Pasteurella

From the AAAP Avian Disease Manual:

[FONT=TimesNewRoman,Bold][FONT=TimesNewRoman,Bold]FOWL CHOLERA[/FONT][/FONT]
(Cholera; Pasteurellosis)
DEFINITION
Fowl cholera is an infectious disease of poultry, waterfowl, and many other birds, usually appearing in
poultry as an acute septicemic disease with high morbidity and mortality. A chronic, localized form occurs in
poultry and may follow the acute form, or may occur independently.
OCCURRENCE
Fowl cholera is a disease of many species of birds, including chickens, turkeys, geese, ducks, quail,
canaries, and many wild and zoo birds. Perhaps all birds are susceptible under appropriate conditions. In
poultry, most outbreaks occur in semimature or mature birds, although there are exceptions. The disease occurs
more frequently in turkeys than in chickens. The disease occurs frequently in domesticated waterfowl and often
causes extensive losses among wild waterfowl. Geese are highly susceptible. Fowl cholera is more likely to
occur in birds that are stressed by such things as poor sanitation, parasitism, malnutrition, and other diseases.
Fowl cholera occurs worldwide and is a relatively common disease. There is no relationship between cholera in
humans and fowl cholera.
HISTORICAL INFORMATION
Fowl cholera has been recognized as a disease of poultry for more than 200 years. About 100 years ago,
Pasteur isolated the organism and used it in one of the first vaccines. In the United States, Dr. Salmon studied
the disease as early as 1880. Fowl cholera was one of four major livestock diseases that stimulated formation of
the Veterinary Division of the United States Department of Agriculture. Although fowl cholera has been
recognized and studied for almost 200 years, it still remains an important disease of poultry.
ETIOLOGY
1. The etiologic agent is

[FONT=TimesNewRoman,Italic][FONT=TimesNewRoman,Italic]Pasteurella multocida[/FONT][/FONT], a Gram-negative, bipolar-staining bacillus that grows readily
on blood agar but not on MacConkey agar. Virulence among isolates is highly variable. Encapsulated
strains are usually highly virulent; unencapsulated isolates are typically of low virulence.
2. The organism varies greatly in its antigenic makeup, a characteristic responsible for difficulties in
producing effective bacterins and vaccines. The gel diffusion precipitin test has been used to describe 16 P.
multocida serotypes, all of which have been isolated from avian hosts. Serotypes 1, 3, and 3X4 are most
commonly isolated from poultry outbreaks.
3.

[FONT=TimesNewRoman,Italic][FONT=TimesNewRoman,Italic]P. multocida [/FONT][/FONT]is easily destroyed by many disinfectants and by sunlight, heat, and drying. However, the
organism persists for months in decaying carcasses and moist soil.
EPIDEMIOLOGY
1. Poultry flocks that have recovered from an outbreak of fowl cholera will remain carriers of

[FONT=TimesNewRoman,Italic][FONT=TimesNewRoman,Italic]P. multocida[/FONT][/FONT]
and spread the disease to susceptible flocks. These carriers harbor the organism in the choanal cleft and
contaminate feed, water, and the environment with oral fluids. Likewise, wild birds may carry the
organism and introduce it into the poultry flock if appropriate biosecurity practices are not followed.
2. Several mammalian species are carriers of

[FONT=TimesNewRoman,Italic][FONT=TimesNewRoman,Italic]P. multocida [/FONT][/FONT]and may introduce the organism to poultry flocks.
Swine and raccoons have been shown to be carriers of

[FONT=TimesNewRoman,Italic][FONT=TimesNewRoman,Italic]P. multocida [/FONT][/FONT]and those isolated have been shown to
be pathogenic in poultry.​

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[FONT=TimesNewRoman,Bold][FONT=TimesNewRoman,Bold]FOWL CHOLERA[/FONT][/FONT]
3. Birds that die of septicemic cholera have the agent in most of their tissues. Cannibalism of sick or dead
birds is an important method of dissemination of the disease.
4. Resistance to cholera is correlated to humoral immunity. Immunosuppression increases susceptibility.
5.

