Preface Since past few decades because of changing demand for white meat from red meat, the small poultry farms and backyard poultry units developed to commercial farms. The adaptation of intensive poultry keeping methods and rearing of different species of poultry together has given rise to many disease problems. Since the inception of intensive poultry production worldwide farmers were struggling with severe diseases and huge economic losses in their unit. In order to keep pace with ever expanding poultry industry and meeting the increased demand for poultry products, knowledge for prevention and control of poultry diseases will be crucial. Realizing the importance of the knowledge of poultry diseases for future veterinarians, Veterinary Council of India (VCI) included “Avian Pathology” course in the syllabus of graduates in Veterinary Science. Since the book is in accordance with the VCI syllabus, the book will enable veterinary students to have sound understanding and working knowledge of poultry diseases. I hope the students will find this book a useful learning. The book will also assist personnel at the poultry disease diagnostic laboratories and progressive farmers. The book devotes total seven sections including basics about avian, bacterial diseases, viral diseases, fungal diseases, parasitic diseases, nutritional deficiency diseases and miscellaneous disorders affecting poultry. There are total 55 chapters in a capsule form. Emphasis has been put on etiology, transmission, epizootiology, clinical signs, gross and microscopic lesions, diagnosis, treatment and control. Where necessary, mention has been made on zoonoses. Necessary images and tables have been added to enhance the understanding of the diseases. I thankfully acknowledge the source of images taken from American Association of Avian Pathologists continuing education program- slide study sets, a color atlas of diseases of domestic fowl and turkey; by C.J. Randall 1st edn. (1987) Wolfe medical publication ltd, Self assessment color review of avian medicine by R.B. Altman and N. A. Forbes, Iowa state university press and contribution by students of veterinary medicine at St George’s University Grenada. I appreciate the help of Dr. Keshaw P. Tiwari, Assistant Professor, Department of Veterinary Pathology, School of Veterinary Medicine, St George’s University, Grenada in preparation and review of the book.

A Abdomen: Area between the keel and the pubic (hip) bones. Abdominal capacity: The distance between the two public bones (width) and between the pubic bones and the tip of the keel (depth). Addled: An egg where the contents are decomposing. Air cell: The air space between the two shell membranes, usually at the large end of the egg. Albumen: The white of an egg. Alektorophobia: The fear of chickens. Allantois: A sac connected to the embryo’s abdomen and involved in embryo respiration. Amnion: A sac surrounding the embry filled with amniotic fluid which protects the developing embryo from shock and provides a medium for the develop embryo to exercise their muscles. Antibody: A natural substance in the blood that recognizes and destroys foreign invaders and that causes an immune response to vaccination or infection. Anticoccidial: An anticoccidial drug used to treat or prevent coccidiosis. Antigen: A foreign protein in the blood that differs from nautral body proteins and, as a result, stimulates the natural production of antibodies. Artificial insemination: The introduction of semen into the female oviduct by methods other than by natural mating. As hatched: Description of a group of chicks that have not been sorted.

Taxonomic classification of avian species is beyond the scope of this booklet. However, since the preliminary knowledge of bird species for students of avian medicine class is of interest, the following description of most common pet and wild birds are being attempted for their benefit. GALLINEFORMES: This order includes domestic chicken, turkey, pheasants, peafowl, grouse, quail, guinea fowl, guans and curassows. COLUMBIFORMES: Includes pigeons and doves. PSITTACIFORMES: Includes parrots, which have strongly hooked maxilla with a flexible attachment to the skull. They also have dexterous zygodactyl feet (two digits point forward and two backwards). The order includes.

Introduction Anatomy of the immune system in birds differs from that in mammals. Immune cells are present in primary lymphoid organs (PLO) and secondary lymphoid organs (SLO). In birds, thymus and bursa of Fabricius (cloacal bursa) are primary lymphoid organs. Secondary lymphoid organs include the spleen, bone marrow, Harderian gland, aggregates of lymphoid tissue in various organs; i.e. in the gut called gut-associated lymphoid tissue (GALT); in bronchi called bronchial- associated lymphoid tissue (BALT). SLO contains aggregates of lymphocytes and antigen presenting cells. Birds do not have lymph nodes. In PLO, the lymphoid cells are processed for differentiation and maturation. T lymphocytes differentiate and mature in the thymus, whereas B lymphocytes mature in bursa of Fabricius. Functional lymphocytes move from PLO to SLO. Like mammals, birds defend the body against pathogens through innate immunity (non-adaptive immunity) and adaptive or acquired immunity. Under innate immunity system, physical barriers present in birds play their important role preventing the entry of pathogens into the body. Physical barriers are feathers, skin, aggregates of lymphoid cells in various organs and ciliary defence in the respiratory system. Phagocytosis is first defence for pathogens entering the body, evading the physical barriers. Phagocytic cells include mainly heterophils and macrophages. Natural killer cells (NK cells), thrombocytes and complement also help in innate immunity. Adaptive immunity is a particular defence which develops when the innate immunity is inadequate to impart protection. Adaptive immunity is antigen specific. T cell, B cell and macrophages play a major role in adaptive immunity. Adaptive immunity is brought about by antibodies (humoral immunity) or also by cells (cell-mediated).

