Herpes Virus Infections in Pet Trade Tortoises - A Warning
Herpes is an extremely serious, usually fatal disease in tortoises. It should not be confused with herpes-virus infection in humans, which is a relatively mild condition. In chelonia, herpes-virus infection can cause massive lesions, swelling, respiratory distress, hepatitis and subsequent death. Affected animals may also suffer from concurrent fungal, bacterial and protozoan infections, presumably as a result of a compromised immune system. There is no effective treatment at present. Mortality once advanced symptoms appear is typically 100%.
This disease is contagious. A single affected animal can infect others that come into contact with it. Direct contact involving shared feeding, or contact with an affected animal’s bodily fluids or excretions is particularly dangerous. Such situations, this disease can spread rapidly through an entire tortoise collection and there are many reports in the veterinary literature that support the view that should that occur, 100% mortality can be expected (see below). Certainly, in all the cases we have seen, there have been no long-term survivors once advanced symptoms commence.
There are a number of points which at present remain unclear.
The first is the ‘incubation’ time from infection to the time when first symptoms appear. There is evidence that this may be measured in years. In one case, the tortoise did not develop serious symptoms for 10 years following exposure. Most cases, however, do develop very much more rapidly. Throughout this period the infected animal can be shedding virus that can in turn infect others. Such animals may display no outward sign that they are infected.
The second question to which at present we do not have an answer is whether the Herpesvirus detected is primary, or is itself secondary to an as yet unidentified causal organism. Several different viral pathogens have been identified as possible agents.
The most important thing that keepers can do is to maintain strict quarantine of all existing stock. On no account introduce other animals of unknown origins, and especially animals of trade origin. Because of the way in which trade animals are both exposed to multiple contacts with other tortoises, and are subject to high levels of stress, these tortoises are exceptionally high risk. Unfortunately, six or even eighteen months quarantine is completely inadequate when confronting a viral disease of this nature. The only effective solution is not to allow contact on a permanent basis. Feeding together, fighting or mating are highly effective routes for transmission.
Good hygeine measures are also essential. Wash hands thoroughly between handling tortoises. Do not share feeding utensils. Avoid spreading particles from one pen or enclosure to another. Wear disposable latex gloves when handling sick tortoises. Dilute bleach is an effective disinfecting agent for utensils, etc.
It should be noted that herpes has now been diagnosed in tortoises purchased from online dealers in the UK. We would strongly recommend that you do not buy such imports as they are at extremely high risk of being carriers of this devastating disease. If you do buy them please see the FAQ below for recommended handling procedures.
Do ensure that you obtain a written statement of the origins of any animals that you do purchase in advance (import or UK captive-bred) as knowing the origins of an animal is vital to forming an accurate risk assessment. We would not advise relying upon verbal assurances. While some sources are honest, others are not, and may present wild-caught imports as captive-bred in this country. If someone is reluctant to provide a written assurance of origin you should treat this with suspicion. An honest breeder or dealer will have no problem with such a request.
Symptoms in the tortoise recently diagnosed included severe lesions with blisters, diphteresis of the tongue and
pharynx, oedema, and puffy eyes. The tortoise did not eat voluntarily since
it was purchased. Ultimately, euthanasia was
advised, but death from the infection ocurred first.
FAQ
We have added this Frequently Asked Questions section to deal with some of the misinformation on this topic circulating on the internet.
Q. Is it true that the Tortoise Trust is claiming that there is a Herpes epidemic among imported tortoises?
A. No. Absolutely not. What we have actually said - repeatedly - is that such animals should be regarded as "high risk". The reasons for this are fairly obvious when you consider the number of animals involved in these imports, their inevitable close contact with each other during holding and transit, the levels of stress they are subjected to (stress has been suggested as an agravating factor in chelonian herpes), and the difficulty of establishing and tracing any contacts. With any contagious or infectious disease these factors inevitably amplify risk.
Q. Is it appropriate to warn of such a danger on the basis of only a few suspected or confirmed cases?
Yes. Firstly, for a tortoise to manifest with advanced symptoms and die within a
few weeks of purchase it is beyond any doubt whatsoever that that animal has
been actively shedding infective live virus particles in huge numbers for
months. Any other tortoise that contacts those particles is highly likely to
have acquired the disease. The "incubation time", from first infection to
first symptoms appearing can be very extended: months or even years. Throughout
that time, though appearing outwardly healthy, those animals themelves shed
live virus and are highly contagious. This tends to create a false sense of
security for keepers.