[FONT=TimesNewRoman,Italic][FONT=TimesNewRoman,Italic]P. multocida [/FONT][/FONT]is resistant enough to be readily spread on contaminated crates, feed bags, shoes, equipment,
etc.
CLINICAL SIGNS
1. With acute cholera, sudden unexpected deaths occur in the flock. Mortality often increases rapidly. Laying
chickens may be found dead on the nest. Geese have been reported to just drop dead while walking across
a barnyard. Poisoning is often initially suspected in outbreaks of acute cholera.
2. Sick birds show anorexia, depression, cyanosis, rales, nasal and oral discharge of mucus, and white watery
or green mucoid diarrhea. The course of illness is short and often followed by death. Affected chickens
often conceal themselves under equipment.
3. Chronic fowl cholera is most common in chickens. Often there is swelling of a joint, wattle [

Fig. 1; Fowl
Cholera; AAAP


], foot pad, or tendon sheath. Exudate, often cheesy, may accumulate in a conjunctival sac
or infraorbital sinus. There may be torticollis in a few birds [

Fig. 2; Fowl Cholera; AAAP].
4. Abscesses of the infraorbital sinuses and middle ear infection resulting in torticollis, often occur in turkeys
with chronic cholera.
5. In turkey breeders there is a drop in egg production and increased mortality following handling of hens
during insemination. Affected toms produce thin, watery, poor quality semen.
LESIONS
1. Lesions may be absent if the disease is very acute. Usually there are petechial and ecchymotic
hemorrhages at a few sites, for example, on the heart, under serous membranes, in mucous membranes, on
the gizzard, or in abdominal fat. There is often a generalized hyperemia of the upper intestine. Acute
lesions develop as a result of disseminated intravascular coagulation. In layers and breeder hens, free yolk
in the peritoneal cavity, acute oophoritis with regressing follicles, and acute diffuse peritonitis are
frequently seen. These lesions can accompany many other acute diseases.
2. In acute cases of cholera there often is enlargement of the liver. If the birds live a few days, there may be a
few or many small necrotic foci in the liver [

Fig. 3; Fowl Cholera; AAAP]. Consolidation of lungs is a
common finding in affected turkeys [

Fig. 4; Fowl Cholera; AAAP], [Fig. 5; Fowl Cholera; AAAP]. With
time, these lesions become sequestered as necrotic areas in the lungs and these lung lesions often are
extensive.
3. In chronic cases there may be localized inflammatory lesions. These often involve a joint, tendon sheath
[

Fig. 6; Fowl Cholera; AAAP], wattle, conjunctival sac, infraorbital sinus, the nasal turbinates, the middle
ear, or cranial bones at the base of the skull. Caseous exudate in a localized lesion [

Fig. 7; Fowl Cholera;
AAAP


] should arouse suspicion of cholera.
DIAGNOSIS
1. At necropsy, Gram-stained impression smears of liver or heart blood from septicemic cases often reveal
bipolar-stained, Gram-negative rods suggestive of cholera. Use of blood stains or methylene blue readily
demonstrates the bipolar morphology of the organism.
2. Although the history, signs, and lesions may strongly suggest fowl cholera

[FONT=TimesNewRoman,Italic][FONT=TimesNewRoman,Italic], P. multocida [/FONT][/FONT]should be isolated
and identified for confirmation. Isolates should be tested for antibiotic susceptibility because of widespread​

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[FONT=TimesNewRoman,Bold][FONT=TimesNewRoman,Bold]FOWL CHOLERA[/FONT][/FONT]
resistance and should be serotyped, especially if routine treatment and vaccination procedures appear
ineffective.
3. Cholera must be differentiated carefully from erysipelas and acute colibacillosis in turkeys and other birds
that are susceptible to both diseases. Erysipelas is caused by a Gram-positive rod. Cholera can be
differentiated readily from most septicemic and viremic diseases of poultry by the isolation of

[FONT=TimesNewRoman,Italic][FONT=TimesNewRoman,Italic]P. multocida[/FONT].
4. Cholera always should be suspected if there are epizootic losses in domesticated or wild waterfowl.
5. Related organisms can cause cholera like diseases or complicate other diseases. These include [/FONT]

[FONT=TimesNewRoman,Italic][FONT=TimesNewRoman,Italic]Pasteurella[/FONT][/FONT]
[FONT=TimesNewRoman,Italic][FONT=TimesNewRoman,Italic]gallinarum, P. haemolytica, P. anatipestifer, Moraxella osloensis[/FONT][/FONT]


, and [FONT=TimesNewRoman,Italic][FONT=TimesNewRoman,Italic]Yersinia pseudotuberculosis.[/FONT][/FONT]
6. Several serological tests have been developed. Currently an enzyme-linked immunosorbent assay (ELISA)
is commercially available and widely used. Serology is used primarily to evaluate efficacy of vaccination
rather than for diagnosis of a disease outbreak.
CONTROL
1.

