In this article we will discuss about how to control and prevent some major contagious diseases of poultry that are usually caused by virus, bacteria and protozoa.
The common diseases caused by these are briefly described below:
1. Viral Diseases:
(i) Ranikhet Disease (New Castle Disease):
Nature of Disease – It is by far the most destructive of the poultry diseases with 100% mortality in broilers. It affects the birds of all ages.
In chicks respiratory symptoms viz. sneezing, coughing and gasping for breath are noticed. But in severe outbreaks many young chicks may die suddenly without any apparent sign of illness.
They may survive for few more days suffer from a greenish watery diarrhoea with a characteristic odour, followed by nervous symptoms such as twisting of the head.
The chicks stagger or walk in circles and rapidly develop paralysis of one or both legs or wings. Appetite is usually lost and the birds become dull and huddle together in corners.
In other birds sudden outbreak of coughing, sneezing and gasping may be noticed. It is soon followed by a yellowish green watery foetal diarrhoea marked respiratory disorder, nervous symptoms and paralysis leading to death.
Prevention and Control/Treatment:
Chicks should be vaccinated with FI strain or Lasota strain on the first day 1-2 drops or within 5 days after hatch and with a booster dose of R2B Mukteswar strain at 8-10 weeks.
The second dose of FI or Lasota may be given in 4th week if necessary. Usually, R2B Mukteswar strain vaccine against this is given 9th to 12th week (0.5 mL injection).
Some advocates vaccination of pullets with an oil adjunct inactivated RD vaccine just before laying. Recently a feed-pellet vaccine has been developed using a virulent strain of Australian origin. The commercially available pellet chick feed is sprayed with an aqueous solution containing 1% strain of virus.
The feed pellet vaccine will have sufficient virus concentration to immunize the chicks by oral route. The vaccine can be distributed in plastic bags and stored at 4° temperature for considerable period.
(ii) Fowl Pox (Chicken Pox Caused by Pox Virus):
Nature of Disease – It is highly contagious and infectious disease. It affects birds of all ages, but young chicks are more susceptible to it and succumb at once.
In the cutaneous form yellowish wart like growth is seen on combs and wattles, the diphtheritic form, white patches and slightly elevated nodules occur inside the mouth, tongue and eye. Diptheritic form is more fatal and birds die due to feed and water deprivation, e.g., Production drops in layers. These birds are more susceptible to secondary bacterial infection, with mortality as high as 50%.
Prevention and Control/Treatment:
The disease will run its course of three weeks, the first five days being severe.
If detected early, an injection of streptopenicillin ointment or a paste of neem leaves and turmeric will help save the birds. Juice of unripe tomato is said to give relief when rubbed on the affected parts.
Five drops of spirit or camphor can be given internally Preventive vaccination with pigeon pox vaccine during the first week followed by fowl pox vaccine at 6-8 weeks of age. Control of mosquitoes is essential to check its spread. Hygiene conditions should be improved.
(iii) Mareck’s Disease (Caused by a Virus of the Herpes Group VVMD):
Nature of Disease – Variation in susceptibility among the birds depends on the strain (breed) of the bird.
Symptoms:
In affected birds tumors may develop in liver, spleen, kidney, gonad, skin and eye. They are usually deformed pupil gray vision, unilateral or lateral-I blindness; paralysis deformed wings and neck may be observed.
Death rate is highly variable; young chicken may suffer from acute form; skin lesions are usually associated with feather follicles.
Prevention and Control/Treatment:
Treatment is of no avail.
Certain strains are somewhat resistant to Mareck’s disease and such poultry is always advantageous; Vaccination with herpes virus of turkey (THY) vaccine at a day old stage keeps the causative virus under check though it does not prevent the infection (chick embryo vaccination is good). Strict isolation of the infected birds has to be maintained.
Purchase only chick vaccinated against Mareck’s disease. The only method of protecting is vaccination of a day old chicks with a virulent strain in combination with HVT, given intramuscularly.
(iv) Gumboro Disease (Infectious Bursitis Vaccine IBD):
Caused by – Ringe Seretype of IBD Virus.
Nature of Disease:
It is highly contagious disease and so disastrous hat affected, chicks are immunologically crippled and highly susceptible for other Infection and the birds of 3 weeks of age are prone to the infection and layers are more sensitive than broilers. Early IBD infection reduces the efficacy of vaccine against viral disease like ND, IB, Mareck’s disease and fowl pox.
The symptoms are white watery mucoid droppings, soiled vent feathers, loss of appetite and severe tremors and unsteady gait, listlessness, Jess mortality but high morbidity.
