Poultry

Disease Management

Aspergillosis Marek disease Marek disease control Anemia Inclusion Body hepatitis Bronchitis Infectious Bursal disease(Gumboro) Chronic respiratory disease Coccidiosis Coryza Egg drop Endoparasites Epidemic tremor Fowl Cholera Fowl pox Loose droppings Malabsorption syndrome New castle disease Pollorum/typhoid Synovitis Viral arthritis Vitamin D3 deficiency Vitamin E deficiency

• The disease is caused by a fungus, Aspergillus fumigatus.

• Transmission is by inhalation of fungus spores from contaminated litter (e.g. wood shavings) or contaminated feed.
• Hatcheries may also contribute to infection of chicks.

• Young chicks are very susceptible, older chickens are more resistant to infection.
• Turkey poults, pheasant chicks, quail chicks, ducklings, and goslings may also become infected

• Infected chicks are depressed and thirsty
• Gasping and rapid breathing ("pump handle breathing") can be observed.
• Mortality is variable, from 5 to 50%.
• Gross lesions involve the lungs and airsacs primarily.
• Yellow-white pin-point lesions can be found.
• Sometimes all body cavities are filled with small yellow-green granular fungus growth.

• The presence of Aspergilllus fumigatus can be identified microscopically or sometimes even with the naked eye in the air passages of the lungs, in the air sacs or in lesions of the abdominal cavity.

• There is no treatment for aspergillosis.
• Affected chicks should be removed and destroyed.
• Strict hygiene in breeder and hatchery management is necessary.
• Choice of litter material is important so that no spore-bearing wood shavings are used.

• Marek's disease is caused by a herpes virus.

• Main transmission is by infected premises, where day-old chicks will become infected by the oral and respiratory routes.
• Dander from feather follicles of MD-infected chickens can remain infectious for more than a year.
• Young chicks are particularly susceptible to horizontal transmission.
• Susceptibility decreases rapidly after the first few days of age.

• The domestic fowl.

• Infected birds show weight loss. or may exhibit some form of paralysis.
• Mortality varies from 5 to 50% in unvaccinated birds.
• The classical form (paralysis) with leg nerve involvement causes a bird to lie on its side with one leg stretched forward and the other backward.
• When the gizzard nerve is involved, the birds will have a very small gizzard and intestines and will waste away.
• Mortality usually occurs between 10 and 20 weeks of age.

• The presence of tumours in liver, spleen, kidneys, lungs, ovary, muscles, or other tissues is indicative of MD, but they can also be indicative of lymphoid leucosis.
• However, nerve involvement, either grossly (swelling of leg, wing or other nerves) or microscopically, is typical of MD.
• Eye involvement can be visible as an irregular constriction of the iris (ocular lymphomatosis).
• Skin involvement (skin leucosis) often consists of tumours of feather follicles or in between follicles.
• Skin leucosis is a reason for broiler condemnation in certain parts of the world.
• A proper diagnosis to differentiate MD from LL requires histological examination.

• Vaccination of day-old chicks is an effective mean of control.
• It has been demonstrated that MD vaccine only prevents the appearance of Marek's disease tumours and paralysis, it does not prevent the birds from becoming infected with MD -virus.
• It is therefore of major importance to maintain high hygienic and sanitary measures by good management to avoid early exposure of young chickens.

• Presence of pathogenic M.D. virus at the farm is the biggest etiologic factor of M.D The infection is followed by a quick and heavy multiplication of the virus in the defense organs of the body such as bursa, thymus, spleen etc.
• This explains why M.D. is an immunosuppressive disease. Then a stage comes when multiplication of virus decreases and now we can see formation of tumors and affection of the nerves.

• Several lines of chickens with genetic resistance to MD have been selected and maintained experimentally.
• Spencer et al (1976) found genetically resistant chickens were protected by vaccination to a greater extent than more susceptible ones.
• Breeding for genetic resistance may be a valuable adjunct to immunization for control of MD.

• Prevention of early exposure of vaccinated birds with virulent M.D virus (MDV) enhances the efficacy of the vaccine.
• If one can achieve his, he will definitely emerge victorious over M.D.

• It is interesting to know that females are more sensitive to M.D. than males. This is indicated by a shorter duration incubation period, higher frequency of clinical manifestations and larger no.of females with tumors.

• The presence of maternal antibodies (MABs) significantly impedes the multiplication of MDV during the first stage of disease.
• The degree of this procection depends on the antibody titre. Maternal antibodies also impede propagation of MD vaccine virus.

• Chicken anaemia agent (CAA) and Reo virus can predispose the birds to or aggravate MD.

• Mycoplasma synovie can act as a predisposing factor for MD

• Aflatoxin induced immunosuppression can make the birds prone to MD.
• Sanitation and biosecurity play very important role in the occurrence of Marek's disease.

