Prevention, diagnosis and treatment of Babesiosis
21 March 2016
Recent reports of Babesia canis being diagnosed in the UK have been especially notable in that the cases referred to a small number of dogs in Essex that had not travelled outside the UK. This is a reminder of the need to be alert to the presence of vector borne diseases not only in pets which have been abroad but also those with no history of travel.
Having received a number of enquiries from members, BSAVA has produced key information for the profession about the prevention, diagnosis and treatment of Babesiosis.
You can find this information below, along with references and useful links.
It is important to note that dog owners as well as members of the veterinary profession can send any ticks they might find to Public Health England’s Tick Recording Scheme or the Big Tick Project for identification.
Babesiosis has generally been considered a disease identified in dogs returning from travel to Europe, although there have been reports of babesiosis in untraveled dogs 4. Babesia spp. are recognised worldwide as intraerythrocytic tick-borne protozoan parasites. Babesia canis, Babesia gibsoni, Babesia vogeli and Babesia vulpes are all known to infect dogs in Europe 3,5,9,10.
B. canis is an intraerythrocytic tick-borne protozoan parasite endemic in much of mainland Europe. It is naturally transmitted by Dermacentor reticulatus ticks, which are found in the UK 7, and by Rhipicephalus sanguineus ticks, which are currently rare in the UK but there is concern that they could become established here 1,2,6, particularly after the removal of the need for mandatory tick treatment before entry into the UK with the change in pet travel regulations on 1st January 2012 1,2. Transmission via blood transfusion, transplacental transfer and dog bites has been reported. Feline babesiosis has been reported in South Africa and Israel 10, with one case report of a cat in the UK developing babesiosis 3 weeks after being imported from South Africa 13.
Recently, B. canis in three dogs in Essex with no history of foreign travel or contacts 11, and associated ticks, has been detected by the APHA.8
Babesiosis has a wide range of clinical presentations which vary with the species of Babesia and the host 3,9, with asymptomatic carriers are recognised. The signs can be subclinical to acute, and may be fatal. Owners may report lethargy, weakness and anorexia, and pallor or jaundice. Pyrexia, splenomegaly, haemolytic anaemia and thrombocytopaenia are typical clinical findings 3,8.
Vets should consider the possibility of babesiosis and other imported diseases as a differential diagnosis when presented with an animal with compatible clinical signs, even if there is no reported history of travel.
B. canis can be detected by direct visualisation and identification of the organism at the edge of blood smears taken from peripheral capillary beds (e.g. ear pricks). They usually occur in pairs and appear pear-shaped. B. gibsoni are smaller and circular. It is not always possible to see the organisms, and higher diagnostic sensitivity is found in sick animals when compared with sub-clinically infected dogs or cats.
Molecular techniques, including qPCR on EDTA blood, provide the most sensitive and specific diagnostic tests, these can give an indication of pathogen load and allow identification of the species which may offer prognostic information. Assays can vary between labs, and false positives and negatives can occur. The test should include internal positive controls to confirm successful nucleic acid isolation from the sample tested, the absence of inhibition, and correct functioning of the PCR reaction, and negative controls to ensure that DNA contamination has been avoided. Genetic sequencing is also available at specialist labs.
Serological testing is not very useful as it may indicate past exposure and not necessarily current infection, false negatives may occur early in the disease or with certain species, and there is also cross-reactivity with other species of Babesia. 11
Accurate diagnosis is most likely when multiple pathogen diagnostic assays are used, including microscopic examination, serology and molecular assays. Moreover, the presence of co-infections or concomitant diseases can complicate the diagnosis.
Blood-borne pathogens can remain viable and infective in blood products for long durations, and canine blood donors should be screened accordingly, preferably using multiple techniques 12.
Imidocarb dipropionate (licensed for cattle as Imizol) used off-licence with informed consent at 6.6mg/kg given i/m or s/c once and repeated in 14-21 days is considered the most effective drug for potential clearance of B. canis, but is often not effective in clearing smaller Babesia species. The safety and effectiveness of imidocarb have not been fully determined in puppies or in breeding, lactating or pregnant animals Clinical improvement is normally seen within 24–48 hours of starting treatment. Other supportive treatment options should be considered, including blood transfusion 5.
Treatment may not completely eliminate the parasite and dogs can become chronic long term carriers. These dogs should not be used as blood donors. The disease may recur if such dogs have immunosuppressive therapy or concurrent illness. 5
Avoidance of known tick areas, particularly during “tick seasons&”, use of an effective anti-tick product and daily checking for/effective removal of ticks may help reduce the risk of disease transmission.
1. Abbott, E. M., Arthur, J., Elsheikha, M. A., et al. (2011) Removal of tick controls for animals entering the UK. Veterinary Record 169 , 394
2. Anon (2012) Ticks and tickborne diseases: raising awareness of the risks. Veterinary Record 170, 351-352
3. Eichenberger, R. M., Riond, B., Willi, B., et al. (2016) Prognostic markers in acute Babesia canis infections. Journal of Veterinary Internal Medicine 30 , 174-182
4. Holm, L. P., Munro, E. R., Kerr, M. G., et al. (2006) Fatal babesiosis in an untraveled British dog. Veterinary Record 159 , 179-180
5. Irwin, P. J. (2009) Canine babesiosis: from molecular taxonomy to control. Parasites & Vectors 2 (Suppl 1):S4 1-9
6. Jameson, L. J., Phipps, L. P., & Medlock, J. M. (2010) Surveillance for exotic ticks on companion animals in the UK. Veterinary Record 166, 202-203
7. Medlock, J. M., Jameson, L. J. & Phipps, L. P. (2011) Status of Dermacentor reticulatus in the UK. Veterinary Record 168, 386-387
8. Phipps, L. P., Fernandez De Marco, M. D. M., Hernández-Triana, L. M., et al. (2016) Babesia canis detected in dogs and associated ticks from Essex. Veterinary Record 178, 243-244
9. René-Martellet, M., Valiente Moro, C., Chêne, J., et al. (2015) Update on epidemiology of canine babesiosis in Southern France. BMC Veterinary Research 11 , 223-233
10. Solano-Gallego, L. & Baneth, G. (2011) Babesiosis in dogs and cats – Expanding parasitological and clinical spectra. Veterinary Parasitology 181, 48-60
11. Swainsbury, C., Bengtson, G. & Hill, P. (2016) Tickborne diseases: Babesiosis in dogs Veterinary Record 178, 172
12. Wardrop, K. J., Reine, N., Birkenheuer, A., et al. (2005) Canine and feline blood donor screening for infectious disease. Journal of Veterinary Internal Medicine 19 , 135-142
13. Wells, R. (2012) Babesiosis in a recently imported cat. Veterinary Record 171, 654
How to pick your way through the jungle of ectoparasite treatments for dogs and cats from Companion January 2012
The 3rd edition of the BSAVA manual of Canine and Feline Clinical Pathology will include a chapter on the Diagnosis of protozoal and arthropod-borne disease and will be available at BSAVA Congress.