Veterinary Article

BOVINE BABESIOSIS

Dr. Mahwash Nazki, School of Animal Biotechnology, Gadvasu, Ludhiana.
Dr. Rabyia Javed, Department of Veterinary Microbiology, Gadvasu, Ludhiana.

Dr. Mahwash Nazki

Introduction

         Babesiosis is a tick-transmitted disease caused by protozoans of the genus Babesia and it is characterized by haemolytic anemia and fever, with occasional hemoglobinuria and death[1]. In India, babesiosis in bovines is mainly caused by Babesiabigeminaand Babesiabovis. Bovine babesiosis is a tickborne, intra-erythrocyticprotozoan parasitic infection that causes significant livestock loss. It is the most important arthropodborne disease of cattle worldwide. The most prevalent species, Babesiabovisand B. bigemina are found throughout most tropical and subtropical regions.The crossbred cattle exhibited higher rate of susceptibility than zebu and buffaloes, which mainly act as carrier [2].

Transmission

          B.bovis is transmitted by rhipicephalus ticks.The major vectors for B. bigemiaand B.bovis are Rhipicephalusmicroplus and R. annulatusbut B.bovis can also be transmitted by R. Geigyi.B.divergensis transmitted mainly by Ixodesricinus.

Symptoms

          The infected animals establish a life-long immunity against getting reinfected with the same species and cross-protection is seen in B. bigeminaimmune animals against subsequent B. bovis infections.Symptoms include high fever, dark coloured urine,anorexiaand neurologic signs such as incoordination, teeth grinding and mania are seen. Some of the cattle may even be found on the ground with the involuntary movements of the legs. InB. bigeminaa less severe form of symptoms are seen when compared to B.bovis.Fever,anorexia and haemoglobinuria are seen.However neurological signs are rarely seen.The survivors of the disease may be weak, although they often recover fully.

Diagnosis

           Babesiosis can be diagnosed by identifying the parasites in blood or tissues, polymerase chain reaction assays and serology. Mostly in acute infections the parasites are found in blood and tissues.Thick films may be of certain help in detecting small numbers of parasites,but identification of species is the best in thin films.Babesiacan be identified under oil immersion in stained blood and tissue smears. To supplement a blood smear, diagnoses should be made with an indirect fluorescent antibody (IFA) test. IFA testing has a much higher specificity than stained blood smears with antibody detection in 88-96% of infected patients[3].B. divergensresembles B. bovisbut the pairs are mostly found at the edge of the RBC .However B. bigeminais much longer (3–3.5 μm x 1–1.5 μm). Polymerase chain reaction (PCR) assays can detect and differentiate Babesiaspecies, and are mostly useful in carriers. Diagnosis of carriers is also done with in vitroculture. These animals may occasionally be identified by transfusing blood into a test calf but the procedure is laborious.Detection of antibodies to babesia can be done with an indirect fluorescent antibody (IFA) test or enzyme-linked immunosorbent assay (ELISA). Complement fixation and agglutination assays (latex andcard agglutination tests) can also be used.

Differential diagnosis

           Babesiosis resembles the conditions that cause fever and hemolytic anemia. The differential diagnosis includes theileriosis, bacillary hemoglobinuria, leptospirosis, anaplasmosis, trypanosomiasis,eperythrozoonosis and chronic copper poisoning. Rabies may also be a consideration in cattle with CNS signs.

Treatment

            Antiparasitic drugs are given. If the disease is diagnosed early treatment is most likely to be successful but it may fail if anemia has weakened the animal.Imidocarb has been seen to protect animals from disease .Blood transfusions and other supportive therapy shouldalsobe considered.

Prevention

            The most effective public health measure for Babesia is avoidance of tick exposure. This can be performed through personal prevention strategies such as avoiding tick-infested areas (especially during high tick season between May and September), remaining covered with light clothing, searching for ticks after being outdoors, and removing discovered ticks from the skin[4].

References

  1. Ristic M. Diseases of Cattle in the Tropics. Firts Edition ed. Ristic M, McIntyre I, editors. Vol. 6. The Hague: MartinusNijhoff Publishers; 1981. pp. 443–468.
  2. Jithendran K.P. A note on haemoprotozoan parasites of cattle and buffaloes in Kangra valley of Himachal Pradesh. Indian J. Anim. Sci. 1997;67:207–208.
  3. Laboratory Identification of Parasites of Public Health Concern, Babesiosis. CDC. Retrieved on 2009-03-05.
  4. Gelfand, Jeffrey A,Vannier, Edouard. "Ch. 204 : Babesiosis". Harrison's Principles of Internal Medicine, 17e. McGraw-Hill's Access Medicine