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==Description==

==Description==

Equine babesiosis is a tick-borne protozoal infection of donkeys, mules, horses and zebra characterised by acute haemolytic anaemia. The disease is caused by the intraerythrocytic protozoa ''Theileria equi'' (formerly ''Babesia equi'') and ''Babesia caballi'' and is transmitted primarly by ixodid ticks. Equine babesiosis is endemic in most tropical and sub-tropical regions of the world where tick vectors are present. Only the United States, Canada, Australia, Japan, England and Ireland are not considered to be endemic areas. The disease is associated with high economic losses relating to treatment costs, loss of performance, abortion and death.

Equine babesiosis is a tick-borne protozoal infection of donkeys, mules, horses and zebra characterised by acute haemolytic anaemia. The disease is caused by the intraerythrocytic protozoa ''Theileria equi'' (formerly ''Babesia equi'') and ''Babesia caballi'' and is transmitted primarly by ixodid ticks. Equine babesiosis is present in most tropical and sub-tropical regions of the world where tick vectors are present. Only the United States, Canada, Australia, Japan, England and Ireland are not considered to be endemic areas. The disease is associated with high economic losses relating to treatment costs, loss of performance, abortion and death.

==Aetiology and Pathogenesis==

==Aetiology and Pathogenesis==

 

''B. caballi'' and ''T. equi'' are transmitted by ticks, which become infected when they ingest parasites in the blood of infected horses. Approximately 15 species of ticks in the genera Dermacentor, Hyalomma and Rhipicephalus can be vectors for these organisms. ''T. equi'' can also be transmitted by ''Boophilus microplus''. Infected adult ticks host several cycles of replication of Babesia spp and final maturation of the parasite occurs when the tick attaches to a new host. For this reason, the tick must remain attached to the host for a period of time (up to a few days) before infection can occur. Equine babesiosis may also be transmitted via contaminated surgical instruments, blood products or syringes. Currently, there is no evidence suggesting transmission by other insects. Following recovery from infection, horses may become lifelong carriers of the disease and represent a potential reservoir of parasites.  

''B. caballi'' and ''T. equi'' are transmitted by ticks, which become infected when they ingest parasites in the blood of infected horses. Approximately 15 species of ticks in the genera Dermacentor, Hyalomma and Rhipicephalus can be vectors for these organisms. ''T. equi'' can also be transmitted by ''Boophilus microplus''. Infected adult ticks host several cycles of replication of Babesia spp and final maturation of the parasite occurs when the tick attaches to a new host. For this reason, the tick must remain attached to the host for a period of time before infection can occur; this may require up to a few days. Equine babesiosis may also be transmitted via contaminated surgical instruments, blood products or syringes. Currently, there is no evidence suggesting transmission by other insects.  

 

Following recovery from infection, horses may become lifelong carriers of the disease and represent a potential reservoir of parasites.  

==Clinical signs==

==Clinical signs==

==Diagnosis==

==Diagnosis==

The clinical signs of babesiosis are variable and diagnosis may not be straightforward. Babesiosis should be considered in any horse that is pyrexic and icteric and has been imported from an endemic area. Direct identification of the parasites in blood using a Giemsa-stained blood smear is a commonly used method of diagnosis but is not suitable for identification of babesiosis in carrier horses. For these animals, serology using an indirect fluorescent antibody test or ELISA is recommended and are the basis of pre-import tests required by many countries.

The clinical signs of babesiosis are variable and diagnosis may not be straightforward. Babesiosis should be considered in any horse that is pyrexic and icteric and has been imported from an endemic area. Direct identification of the parasites in blood using a Giemsa-stained blood smear is a commonly used method of diagnosis but is not suitable for identification of babesiosis in carrier horses. For these animals, serology using an indirect fluorescent antibody test or ELISA is recommended and these are the basis of pre-import tests required by many countries. PCR in combination with reverse line blot (RLB) allows simultaneous detection and identification of different species infecting horses.

==Pathology==

==Pathology==

==Treatment==

==Treatment==

Specific anti-Babesia antibiotics (imidocarb diproprionate and buparvaquone) are used to treat the disease. The two drugs must be used in combination as used individually may lead to incomplete elimination of the parasite and the development of a carrier animal.  

Specific anti-Babesia antibiotics (imidocarb diproprionate) are used to treat the disease. Higher success rates are associated with treatment of ''B. caballi'' compared with ''T. equi''. Complications such as colic, hypersalivation and death have all been reported following treatment for Babesiosis and donkeys are particularly susceptible to secondary complications.

 

It has recently been reported, however, that even high dose treatment with imidocarb may not be capable of eliminating ''B. caballi'' and ''T. equi'' from healthy carriers.  

==References==

==References==

*Knottenbelt, D. D., Pascoe, R. R. (2003) '''Diseases and Disorders of the Horse''' ''Elsevier Health Sciences''

*Knottenbelt, D. D., Pascoe, R. R. (2003) '''Diseases and Disorders of the Horse''' ''Elsevier Health Sciences''