HERD HEALTH                                       PIH-30


               Enteric Colibacillosis of Newborn Pigs

Erwin M. Kohler, Ohio State University
    O.A.R.D.C., Wooster, Ohio
Harley Moon, USDA, Ames, Iowa

Dwight Armstrong, Lewisburg, Ohio
Gerald Bernard, New Vienna, Ohio
H. Fred Troutt, Virginia Polytechnic
    Institute and State University

     Names such as E. coli diarrhea or scours, baby  pig  scours,
and  colibacillosis are popularly used today to label an intesti-
nal disorder of newborn swine characterized by large  amounts  of
liquid feces. Research has shown that some strains of Escherichia
coli bacteria can cause such intestinal disorders, but other bac-
teria and viruses can cause diseases with similar clinical signs.
Within any herd, these  different  infectious  agents  may  cause
disorders   concurrently   or  sequentially.   This  summary  was
prepared specifically to help the readers understand some of  the
current knowledge about E. coli infections.

     It is often necessary to conduct laboratory tests to  estab-
lish  an  accurate  diagnosis.  Properly collected specimens from
carefully selected pigs are required  for  meaningful  diagnostic
efforts. Even then it may be difficult to establish the diagnosis
for a particular episode  of  diarrhea.  Too  frequently,  costly
chemotherapeutic  agents  are administered on the assumption that
the diarrhea is being caused  by  E.  coli  when,  in  fact,  the
disease  is being caused by a virus (such as TGE or rotavirus) or
another microorganism that is completely unaffected by the  drugs


     E. coli are normal inhabitants of the intestinal  tract  and
are  present  in large numbers in the large intestine but not the
small intestine of normal animals. However, certain  strains  are
classed as enteropathogenic, meaning that they produce disease by
developing in the  intestine  without  necessarily  invading  the
other  tissues  of  the  body. Enteropathogenic E. coli are found
throughout the world. There is probably at least  one  strain  in
each  herd.  It  is important to understand that the incidence of
disease caused by enteropathogenic E. coli is greatly  influenced
by the management of herd and facilities. Such strains of E. coli
have the ability to propagate rapidly  in  the  small  intestine.
Additionally,  these  strains produce toxins (enterotoxins) which
cause massive fluid losses from the body. The amount of fluid and
electrolytes  in  the small intestine soon exceeds the absorptive
capacity of the intestine. Consequently, large quantities of pale
yellow,  watery  feces  are passed. The fluids are lost at such a
rapid rate that the pig becomes dehydrated and also develops aci-
dosis  because  a  large  proportion of the electrolytes lost are
basic (alkaline). The liquid feces are  usually  quite  alkaline.
The  pigs  usually  are  thirsty and continue to nurse until they
become too weak and depressed to do so.

     This fact sheet is directed primarily  to  neonatal  enteric
colibacillosis,  which  is diarrhea caused by enteropathogenic E.
coli in pigs less than 7 days old. A number of host and  environ-
mental  factors  affect the incidence of E.  coli-caused diarrhea
of newborn pigs. The stomach and intestine of  pigs  are  quickly
flooded  with bacteria immediately after birth. Many of these are
``harmless,'' but if large numbers of  enteropathogenic  E.  coli
are present, many pigs can be infected immediately after birth.

     Large numbers of E. coli are usually present in the  immedi-
ate  environment whenever it is dirty and wet, the ventilation is
poor, and the humidity  is  high.  However,  the  most  important
source  of  infection  is other young pigs with E. coli diarrhea.
These pigs will shed up to 1 billion E.  coli/cc  of  the  liquid

     Temperature is  probably  the  most  important  of  all  the
environmental  influences  on  the  well-being of the pigs. It is
also one of the easiest to control in  modern  farrowing  facili-
ties.  Young  pigs  are extremely sensitive to chilling, and this
stressor lowers the resistance of pigs to infections including E.

