1. Dr. Latif Ahmad, PhD Assistant Professor
Fowl pox (Avian pox)
Dr. Latif Ahmad, PhD
Assistant Professor

2. Defining Fowl POX
It is a contagious, slow spreading viral disease of chickens, turkey and other birds characterized by:
cutaneous lesions (eruptions) on unfeathered skin (head, neck, legs and feet) and/or by
diphtheritic lesions on mucous membranes in the upper digestive and respiratory tract.

3. Aetiology
Genus Avipox viruses belonging to family poxviridae: FPV (fowl), TPV (turkey), PPV (pigeon), CPV (canary/kikuth’s disease).
Brick-shapped, DS DNA core; size: nm
Viable in dried scabs for decades
Sensitive to lipid solvents, disinfectants (phenolic) and heat

4. Hosts Genus avipox Chickens, turkeys, pigeons
Less common in quails, geese, ducks, guineas, pheasants, canaries and certain wild birds
Mammalian poxviruses are of genus Orthopox
Pigeons resistant to FPV, but PPV can cause a mild reaction in fowl and provides temporary immunity to FPV in those birds

5. Epizootology Between flocks Within flocks Direct contact
Mech. carriers: mosquitoes, ticks, lice, flies
Within flocks
Cannibalism
Relatively slow spread (2-3 wks)
Injury: Sharp grit; Excited, un-feathered birds
Stress, over-crowding
5-12 months of age
Latent inf. activated by resp. dis., vaccination etc.

6. Clinical Signs Incubation period
Natural infection is 4-10d
Experimental inf. 5-10d
The disease can be associated with drop in egg production and mortality
Cutaneous form: Focal vesicles; wart-like lesions which soon dry; rough irregular surface; first yellow-brown, then dark-brown. In severe cases, numerous lesions, which later coalesce and closure of one or both eyes may result. Otherwise plaques may form, which get infected forming pustules. Removal of lesions leads to dry or moist haem. surface, followed by scab (2-4wks) and scar.

8. Diphtheritic (wet) form:
Lesions on mucous membranes in mouth, pharynx, esophagus, trachea
White or opaque eruptions in mouth, pharynx
Vesicles -> ulcers
Extensive fibrino-necrotic process in muc. memb. affects water & feed intake
Dyspnoea, gasping and suffocation due to caseus material in larynx. This resembles ILT
Oculo-nasal form:
Conjunctivitis
Swollen intra-orbital sinuses

9. Numerous multifocal to coalescing proliferative yellow-tan nodular masses, which are covered in necrotic debris and fibrin in oral cavity – Wet Fowlpox

10. Gross Pathology Cutaneous lesions:
The reaction against poxvirus is mainly proliferative rather than exudative. Characterized by appearance of wart like papillae or nodules, on face and unfeathered areas, comb and wattles, which soon become dark brown and hard.

11. Diphteritic lesions:
Small white nodules on muc. memb. of mouth, esophagus and URT.
Pinkish, grey, yellowish, purullent material may partially or completely block trachea
Caseus material in larynx. This resembles ILT
Lesions in internal organs:
Internal organs are usually normal, but lesions may also be found liver, pancreas and salivary glands

13. Caseus material in larynx in FT resembles ILT

15. Wet-pox: patchy lesions in trachea

16. Histopathathology Balloon-like deg. in sq. epi. cells of skin
Hyperplasia of inf epi of oral/tracheal mucosa
Affected epi cells enlarge due to eosinophilic inclusions (2-3 µ) in cytoplasm (Bollinger bodies), which are readily identified by m/s. Whitish large inclusions small Borrel bodies
During later stages, inflam. cells infiltrate the area and necrotic changes are present

17. Eyelid (H&E) Fowl Pox: Multifocally, within the feathered skin, areas of marked epidermal hyperplasia and hypertrophy (arrows).

18. Bollinger bodies in Avipox
Oral cavity Hematoxylin and Eosin | 260x  Epithelial cells within the hyperplastic mucosa often undergo ballooning degeneration and contain a um, eosinophilic, intracytoplasmic inclusion/Bollinger body (arrow)

19. Diagnosis Diagnosis Fowl Pox DD's: Clinical signs
EM – characteristic virion size\shape (bricks)
Virus isolation: The virus can be isolated by inoculating CAM of developing chicken embryos (9-12 d old); most convenient host for virus isolation 
PCR: useful for detection of extremely small amount of viral DNA and has been used effectively to differentiate field and vaccine strains
Fowl Pox DD's:
Injuries due to pen mates pecking
ILT
T-2 toxins

20. Prevention and Control
Prophylactic vaccination.
Fowl pox vaccine at 4-6 weeks of age
Second dose at weeks of age
Pigeonpox and turkepox vaccines have been used with variable success
Vector control
Prevent spread by fomites and use quarantine procedures
Treatment is supportive, Vit A

21. MCQs
Choose the MOST CORRECT or THE ONLY CORRECT answer for the following questions:
Which of the following avian viruses does cause pocks on chorio-allantoic memb. on embryonated chiken eggs?
Poxvirus
Pox and ILTV
Poxvirus and viral arthritis virus
ILTV and viral arthritis virus
Poxvirus, ILTV and viral arthritis virus

22. 2. Birds vaccinated by the wing web stab method for which of the following diseases should be examined for “takes”?
Pox
Pox and FC (Fowl Cholera)
Pox and AE (Avian Encephalomyelitis)
FC and AE
Pox, FC and AE

23. 3. Birds vaccinated with poxvirus vaccine by the wing web stab method should be examined for “takes”, how many days after vaccination?
4. Cell-mediated immunity is known to be protective in which of the following diseases? A. MD, AE and IBD B. MD, AE and ILT C. MD, AILT and IB D. MD, AILT and Pox E. MD, IBD, AILT and Pox
2-3 d
4-6 d
7-10 d
14-21 d

24. 5. There was slight increase in mortality in a flock of 14-wk old layer pullets. The farm manager described the birds as “could not breath and died”. PM revealed only thickenings of the laryngeal tissues with presence of caseus material in larynx. What could be your tentative Dx.
Trichothecens mycotoxicosis
CuSO4 Toxicity
Quaternary amm. Comp. toxicity
Pox
ILT

25. 6. It is recommended to vaccinate turkeys with live fowl poxvirus vaccine by which of the following vaccination methods?
I/M inj
S/C inj
Thigh stick method
Wing web stab
Key to MCQs:
1. e, 2. b, 3. c, 4. d, 5. d, 6. c