[FONT=TimesNewRoman,Italic][FONT=TimesNewRoman,Italic]P. multocida [/FONT]is not transmitted through the egg. Obtain clean birds and raise them in quarantine on
disease-free premises and away from all birds and mammals that might be carriers. Never add birds to the
flock as they may be carriers. Avoid stresses, insofar as is possible, and practice a high standard of
sanitation.
2. Pick up and destroy all sick or dead birds before they can be cannibalized. Birds with cholera are teeming
with [/FONT]

[FONT=TimesNewRoman,Italic][FONT=TimesNewRoman,Italic]P. multocida [/FONT]and are important in the transmission of the agent. Dispose of carcasses by burying or
burning to prevent them from being fed on by scavengers (including dogs and cats).
3. Although bacterins are not always effective, in many instances they do a good job of immunizing birds,
especially if they can be repeated at least once. They often are given when birds are about 8 and 12 weeks
old. Bacterins do not provide good cross-protection between serotypes. Oil-emulsion bacterins are used to
immunize breeders prior to production. They can cause serious drops in egg production if given to laying
birds.
4. Live vaccines are given via wing web inoculation to chickens and via drinking water or wing web
inoculation to turkeys. In the United States live vaccines are based on the Clemson University (CU) strain
of [/FONT]

[FONT=TimesNewRoman,Italic][FONT=TimesNewRoman,Italic]P. multocida[/FONT]. This is a naturally occurring low-virulent organism. Since its introduction as a
commercial product, two milder mutants of the original CU strain have been produced: PM-1 and M-9
strains. They frequently are given to turkeys at 2-6- week intervals beginning at 6-7 weeks of age in the
drinking water. Some turkey breeders are vaccinated via the wing web. Layers and breeders are
inoculated by wing web stick at 10-11 weeks of age, and revaccinated in 6-8 weeks. Fowl pox vaccine may
be given concurrently in the opposite wing. The live vaccines have been shown to be safe but vaccine
reaction problems can occur in the field, presumably because of immunosuppression, concurrent diseases,
breed sensitivity, late vaccination, or management stress such as intentional feed restriction. Parenteral
administration may result in a localized lesion, or, more seriously, arthritis. Live vaccines confer better
resistance than killed bacterins and offer a broad spectrum of protection against most serotypes.
5. Following an outbreak, depopulation should be considered because many surviving birds become carriers
and transmit [/FONT]

[FONT=TimesNewRoman,Italic][FONT=TimesNewRoman,Italic]P. multocida[/FONT]. Following depopulation, the premises and equipment should be thoroughly
cleaned and disinfected and, if possible, kept free of poultry for a few weeks.
6. Continuous medication programs have been used but are generally more costly than a vaccination program.
7. Reduce rodents, scavengers, and predators in the farm environment and limit their contact with flocks.
8. Differing susceptibilities among genetic lines of turkeys have been shown, suggesting that
selection for resistance to fowl cholera may be possible.[/FONT]​

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TREATMENT
1. Many sulfa drugs and antibiotics will lower the mortality from cholera but mortality may resume when
treatment is discontinued. Most medications are given in the feed or water. Sulfaquinoxaline is one of the
better treatments but will depress egg production in layers and may throw them completely out of
production. Care should be taken to use only those products approved by the Food and Drug
Administration for the class of poultry being treated. Drugs and antibiotics in common use include:
Sulfadimethoxine Tetracyclines
Sulfaquinoxaline Erythromycin
Sulfamethazine Streptomycin
Penicillin
2. Moving an infected flock to clean premises or markedly improving sanitation during an outbreak may slow
the course of cholera. Use of live vaccine during the early course of an outbreak may be effective.
3. If cholera cannot be controlled, it may be necessary to market the flock early. Be sure to adhere to
regulations relating to withdrawal of medication.​

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If you aren't going to eat him, ask your vet if Clavamox or Baytril would work.

-Kathy

 

Keeping him warm and hydrated is key, but do call your vet and ask about Clavamox and Baytril, those you could give orally very easily. While you're at it, ask him if he could set you up with tube feeding supplies.

-Kathy

 

Tubing is easy, but if he's eating and drinking, ther'es no need to.

-Kathy