bovis - Articles
Babesiosis
Synonym(s): Redwater
Introduction
- Cause:
- Babesia divergens is responsible for clinical disease in temperate Europe and the U.K. and is spread by the sheep tick, Ioxodes ricinus.
- Babesia bigemina is responsible for clinical disease in Africa, Australia, Southern Europe, Central and Southern America.
- Although not present in the UK, Babesia bovis, is found throughout the world where boophilus ticks proliferate, in particular Southern Europe.
- Babesia major is a non-pathogenic species found in South East England.
- Signs: pyrexia, pallor, tachycardia, tachypnea, hemolytic anemia, icterus, hemoglobinuria and death. Cattle with the chronic form may suffer from marked emaciation, depressed milk yields and abortion.
- Diagnosis: demonstration of the organism on blood or tissue smears using Giemsa stain.
- Treatment: imidocarb (1-3 mg/kg) via the subcutaneous route.
- Prognosis: guarded.
Geographic incidence
- Worldwide.
- In the UK, certain regions are more at risk; eg parts of the Southwest and North Dorset.
Age predisposition
- Clinical disease is usually seen in older animals (over two year of age).
- It is seen in younger animals, but is less severe and farmers may not even notice it.
Breed/Species predisposition
- Bos indicus have a higher degree of resistance to disease and infected ticks than Bos taurus Bos taurus.
Public health considerations
- Although generally host specific, babesia divergens and babesia bovis are zoonotic agents.
Cost considerations
- Depressed milk yield in dairy cows and mortality in 5-10% of treated cases.
Special risks
- Profound anemia.
Pathogenesis
Etiology
- Cattle and the tick hosts serve as the main reservoir of infection Cattle ticks: overview.
- Clinical disease is almost always transmitted by ticks, but like other blood borne diseases, iatrogenic transfer via needles or surgical interventions is possible.
Predisposing factors
General
- Naïve cattle introduced into an endemic area.
- Infected cattle introduced into an uninfected area.
- Cattle grazed on rough grazing.
- Infected ticks transported on cattle or wildlife such as deer into an uninfected area.
- Physiological stress, for example, malnutrition, transportation or parturition.
- There is an increased incidence of disease during periods of peak tick activity, namely the spring and autumn.
Pathophysiology
- After inoculation as sporozoites, the parasite enters the erythrocytes and undergoes further division into trophozoites and then merozoites
. - Rupture of the erythrocytes occurs with emergence of the merozoites and the classical signs of the disease.
- Ticks become infected by feeding on infected cattle and the parasites are passed onto the ovaries of the ticks so that all new generations of ticks are infected.
Timecourse
- Clinical signs manifest 2-3 weeks after tick infestation.
Epidemiology
- Passively acquired resistance from colostrum Colostrum: overview lasts about 2 months but is followed by innate immunity to babesiosis from 3 to 9 months of age.
- In endemic regions calves are usually exposed to babesia between 3-9 months of age and rarely develop clinical disease followed by long term immunity of up to 4 years duration. However, should calves fail to be exposed within this 3-9 month window for example following a decrease in infected tick numbers, endemic instability will ensue, making these calves susceptible to disease outbreaks later in life.
Diagnosis
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Treatment
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Prevention
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Outcomes
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Further Reading
Publications
Refereed Papers
- Recent references from PubMed and VetMedResource.
- Hoch T, Goebela J, Agoulona A & Malandrina L (2012) Modelling bovine babesiosis: A tool to simulate scenarios for pathogen spread and to test control measures for the disease. Prevent Vet Med (106), 136– 142 PubMed.
- Taylor M (2000) Protozoal disease in cattle and sheep. In Practice (22), 604-617.
Other sources of information
- Zaugg J L (2015) Diseases of the Organ Systems. In: Smith B P Large Animal Internal Medicine. 5th edn. Elsevier, USA. pp 1056-1058
- Brown C & Torres A (2008) USAHA Foreign Animal Diseases. 7th edn.