AVIAN POX: A REVIEW
¹ Dr. M. Prakash, ² Dr. P. Gowtham
¹ M.V.Sc., PG Scholar, Dept. of Animal Genetics and Breeding, SVVU, AP
² M.V.Sc., PG Scholar, Dept. of Livestock Products Technology, SVVU, AP
Fowl / Avian pox is a slowly spreading viral disease of chicken, characterized by development of discrete nodular proliferative skin lesions on the non- feathered part of the body (cutaneous form) or fibrino-necrotic and proliferative lesions in the mucous membrane of upper respiratory, mouth and oesophagus (Diphtheritic form).
Etiology;
Avipox vius of family pox viridae, a single linear double stranded DNA with hairpin loop at each end. The virus is inactivated by 1% caustic potash and resistant to chloroform and ether. The virus can survive in dried scab for months or even years.
Epidemiology:
Mortality rate: Cutaneous form- low and Diphtheritic form- high
Avipox virus infection of canaries and finches can significantly cause high rate of mortality than those of chicken
Transmission:
Mechanical transmission of virus to injured or lacerated skin
Inhalation or ingestion of virus
Clinical signs:
Incubation period: 4-10 days in chicken, turkey and pigeon, and about 4 days in canaries
Cutaneous form (Dry pox)
Characterized by the appearance of nodular lesions on the comb, wattle, eyelids and non-feathered area of the body
Cutaneous eye lesions will interfere with bird’s ability to reach food and water leads to starvation and death
Diphtheritic form (Wet pox)
Cankers or diphtheritic yellowish lesion occur on the mucous membrane of the mouth, oesophagus or trachea with accompanying coryza like mild or severe respiratory signs similar to ILT
Lesions in the corner of the mouth, on the tongue, throat and upper part of the throat interfere with eating, drinking and breathing
Emaciation, poor weight gain
Unthriftiness and reduced egg production
Necropsy finding:
Characteristic cutaneous form of lesion – epithelial hyperplasia such as scab in head, feet and legs.
Diphtheritic form- white opaque nodule or yellowish patches develop on the mucous membrane of the mouth, oesophagus, tongue and upper trachea
Histopathology:
-intracytoplasmic eosinophilic inclusion bodies (borrel bodies) on the affected tissue
Sample collection:
Live birds-Scab in 10% glycerol saline and paired sample
Dead birds- trachea and oseophagus
Diagnosis:
Based on clinical signs and lesions
Isolation of virus in embryonated egg by chorio-allantoic route of inoculation (10-12 days)
Isolation of virus in cell culture
Molecular diagnosis of viral antigen by PCR and Restriction fragment length polymorphism (RFLP) is used to identify the strain of virus
Antibody detection by AGID, VNT and ELISA
Differential diagnosis;:
Infectious laryngiotracheitis
Caring for a Pox-Infected Flock
The biggest concern when Pox infects the flock is to keep immune systems running at their best.
Depending on the size of the flock, birds can and should be given vitamins that strengthen the defence mechanism of the skin and mucous membranes, boost respiratory and ocular health, and promote rapid healing.
Vitamins A, D, and E are marvelously handy any time a flock is ill and particularly for pox cases. These oil vitamins are most effective in an oil form such as a liquid drop.
Vitamin B12 or the range of B vitamins should also be provided as they give the birds energy and fostering a healthy appetite.
A bird that does not feel well will not heal well so helping them to feel better encourages healthy eating and drinking and reduces dehydration and malnutrition.
Feeding the Infected Flock:
Care should be taken at this time not to change the basic diet the digestive tract, already vulnerable, is no shocked.
The nutrition in an egg is concentrated, which can certainly help when birds are not eating as much as usual. Boiled and crushed eggs are a wonderful source of vitamins, minerals, and proteins that truly provide the building blocks for cells to replace the damaged, sick cells. Mashed egg yolk also provides a perfect hiding place for liquid vitamins. Adding a little chick starter-grower to the mix (less than 10%) can also boost protein and over-all nutrient levels.
Water quality is particularly important to a flock affected by pox. Birds should always remain hydrated and do best with clean, fresh, untreated water.
Medicating the Infected Flock:
Fowl Pox is a virus and cannot be treated with any antibiotics (which are all designed to fight bacteria not viruses); however, secondary infections are common with FP.
For the dry form, triple antibiotic ointments and creams can be used in treating the external sores. Dotting troublesome sores with an iodine-soaked cotton bud can penetrate deep into the core of these sores, fighting bacteria and sterilizing in areas other than those around the eyes. Regular triple-antibiotic ointment can be used even in the corners of the eyes and mouth as long as the ointment does not contain pain-killers.
In the case of wet-pox, it is rarely necessary or effective to treat with a systemic antibiotic as the respiratory problems are caused by lesions that are viral in nature. If severe respiratory distress happens, a veterinarian should be consulted.
Prevention and control:
Prevention is always the best medicine. Prevention by proactive measures and maintaining good biosecurity- being sure to isolate new flock members for a period of no less than 30 days.
Fowl pox vaccine is commonly applied to chicken by the wing web method at 6-8 weeks and also to be administered as early as 4 weeks old. The pullet birds are vaccinated 2 months before egg production is expected to start. Vaccination should not be done when birds in laying
Live virus vaccines used for immunization of birds against pox. Vaccines of fowl pox and pigeon pox virus origin is routinely used for vaccination of chicken and turkeys
Recombinant fowl pox vaccine is also available for vaccination.
Fowl pox vaccine should not to be used in pigeons
Turkeys are vaccinated at 2-3 months old; breeders should be revaccinated before egg production. Site: midway of thigh stick or wing web method
Simply plant some popular Australian Pennyroyal and keep disease carrying mosquitoes and flies away from your chicken flock.
Natural protection also by planting some Basil, Catnip, Marigolds, Peppermint, Rosemary and Thyme which will repel annoying insect pests, and also add a little beauty and scent-sational scents for you to enjoy while tending your fine feathered flock.