• All strains of MDV develop in an infectious form in the cells of feather follicles. Therefore, the no.of produced and released MD viruses increase during the chicks, a young animal and layer's moult.
• From the feather follicles, MDV reach the air and get settled in the dust. In dust, the effectively of MDV is preserved for a very long time.
• The dust usually concentrates on the ceiling and walls but also in the ventilation of the chicken house. A through mechanical removal and an innocuous disposal (heating) of the infectious dust are important measures against further infections.
• Various insects which live in the litter as for ext. black lesser mealworm is a carrier of MDV. If these insects (beetles) are eaten by chickens, they might be infected.
• The most significant way of MDV transmission is the inhalation of infected dust. Any alternate ways of infection (mentioned below) which are common with other viral diseases, are meaningless for MD.

1.    Vertical spread (Vertical via the hatching eggs)
2.   Genital spread (during the mating of a male and female)
3.   Oral communication (through feed or drinking water)

• The occurrence of Marek's disease can be successfully prevented if one carefully studies the following points:

• MDV strains are never vertically transmitted (i.e. via the hatching eggs). The only source for infection for chicks and chickens of all age groups is dust containing the virus.
• They get infected in an environment which is contaminated with MDV Cleaning and disinfecting can decontaminate the chicken houses.
• The interested readers can obtain the protocol of disaffection program from our office. The introduction and spreading of MDVs in farms can be effectively and continuously prevented by appropriate architectural measures.
• This method is used by the producers of specific pathogen free (S.P.F) hatching eggs. SPF flocks are kept in positive pressurized houses having filters to nullify possibility of entry of any microorganisms.

• Faulty application of the vaccine such as dilution mistakes during the preparation, faults in the technique of injection, too long times of storage or too high ambient temperate of reconstituted vaccines.
• In the modern hatchery practices possibility of such lapses is very minimum. · Too low content of viruses in the vaccine. The protection by inoculation depends on the dose of injected viruses.
• Ventri's MD vaccine contains minimum 4000 to 5000 P.F. US/ dose as against British pharmacopea (Vet), standards of 1500 PFU/close. A higher content of viruses does not lead to any significant improved protection. In case of severely affected farms, a booster dose of MD vaccine may be tried on 18th day. There are some reports of encouraging outcome with such practice of MD booster vaccination.
• If an infection with virulent MDV occurs simultaneously with or a few days after the vaccination, there can be no sufficient protection from the vaccine. In our opinion, this applies to all available vaccines. The older the chicks are at the time of infection by MDV, the lower the rate of spread of field strain (pathogenic) is. This can be achieved only with the help of accurate cleaning / disinfection and strict biosecurity measures, for first 15 days post hatchery vaccination. ·
• As it is known of other live virus vaccines, the contamination of a vaccine can lead to damage to the inoculated chick by concurrently present microorganisms. This explains the need of accurate sterilization of injection appliances before being used.
• The presence of high maternal antibodies can also impede the development of immunity in the vaccinated chicks
• In short, occurrence of MD cases despite of vaccination can be attributed to

1.   Improper sanitation and poor biosecurity.
2.   Early exposure to virulent MDV
3.   High maternal antibody
4.   Poor vaccination procedures

• In 1982, two American scientists found that vaccination of 18-day-old embryos accelerated development of protective immunity by several days and proposed this technique for controlling detrimental effects of early exposure to virulent MDV. This technique is named as: In ovo Mark's vaccination".The in ovo method eliminated the need for manual post-hatch inoculation of day old chicks and result in healthier chicks due to earlier introduction of disease preventing vaccines and less stress to the chicks. Tri-bio laboratories, U.S.A. (collaborator of Ventri biologicals Divn) have already produce one such in ovo MD vaccine.

• clinically healthy chicken only can develop protective immunity after the vaccination. This means that in order to have a successful program to control MD., other pathogenic agents must be eliminated. Certain infections which can make the bird susceptible to Mark's disease are mentioned below:
• Certain species of avian mycoplasma enchase the multiplication of Marek's disease virus in cell cultures according to Dr. Kaleta Gieban, an eminent European scientist.
• Chicken Anaemia Agent (CAA)- Experimental dual infections with CAA and subclinical doses of MDV caused enhancement of MDV antigen shedding to feather follicles.

• Aflatokins increase susceptibility of poultry to Marek's disease.
• The mechanism is through depression of the cell-mediated immune response. Certain vitamins like vitamin A, C, E, B6, H etc., are very essential for the development of lymphoid (defense) organs of the body like bursa, thymus, spleen, liver etc., one should always use the vitamins which are procured from a dependable source only because the use of substandard vitamins may lead to imunosuppression.

• According to a study undertaken in hot climates successively for two years by Dr. Raghard Al-Khoja, the heat stress can affect the efficiency of immunity build up against Marek's disease. He found that the chicks hatched during summer (i.e March to June) are more susceptible to MDV infection. So one should take extra care during summer to prevent MD incidences.
• Mark's disease vaccination is carried out during the 1st 24 hours of a chick's life and its effectiveness is determined until the chicks reach the age of at least six weeks. Therefore, chicks should be protected from exposure to field (Pathogenic) MDV for atleast first 6 weeks are even more crucial.
• Only persons working on the farm and dressed in clean protective clothing shall be admitted to the chicken houses.