     Newborn pigs  normally  have  no  antibodies  at  birth  but
receive  them from the colostrum (first milk) of the sows. Colos-
trum has antibodies against many different microorganisms depend-
ing  upon  what  the  sow has been exposed to or vaccinated with.
Frequently, gilts have had less exposure to the  enteropathogenic
E.  coli in the herd and consequently don't protect their pigs as
well as sows do. If the pigs drink colostrum (containing adequate
levels  of  antibodies  against the infecting strain) immediately
after birth, and if they continue to  suckle  regularly,  the  E.
coli  will  usually  be  inhibited  sufficiently  to  prevent the
occurrence of clinical disease. However, all protection is  rela-
tive,  and  infection with very large numbers of enteropathogenic
E. coli or anything that interferes with frequent suckling  (such
as  lactation  failure,  injuries, or other infections) increases
the probability of development of clinical colibacillosis.

     Pigs that develop E. coli-caused diarrhea  must  be  treated
very  promptly  with antibacterial drugs which have been shown to
be effective against the enteropathogenic E. coli  in  the  herd.
The  disease  is  so  acute  in young pigs that, even with proper
treatment, death and performance losses make this a  very  costly
disease.  It is much more profitable to prevent this disease than
to be continuously treating affected pigs.

     With this introduction, it should be obvious that  the  best
possible  results in the prevention of E. coli-caused diarrhea of
baby pigs can be attained only by a complete  program  using  all
the good management practices available.


     There are three basic approaches to  the  prevention  of  E.
coli  scours.  The first approach is a good sanitation program to
reduce the number of enteropathogenic E. coli. Sanitary farrowing
facilities  and  adequate ventilation are essential to reduce the
number of pathogenic organisms and to prevent high  humidity  and
damp  or wet floors. Promptly covering the liquid stools with dry
bedding or soil can help reduce the spread of bacteria from  pigs
with  E. coli diarrhea. Modern mesh flooring reduces the exposure
of pigs to feces. In addition, if E. coli diarrhea is  diagnosed,
the  affected  pigs should be promptly treated with antibacterial
drugs known to  be  effective  (either  by  laboratory  tests  or
experience  in  that herd) against the particular strains present
in the herd.  This, of course, is a treatment  for  the  affected
pigs, but it is also an attempt to decrease the number of entero-
pathogenic E. coli that these pigs are  shedding  in  the  liquid
feces.  It  is important that the antibacterial drugs not be used
indiscriminately because E. coli often rapidly develop resistance
to these drugs.

     The second approach is to use good management  practices  to
maintain  the  ``natural''  resistance  of the newborn pig at the
highest possible level.  Attention to the nutritional and general
health  status  of the breeding herd helps insure the delivery of
vigorous pigs and satisfactory lactation. Prompt  suckling  after
birth,  and  frequent  suckling  thereafter, is necessary for the
pigs to acquire the full benefits of the specific and nonspecific
protective  substances in the sow's colostrum and milk. Colostral
antibodies must be swallowed every few hours to  keep  enough  in
the  intestine  to  protect  the  pigs.  As previously mentioned,
chilling caused by drafts, and wet or cold floors  or  inadequate
heaters  must  be  avoided  because  chilling  is one of the most
severe stressors a young pig can encounter. Pigs should  be  warm
enough  to sleep soundly in a stretched-out position. Pigs in wet
pens, or pens with inadequate heat, huddle, shiver, and are rest-
less, continually moving to find a warmer spot in the pile group.

     The third approach to the prevention of E.  coli  scours  of
baby  pigs  is  to  increase  their  resistance.  The pig can get
specific protection against  infectious  diseases  from  its  dam
through  the colostrum and milk. This can be enhanced by vaccina-
tion of the dam. Vaccination of sows to increase  the  protective
value  of  their  colostrum  and  milk  against  enteropathogenic
strains of E. coli has been attempted by many people.
  One vaccination method currently  being  used  successfully  in
numerous  herds  by veterinarians involves feeding cultures of E.
coli to dams late in gestation. The vaccinated dams then  protect
their  newborn  pigs  via antibodies in their colostrum and milk.
The program must be custom-developed  for  each  herd,  partially
because  there  are  so  many  strains  of E. coli that can cause
scours of baby pigs. Antibodies produced against any one of these
strains are not very effective against most of the other strains.

