Causative agent  
- Pasteurella multocida
  (Type A:1 is the most prevalent in Thailand)



Differential diagnosis  
- Anatipestifer infection



1. History taking  
- High morbidity and high mortality (10 to 75%)
- All types of birds including wild birds are
  susceptible
- Mature chickens are more susceptible
- Route of infection : oral, nasal, conjunctiva or
  through wounds



2. Clinical signs  
- Acute form : sudden death, high fever, anorexia,
  marked depression, mucous discharge from the
  mouth, diarrhea, ruffled feather, dyspnea, cyanosis
  and death. Survived birds develop dehydration
  later
- Chronic form : local inflammation (swelling of
  wattle sinuses, legs or wing joints, foot pads, and
  sternal bursa), exudative conjunctivitis, torticollis,
  tracheal rales and dyspnea



3. Necropsy  
Acute form :
- General hyperemia (most evident in veins of the
  abdominal organs especially of duodenal mucosa)
- Petechial and echymotic hemorrhage widely
  distributed
- Subepicardial and subserosal hemorrhage
- Increase of pericardial and peritoneal fluid
- Swollen liver with multiple small focal necrosis
- Flaccid ovarian follicles or ruptured follicles in
  laying hens
- Free yolk in the body cavity
Chronic form :
- Localized infections, generally suppurative foci
  distributed in the body
- Respiratory tract, sinuses and pneumatic bones are
  often involved
- Edema of lungs, pneumonia and perihepatitis
- Chronic conjunctivitis and facial edema
- Gaseous exudate in hock joints, sternal bursa, foot
  pads, peritonial cavity, oviduct, middle ear

4. Histopathological observation  
Acute form
- Lymph nodes are swollen and hyperplasia
- A lot of bacterial mass in the hyperemic vessels
- Multiple focal coagulative necrosis of liver
- Heterophil infiltration in liver, lungs and other
  parenchymatous organs
Chronic form
- Heterophil infiltration and fibrin in the air spaces
  of the cranial bones, middle ear, and menings
- Multinuclear giant cells in air spaces



5. Microscopic examination  
- Tissue smear : Gram negative oval or short rod
  shape bipolar


6. Experimental animal inoculation  
- Emulsion of internal organs in broth, and 0.2 ml
  of this broth is injected IP into 1-2 mice
- Toxigenic P. multocida may be isolated from the
  mouse after death (within 24 hr)


7. Bacterial isolation  
Specimen : visceral organs (liver, spleen, heart blood
                  or exudative lesions, bone marrow)
Medium    : blood agar or dextrose agar with 5%
                  avian serum aerobically or under 5-
                  10% CO₂ condition, incubate 37°C for
                  18-24 hr
- Colony : moderate size, round and gray (some
  strains produce large mucoid colony). Fresh
  cultures have characteristic musty odor
- Biochemical characteristics : non-hemolysis, non-
  growth on MacConkey agar, non motile, positive
  to indole, catalase and oxidase, fermants glucose,
  sucrose but does not ferment lactose and maltose
  or liquified gelatin



8. Serotyping  
- Capsular typing : lHA test
- Somatic typing : AGID test

Control and Treatment  
- Vaccination with bacterin or live attenuated vaccine
- Antimicrobial agents
- Eradication of infection : clean and disinfect the
  building, equipment and environment and vermin