• Prior to the use of vaccines, MD constituted a serious economical threat to the poultry industry because of heavy mortality and losses. Since vaccine does not mean full proof protection, losses still occur but they are no longer as serious a problem.
• Perhaps the greatest impact of MD is immunosuppression (impairment of immune system) apparently caused by the damage to the bursa, thymus, spleen, liver etc. Both humoral antibody and cell mediated immunity can be depressed by MD. These are reflected by reduced antibody response to a variety of vaccines and by alteration of T cell functions. MDV infection could increase susceptibility to primary and secondary infections with coccidia and reduced antibody response to M. sysnoviae.
• In broilers, MD may exist in sub clinical form if not in clinical form. This may lead to vaccine failure. That is why MD vaccination (at least half dose) is recommended in day old broiler chicks.

• A very resistant small virus known as CAA (Chicken Anaemia Virus) or CIAV (Chicken Infectious Anaemia Virus) causes infectious Anaemia.

• The major mode of transmission of Infectious Anaemia is vertical transmission from infected breeder hens.
• Horizontal transmission from bird to bird or by infected equipment, clothing, etc. is also possible.

• CAA causes a syndrome in young chicks up to approximately 3 weeks of age.
• Adult birds may get infected but will not develop clinical signs.
• The disease is characterized by increased mortality and anaemia associated with atrophy of the haematopoietic tissues in the bone marrow.
• Subcutaneous and intramuscular haemorrhages can be found accompanied with atrophy of the lymphoid system.
• Affected birds may show focal skin lesions (also known as blue wing disease).
• Mortality rates vary from 20% to 70%.
• Affected flocks will show poor growth reflected in economic losses.

• The diagnosis can be based on the clinical signs and pathological findings in affected birds.
• Blood serum testing for specific CM antibodies can be carried out (IFT, VN, etc.) Virus isolation is also possible but it is time-consuming and expensive.

• No treatment is available for Infectious Anaemia.
• Maternally derived antibodies can offer protection.
• The induction of high maternal immunity in the progency by vaccinating breeders is the best approach to successful CM control.

• The disease is caused by an avian adenovirus (for example the Tipton strain) and is usually simultaneously accompanied by other immunosuppressive diseases such as Infectious Bursal Disease or Infectious Anaemia.
• There are 12 known serotypes of avian adenoviruses that may be involved in the development of this disease.

• Egg transmission is an important factor.
• Horizontal transmission from bird to bird by contact with droppings.
• Once the bird becomes immune, the virus can no longer be isolated from the droppings.

• Chickens, turkeys and pheasants and possibly other birds can be affected by avian adenovirus.

• Chickens with inclusion body hepatitis are affected at usually 5 to 7 weeks of age.
• The birds are listless, with ruffled feathers.
• Mortality is usually quite severe, up to 25% in the first 10 days of the disease.

• Affected chickens have mottled livers, many with pinpoint necrotic and haemorrhagic spots.
• Pale bone marrow and, in some cases in presence of Infectious Anaemia, gangrenous dermatitis can be seen.
• Kidneys are pale and swollen.
• The spleen is usually quite small (atrophy)
• If Gumboro disease (Infectious Bursal Disease) has been present in the birds, even if sub-clinical, the Bursa of Fabricius will be very small (atrophic).
• Such chickens are immune-suppressed and usually have more severe cases of inclusion body hepatitis and/or infectious anaemia.
• Mature birds do not have clinical signs of adenovirus infection, they only start showing antibodies in their blood.

• Typical mottled livers with pin-point lesions, pale bone marrow and kidneys, small spleen and bursa are good indications of the disease.
• Histological examination (intranuclear inclusion bodies) of liver and/or virus isolation are helpful means of diagnosis.

• No treatment exists.
• Antibiotics can be used to prevent secondary bacterial infection and possible gangrenous dermatitis.
• The best method of control is to ensure adequate immunity against other immune suppressive diseases (e.g. Infectious Bursal Disease).
• Breeder chickens may be vaccinated with live vaccine, followed by inactivated oil-emulsion vaccine application before egg production begins.
• This procedure ensures adequate maternal immunity against IBD disease in the offspring which assists in preventing inclusion Body Hepatitis.

• Corona-virus is the causal agent.
• Several different serotypes of IB virus are known to exist.

• The virus is transmitted from bird to bird through the airborne route.
• The virus can also be airborne between chicken houses and even from farm to farm.

• Only chickens are susceptible to IB virus.

• Respiratory signs include wet rales, gurgling, and wheezing.
• Egg production will decrease dramatically, deformed eggs with wrinkled shells will often be laid.

• Mucus and redness in tracheas froth in airsacs in older chickens.
• In young chicks a yellow cheesy plug at the tracheal bifurcation is indicative of IB infection.

• There are three main factors to be considered in order to arrive at a diagnosis
• The clinical picture including post-mortem findings in the flock.
• lsolation of the virus In the laboratory.
• Rising antibody titre when the serum is tested against a known strain of bronchitis virus.

• There is no treatment for Infectious Bronchitis.
• Secondary bacterial infections may be prevented by, or treated with antibiotics.
• Prevention by vaccination is the best method to control.

• The disease is caused by a birna virus of serotype.
• Virus strains can be divided in classical and variant strains.
• The virus is very stable and is difficult to eradicate from an infected farm.

• IBD virus is very infectious and spreads easily from bird to bird by way of droppings.
• Infected clothing and equipment are means of transmission between farms.