Dealer's and shipper's premises are not geared
to disease control and
prevention. Large numbers of animals are in very
close proximity and even physical contact. As such, they are a very
effective amplification mechanism for infectious and contagious diseases.
You only need one animal shedding virus particles in that environment to
infect hundreds or even thousands. That is why even a single case is important and should not be underestimated or dismissed.
Q. Should I be worried?
A. We would prefer to say that you should be concerned. The wisest course of action is to assume the worst and hope for the best. Take extra precautions and be particularly careful of "holiday homing", tortoise meetings where animals are present, breeding loans, etc.
Q. Can this affect humans? Am I in any danger myself?
A. There is no evidence to suggest that at all.
Q. Does it just affect Russian tortoises?
A. No. It has been recorded in many species. See list of references. It can also "jump the species barrier" between different tortoises.
Q. What would happen if this did get into my collection of tortoises?
A. We can only refer you to an actual case history reported by one of our members and subsequently reported in the veterinary literature. The consequences are extremely serious and far-reaching. That is why we take such a strong stand on this subject. We have also seen this ourselves at first hand. To those who allege that the Tortoise Trust is "scaremongering" on this topic, we simply urge you to read the above.
Q. Is this new, or has this happened before?
A. The first recorded cases date back more than 20 years. In fact, as long ago as 1989 the Tortoise Trust was the first organisation in the world to specifically highlight the potential importance of viral diseases to tortoise keepers and to issue specific guidelines to avoid cross infection. We were also the first organisation to highlight the dangers of mixing different species. So, this is not "new". The threat has been there for some time and outbreaks have been reported from all over the world, including Japan, the US, South Africa and throughout Europe (see the list of references below for some specific examples). What is relatively new is the vast surge in imports of questionable origins and in such a situation, the danger of wider disemination of such diseases increases exponentially. With reduced animal movements, the risk decreases.
Q. Can this travel through the air?
A. Not directly. It is contagious rather than infectious. What that means is that some form of physical contact or transfer is required. In the latter case, faecal material, or contaminated feeding equipment, or transfer of substrate should be regarded as a possible way to spread the disease. Precautions to eliminate this possibility should be undertaken. We have some practical suggestions written by a qualified microbiologist on the veterinary section of this website.
Q. Is it true that only tortoises from dealer's might be affected? What about rescue centres? What about animals from UK breeders?
There is some element of risk with all tortoises, from any source. It is only the degree of risk that varies. At the lowest end would be a single tortoise that has been in isolation for very many years without ever being mixed with others. For example, a 'pet tortoise' obtained 30 years ago and kept by one owner. The risk in a case like that is absolutely minimal. Of very low risk would be animals from an enthusiast who has kept a closed group for many years and who has never mixed species or allowed any form of contact with other tortoises. In the low-medium risk category would be animals from a careful genuine breeder who has very good quarantine and hygeine practices and who does not mix species or introduce new breeding stock. In the medium risk category we could place enthusiasts with larger collections and less careful breeders . Well managed rescue centres must also be considered medium risk as it is not always possible to know the history of all the animals involved. The more animals that pass though a location, the higher the risk. That would increase to very high risk if the recue centre has poor hygeine standards or mixes different species. Enthusiasts who attend meetings with tortoises or who constantly add new animals to their groups are also placing themselves in the very high risk group. It should be noted that by adopting good practices and by being very careful you not only massively reduce the danger of introducing diseases such as herpes-virus, you also massively reduce the risk of many other diseases too, such as 'Runny Nose Syndrome' and bacterial stomatitis, shell-rot, etc.
Q. What should I do if I already have, or plan on getting, tortoises from a high-risk source?
A. It would be best to establish these as a completely separate, self-contained group and to take adequate steps to prevent any cross-contamination taking place with other tortoises. Ideally, they should be in pens physically as far removed as possible from your other animals. Do not share vivariums or other accessories and do not walk between pens without changing or sterlising footwear. See the article on disease prevention for guidelines on how to reduce the risk of any disease that might be present from spreading.