Prevention and Control/Treatment to Minimize Infection:
a. Avoid rearing layer and broiler chicken in close vicinity.
b. Chicks should be vaccinated at 5-7 days with Lasota,
c. Give Gumboro vaccination at 18-21 days and to booster at seven weeks,
d. Every worker entering sheds should disinfect feet and hands; limit visitors,
e. Incinerate dead birds; burn Jitter after removal and make sure that sheds are clean and disinfected.
f. Supplement low level vitamin-A compounds to minimise the effect of the vims.
(v) Avian Encephalomyelitis, or Epidemic Tremor or Atoxia:
Nature of Disease – This disease is caused by an entero virus; mostly chicks upto six weeks of age are affected.
Incoordination, tremor of body, partial or complete paralysis and in adults there is drop in egg production.
Prevention and Control/Treatment:
Cull the affected flock, birds surviving the attack should not be used for breeding.
(vi) Infectious Bronchitis or IB (Caused by Virus):
Nature of Disease Sudden onset, rapid spread with high morbidity and mortality upto 25%. The infection lasts for about 15-30 days and is mostly complicated with CRD infection.
Symptoms are gasping coughing and sneezing, discharges from eyes and nostrils. Egg production drops by 60-90 %, the egg quality deteriorates; it is often, shelled, wrinkled, small in size and has poor albumin quality.
Prevention and Control/Treatment:
Vaccination with J inactivated or attenuated live virus vaccine when day old along with RD vaccine. When it is complicated, antibiotic treatment is desired.
(vii) Leucosis (Caused by a Virus):
Nature of Disease – It is spread mainly through the egg or repeated close contact. It affects adult birds causing very heavy mortality among layers.
Comb and wattle get anaemic, low weight, poor egg yield, liver is very much enlarged and pale.
Prevention and Control/Treatment:
Purchasing birds only from leucosis free flocks, is the only way of prevention of this disease, as birds do not respond to any treatment.
2. Bacterial Diseases:
(i) Infectious Coryza:
Nature of Disease – Caused by a bacteria Haemophilus gallinarum. It affects birds upto weeks of age. Mortality six is heavy in young chicks (ranging between 70-80 %).
Discharge from eyes and nostrils, sometimes the discharge are purulent and fowl smelling. Eyelids stick together. There is swelling of eyes and face.
Prevention and Control/Treatment:
Sulphadrug @ 0.05% in feed or water for seven days can control the out outbreaks; tylosin, tetracycline and streptomycin are also effective for treatment and control. Greens, rich in vitamin-A such as berseem and lucerne may be fed.
(ii) Coliibacillosis (Caused by Escherichia Coli):
Nature of Disease – Escherichia coli may be the primary or secondary cause of several diseases. It is aggravated during infection by other pathogen and environmental stress factors.
The affected birds show diarrhoea of varying degrees. Swelling on joint wattle and comb is seen. Very young chicken often die suddenly. When survived, their growth rate is very poor. Sick chicks fall victims to other diseases and die early.
Prevention and Control/Treatment:
Furazolidones and sulphamethoxine drugs are useful for its control. Stress should be reduced to the extent possible.
3. Protozoan Diseases:
(i) Coccidiosis (Caused by Coccidia Species):
Nature of Disease – It is a host-specific disease caused by a group of intracellular parasites mainly affecting the, intestine of chicks between 3 and 10 week; causing very heavy mortality (50-70%).
a. The affected birds do not feed
b. Blood and mucus in the droppings
c. Birds are dull with ruffled feathers and drooping of wings
d. Emaciation and dehydration of combs and wattles.
e. Reduction in egg yield
f. Vent is soiled with blood
Attempted in early stages, recovery is 80%.
Drinking water disinfected with any of the following drugs be given:
a. Amprolsol at 30 g in 25-50 L of water for 5-7 days
b. Sulphamezathine 16% or Diadin 16% @ 10 mL in 1 L of water for three days
c. Bifuran soluble tablet (one) in 1 L of water for seven days and
d. Codrinal 4 g in 1L of water for 2 or 4 days.
a. Avoid overcrowding and dampness
b. Rear chicks separately from
c. Rear chicks not on floors but on wire mesh or deep litters
d. Strict hygiene measures should be observed.
(ii) Spirochaetosis (Tick Fever):
Caused by – Blood parasite called Sprirochaetia ansesina.
Nature of Disease – Females are more susceptible than males.
High fever, stops feeding and laying, wings droop unsteady gait, eyes closed and restlessness, rapid emaciation and great thirst and Diarrhoea.
Prevention and Control/Treatment:
Vaccination prevents the disease. Ticks, which act as vectors should also be controlled with insecticides such as DDT, gammaxene malathion and buttox.