Bovine Babesiosis: Overview and Current Issues

Jose S. Portugal III1 and Pete D. Teel2

1Senior, Entomology Major and, 2Professor and Associate Department Head

Department of Entomology, Texas A&M University, College Station, TX

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Bovine Babesiosis Common Names

• Tick Fever• Cattle Fever• Texas Fever• Redwater• Piroplasmosis

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History and General Information

• Historic Perspective 1893 first recognized arthropod vector Spread over 14 southern states and California Major cause for the demise of early cattle drives Retarded economic development of cattle

industry Tick Eradication Programs initiated 1906 Declared successful by the USDA in 1943 Threat continues from cattle and ticks in Mexico

• Impact of Pathogen Estimated costs of out break in American herds

in the billions annually A mortality rate exceeds 50% in naïve cattle of

European breeding (Bos taurus)

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History and General Information(cont.)

• Pathogen InformationIntra-erythrocytic ProtozoanRed blood cell destruction leads to anemia & death No effective vaccinesNo anti-babesial drugs approved for use in USBabesia bigemina and B. bovis are principle

pathogens in Western Hemisphere

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Principle Tick Vectors

• Rhipicephalus (Boophilus) microplus, known as the Southern or tropical cattle tick

• Rhipicephalus (Boophilus) annulatus, known as the cattle tick

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Rhipicephalus (Boophilus) microplus

• Prefers tropical and sub-tropical environment Regions with high rainfall ideal

• Distribution pan-tropical Mexico/Central America South America Southern Asia Australia Brazil Indian Subcontinent Parts of Africa

• Identified in quarantine zones on Texas/Mexico border typically east of Laredo as well as on the California/Mexico border

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Rhipicephalus (Boophilus) annulatus

• Associated with temporate to sub-tropical climates

• Global distribution includes Mexico/Central/South America Middle East Mediterranean Area Southern Asia

• Identified in quarantine zones on

US/Mexico border typically west of Laredo

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One Host Tick Biology

Larvae, nymphs and adult ticks feed, molt, and mate on one host The on-host sequence requires 20-25 days Engorged female ticks drop to ground to lay eggs and produce 6-legged

larvae The off-host sequence may last 6-9 months without a subsequent host Multiple generations of ticks are produced each year.

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Pathogens of Bovine Babesiosis

• Babesia bigemina

• Babesia bovis

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Transmission

• Sporozoites pass to cattle from infected ticks through blood feeding & enter red blood cells

• Reproduce asexually rupturing red blood cells upon release of merozoites

• Re-enter gut of subsequent ticks through feeding process

• Reproduce sexually within tick• Infect developing eggs of next tick

generation

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Extended Risk-Native and Exotic Ungulates

• Native– Cattle– Buffalo– White-tailed Deer– Horses

• Exotic– European red deer– Nilgai Antelope

• Possible Babesia reservoir

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Physical Symptoms

• Hemoglobinuria• Fever• Malaise• Confusion• Icterus/Jaundice• Weight loss• Depression• Lack of coordination

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Laboratory and Genetic Testing

• Microscopy Wright-Giemsa stain >1 parasite in 106 RBC’s

• PCR (Polymerase Chain Reaction) Via ELISA (Enzyme Linked Immunosorbent

Assay) Detects presence of antigen only Confirms exposure not infection

• IFA (Indirect Fluorescent Antibody) Detects antibodies due to exposure Not specific Requires high antibody titer

• In-vitro Cultures and Latex Agglutination Still in testing phases

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Eradication, Prevention and Control

• Tick EradicationUS Policy to prevent transmissionTick surveillance and detection by

physical scratching of animalsQuarantine infested areas

Treat infested animals in Acaracide dips on 14 day cycle

Regulate animal movementEstablish international Buffer Zone

along Texas/Mexico Border

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Eradication, Prevention and Control(cont.)

• Disease ControlPolicy practiced by Mexico, Brazil,

Australia and most other countries Develop endemic stabilityUtilize supportive therapy to aid the

recovery of infected animalsDirectly or indirectly induce

immunity in cattle through exposureMinimize economic and animal

health impacts of disease

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Additional Methods Explored to Combat Fever Ticks

• Countries such as Mexico and Australia have begun to target the Fever Tick vector

• Experimentation with “Tick Vaccines”GAVACtickGARD

• Ivermectin treated corn feeders and protein blocks to treat wildlife

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Recent Issues Dealing With Bovine Babesiosis

• Acaricide resistance increasing• Ungulate reservoirs

intermingling with cattle• Eradication vs. Disease Control

incompatibility• Rapid transport of cattle between

regions• Increased demand for beef and

dairy• Lack of funding

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Sources and Additional Information

• http://www.tahc.state.tx.us/animal_health/fevertick/fevertick.html• http://nsu.aphis.usda.gov/inventory/activity.faces?INVENTORY_NUMBER=89• http://vetpda.ucdavis.edu/parasitolog/Parasite.cfm?ID=196• http://www.chron.com/disp/story.mpl/metropolitan/4696674.html• http://www.vet.uga.edu/vpp/archives/NSEP/babesia/ENG/epidemiology.htm• http://ddr.nal.usda.gov/bitstream/10113/10189/1/IND43901455.pdf• http://www.cfsph.iastate.edu/Factsheets/pdfs/bovine_babesiosis.pdf• http://www.tahc.state.tx.us/animal_health/fevertick/FeverTickProgram.pdf• http://www.animalagriculture.org/Information/Publications/Cattle/2007/Spring.pdf• http://www.conasamexico.org.mx/conasaplanestratgarrap.pdf• http://www.nrrbs.com.au/animalhealthivomec.htm• http://www.nsrl.ttu.edu/tmot1/bosetrag.htm• http://wiienvis.nic.in/ungulatesofindia/meghalaya.htm• http://www.aphis.usda.gov/publications/animal_health/content/printable_version/cat

tle_fever_ticks.pdf• http://lib.bioinfo.pl/paper:17186273• http://www.aphis.usda.gov/vs-tx/tick.htm