JOHNE’S DISEASE - PREVENTION AND CONTROL
IN DAIRY HERDS
A Manual for Veterinarians
Designed and edited by:
C. A. Rossiter Cornell
University, D. Hansen Oregon State University, L. J. Hutchinson
The Pennsylvania State
University, R. H. Whitlock University of Pennsylvania
Manual Contents
Designed
for collecting complete herd information in a way that will help organize
problem-solving and establish a baseline of information that can be used to
develop a herd plan.
This
section is based on what is known about Johne’s disease transmission. You will
be guided through steps that will help to develop estimates of herd specific
prevalence and risks that can be used for prioritizing management changes.
Use
and interpretation of diagnostic tests requires an understanding of the
characteristics and limitations of each test, as well as strategies of optimal
use of tests. Completion of this
section will aid in making feasible and economic decisions regarding use of
tests for Johne’s disease control or elimination.
This
document focuses on management recommendations for specific groups of animals,
outlines objectives and procedures and provides for herd specific plans.
A-1
Johne’s Disease Prevention or
Control Date:________________
HERD INFORMATION AND JOHNE’S HISTORY
Farm
Name________________________________________________________________
Owner(s)
Name_____________________________________________________________
Address___________________________________________________________________
__________________________________________________________________________
Phone(____)________________________Fax(____)__________________________
E-mail_______________________________________________
Herd
Veterinarian____________________________________________________________
Key farm management
(decision-makers, key employees)____________________________
__________________________________________________________________________
Type of operation: dairy______
other animal
enterprises_______________________________________
Herd size: adult cattle ______
yearlings ______
birth to 12 months ______
Herd goals (include future herd
size)
Next 2
years______________________________________________________________
________________________________________________________________________
3 to 5
years_______________________________________________________________
________________________________________________________________________
________________________________________________________________________
Do you plan to be in dairy farming
in 10 years? ______
Current and future source(s) of herd
replacements________________________________
________________________________________________________________________
Current herd
performance___________________________________________________
Performance
goals____________________________________________________
______________________________________________________________________
Herd health concerns you are or plan
to address____________________________
_______________________________________________________________________
Management concerns you are or plan
to address___________________________
_______________________________________________________________________
Area(s) you want to improve
profitability in__________________________________
_______________________________________________________________________
Herd History for Johne’s Disease
(JD):
First diagnosed case of Johne’s in
your herd:
Year_______ Animal source (owned or
purchased)_______________________
Clinical cases in the past.
List ID, date, age, source (raised
or purchased) and offspring still in herd for animals that were confirmed or
suspected of having Johne's disease in the last 10 years. If there are no
records, then memory will suffice.
Interpretation. Considering which animals you now
suspect had JD can help you understand how much the infection has spread.
Clinical cases shed, often explosively, billions of the M. avium subspecies
paratuberculosis bacteria in their manure.
Interpretation for raised or
purchased status of suspects or cases: Where animals were born and reared is important, as it can
indicate whether animals were infected on your farm, or possibly brought the
infection with them. If cases have occurred in purchased and not in raised
animals, infection is not likely well established in the herd.
Youngest clinical case (age, date,
source)_________________________________
Interpretation for age of clinical
JD suspects, or test positive animals: Cases in home-raised, first-calf heifers are an alert that
infection may be widespread in the herd. Generally, the younger the clinical case, the greater and/or longer the
exposure that animal had to the JD microbe.
List Cases, Test-Positives, Total
Animals Culled for the last 12 months, and Calculate Johne’s Cases as a percent
of total culls.
Interpretation for number of cases
in past year: This
figure is the most direct measure of the severity of JD currently in the herd.
Losses associated with clinical disease (salvage, production, offspring) are
the major immediate costs of JD in a dairy herd. The number of clinical cases
reflects the spread of infection. Generally, as the number of cases increases
the age of cases decreases.
PREVALENCE AND RISK
Prevalence is percentage of infected
animals in the herd at any one point in time. Prevalence can be estimated by
testing all adult animals with a serologic or fecal culture diagnostic
test. Another way to get a rough
estimate of the prevalence is to apply the interpretative information that
follows. Neither of these methods will
be exact but they can used to measure, a beginning point, status of a
prevention plan or progress made in a control program.
Scoring Johne's Herd Prevalence from
the Herd History
Low,
Score 1 or 2
Ø no culture
confirmed clinical cases (i.e., > 4 yr old animals (raised or purchased)
Ø clinical
cases 1 % or less of herd /year/ on average for several years
Ø
management
history includes low risks for spread,
i.e., good hygiene in calving
areas, minimal contact between calves and adult animals or their manure.
Moderate to Moderate High, Score 3 or 4
Ø occasional
clinical cases in raised animals, generally older (i.e., > 4 years)
Ø clinical
cases are 2 to 5% of herd/year/average over past several years
Ø number of
cases increasing, and/or cases are younger in age (i.e., < 3 years)
Ø occasional
clinical cases in acquired animals
Ø
management
history includes some risks for spread in the past: i.e., overcrowding, poor
colostrum management, some contact between calves and adult animals, manure
contamination of feed or water
High to Very High, Score 5 or 6
Ø frequent
clinical cases or groups of cases in raised animals
Ø clinical
cases are > 6% of herd/year average over several
Ø
progressive
pattern - prevalence has increased rapidly: increasing number of cases/year
over several years; decreasing age of cases; several cases in 2 year old or
younger
Ø significant
cost associated with animals culled for Johne's, and or increased cull rate
Ø cases may
be occurring in acquired animals as well
Ø
several
risks for spread existed in the past: i.e. poor hygiene in calving area, calves
nursed cows, regular contact of young stock with mature animals, manure
contamination of feed or water.
|
1 |
2 |
3 |
4 |
5 |
6 |
low moderate high
Place an X at estimated herd
prevalence
Johne’s Disease Control—Risk
Assessment Checklist for Dairy Herds
Estimate the degree of risk for each
listed item under Risk Factor. The highest risk = the maximum risk score, the
lowest risk = 0 for each item in that Risk Factor category. Enter your risk
estimate of item the Herd Risk column.
For example, under the Risk Factor
Calving area, calves are left with their dams for 6 hours, you estimate the
risk to be 5 on a scale of 0 to10. Place a 5 in the Herd Risk column.
Use comment section to note
differences from current to past situations. For example: Last year calved in
common group, this year isolated close up cows until they calved.
Total the Herd Risk values
for each Factor and multiply by the estimated herd prevalence value from page
B-3, or by 1 if there is no Johne’s disease in the herd.
|
Risk |
Max risk |
Herd risk |
Current Comment |
Past Comment |
|
Calving area: multiple animal use manure build-up calves born in free
stalls, tie stalls, other cow areas calving area used for sick
cows JD clinicals/suspects in
area newborn calves stay with
cows after birth calves nurse cows manure-soiling of calving cows, especially udders |
10 10 10 10 10 10 10 10 |
____ ____ ____ ____ ____ ____ ____ ____ |
|
|
|
Risk Total: Calving area |
80 |
|
1 2 3 4 5 6 x herd prevalence score =
total current risk ______ |
|
|
Risk |
Max risk |
Herd risk |
Current Comments |
Past Comments |
|
Pre-weaned calves · fed pooled colostrum · fed pooled sick-cow milk · calves have direct cow
contact · calves have indirect cow
contact, housed near cows · potential for
contamination of milk, feed, water, stall with cow manure |
10 10 10 10 10 |
____ ____ ____ ____ ____ |
|
|
|
Risk Total: Pre-weaned
calves |
50 |
|
1 2 3
4 5 6 x herd prevalence score =
total current risk ______ |
|