Fowl pox :

   [ sore head , Avian diphtheria , bird pox ]

• It is contagious slow spreading viral disease
• Birds of all age is affected, mainly chickens and turkey
• Some viral type may also affect pigeon , geese , pheasant and quails
• Mortality rate = 1-2%
• IP = 2-3 weeks
• Fowlpox is seen worldwide
• There are 2 forms :

1. Wet form is characterised by plaques in mouth and URT
2. Dry form is characterised by wart-like skin lesions that progress toi thick scabs

Etiology :

• The largest Ds DNA virus , an Avipoxvirus belongs to Family Poxviridae
• Enveloped and brick shaped virus
• Virus is highly resistant in dried scab and under certain condition may survive for months

Transmission :

• Mosquitoes are the most common vectors for transmission of avipoxvirus
• Virus can also be transmitted indirectly by contaminated surfaces or airborne particles
• Contaminated water and feed
• Scales of disease bird also transmit the disease
• Through wound
• Vertical transmission is suspected
• Recovered birds do not remain carriers

Clinical signs :

a. Cutaneous form (dry form):

• Wart like growths are seen on face , comb , wattle and featherless part of body
• They grow readily and then yellow and later turn black / brown lesion
• After 2-3 weeks ; lesions dry up and scabby
• In some cases , lesions are limited chiefly on feet and legs
• Cutaneous lesions on eyelids may cause complete closure of one or both eye

b. Diphtheritic form 🙁 wet form )

• White patches or slightly elevated nodules occur inside the mouth and tongue . This merges together to form raised – yellow cheesy patches
• Mucous membrane of mouth and esophagus are affected
• Breathing may be difficult

c. Oculonasal form :

• Eruption on the opening of eye and nose
• Ear and nose may smell and discharge from eye and nose may be seen
• Affected bird won’t eat and difficulty in swallowing

Postmortem lesions :

• Diphtheritic form is recognised by presence of nodular hyperplasia of mucosa of pharynx and trachea
• Chicken which die of diphtheritic pox may show a plug of desquamated epithelium which lodge in glottis resulting in asphyxiation

Diagnosis :

• History
• Clinical signs [ cutaneous lesions are characteristics ]
• Physical exam
• Histological examination of affected tissue will confirm the presence of intracytoplasmic inclusions ( Bollinger bodies ) in respiratory mucosa and skin
• PCR
• Pox virus – virus isolation , FA test , electron microscopy , agar gel immunodiffusion of scab with underlying epithelium , URT or nodilar lesions

DDx :

• Necrotic dermatitis
• Leg mites
• Thrush and canker