L4-5: Infectious Bronchitis/Laryngotracheitis

Question 1

What virus causes infectious bronchitis

Answer 1

Coronavirus

Question 2

Most contagious poultry dz

Answer 2

infectious bronchitis

Question 3

Which bird species affected by infectious bronchitis**

Answer 3

ONLY CHICKENS

Question 4

Trans. Of infectious bronchitis

Answer 4

Inhalation of virus-containing droplets

• can persist for weeks in cecal tonsils
• carriers can shed for months

Question 5

3 organ systems affected in infectious bronchitis**

Answer 5

Respiratory (most common)
Renal (nephrogenic strains only)
Reproductive (in young pullets)

Question 6

CS of infectious bronchitis in young chickens

Answer 6

Dyspnea, gasping, sneezing,

+/- Ocular/nasal discharge

Question 7

Mb/Mt of infectious bronchitis

Answer 7

Mb near 100%

Mt 30% if 5 wks

Question 8

CS of infectious bronchitis in LAYERS

Answer 8

• 50% egg prod. Drop
• cough, sneeze, rales
• soft misshapen eggs** (due to disruption of Ca deposition in egg shells) with watery egg whites

Question 9

Common necropsy findings of infectious bronchitis

Answer 9

• airsacculitis, sinusitis, fibrinous tracheitis
• pale swollen kidneys, urates in ureters (nephrogenic strains)
• salpingitis –> hypoplastic or cystic oviducts in young female chicks
• caseous plugs in trachea
• thick, cloudy air sacs
• pericarditis, perihepatitis
• intestinal adhesions
• egg peritonitis

Question 10

Lab dx of infectious bronchitis

Answer 10

• virus isolation in allantoic cavity of embryonated egg
• Ag detection from tracheal smears
• RT-PCR
• Hemagglutination NEGATIVE

Question 11

Vax for infectious bronchitis

Answer 11

• must vax with correct serotype
• administered as polyvalent vaccine with NCD vaccine
• given as aerosol or in drinking water 2-4 wks before onset of egg prod.
• live vaccine given q8-10 wks during laying period
• stimulate high Ab titers in breeders and passive Ab in progeny

Question 12

What type of virus is Infectious Laryngotracheitis

Answer 12

Alphaherpesvirus

Question 13

CS of ACUTE Infectious Laryngotracheitis

Answer 13

Severe dyspnea, coughing, rales

• mouth/beak may be blood-stained
• profuse hemorrhages in tracheal mucosa

Question 14

CS of SUBACUTE Infectious Laryngotracheitis

Answer 14

• Lacrimation, tracheitis, conjunctivitis, mild rales
• Mild drop in egg prod.
• caseous plugs obstructing trachea/fibrinohemorrhagic tracheitis/fibrino-necrosis of tracheal mucosa

Question 15

Infectious Laryngotracheitis affects which avian species?

Answer 15

Mainly chickens, sometimes pheasants

-highly contagious

Question 16

Can recovered birds carry Infectious Laryngotracheitis?

Answer 16

Yes

Question 17

Histo of infectious laryngotracheitis**

Answer 17

-intranuclear inclusions in tracheal exudate**

Question 18

Dx of infectious laryngotracheitis

Answer 18

• virus isolation in chorioallantoic membrane of embryonated eggs
• immunofluorescence of tracheal smears
• titer rise
• PCR
• intranuclear inclusions in tracheal smears
• electron microscopy of tracheal exudates

Question 19

What to do after an outbreak of infectious laryngotracheitis

Answer 19

• depopulate, clean/disinfect, rest 4-6 wks
• heating enclosed premises for 72 hrs also destroys virus
• Reportable!!

Question 20

Vax for infectious laryngotracheitis**

Answer 20

• only used in enzootic areas - requires Need State Veterinary Permit**
• MLV, which can be virulent
• vax by eye drop, drinking water, or spray in birds >4 wks
• can vax DURING an outbreak to slow it down