• Chickens and turkeys appear to be natural hosts.

• In subsequent infection on the same farm, mortality is lower and eventually, with successive attacks, there is no mortality noted.
• The sub-clinical form caused by the immunosuppressive effect of the IBD virus is now of more economic importance in that the immune system of the bird is damaged.
• In broilers this form of the disease results in bad performance with lower weight gains and higher feed conversion ratios.

• In acute cases the Bursa of Fabricius is enlarged and gelatinous, sometimes even bloody.
• Muscle haemorrhages and pale kidneys can be seen.
• Infection by variant strains is usually accompanied by a fast bursal atrophy (in 24-48 hours) without the typical signs of Gumboro disease. Also in chronic cases the bursa is smaller than normal (atrophy). The bursa destruction is apparent on histologic examination.
• The lack of white blood cells (lymphocytes) results in a reduction in the development of immunity and decreased resistance of the birds to other infections.
• Typical signs and lesions are diagnostic of IBD.
• Histopathological examination, serology and/or virus isolation are helpful tools. IBD can be confused with sulfonamide poisoning, aflatoxicosis, and pale bird syndrome (vitamin E deficiency).

• No treatment is available for IBD.
• Vaccination of parent breeders and/or young chicks is the best means of control.
• The induction of a high maternal immunity in the progeny of vaccinated breeders is the most effective approach to successful IBD control.

• The underlying cause of CRD is Mycoplasma gallisepticum (Mg). The condition is frequently triggered by respiratory viruses such as NO and 18 and subsequently complicated by bacterial invasion.
• The main agents involved in the infection are Mycoplasma gallisepticum. Stress caused by moving the birds, by de-beaking or other operations or other unfavourable conditions e.g. cold or bad ventilation, make the birds more susceptible.

• The main problem is that parent birds infected with Mycoplasma gallisepticum can transmit the organism through the egg to their offspring.
• In addition, infection can occur by contact or by airborne dust or droplets. The incubation period varies from 4 days to 3 weeks.

Chickens and turkeys.

• Young chickens (broiler chicks or layer pullets) will show respiratory distress. The birds frequently show a lack of appetite, decreased weight gain and increased feed conversion ratios.
• In adult birds the most common symptoms are sneezing, coughing and general signs of respiratory congestion. In laying birds a drop of egg production between 20-30% can occur.
• CRD does not normally cause an alarming number of deaths. The effect is more of a chronic nature causing reduced weight gain and feed conversion ratios in broilers and lower egg production in breeders and layers. In this way the overall economic loss can be very great in broilers but less dramatic in breeders and layers.

• A reddish inflamed trachea and/or cheesy exudates in airsacs, especially in complicated cases (e.g. with secondary E. coli infections) are observed. In mild Mg infections the only lesion might be slight mucus in trachea and a cloudy or light froth in the airsacs.
• Turkeys with Mg infection usually have swollen sinuses under the eyes.

• Diagnosis of Mg infection can be made by blood testing of chickens, post-mortem examination and ultimately by isolating the causative Mg organism from tracheas or airsacs of affected birds.

• Respiratory virus infection (Newcastle disease or Infectious Bronchitis) with secondary infection (E. coli, etc.) can give similar lesions.

• Treatment of Mg-infected chickens or turkeys with suitable antibiotics or chemotherapeutics has been found to be of economic value.
• However, control by medication or vaccination and eradication of Mg infections has been by far the most effective method of combating the disease.
• Fertile eggs from infected birds can be treated with antibiotics such as tylosin to eliminate the Mycoplasma gallisepticum organisms.
• Methods used are the injection of fertile eggs or egg dipping.
• Blood serum testing of breeder chickens for Mg antibodies has become a routine to test flocks for a Mg infection.

• Coccidiosis is caused by protozoa, unicellular parasites.
• In chickens there are 9 different species of coccidia of which the main 5 are Eimeria acervulina, Eimeria necatrix, Eimeria tenella, Eimeria maxima, Eimeria brunetti.

• Infected droppings, containing oocysts of coccidia are the main means of transmission between birds.
• The incubation period is 4 to 6 days.

• Chickens have their own specific coccidiosis types, which do not cross-infect other bird species.

Coccidiosis can be divided into 2 groups.

1. The caesium is involved (Caecal coccidiosis)

• Mainly caused by E. tenella in chickens up to 12 weeks.
• Mortality may run as high as 50%.
• Infected birds are listless, have bloody droppings, a pale comb and show a lack of appetite.
• Laboratory examination will show haemorrhages in the caecal wall.
• After severe bleeding a core will be formed in the lumen.

2. The small intestine is involved (small intestinal coccidiosis) Caused by E. acervulina, E. brunet ti, E. maxima, E. necatrix.

• Birds infected show loss of weight, combs may be shrivelled and a drop or even cessation of egg production in layers may be seen.
• At necropsy, haemorrhagic lesions of E. acervulina are seen throughout the upper portion of the affected intestine and also grey or whitish patches may be present.
• May affect birds of any age.

• Diarrhoea, loss of weight and a drop in egg production of layers, will be seen; bloody droppings are common.
• At necropsy the lower portion of the small intestine is dilated and the wall is thickened; the gut is filled with thick mucus, greyish, brownish or pinkish in colour.

