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

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.

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: 265-334nm Viable in dried scabs for decades Sensitive to lipid solvents, disinfectants (phenolic) and heat

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

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.

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.

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

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

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.

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

Caseus material in larynx in FT resembles ILT

Wet-pox: patchy lesions in trachea

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

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

Bollinger bodies in Avipox Oral cavity Hematoxylin and Eosin | 260x  Epithelial cells within the hyperplastic mucosa often undergo ballooning degeneration and contain a 15-30 um, eosinophilic, intracytoplasmic inclusion/Bollinger body (arrow)

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

Prevention and Control Prophylactic vaccination. Fowl pox vaccine at 4-6 weeks of age Second dose at 12-14 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

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

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

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

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

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