Post on 04-Jul-2015
transcript
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