     There are a number of precautions to follow.  Only  pure  E.
coli  cultures  isolated from the herd to be vaccinated should be
used. The aim here is to avoid bacteria or viruses that are  use-
less  for vaccination, or even worse, feeding bacteria or viruses
that could cause disease problems in the herd.  This program  has
a  number  of  rather  detailed steps. Good results depend upon a
good working relationship between a  veterinarian  and  the  pro-

     Recently, several companies have  introduced  vaccines  con-
taining the virulence factors (pili) which enable most strains of
enterotoxigenic E. coli to heavily colonize the small  intestine.
These  vaccines  are  injected into gilts and sows late in gesta-
tion. The dams respond by producing antibodies to these pili, and
these  antibodies  are  transferred via the colostrum and milk to
the pig's intestine. Antibody against pili prevents  adhesion  of
the  E.  coli to the wall of the intestine. If the E. coli do not
adhere, they cannot grow  to  large  enough  numbers  to  produce
enough  toxins in the small intestine to cause diarrhea, dehydra-
tion, and death. Approximately 95% of the toxin-producing strains
that  affect newborn pigs produce one of the three specific pilus
types:  K88, K987P, or K99. Many strains of both  enterotoxigenic
and nonenterotoxigenic E. coli also produce type 1 pili. The role
of type 1 pili (if any) in the disease has not been  defined  and
is currently a point of controversy among researchers.

     Some of the vaccines contain heat-labile toxin antigen which
is  produced  by  some  strains of enterotoxigenic E. coli. These
antigens should stimulate the sows to produce antibodies  against
heat-labile  toxin and to transfer these to the intestines of the
pigs. These antibodies  could  neutralize  a  limited  amount  of
heat-labile  toxin.  Although prevention of colonization by pilus
antibodies  will  prevent  the  formation  of  diarrhea-producing
amounts  of  heat-labile  toxin,  there is some evidence that the
heat-labile antibodies can be of value.

     Many strains produce  another  type  of  enterotoxin  called
heat-stable-  enterotoxin. This toxin is not antigenic (sows will
not produce antibody against it), and antibody  directed  against
heat-labile  toxin  will  not  protect against diarrhea caused by
strains that produce heat-stable toxin.

     Although the commercial vaccines have been quite safe, there
have  been  a  few instances in which sows have aborted following
vaccination. All E. coli organisms also contain an entirely  dif-
ferent  type  of toxin called endotoxin, and under certain condi-
tions it appears that enough endotoxin has been  present  in  the
vaccine to cause abortion in certain sows.

     To achieve optimal benefits  from  any  vaccination  program
against  E.  coli  scours  of baby pigs, it is still essential to
keep the level of pathogenic E. coli as low as  possible  through
good  management,  to  insure  that pigs suckle promptly and fre-
quently, and to avoid chilling, injuries, and other disease prob-

Colibacillosis in Older Pigs

     The intestinal disorders characterized by  yellow  to  white
runny  or smeary feces frequently observed in suckling pigs 10-35
days of age are often called white or milk scours. In contrast to
those  of newborn pigs with colibacillosis, these stools are usu-
ally neutral or  acidic.  These  stools  also  have  a  different
appearance  from the pale yellow, watery, gassy feces of E.  coli
diarrhea of baby pigs. In many cases this syndrome is also called
colibacillosis.  Current research indicates that enteropathogenic
E. coli can be present and occasionally play a  significant  role
in  the  severity of the disease. However, research reports indi-
cate that a virus (rotavirus) that is  probably  present  in  all
swine  herds  destroys some of the epithelial cells that line the
small intestine. (Although the rotavirus can affect newborn pigs,
field  investigations  indicate  that  it  rarely causes clinical
disease in pigs less than  a  week  of  age  if  they're  nursing
healthy  sows.)  The resulting maldigestion and malabsorption are
similar (although less severe) to those in TGE. Coccidia can also
cause diarrhea in a similar way.

