Babesia spp

From Cow
Intraerythrocytic Babesia bigemina in bovine blood

Babesia spp are an intraerythrocytic rickettsiales protozoan parasite (family Anaplasmataceae) bacteria which causes Babesiosis (tick fever), anaemia and abortion.

Babesiosis is of significant economic concern to the beef and dairy cattle industries in tropical and subtropical regions worldwide.

The main pathogenic species of Babesia include:

The main vectors of Babesia spp are ticks, especially Rhipicephalus spp, in which transmission occurs through feeding by adults and larvae[2]. Cattle that recover from Babesia infections are generally immune for life. Bos indicus cattle are more resistant to ticks and hence development of Babesiosis. In endemic infections, calves are often born immune to infection.

Clinical signs

Acute babesiosis is characterised by fever, anaemia, dyspnea and in severe cases, icterus and hemoglobinuria. Pregannt cows may abort.

Diagnosis

Diagnosis is based on circumstantial evidence of cattle in tick-endemic regions with clinical signs of tick fever, supported by laboratory isolation and identification of Babesia spp in the blood.

Giemsa-staining of blood samples, and serology testing can help identification of Babesia, but PCR assays are considered definitive methods of diagnosis.

A differential diagnosis must include other causes of tick fever such as Anaplasma spp.

Treatment

Effective treatment of individual cattle can be achieved through use of imidocarb, tetracyclines, enrofloxacin or diminazene aceturate.

Live, attenuated vaccines are available in certain countries (Argentina, Australia, Brazil, Israel, South Africa, and Uruguay) but breakdowns have been reported. Several experimental recombinant antigen vaccines have been developed.

Control of this parasite is usually effective with topical acaricides such as ivermectin, doramectin and fipronil[3].

Commercially available synthetic acaricides are commonly used, but indiscriminate practices in their application have resulted in the rapid evolution of resistance[4]. Although single acaricide treatment can destroy all of the ticks on an animal, they will not prevent reinfestation.

The infested pasture must remain free of all livestock for 6 to 9 months or longer, to break the tick life cycle.

References

  1. Shebish E et al (2012) Prevalence and molecular detection of Anaplasma marginale, Babesia bovis and Babesia bigemina in cattle from Puntarenas Province, Costa Rica. Vet Parasitol 188(1-2):164-167
  2. Merck Vet Manual
  3. Kiss T et al (2012) Tick prevention at a crossroad: new and renewed solutions. Vet Parasitol 187(3-4):357-66
  4. Veiga LP et al (2012) Resistance to cypermethrin and amitraz in Rhipicephalus (Boophilus) microplus on the Santa Catarina Plateau, Brazil. Rev Bras Parasitol Vet 21(2):133-136