Epidemiology of Cattle Diseases (Transmission and Prevention)

Floron C. Faries, Jr., DVM, MSProfessor and Extension Program Leader

Texas AgriLife Extension ServiceTexas A&M System

College Station, TX 77843http://extensionvetmed.tamu.edu

I. Sources

A. Carrier/Reservoir Animals1. Aerosol Droplets 8. Milk 2. Nasal Fluid 9. Fetal Fluid3. Ocular Fluid 10. In Utero 4. Saliva 11. Genital Fluid5. Skin 12. Blood6. Manure 13. Carcass7. Urine

B. Vectors 1. Ticks 2. Flies 3. Mosquitoes 4. Scavengers

C. Vehicles 1. Instruments

a. Needle b. Ear tagger c. Tattooer d. Dehorner e. Nose tong f. Knife

2. Utensils a. Bucket

b. Trough

D. Environment 1. Soil 2. Water 3. Food

II. Exposures

A. Susceptible Animals1. Mouth 6. Vagina

2. Nose 7. Prepuce3. Eyes 8. Transplacental4. Skin 9. Venereal5. Teats 10. Blood

III. Incubation Period

A. Long/Short B. Exposure to Symptoms C. Exposure to Positive Tests D. During Incubation Period

1. No Symptoms2. Negative Tests

E. After Incubation Period1. Symptoms

2. Positive Tests

IV. Latent Infections (Recrudescent Infections)A. Extended Incubation Period

1. No Symptoms 2. Negative Tests

B. After Recrudesces 1. Symptoms 2. Positive Tests

C. Injury1. Blackleg2. Malignant Edema3. Black Disease4. Black-Neck Disease

D. Diet Change/Overload 1. Enterotoxemia

E. Flukes 1. Redwater

F. Stress1. IBR/PI3/BVD/BRSV

2. Pasteurella/Haemophilus

G. Pregnancy in Heifers1. Brucellosis

V. Non-Latent Infections

A. Normal Incubation Period 1. Lepto

2. Vibrio 3. IBR/PI3 /BVD/BRSV

4. Pasteurella/Haemophilus 5. Brucellosis in Cows

VI. Stress Factors

A. NutritionB. WeatherC. PregnancyD. CalvingE. WorkingF. WeaningG. ShippingH. BreedingI. Walking

VII. High Risk Herds

A. Identify SourcesB. Separate Carrier/Reservoir Animals

(Shedders)C. Reduce Commingling

D. Vaccinate Susceptible Animals1. Not 100% Protection

a. No responseb. Improper procedures

c. Mishandled vaccined. Expired vaccine .e. Stored opened vaccinesf. Poor quality vaccineg. Primary dose only

2. Long/Short Protection 3. Vaccinate before exposure 4. Does not prevent recrudescence in latent infections

E. Biosecurity Measures1. Raise replacements2. Purchase entries from clean herds3. Test purchased entries4. Vaccinate purchased entries5. Isolate purchased entries6. Restrict visitor and vehicle entries7. Construct buffer zone fencing