• In layers a drop in egg production will be observed.
• At necropsy the middle portion of the intestine is affected, haemorrhage will be seen.
• The unopened intestine looks spotty, white areas (schizonts) intermingled with bright or dull red spots (haemorrhages) will be observed.

• This is most appropriate in the case of coccidiosis as there is no disease group in poultry where both control and treatment are employed more.
• The well-established principles of good management and husbandry are of basic importance.
• It is common practice to include low levels of chemotherapeutics in the feed of birds.
• These chemicals are referred to as coccidiostats and as such keep in check the development of the parasites so that a pathological situation does not develop.
• It should, however, be taken into account that coccidia can develop a resistance to all chemicals so far used for this purpose and for this reason it is necessary to change from one chemical to another periodically.
• Treatment of infected flocks may be carried out by the administration of coccidostats at a higher therapeutic level to the affected birds.
• There are certain products available which are specifically designed for treatment and which are not satisfactory for prevention.
• These chemicals are sometimes referred to as coccidiocidal agents. Whenever administering these products, particular attention should be paid to the dosage recommendation of the manufacturer.

• The bacterium causing this disease is Hemophilus paragallinarum.

• The disease spreads from bird to bird and flock to flock by contact and airborne infected dust particles and via the drinking water.
• Spread by equipment and personnel has also been reported.
• The incubation period varies from 1 to 3 days.

• Chickens appear to be the only natural hosts of H. paragallinarum

• Egg production in laying birds will drop.
• Mortality will vary with the virulence of the infection but is generlly low.

• A field infection produces similar symptoms to Chronic Respiratory Disease, a diagnosis is difficult to establish.
• The most certain diagnosis may be obtained by the isolation of organism from the sinus or airsac exudate from affected birds.
• Procedure must be carried out in the laboratory.

• Treatment with antibiotics can be given to subdue clinical infections but eradication and prevention are the most desirable means of control of coryza.
• Vaccines have been developed, but are only used in areas where the disease is endemic and cannot be eradicated.

• The disease is caused by an avian adenovirus (strain BC14, virus 127), the EDS virus does not belong to any other 12 fowl adenoviruses.

• The virus is transmitted through the egg to a few birds in a flock, these birds carry the virus until the flock comes into lay at which time they begin to excrete virus and infect birds kept in the same house.
• Horizontal spread through infected litter can and does occur once a flock shows the disease but it seems that the virus is not very infectious or the level of virus excretion is low.

• Only chickens are susceptible to clinical disease due to EDS virus; however, the virus is widespread in ducks but does not cause any problems.

• EDS '76 affects only layers and breeders at the start of or during their egg production.
• Affected flocks show a failure to reach peak egg production or a drop in egg production accompanied by an inferior eggshell quality and in the case of brown eggs, a loss of shell colour.
• Affected birds may also appear to be anaemic, may show transient diarrhoea and sometimes the food intake may be reduced.
• No increased mortality or other symptoms are observed.

• No specific internal lesions have been observed.

• Clinical signs provide the diagnosis for EDS '76.
• Virus isolation and antibody tests can confirm this.

• Infectious Bronchitis and to a lesser extent Newcastle disease and Infectious Laryngotracheitis will have to be considered.
• Proper diagnostic tests such as the antibody tests will eliminate doubt.

• There is no treatment against Egg Drop Syndrome 1976.
• Vaccination with an inactivated vaccine before point of lay is the only available, effective, method for the control of EDS '76.

• Worms living in the intestines of chickens fall mainly into four categories.
• Roundworms (Ascarids), usually 5 to 7 cm (2-3 inches) long.
• Hairworms (Capillaria), only measure 1-1.5 cm long.
• Caecal worms (Heterakis), usually 1.5 cm long.
• Tape worms, usually 7 to 10 cm long, consisting of many small segments.

• Mature roundworms are not a major cause of disease, but the larvae can damage the intestinal lining, causing enteritis, anaemia, decreased egg production and at times eggs with pale yolks.
• Capillaria cause more damage to the intestinal lining and can cause enteritis and anaemia with decreased egg production and the appearance of pale egg yolks ("Platinum yolks")
• Caecal worms are found in the caeca and do not cause disease, except that their eggs can transmit blackhead – mainly in turkeys.
• Tape worms are infrequently found and do not cause serious damage, except that they use the nutrients of the host chicken.

• Examination of the intestinal contents will reveal roundworms, caecal worms, and tape worms without difficulty.
• Capillaria can usually be found when intestinal contents are washed through a fine mesh sieve.

• Roundworms and caecal worm infections can be treated with piperazine.
• Piperazine is not effective against tape worms and cappillaria for which other anthelmintics are required.

• Avian Encephalomyelitis (AE) is caused by an enterovirus belonging to the picornavirus group.

• Egg transmission is the major route of transmission of AE virus.
• Infected breeders will transmit the AE virus for several weeks and cause a decrease in egg hatchability.
• Infected chicks that hatch will show clinical signs of the disease and spread the infection in the incubator to other newly hatched susceptible chicks.
• Young chicks can also be infected on the farm.
• The incubation period varies from 5 to 14 days depending on the route of infection.

