US and even some in Australia and New Zealand going back to 1990. The first documented case in the US was Dr Fredric Frye from a breeder colony in Illinois, in 1994.

Dr Jacobson has proposed a joint study with the University of Il (this is the lab that is being recommended for testing right now due to their low cost, prior labs were Univ or Fl and Louisiana State U ) on the fecal samples they get to compare them to PCR testing at his lab. He would like to do more studies on adenovirus, but right now he is concentration on IBD as that is where his intense studies have been for many years and he has much data on that. He did say maybe he could get a graduate student to work on this and then apply for some grants later.

Based on his 30 years experiences and what he does know of adenovirus in bearded dragons, he is very clear that "known positive animals should never be sold in the pet trade."

I think all of us are frustrated that there are not more answer out there for questions about this, but there is so little known of many virus in humans, let alone reptiles. The first human virus was only identified in 1981 I think and even HIV after that. I agree, we do need to step up to the plate, in ANY way that breeders who actually are dealing with this can and also breeders that have healthy non infected colonies... there are NO studies done of the % of the population that might already carry this. There has never been any tracking of the outbreaks of this either before. Sadly it seems that some really object to trying to do that and provide that information to researchers to follow up on. The reserachers are certainly happy to have it!


I am not sure what you mean by your last sentence.

Cheri,

I was going on the published information that is available to the public on this particular study. I found no published information on the animals that may have survived - and nothing to indicate that further studies or tests were being performed on those remaining animals.

I do appreciate the offer to forward emails concerning Susanne’s situation, but there is no need to unless they offer more details. What I would honestly like to review (if it is even available) is follow-up care and testing that was performed on these dragons and their father. We have studied Dan’s paper and conclusions. What is missing, for us at least, is the data to support it… How many EM tests were performed and on which dragons? At what time intervals were they performed? Where were the animals housed? How many animals housed per cage? Were the animals ever bred? If so, was it sibling-to-sibling? Father-to-offspring? How many clutches were produced? Eggs per clutch? Hatch rates and mortality? For us this information is relevant.
Since 2002 there have been no updates or additional papers produced by Dan.


I know of no studies or surveys that would indicate the % population that may be infected with adenovirus either, but by using the study above in a “what if” scenario the viral infection could very well be wide-spread, with occasional outbreaks of illness. Why would we suspect this to be so? There is evidence to support this theory based upon hatch rates and mortality rates alone of various breeders over the years.

In the book Bearded Dragons and Frilled Lizards, written by Andree Hauschild and Hubert Bosch (translated from German to English by John Hackworth in 2000) a summary of Husbandry Experiences of 12 small breeders/collectors of vitticeps (p.56,57) was reported. The dragons ages were 1-11, with 2 to 10 dragons per collection - totaling 47 dragons. (sex ratio of 17.30)
The average hatch rate of the 12 breeders was 79.9% - 3 of the 12 breeders experienced a 50% hatch rate and only 1 with 100% - which is on average 4 failed eggs out of every 20 laid.
In The Bearded Dragon Manual, written by Bob Mailloux and Phillie de Vosjoli it is stated that they estimate 15-25% of their eggs fail to hatch. An average of 20% failure.
The averages from Germany to the USA are almost identical - even with variances in husbandry - at 20% failure to hatch.

On page 30 in the Bearded Dragon Manual, the mortality rates of vitticeps are listed as 9-24% from various clutches.
The German publication does not list any mortality rates for the dragons charted. Based upon the similarity in hatch rates, lets assume the mortality rates are relatively close - possibly being a little better due to smaller size of the collections at 5-20%.

Keeping in mind that the information contained in these books was compiled in the 1990’s or earlier - Both of these scenarios are above the quoted 10% mortality rate that Dan states in his paper to be “suspect” of having the adenovirus.

Also in Dan’s paper regarding adenovirus he says “If two or more clutch mates are kept together and one is much smaller, suspicion should be high.” To keep this short, one statement, in one book attributes retarded growth to stress. Bearded Dragons and Frilled Lizards (p.30,31) “Naturally, it is important that all animals are approximately the same size otherwise problems will be unavoidable. This is illustrated by Sprenkel’s (1990) case in which stressed juveniles became retarded in their growth and then quickly became part of the diet of their siblings which were twice as large.”

Surely, these animals in Germany, in 1990 could have the adenovirus based on Dan’s statement. Or one could choose to apply Sprenkel’s observations and attribute retarded growth to stress. It could be adenovirus, it could be stress - or it could be the combination of the 2. These are only 2 of many contributing factors that could explain retarded growth. How about limited genetics, age/diet/productivity of the female parent, immune systems, coccidia levels, other pathogens, food preferences, temperature preferences, etc… There is also a theory on separating sexes at a very young age. All of these factors along with many others need to be considered. It is very easy (and we believe commonplace) to identify a specific factor and attribute blame without investigating the other possible factors.


We are not basing anything on what Bruce has posted himself or any of his quotes. All of our information has come from either documented scientific research, printed information or through our own experiences, conversations with various professionals and long-term breeders.

We simply did'nt mention the other cases that were in Australia or Illinois because they were respectively barbatus and henrylawsoni that were examined. I apologize, I should have been more clear in my statement… To the best of my knowledge, the first documented case of adenovirus in a vitticeps was by Dr. Jacobson in 1996.

I am happy that there is an opportunity for further study of the fecal samples being submitted. My hope is that those which test positive for adenovirus on an EM will go on to the PCR for further identification and classification. Even if studies are not being actively performed at this time - the data can still be processed and documented for future use. I understand that there are time & funding constraints and priorities to consider when it comes to a research project of this magnitude and I am not presuming that Dr. Jacobson and his team are even willing to do the studies.

I am not frustrated at the lack of available answers… but more so the un-asked questions, and the disregard of other available data/observations. I don’t mind receiving the response “I don’t know” but we believe the very next question should be “What can we do to find out?”

“Adenoviruses were first isolated from adenoids surgically removed from children in 1953 as part of a study to evaluate different tissues for growth of polio viruses by Rowe et al.” The information now available for the various types of human adenoviruses is invaluable. It has been 40+ years of gathering information - Information which has proven to be applicable to other species - if the medical/scientific connections can be made.
The problem is, there is no data to utilize - therefore no conclusions can be made.

Per Dr. Jacobson :
“It may turn out that there may be different strains of this virus in bearded dragons that cause different degrees of mortality. This eventually needs to be studied. Outcomes of lizards that are infected need to be studied. How long can a BD shed virus? The questions go on and on. Ultimately, transmission studies are needed to show that a specific virus can kill lizards.”

My last statement was in regard to the fact that there is much innuendo, supposition and guesswork on the adenovirus - but relatively no factual data that is available. If the experts’ responses are vague due to lack of research - how can we be specific?

The available “facts” can be spun to fit any scenario - as we did above.


Rob & Vickie