Exotic diseases – a growing concern?
Article first published online: 23 JUL 2013
© 2013 British Small Animal Veterinary Association
Journal of Small Animal Practice
Volume 54, Issue 8, pages 393–394, August 2013
How to Cite
Tasker, S. (2013), Exotic diseases – a growing concern?. Journal of Small Animal Practice, 54: 393–394. doi: 10.1111/jsap.12108
- Issue published online: 23 JUL 2013
- Article first published online: 23 JUL 2013
The UK Pet Travel Scheme was established in 2000 and allows the movement of dogs and cats into the UK from other countries. Between 2000 and 2012, approximately 973,000 dogs and cats travelled on the Scheme; with over 90% being dogs (data obtained from the PETS Statistics Database, ©Crown Copyright 2013). A relatively sharp rise in the number of dogs and cats travelling was seen in 2012, most likely because of new regulations introduced on January 1, 2012, which saw harmonisation of the UK's pet movement rules with the remainder of the European Union (EU) and an ease in the regulations required for pet travel. Under the new rules, pets from other EU Member States and listed approved countries no longer require blood sampling for rabies serology and a 6-month wait afterwards before entry into the UK is allowed. Pets can now enter the UK 21 days after their rabies vaccination. These changes were largely based on the results of quantitative risk assessment (available to download from http://webarchive.nationalarchives.gov.uk/20130407103041/http://www.defra.gov.uk/animal-diseases/a-z/rabies/) undertaken by the Veterinary Laboratories Agency, which concluded that the risk of rabies being introduced into the UK would remain very low despite the introduction of these changes.
Although consideration of the risk of rabies is necessarily important, an emphasis on this means that we often overlook the importance, and huge implications, of the development of “exotic” diseases, such as leishmaniasis, babesiosis and ehrlichiosis, in the UK in our travelling pets. The Acarus Laboratory in the Molecular Diagnostic Unit of Langford Veterinary Services, University of Bristol, has offered a diagnostic polymerase chain reaction (PCR)-based testing service since 2001, and over that time has diagnosed infection with Leishmania infantum in over 350 dogs, Ehrlichia spp. infection in over 170 dogs and Babesia spp. infection in over 160 dogs. Indeed, the Acarus Laboratory receives daily calls from veterinary surgeons seeking advice on the diagnosis and management of these conditions in imported or travelled dogs. The Dog And Cat Travel Risk Information (DACTARI) scheme was set up by DEFRA in 2003 as a voluntary national reporting scheme to investigate the occurrence of exotic diseases in dogs and cats in England, Wales and Scotland (reporting form available to download from www.defra.gov.uk/forms/files/dced1i-exotic-disease.pdf). However, it appears that only a minority of cases are being reported as data obtained from this scheme have documented only 71 cases of leishmaniasis, 23 cases of babesiosis and 23 cases of ehrlichiosis since 2001 (©Crown Copyright 2013), which is far lower than the numbers reported by the Acarus Laboratory alone; and the latter represents only one of several diagnostic laboratories in the UK that test for these exotic infections.
Babesia spp. and Ehrlichia spp. are transmitted by ticks, and the UK's new pet movement rules have also seen the removal of the obligatory requirement for tick treatment of pets before entry into the UK (the need for tapeworm treatment remains to prevent the introduction of Echinococcus multilocularis). The rationale for this is said to be because ticks are also able to enter the UK via non-pet means, such as vehicles and humans, so targeting pets for control is futile. However, avoiding the importation of ticks on our travelling pets is seen by many as something we should be doing by effective tick control; prevention of the introduction of novel vectors into the UK is potentially becoming more important as climate change may allow the establishment of such vectors in the UK, leading to these exotic diseases eventually becoming endemic. Regardless of the risks of tick introduction into the UK, the need for tick control, particularly prophylactically, for pets travelling outside of the UK is extremely important to help prevent dogs acquiring these infections and developing associated disease. Sand fly (for L. infantum control) and heartworm control may also be important, and a vaccine for leishmaniasis has recently been launched in the UK. Clients need to be educated that the UK's pet movement rules are not there to protect their pets and so they must seek veterinary guidance in employing appropriate preventive measures for the infections present in the countries they are travelling to.
Certainly the above facts highlight the risks we must appreciate in our travelling pets. But is a history of travel always required for these exotic diseases in UK pets? A very interesting case report appears in this edition of the Journal of Small Animal Practice (Wilson et al. 2013), in which the authors report a two-year old female neutered Tibetan terrier that was diagnosed with Ehrlichia canis infection despite not having travelled outside of the UK. The dog resided in London, travelling only to Sussex. Indeed, the authors also mention another case of E. canis infection being recently diagnosed in their clinic; a dog from Kent that had also never travelled outside of the UK. The authors postulate that E. canis could be becoming established in the southeast of the UK, or that ticks transmitting the infection have come into the UK via other dogs. Additionally, the Acarus Laboratory has also been involved in the diagnosis of Babesia spp. infections in two non-travelled dogs, both residing in Kent (unpublished data). However, dogs residing in the southeast of the UK are not the only ones found to have such infections as we have recently diagnosed a case of E. canis in a dog in Scotland (unpublished data). Leishmania infection in non-travelled dogs in the UK has also been documented (Harris 1994, Shaw et al. 2009 and unpublished data). It is, therefore, important to recognise the signs associated with these diseases and to test appropriately for them if consistent clinical signs are present, even in the absence of travel in the history.
The risk of these infections in healthy, non-travelled UK dogs, however, remains extremely low, as evidenced by another study published in this month's Journal of Small Animal Practice. Crawford et al. (2013) measured the prevalence of certain blood-borne infections by PCR in healthy, non-travelled UK dogs undergoing screening to be blood donors. They found that only 2 of 262 dogs had positive results when testing for Babesia spp., leishmania infection and Ehrlichia spp.; both positive results were for leishmania DNA, and both dogs were negative on repeat PCR testing, questioning the significance of even the small number of positive results reported.
Thus, as veterinarians, we need to be vigilant and aware of the potential for these infections to develop in our travelled, and non-travelled, pets. We need to be aware of the disease manifestations associated with infection, as testing animals showing clinical signs consistent with the diseases is important, and we need to be confident in how to confirm a diagnosis. Reporting confirmed cases is also important via the DACTARI system so that we have an objective method of documenting case numbers of exotic diseases in the UK, and whether they are, indeed, becoming less exotic. Lastly, as most cases still thankfully occur mostly in travelled dogs, we need to advise our clients regarding effective preventive measures available when travelling abroad with pets.
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Dr SéverineTasker, after graduation from Bristol Veterinary School in 1994, spent time in practice before moving to the Royal (Dick) School of Veterinary Studies, Edinburgh to take up a Feline Advisory Bureau Residency in Feline Medicine. She returned to the University of Bristol in 1999 where she undertook a PhD investigating feline haemoplasma infection, and is now a Senior Lecturer in Small Animal Medicine there. Séverine holds the RCVS Diploma in Small Animal Medicine, is a Diplomate of the European College of Veterinary Internal Medicine and has been a RCVS Recognised Specialist in Feline Medicine since 2003. Séverine currently works in the Feline Centre and is academic lead for the Acarus Laboratory, both in Langford Veterinary Services. Séverine is a recent recipient of the BSAVA Woodrow Award for outstanding contributions in small animal veterinary medicine and the Petplan Charitable Trust Research Award for outstanding contributions in the field of veterinary research. She has recently finished editing the BSAVA Manual of Feline Practice: a Foundation Manual.