• Primarily chickens are susceptible to AE, but turkeys and pheasants have been reported as natural hosts.

• The disease is mainly seen in young chicks, between 1 and 3 weeks of age.
• Affected chicks sit on their hocks, do not move well, and many fall on their sides.
• A fine, rapid trembling of the head and neck can be seen, but especially felt when affected chicks are held in the hand.
• In laying and breeding flocks, AE virus infection causes a marked drop in egg production, which returns to normal in about 2 weeks.
• Mortality in naturally infected chicks varies and can be as high as 75%.

• Clinical tremors in chicks, together with a drop in production and hatchability in the parent breeders, is indicative of AE infection.
• Chicks will not have gross lesions, but histological examination of brain, proventriculus and pancreas reveals typical lesions of AE.
• This will also differentiate the diagnosis of AE from encephalomalacia (vitamin A deficiency, crazy chick disease).
• Laboratory testing of blood serum from breeder flocks, or their hatching eggs, can determine if an infection occurred.

• Preventive vaccination of breeder pullets with live AE vaccine before egg production is the only effective means of AE control.
• If a breeder flock has not been, or has been inadequately, vaccinated against AE and an outbreak occurs, it is advisable to stop hatching eggs from the flock for several weeks until the breeders have acquired immunity and no longer transmit AE virus through their eggs.

• Fowl cholera is caused by a bacterium: Pasteurella multocida. (several serotypes)

• Transmission of fowl cholera is mainly from bird to bird by water or feed contamination.
• Rodents (rats and mice) also appear to play role in contamination of water and feed with Pasteurella multocida.

• Chickens, turkeys, game birds and other bird species are susceptible.

• Chronic fowl cholera will not cause high mortality, although there will be an increase in deaths.
• Swollen wattles is a feature of chronic fowl cholera.

• Gross lesions in acute cases are mainly internal haemorrhage and congestion of liver, spleen and kidneys.
• In chronic fowl cholera cheesy exudates can be found between the intestines, and on liver and heart.

• Treatment with appropriate antibiotics or chemotherapeutics can be successful in halting mortality and restoring egg production.
• However chronic carrier birds have been found in flocks of chickens after treatment.
• If clinical fowl cholera, with mortality, reappears in such flocks, one must treat again.
• Rodent control is also very important to prevent reintroduction of the infection.
• Vaccines, both inactivated bacterins as well as live vaccines are available.

• Fowl Pox is caused by a poxvirus.

• Introduction of infected or "carrier" birds in a susceptible flock will cause an outbreak by direct contact and water or feed transmission.
• Mosquitoes and other flying insects can also transmit the virus from bird to bird and also transmit the disease to nearby flocks.
• The incubation period varies from 4 to 20 days.

• Chickens, turkeys, pheasants and pigeons can be affected by different fowl poxvirus strains.

• The lesions of Fowl Pox can be external (mainly on the head) or internal ("wet pox") in the mouth, oesophagus and/or trachea, they can also be found on other parts of the body (skin of legs, cloaca etc.).

• Mortality is variable, from a low 1 to 2%, when slight head lesions are present, to over 40% when the diphtheritic form ("wet pox") is more prevalent.
• Reduced egg production can be observed in laying birds, this will return to normal in a few weeks.

• Wart like lesions of the head particularly of the comb and around the eyes or yellow cheesy lesions of the mucous membranes of the nasal and buccal cavities are suggestive of Fowl Pox.
• A definitive diagnosis can be made in a diagnostically laboratory by histological examination (inclusion bodies) or virus isolation in embryonated chicken eggs.

• It is difficult to treat affected birds.
• Treatment of local lesions with disinfectant and/or removal of the diphtheritic membranes from the throat to improve respiration has been practised.
• Preventive vaccination using a live vaccine is by far the most successful control method.
• Even when an outbreak of Fowl Pox has been diagnosed, it is advisable to vaccinate the flock immediately to stop further spread of the infection.

• Loose droppings in poultry are not a strange or a new phenomena. This usually occurs in various conditions such as,
• High salinity in drinking water or high salt content in the fish
• High fiber or molasses content in the feeding stuff and
• Enteritis.
• The above situations can be tackled by setting right the causative factor or administer a suitable anti-diarrhoeal agent.
• There is one more "Loose Droppings" phenomena particularly in "young layers" with high production.
• There is no apparent reason for this loose droppings and even the salt, fiber adjustment or using of anti-biotics or chemotherapeutic does not give any desired results.
• The reason being that this is a physiological diarrhea.
• When the production is high the oviduct jerks backwards pushing the formed egg towards the cloeca for laying.
• Since the alimentary canal is situated just beneath the oviduct the rate of peristaltic moments are increased resulting intestinal "Hurry" and loose watery faecal matter resulting in loose droppings.
• This watery droppings phenomena when continued for long the farm becomes a breeding centre for number of bacterial and parasitic infections with formation of Ammonia gas, worms, maggots and obnoxious stink.
• The entire farm will be under a bad sanitary condition with poor bio-scrutiny rendering the birds more suspectable for diseases and other stress conditions including opacity of the cornea due to ammonia liberation.
• Various compounds that work on the 10th cranial nerve were tried including Atropine and Belladonna alkaloids.
• The results with alkaloids were good but with serious side effects.
• Due to the inhibition of the "Vagus" the digestion got disturbed as sufficient enzymes were not liberated.
• Further due to the dilation on egg laying, some other compounds inhibited the peristalysis and also movements of the uterus as they are working on the smooth muscles of the internal organs effecting the laying and also recorded shall less eggs.
• Screening of old compounds resulted in finding out Pot.
• Phenolanamide, which is only an intestinal sedative that reduces the peristaltic moments with out disturbing the endogenous liberation of digestive enzymes or dilation of the pupils disturbing the photoperiodism and the Hormonal secretion (FSH & LSH) and stimulation.
• There was no other adverse effect on Liver, Kidney, Lungs, Heart or Production to the best of our knowledge and no other side effects, ill effects or after effects.

