E2O-Lancastar Farming, Saturday, February 11, 1995
GENERAL STRATEGIES
TO TREAT, PREVENT
AND CONTROL
POULTRY DISEASES
Patty Dunn, DVM
Animal Diagnostic Lab
Dept. Of Vet Science
Anyone who has raised or tended poultry on any scale,
from a small hobby flock to a large commercial enterprise,
has encountered disease problems in individual birds or
throughout the flock from time to time. Birds, like other ani
mals and people, are susceptible to their own sets of diseases.
Fortunately, very few of them are transmissible to man.
Infectious avian diseases (those that are contagious or
transmissible from bird to bird) are caused by viruses, bacter
ia, fungi (mold), and parasites. Due to vast increases in
medical/scientific knowledge regarding the relationships of
these disease-causing agents with their hosts over the last
several decades, several effective control strategies have
been developed to decrease infectious disease outbreaks in
flocks. Employment of these strategies is crucial to the suc
cessful raising of healthy groups of birds, especially as num
bers of birds and flock densities increase as poultry producers
strive for efficiency of production and maximum use of
facilities.
To follow are five general methods of disease control that
are widely used to control infectious diseases in poultry. The
ideal goal of all the strategies is to prevent outbreaks of clini
cal disease which should result in optimizing productivity.
1. REDUCE THE LEVEL OF EXPOSURE. A critical part
of the control method is biosecurity. Biosecurity is the buzz
word for the total health plan designed to reduce (or in some
cases, eliminate) the number of disease agents that come in
contact with a flock. There is much published infoimation on
the components of a complete biosecurity plan. They include
wearing clean protective clothing and foot wear into your
poultry houses, keeping out unnecessary vehicles and visi
tors, etc. Sanitation, especially cleaning and disinfecting
(C&D) of the house and equipment between flocks, is
extremely important to decrease die numbers of viable infec
tious agents left from the last flock to levels thatwon’t over
whelm the incoming birds. This is particularly true if there
has been a clinical disease problem in the previous flock.
C&D involves both physical removal and chemical deactiva
tion of agents. Unfortunately, some microbial agents are
extremely hardy, and a few may remain in the environment
regardless of the stringency of the C&D procedures.
Rodent and insect control is important at all times, but par
ticularly between flocks. Mice and rats are effective carriers
of many types of bacteria. Beetles and flies can mechanically
transfer various types of infectious agents.
If these pests are not removed between flocks, they will
serve as reservoirs of the agents to infect the next birds
housed.
“Down Time” is the period of time between flocks when
the house (or premise) is empty of all birds. The longer the
down time before restocking, the less chance of carryover of
large amounts of disease agents, especially the more fragile
viruses. Even if complete C&D and pest control are not prac
ticed during the down time, some viruses and' bacteria
become inactivated with time because no suitable hosts
(birds) are present to allow them to live and maintain their
population. On the other hand, some hardy organisms can
remain viable in the environment for years, and can re-infect
any birds put back on the premise during that time.
It is important to remember that disease control is a “num
bers game” in many respects: X number of organisms may
not be able to establish an infection in a healthy bird, but 10 X
or 100 X organisms can overwhelm the host’s immune
defenses and cause serious disease. Once disease is estab
lished in the bird, the agent usually multiplies rapidly and
numbers of organisms build up exponentially and are shed
into the environment, thus perpetrating the cycling of disease
in the flock.
2. REDUCE STRESS. “Stress” is a very general word that
is sometimes hard to define. It implies that a condition or con
ditions exist that cause discomfort on a physical or mental
level. A low level of stress may actually help the immune sys
tem operate at peak efficiency. However, moderate or high
stress levels cause the body to release certain “stress hor
mones" that suppress the activity of certain key components
of the immune system thereby rendering the bird more sus
ceptible to disease.
High stress is both a cause and an effect of disease. Proper
management is the cornerstone of reducing stress. Birds
should not be overcrowded. Do not exceed bird density
recommendations for your housing situation. Control dam-
age from picking or other vices by trimming beaks, toes, or
snoods (depending on the species and production type) and
by be controlling light intensity. These procedures are to
some extent stressful in themselves, but when accomplished
at the appropriate age and level, should decrease total addi
tive stress in the long run. Birds should always be handled
and moved carefully, especially at the hatchery and during
catching, loading, transport and vaccination procedures.