Q. If I breed from a high risk tortoise or group, will the hatchlings be safe or will they also present a threat?
A. We simply do not know the answer to that at present. More research is required.
Q. Are you saying that people should not ever buy imported tortoises?
A. We are merely pointing out that they are in a very high risk group. If you do buy them, and permanently quarantine them in accordance with the advice above then you should be reasonably safe even if the worst happens as any outbreak will be restructed to that single, isolated group. If you have mixed them, or allowed cross-contamination with other tortoises in your collection, the consequences will of course be much worse.
In summary, there is no reason for panic at all. Simply take extra precautions by being ultra-careful in terms of handwashing and general hygeine, and do not introduce high risk animals into your collection. A 'closed' collection is by far the safest course of action.
Further Reading:
Cooper, J.E., Gschmeissner, S. and Bone, R.D. 1988. Herpesvirus- like Particles in Necrotic Stomatitis of Tortoises. Veterinary Record 123, (21), p544.
Frost, J.W. and Schmidt, A. 1997. Serological evidence for susceptibility of various tortoise species to herpesvirus infection. 38 Intemationalen Symposiums uber Erkrankungen der Zoo und Wildtiere Vom 7-11 Mai. 1997. Zurich / Scweiz. pp25-27.
Heldstab, A. and Besetti, G. 1982. Spontaneous Viral Hepatitis in a Spur-Tailed Mediterranean Land Tortoise. Journal of Zoo Animal Medicine. 13, pp113-120.
Marschang, R.E., Gravendyke, M. and Kaleta, E.F. 1 a. Herpesviruses in tortoises: Investigations into Virus Isolation and the Treatment of Viral Stomatitis in Testudo hermanni and T graeca. J Vet Med B 44, pp385-394.
Marschang, R.E., Gravendyke, M. and Kaleta, E.F. 1997b. New Investigations on herpesviruses in tortoises. 38 Internationalen Symposiums uber die Erkrankungen der Zoo und Wildtiere Vom 7-11 Mai 1997. Zurich / Scweiz. pp29-34.
Muller, M., Sachsse, W. and Zangger, N. 1990. Herpesvirus- Epidemie bei der griechischen (Testudo hermanni) und der maurischen Landschildkrote (Testudo graeca) in der Schweiz. Scheiz. Arch. Tierhilkd. 132: pp199-203.
Oettle, E.E., Steytier, Y.G.M. and Williams, M.C. 1990. High Mortality in a Tortoise Colony. South African Journal of Wildlife Research 20, (1), pp21-25.
Necrotic Stomatitis of Tortoises. Veterinary Record 123, (21), p544.Frost, J.W. and Schmidt, A. 1997.
Serological evidence for susceptibility of various tortoise species to herpesvirus infection. 38 Intemationalen Symposiums uber Erkrankungen der Zoo und Wildtiere Vom 7-11 Mai. 1997. Zurich / Scweiz. pp25-27.
Heldstab, A. and Besetti, G. 1982. Spontaneous Viral Hepatitis in a Spur-Tailed Mediterranean Land Tortoise. Journal of Zoo Animal Medicine. 13, pp113-120.
Marschang, R.E., Gravendyke, M. and Kaleta, E.F. 1 a. Herpesviruses in tortoises: Investigations into Virus Isolation and the Treatment of Viral Stomatitis in Testudo hermanni and T graeca. J Vet Med B 44, pp385-394.
Marschang, R.E., Gravendyke, M. and Kaleta, E.F. 1997b. New Investigations on herpesviruses in tortoises. 38 Internationalen Symposiums uber die Erkrankungen der Zoo und Wildtiere Vom 7-11 Mai 1997. Zurich / Scweiz. pp29-34.
Muller, M., Sachsse, W. and Zangger, N. 1990. Herpesvirus- Epidemie bei der griechischen (Testudo hermanni) und der maurischen Landschildkrote (Testudo graeca) in der Schweiz. Scheiz. Arch. Tierhilkd. 132: pp199-203.
Oettle, E.E., Steytier, Y.G.M. and Williams, M.C. 1990. High Mortality in a Tortoise Colony. South African Journal of Wildlife Research 20, (1), pp21-25.