Johne s Disease and its Impact on Red Meat Production Frank Griffin, University of Otago http://www.otago.ac.nz
Mycobacterium avium spps paratuberculosis (Map) causes Johne s disease Map looks harmless Map has waxy cell wall Map grows very slowly
A Map Attack in the gut tissues of animals Map Attack
Severe Haemorrhage/ Thickening Map attack (deer) Gut thickening after Map attack (cattle) ***This looks remarkably similar to Crohn s Disease in Humans
Extreme form of Map attack in deer gut tissues Multibacillary
Extreme Map attack in deer mimics Tb
Causative agent: Mycobacterium avium spps paratuberculosis (Map) Transmission of Map Faecal - Oral Highest risk to young fawns. May be controlled by improved farm hygiene Mother - Fetus May occur commonly with seriously diseased hinds (Colostrum after birth) Relative risk Deer to deer > Cattle to deer > Sheep to deer to deer
Strategies for Map control Different for each species (cattle, deer & sheep) Epidemiological (define risk and transmission) Management Options Diagnostics Microbial (fecal-live or tissue -dead) Immunological (Deer > Cattle > Sheep) Vaccination Cross reactivity in Tb testing (Sheep < Cattle and Deer) Select for Heritable Resistance Generic for all 3 species
Diagnosis of Map in farmed animals Microbial culture Slow (6-24 weeks) Most sensitive with Pm tissues ( Gold standard ) Histopathology Difficult to distinguish from TB Immune diagnosis Cross reactivity with other bacteria
Serology: An IgG1 ELISA for diagnosis of Infection Sensitivity of Test No. Test (+)/Total No. Infected. Specificity of Test No. test (-)/Total No. Not-infected.
Dataset for establishing Test Parameters Sensitivity : 300 Johne s disease animals Specificity : 500 Uninfected animals Use ROC analysis of data retrospectively to establish cutpoints for the assay
Specificity and Sensitivity values with PpAg 100 90 40 85 80 Sensitivity/Specificity (%) 70 60 50 40 30 sens specificity Linear (sens) 20 10 0 0 20 40 60 80 100 120 140 160 180 200 220 EU (490nm) The Test might be viable!!
Relationship : ELISA(+) and disease severity Lesion-positive animals Culture (+) H-1 H-2 H-3 ELISA(+) 77/100 39/43 37/40 66/67 ELISA sensitivity 77% 91% 93% 98.5% Inverse Relationship: Antibody & Disease Severity
Disease is the exception with Map Infection Farm No. Killed Johne s disease MAP +ve A 24 1 21 B 10 3 10 C 17 1 17 D 10 0 10 E 12 0 12 F 13 1 13 G 15 1 15 H 15 1 12 Total 116 8 (6.9%) 110 (94.8%) Most JD animals are undetectable at Meat Inspection
Proportion of Herds with Jd Reactors Herds Tested Number MAP(+) % NI 122 76 62.3% SI 525 332 63.2% Map infection is widespread equally throughout New Zealand
Trends for Jd Reactivity in Deer 20 Percentage Jd 10 0 SpringSummer AutumnWinter '03 '03/'04 '04 '04 Spring '04 Summer AutumnWinter '04/'05 '05 '05 Spring '05 Summer Autumn '05/06 '06 * Map infection is increasing annually throughout NZ
Reactor rate in infected herds 45 40 35 30 25 20 15 10 5 0 0 5-10% Herd prevalence (n>30) 15-20% % sero positive for JD 25-30% NI (n=9) SI (n=105) South Island n = 31,508 North Island n = 2,249 2006 Data 2007 data shows increase to higher infection levels
Serodiagnosis : Map Infection in a Herd involved in a Control programme 70 60 50 40 30 20 10 0 2002 2003 2004 2005 2007 Yea hinds stags
Production values and death rates in young deer relative to IgG 1 ELISA status Total IgG 1 test result Death Rate Mean weight (15 mo) Percent > 95 kg (15 mo) 201 Neg - Neg* 3% 104 kg 93% 39 Neg - Pos* 8% 100kg 77% 76 Pos 43% 90.3 kg 30% * 1st Test 6-8 mo: all Neg animals retested at 12-15 mo
Contribution Serodiagnosis could make at the herd level Removal of shedder animals - Reduce spread of Map Removal of subclinicals - Minimise production losses Accelerate removal of susceptible animals Increase proportion of resistant animals Diagnostics will reduce disease prevalence, but may not eradicate infection
Rates of seroreactivity in herds with a PLAN 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 1 2 3 4 5 6
Whimsical observations!!!
The Genome Deer Breed (A - G) effects on resistance 90.00% 80.00% 70.00% 60.00% 50.00% 40.00% Mixed sex Female Male 30.00% 20.00% 10.00% 0.00% A B C D E F G
The Phenome 0.7 0.6 0.5 0.4 0.3 Male Female 0.2 0.1 0 0 25 50 75 100 % of Breed xx xx xx xx
0.50 0.45 0.40 0.35 0.30 0.25 0.20 0.15 0.10 0.05 0.00 The Physiome Relationship between reactor rate and breeding values R 2 = 0.78 0 5 10 15 20 25 EBV
Conclusions! Take Home SIX PACK Map infection likely affects >50% of NZ Deer herd and > 10% of animals within most infected herds. Probably similar to NZ Dairy herds. The Iceberg Effect: Majority of Map infections do not cause overt Johne s disease (Pathology/ Clinical symptoms) Deer develop more florid cases of Johne s, than cattle or sheep, and could be more amenable to diagnosis than infection in cattle or sheep. Johnes may be the most, important & underestimated, infectious threat to primary farm production profitability in NZ. Host genes for Immune Responsiveness and Production Traits may significantly affect disease susceptibility. Should the link with Crohn s Disease become more credible, NZs Red meat and dairy products may be at SERIOUS RISK!
Acknowledgements: Farmers and Veterinarians - field support Douwe Bakker - Lelystad - PPDj John Bannantine - NADC, Iowa - r-proteins Geoff de Lisle and Gary Yates - AgResearch - culture Gary Clark - Histopathology FoRST NZ - Financial support
The Diagnostome: Diagnosis across the Infectious spectrum Th1 Th2 Exposure Immunity Infection Disease (Vaccination) (Diagnostics) (Resistance) (Susceptibility)