Johne’s Disease: Milk ELISA Testing

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Johne’s Facts

• Myobacterium paratuberculosis is the causative agent of Johne’s disease and attacks the lower intestine.
• Johne’s is usually introduced to a herd through the purchase of infected animals.
• The organism is spread via contaminated manure or milk (colostrum) or in utero. A majority of animals contract Johne’s when they consume feed or water that is contaminated with the bacteria.
• Newborn calves or young animals are the most susceptible to infection.
• Symptoms include weight loss (even with normal appetite), lower milk production, diarrhea, and eventually death.
• Average cost to a dairy producer who has at least 10% of cull cows showing clinical signs of Johne’s is $227/cow per year.
• This could result in an annual loss of nearly $23,000 in a 100-cow herd.

About Lancaster DHIA Johne’s Milk ELISA

• Detects antibody response to M. paratuberculosis in fresh, frozen or DHI preserved milk samples.
• The Johne’s Milk ELISA is equivalent to a commercial blood ELISA test.
• USDA NAHMS 2002 Survey: “The milk ELISA performed equivalent to the serum ELISA, and has the advantage of decreased labor costs on farms that use DHI testing.”
• ELISA E (Milk ELISA) performed as well or better on milk samples than the ELISAs that used sera (blood) … Assays that use milk samples are ideally suited for paratuberculosis control in dairy herds… (from Collins et. Al. (2005), Clin. Diagn. Lab Immunol. 12:685-692)
• The ELISA used for milk samples in the present study had a higher level of agreement with results of bacterial culture than did the ELISA used for serum samples. (from Hendrick et.al. (2005) JAVMA 226:424-428)

Advantages of the Johne’s Milk ELISA

• Send samples through your DHI technician — no additional sampling or shipping
• Set a testing schedule that works best for you, from one cow to your whole herd each month
• One industry suggestion is to check all cows prior to dry-off. This will give you the best management opportunity to manage her thru the calving period
• Beneficial screening test for effective management on dairy farms
• Contact your veterinarian for best on-farm practices

For every Stage III cow expect:

• 1-2 more cows in Stage III (clinically diseased)
• 6-8 cows in Stage II (unapparent carrier adults)
• 10-15 cows in Stage I (infected calves & young stock)

Interpreting Test Results

New ELISA Johne’s Scoring System

• An ELISA score greater than 0.4 absorbance units is considered a Positive result. This indicates the animal(s) may be infected with M. paratuberculosis. The animal ID and corresponding score are highlighted in yellow on your customer report.
• An ELISA score greater than 0.30 but less than 0.40 absorbance units is considered Suspect. The animal ID is highlighted in yellow on your customer report.
• An ELISA score less than or equal to 0.30 absorbance units is considered Negative.
• Animals that are within 7 days of freshening have a high probability of giving false positive results when tested with the Milk ELISA.
• As with any test results, contact your veterinarian for management options.

Old Results

Prior to April 14, 2014 results were displayed as less than 0.07 is Negative, greater than 0.07 but less than 0.1 is Suspect and greater than .01 is Positive.

Yellow color indicates presence of Johne’s antibodies

Available Services

• Individual Animal Analyses
  • Johne’s Milk ELISA
• DHIA Technicians will collect samples during regular DHIA tests (no shipping charge).
• Call 1-888-202-3442 to request sample collection or for more information.

Additional Testing Options

• Johne’s Disease: Blood ELISA, traditional fecal cultures, rapid fecal test
• Leukosis: Blood & Milk ELISA
• BVD: Bulk tank (group) milk PCR, blood ELISA, ear notch ELISA
  • Individual Analyses
  • Bulk Tank Analyses – BVD
    • One — 2 ounce vial per 50 cows milked for bulk tank screening
• Shipping and handling fee per submission