Working calmly around the birds is also important. On-time
routines of caretaking and feeding are ideal. Changes in feed
schedules or running out of feed, even for a relatively short
period of time, can be extremely stressful. Supplemental vita
mins or other nutrients may be given to combat nutritional
stress.
3. VACCINATE. Vaccination is a planned and controlled
exposure to a specific disease agent or agents in order to sti
mulate the bird to build protective immunity specific to the
agent(s) contained in the vaccine preparation. In most cases,
it is used to prevent a disease break before it occurs. In some
special situations, vaccine may be applied to a flock currently
experiencing a particular disease to limit the disease’s prog
ress and effects. Some poultry vaccines are used very exten
sively. For example, virtually every chick from commercial
hatcheries in the U.S. is vaccinated for Marek’s Disease at
day of age. Other vaccines have a much more limited applica
tion. In the U.S., infectious coryza vaccine is used in only a
few areas (California, extreme Southeast) where the disease
can be a commercial problem.
Types of vaccines used on a farm should be chosen based
on what is known about the particular disease challenges in
the geographic area. A vaccine should not be used if there is
no known problem or direct potential problem with the dis
ease. Not only is it economically unsound to do so, it is also
potentially dangerous. There have been instances in which
live vaccine strains, introduced into an area with good inten
tions, have caused more disease problems than they pre
vented. Fortunately, this has been the exception rather than
the rule. (Turn to Pag* E2l)
SEE ONE OF THESE DEALERS FOR A DEMONSTRATION:
ADAMSTOWN
EQUIPMENT INC.
Mohnton, PA
(nw Adwntlown)
CARROLL’S EQUIPMENT
Rout* 235
Dimoron, MD
301-5724553
717-45M301
BARTRON
S CLUSBTOH FABM OUNKLE«
71743M011 EQUIPMENT GRIEB INC.
Nttdmor*, PA Cwrtr* Hill, PA
717-6734216 614-364-1421
Hydra-Push" Spreader:
Two Sizes, Many Advantages
• Two sizes of
Hydra-Push
Spreaders. No
CARLYLE A
MARTIN, INC.
Higirttown, MD
301-733-1873
DEERFIELD AG &
TURF CENTER, INC.
WrtMntwrn, PA
7174314557
JOHN DEERE
• Resists corrosion
and freeze-up.
[Alt
CLUGSTON AG
A TURF, INC.
Chunbmburg, PA
717-2134103
ENFIELD
EQUIPMENT, INC.
Oxford, PA
KERMIT K
ENFIELD KISTLER 111
EQUIPMENT INC. GUTSHALL’S INC. 7W< King* Hi)
WhHrford, MD RO «2 Box 74-A Lynnport, P
301-412-12(2 Loyovlllo, PA 610-2 M-201
GREAT
DEAL!
FFA Officer
ALEXANDRIA, Va. Six
agricultural youth leaders from the
United States will continue with
their plans to visit agribusiness
and government leaders in Japan
as part of the 199 S National FFA
Officer International Experience
Program January 27-February 10,
“The hosts in Japan have been
most helpful in this time of crisis
to reorganize travel plans so that
the tour could continue. Their na
tion is an important customer of
American agriculture.” said Dr.,
Larry Case, national FFA advisor
and coordinator of agricultural
and rural education, U.S. Depart
ment of Education. “This is an ex
cellent opportunity for our future
agricultural leaders to team about
the changing opportunities which
face the agricultural industry.”
This international tour is an im
portant part of the national offi
cers’ preparation to serve the Na
tional FFA Organization. During
their time in Japan, they will re
ceive a briefing by U.S. Embassy
officials on agricultural trade, tour
one of Tokyo’s largest fish, vege
table and floral market facilities
and visit several agricultural high
schools.
In addition, the group will tour
FINCH SERVICES
HANOVER INC.
Hanovir, PA
717432-2 MS
DUNKLE l<
GRIEB INC.
Min Hill, PA
717-72 C-3115
K t W EQUIPMI
A.B.C. GROFF, INC. MMraffild^WV
Now HoHind, PA 304-53640
717-854-41(1
• Fast unloading,
no conveyor
fall-back, self
cleaning.
GUTSHAIT
CirlWi,
717-24 M
A