• This complex disease has been reported under various names such as helicopter disease, femoral head necrosis, brittle bone disease, infectious proventriculitis, pale bird syndrome, running disease and stunting disease.

• The malabsorption syndrome appears to be a disease complex involving avian reoviruses and other viral and bacterial agents which may affect the digestive system resulting in nutritional and deficiency signs and lesions.

• Only circumstantial evidence is present at the moment to indicate that the causal organism(s) may be vertically transmitted.
• Horizontal transmission also seems to playa role on infected sites.

• Chickens and possibly turkeys.

• Light or dark brown, foamy droppings can be found with undigested food particles. Several affected broilers in a flock may exhibit mal-positioned feathers, especially on the wings.
• Early rickets with extreme paleness of legs and heads can be observed. Encephalomalacia is also regularly found.
• At a later age (5-6 weeks) osteoporosis becomes clinically evident, frequently unilateral causing the birds to limp.
• Later an important effect is the delayed growth of the affected birds. Mortality is variable and in general as low as 4%.

• The clinical disease is characterized by one or more of the Following lesions: enteritis with watery brown and foaming contents and the presence of undigested food in the intestine.
• Mucosal and submucosal proventricular lesions. Pancreatic inflammatory infiltration with degenerative changes have been found.
• Osteoporosis and osteomyelitis, femoral head necrosis whereby the bone of the epiphysis of the femur is unusually soft.
• Since the causal agent may differ it is difficult to base a diagnose on virus isolation or serology.

• Treatment is impossible, vaccination against reovirus in the breeders helps to reduce problems in the progency.
• Strict hygienic and sanitary measures will reduce the incidence

• Newcastle disease is caused by a paramyxovirus.
• Only one serotype is known.
• ND virus has mild strains (lentogenic), medium strength strains (mesogenic), and virulent strains (velogenic).
• The strains used for live vaccines are mainly lentogenic.

• Newcastle disease virus is highly contagious through infected droppings and respiratory discharge between birds.
• Spread between farms is by infected equipment, trucks, personnel, wild birds or air.
• The incubation period is variable but usually about 3 to 6 days.

• x Chickens and turkeys.

• Newcastle disease causes high mortality with depression and death in 3 to 5 days as major signs.
• Affected chickens do not always exhibit respiratory or nervous signs.
• Mesogenic strains cause typical signs of respiratory distress.
• Laboured breathing with wheezing and gurgling, accompanied by nervous signs, such as paralysis or twisted necks (torticollis) are the main signs.
• Egg production will decrease 30 to 50% or more, returning to normal levels in about 2 weeks.
• Eggs may have thin shells and eggs without shells may also be found.
• In well-vaccinated chicken flocks clinical signs may be difficult to find.

• Inflamed tracheas, pneumonia, and/or froth in the airsacs are the main lesions.
• Haemorrhagic lesions are observed in the proventriculus and the intestines.

• Is made by virus isolation from tracheal or cloacal swabs together with blood testing to demonstrate high antibody levels.
• Infectious bronchitis or infectious laryngotracheitis can give similar clinical signs, but lesions, blood tests, and virus isolation tests are decisive.

• There is no treatment for Newcastle disease.
• Vaccination against ND with live and/or inactivated (killed) adjuvant vaccines is the only reliable control method.

• Pullorum disease is caused bya bacterium, Salmonella pullorum.
• Fowl typhoid is caused by Salmonella gallinarum, which is related to, but not identical to, S. pullorum

• Pullorum can be transmitted by infected (carrier) breeder hens through their eggs.
• Chicks that hatch from such infected eggs will have typical pullorum disease (white diarrhoea) and high mortality.
• Infected chicks can also infect other chicks via droppings.
• Fowl typhoid is more a disease of adult chickens, with high mortality and morbidity.
• Horizontal transmission is important with fowl typhoid through infected droppings, dead bird carcasses, and infected clothing, shoes, utensils and other fomites.

• Chickens, pheasants, ducks, geese and guinea fowl can contract both pullorum and fowl typhoid.

• Pullorum in chicks causes typical white bacillary diarrhoea, with pasted cloacas and high mortality.
• Infected adult breeders do not have clinical signs of the disease but have internal lesions in the ovary (mis-shaped, dark coloured follicles).
• Fowl typhoid in adult chickens causes listlessness and sulfur- coloured diarrhoea.
• The birds have generalized infection with swollen livers, spleens, and kidneys and haemorrhages in such tissues.
• Mortality is usually high: 25 to 60%.