     The diseases caused by these viruses are discussed in  other
fact sheets.  The role of enteropathogenic E. coli in these cases
is secondary to the damage caused by the virus. In some cases, E.
coli  may contribute to fluid losses.  In other cases, it appears
that the E. coli become closely associated with the damaged  lin-
ing  of  the  intestine  and may enter the body or release toxins
(endotoxins) that are absorbed into the body and cause shock  and
rather  sudden  death.  Complete  diagnostic procedures are indi-
cated, but in the absence of the demonstration of a definite role
for  E.  coli  in  the  outbreak  it  is difficult to justify the
administration of chemotherapeutic agents. In fact, it  has  been
repeatedly observed they are ineffective in controlling ``white''
or ``milk'' scours.

     Although enteropathogenic E. coli  undoubtedly  can  and  do
contribute  to  postweaning scours, the precise role and signifi-
cance is not well defined. As  additional  research  is  directed
toward  postweaning  scours, it may well be found that there is a
complex interaction of etiologic agents and factors  among  which
E. coli may act only in a secondary role here as well.

     If a  complete  diagnosis  has  been  made  that  definitely
incriminates  enteropathogenic  E.  coli  as having a significant
role in an outbreak of diarrhea in pigs over a week of  age,  the
incriminated  strains  of  E.  coli should be tested to determine
which  antibacterial  drugs  are  effective  against  them.   The
selected  drug should be given orally. Good sanitation and venti-
lation, avoiding overcrowding, and adequate heat as well as prop-
erly  formulated feed and feeding practices are important manage-
ment practices. At present, further proof is needed before a vac-
cination  program  directed  at preventing colibacillosis of pigs
over 10 days of age can be recommended.


     Colibacillosis is a term often used loosely and consequently
used  both correctly and incorrectly. Careful diagnostic study of
appropriately collected specimens from carefully selected pigs is
required  to  render  an  accurate  diagnosis. In addition to the
detection of substantial numbers of enteropathogenic E. coli, the
possible role and significance of other enteric pathogens must be
evaluated in each outbreak of diarrhea.

     Although many drugs are advertised for use  in  treating  E.
coli  diarrhea  of  newborn pigs, most of these drugs have little
effect in many herds since strains of E. coli have developed con-
siderable resistance to them. Laboratory tests with the causative
strain of E. coli or experience in the herd are necessary to make
accurate  recommendations about the particular antibacterial drug
to use for treatment.

     Prevention of E. coli  diarrhea  of  newborn  pigs  is  more
economical  in  the  long  run than treatment of large numbers of
cases. There are three basic approaches to prevention. The  first
is  a  good sanitation program, including adequate ventilation to
maintain dry farrowing pens and to keep  the  number  of  entero-
pathogenic  E.  coli  as  low  as possible. The careful design of
facilities with only a few farrowing crates per room can be  very
helpful  in making a sanitation program work. The second approach
is to establish a good nutritional and  health  program  for  the
breeding  herd  to  insure  the birth of vigorous pigs and a good
milk supply. The  farrowing  house  must  be  operated  to  avoid
stressful  conditions for the sows (particularly overheating) and
the pigs (particularly chilling). The third approach is  to  vac-
cinate  the  sows  so that they can provide better protection for
the pigs.

     A vaccination program may be indicated where there is a high
incidence  of E. coli scours of newborn pigs. This may occur when
a very pathogenic strain is introduced into a herd or when  there
are  deficiencies  in  the  management  and farrowing facilities.
Either a commercial vaccine containing the 3  pilus  antigensK88,
K99,  K987P, or the oral vaccination method using enterotoxigenic
strains isolated from the herd can be used. The optimal  benefits
from  vaccination can be achieved only when these deficiencies in
the management and farrowing facilities are  corrected.  Diarrhea
in  pigs over a week of age should not be assumed to be caused by
E. coli, but a careful diagnosis should be made. If E.  coli  are
demonstrated  to  be  an important cause of the problem, antibac-
terial drugs that are effective  against  the  causative  strains
should be given orally.

|Related Publications                       |
|PIH-47 Transmissible Gastroenteritis (TGE) |
|PIH-61 Rotaviral Diarrhea in Pigs          |

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be  an  endorsement to the exclusion of others which may be simi-
lar. Persons using such products assume responsibility for  their
use in accordance with current directions and the manufacturer.

REV 6/84


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