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 Information

Intra-erythrocytic Protozoan

Red blood cell destruction leads to anemia & death

No effective vaccines

No anti-babesial drugs approved for use in US

Babesia 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 includesMexico/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 Eradication

US Policy to prevent transmission

Tick surveillance and detection by physical scratching of animals

Quarantine infested areasTreat infested animals in Acaracide

dips on 14 day cycle

Regulate animal movement

Establish international Buffer Zone along Texas/Mexico Border

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Eradication, Prevention and Control

(cont.)

• Disease Control

Policy practiced by

Mexico, Brazil, Australia and most

other countries

Develop endemic stability

Utilize supportive therapy to aid the

recovery of infected animals

Directly or indirectly induce immunity

in cattle through exposure

Minimize 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”

GAVAC

tickGARD

• Ivermectin treated corn feeders and protein blocks to treat wildlife

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Recent Issues Dealing With Bovine Babesiosis

• Acaracide 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/cattle_fev

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