• Treatment of pullorum disease will not bring about a cure and is undesirable from a standpoint of eradication.
• It is far more practical to control the disease by elimination of infected carrier breeder hens.
• Blood testing of breeder chickens by the serum plate or tube agglutination test with suitable S. pullorum antigen will detect infected carrier birds, which can then be culled.
• Such control measures will stop the incidence of egg-transmitted pullorum disease.
• If hatching eggs from tested pullorum-free breeders are kept free from contamination through infected eggs from infected breeders or through contaminated incubators, or through other contaminated equipment, chickens can remain pullorum-free.
• Treatment of fowl typhoid with drugs like sulfonamides, tetracyclines, or furazolidone, has been more or less successful however, infected carriers may remain after treatment.
• The best control method is eradication of infected birds.
• Breeder flocks should be blood tested with antigen for typhoid.
• The typhoid carriers can then be eliminated.
• Vaccination for fowl typhoid with a special S. gallinarum (9R strain) has been practised in several countries, but it should be discouraged in breeders when an eradication programme is in operation.

• This disease is caused by Mycoplasma synoviae (Ms)

• The major mode of transmission of Ms is vertical (egg) transmission from Ms-infected breeder hens.
• Horizontal transmission from bird to bird and by infected equipment, clothing, shoes, egg boxes and other fomites.

• Vary from a symptomatic infection to mild respiratory signs, airsacculitis and synovitis, an inflammatory swelling of the joints of legs and wings and inflammation of the sternal bursa ("breast blisters").
• Creamy exudate in joints extending into tendon tissues is indicative.
• Airsacculitis with frothy to cheesy exudates in the airsacs can be found, especially if secondary infection with E. coli is present.

• Blood serum testing for specific Ms antibodies with Ms antigen and the findings of specific lesions are indicative of Ms infections.
• Isolation of the causative Ms organisms is decisive for diagnosis.

• Staphylococcus arthritis can also cause swollen joints with a creamy exudate sometimes extending into the tendon sheaths.
• Viral arthritis/tenosynovitis can also cause swelling of joints and tendon sheaths, but the exudate is more watery or blood-tinged, unless secondary Staphylococcus infections occur.

• Ms infections can be treated with antibiotics with variable degrees of success (tetracycline, erythromycin, tylosin, tiamulin).
• However, control of Ms has been largely successful by blood testing of breeder chickens and elimination of positive Ms reactors.

• Viral arthritis/tenosynovitis is caused by an avian reovirus.

• The virus may be transmitted by droppings from bird to bird.
• Egg transmission is also a factor when breeder flocks become infected during egg production.
• Reovirus is a common inhabitant of the intestines of birds and not all strains are pathogenic.

• Chickens, turkeys and possibly pheasants are natural hosts.

• The hock joint may be somewhat swollen, but usually not as severely as with Mycoplasma synoviae or Staphylococcus infections.
• Upon opening the legs the tendons usually appear discolored, brown or blood-tinged, with straw coloured fluid between them.
• Ruptured tendons may occur and, in older broiler breeders (29-30 weeks old), one may feel a hard scarry knot in the tendon above the hock joint. When the infection is complicated by Ms or Staphylococcus the fluid may appear yellow and creamy.
• In commercial egg-laying breeds of chickens, the disease is not .as common as in broiler breeders and broilers.

• Leg problems in broilers or broiler breeders associated with swelling of shank tendons or tendons above the hock joint sometimes accompanied by ruptured tendons, are indicative of viral arthritis/tenosynovitis.
• A positive blood test with the agar gel precipitatlon (AGP) test is of some value as an indication of exposure to reovirus, but does not constitute proof of diagnosis.
• Histopathological examination of affected tissues and isolation of virus from such tissues are needed for a definite diagnosis.

• Viral arthritis/tenosynovitis cannot be treated successfully, but antibodies are of help in preventing secondary bacterial infections, particularly Staphylococcal infections.
• Vaccination of broiler breeders with certain live and inactivated vaccines to ensure maternal immunity in their offspring appears to be of benefit to the birds themselves.

• The rib joints are swollen like beads and curved inward, the breastbone often twisted.
• In layer chickens, Vitamin D3 deficiency causes soft-shelled eggs and a drop in production.

• Vitamin D3 can be given as treatment, usually in combination with calcium and phosphorus.

• Clinical signs and gross lesions
• Vitamin E deficiency in chickens affects the brain, causing degeneration, oedema and haemorrhage, especially in the small brain (cerebellum).
• Affected young chicks appear unable to walk, they fall on their sides or stand with their heads between their legs.

• The cerebellum shows gross swelling, with yellow or brown discolouration and pinpoint haemorrhages may be observed.
• Encephalomalacia can also be found in mature chickens.

• Adequate levels of Vitamin E and selenium in the diet of chickens and their parent breeders is of prime importance.
• Treatment of affected birds with Vitamin E preparations (alpha- tocopherol) is effective if the condition is not too far advanced.