Introduction Avian salmonellosis is the term used to describe a large group of acute or chronic diseases caused by one or more members of the bacterial genus Salmonella, which is a member of the large family Enterobacteriaceae. Domestic poultry is known to constitute the largest single reservoir of Salmonella organism existing in nature. They include host specific and nonmotile members of the genus S. enterica subspp. enterica pullorum/gallinarum. If the infection of poultry is due to other Salmonella organisms other than Salmonella enteric subspp. enterica gallinarum/pullorum, the infection is then referred to as paratyphoid.

Introduction Disease caused by motile Salmonella species in birds is called “Paratyphoid infections”. Paratyphoid infections are present in all parts of the world. Etiology Salmonella enterica includes six subspecies. Only one of that subspecies; S. enteric subspecies enterica includes more than 2500 motile serotypes.

S. enterica subspecies arizonae (Salmonella arizonae), the cause of an acute septicemic disease in young turkey poults. Host Range S. arizonae are reported from a variety of avian, mammalian and reptile species. Among avian in addition to turkeys, it has been reported in chicks, ducklings, psittacines and passerines. Transmission Organism is present in the intestinal tract of infected birds. Hence transmission is similar to motile salmonellae. Many workers have reported transmission in turkeys through infected ovaries. Wild birds, reptiles, rats and mice are reported as the common reservoir of the organism. The organism is also transmitted by direct contact and through contaminated feed and water.

Introduction From avian species alone approximately 20 mycoplasma serotypes have been isolated and characterised. Out of them, three serotypes (M. gallisepticum, M. meleagridis and M. synoviae) are most typical and pathogenic. A serotype M. iowae causes low hatchability in turkeys. Mycoplasmas are bacteria that lack cell wall and belong to the class Mollicutes. Although they have been considered extracellular agents, scientists admit nowadays that some of them are obligatory intracellular microorganisms, whereas all other mycoplasmas are considered facultative intracellular organisms

Introduction Escherichia coli (E. coli) infections are responsible for significant economic losses to the poultry industry, worldwide. Disease conditions caused purely or partly by E. coli are as under:

Disease is worldwide in distribution Etiology Pasteurella multocida, a gram negative non spore forming, non motile rods which stain bipolar. Epizootiology Most species of birds are infected. Turkeys are more susceptible than chickens, and older chickens are more vulnerable than young chickens. Geese and ducks of all ages are highly susceptible to fowl cholera. Survivors of fowl cholera outbreaks become carriers and are the reservoir of infection. P. multocida isolates of pigs are pathogenic to fowls. Spread of P. multocida in a flock is by feed and water contaminated with excretions. Crates, feed bags and utensils serve as a mechanical carrier of the organism.

(New duck disease, Duck septicemia, Anatipestifer syndrome, Infectious Serositis, the disease in goose is called “goose influenza”) Etiology The disease was first described in ducks from 3 farms in Long Island, N.Y. in 1932. R. anatipestifer (Pasteurella anatipestifer) is a gram negative, non- motile, non-spore-forming rod occurring singly, in pairs and occasionally in chains. To date, 19 serotypes are reported. Natural and experimental hosts: primarily a disease of domestic ducks. Outbreaks also reported in turkeys. Bacteria have been isolated from pheasants, chickens, guinea fowl, quail, partridge and other waterfowl.

Etiology Erysipelothrix rhusiopathiae. Disease Occurrence The disease is worldwide in distribution. Host Range Outbreaks of significant economic loss are in turkeys. Occasional outbreaks have been reported in pheasants, ducks, geese, guinea fowl, chukars, grebes and emus. Erysipelas also occurs in swine, sheep, sea mammals, fish and many wild animals. In humans (fish handlers, butchers, kitchen workers, turkeygrowers and veterinarians) it causes a localised inflammation called “erysipeloid”.

Etiology Yersinia pseudotuberculosis, non-motile at 37 C but motile at room temperature around 25 C. It is a disease of turkeys, ducks, geese, chickens, guinea fowl, and companion birds and free flying birds. It has also been reported in many species of mammals including man. In man, it causes symptoms of appendicitis. The disease has been reported in many countries. Body excretions of diseased birds or mammals that contaminate soil, food and water are the important factor in the transmission of the disease. The disease usually occurs as an acute septicemia of short duration, followed by a chronic focal infection.

Etiology There are 18 species in genus Campylobacter. Campylobacter species in poultry include C. jejuni, C. coli and C. lari. The most predominant species is C. jejuni. Epizootiology The infection has been reported in chicken, but the organisms have been isolated from ducks, turkeys, black birds, sparrow and pigeons. Transmission Possibly through faeces, as organisms are in the intestinal tract. Egg transmission of bacteria on or in the egg through hatchery is strongly suggested.

Causative Organism: Borrelia anserina B. anserina and B. burgdorferi (borreliosis of humans) share common flagellar antigens, suggesting their close relationship. B. burgdorferi infect both mammals and birds (mallards and bobwhite quail). Geese, turkeys, chickens, ducks, pheasants and canaries are natural hosts of B. anserina. All age birds are susceptible. Transmission Infection is mainly transmitted by a soft tick- Argus persicus. Transmission is also by ingestion of blood, excreta or tissues from infected or dead birds, through contaminated feed or water. Use of syringe and needles on multiple birds also makes transmission possible.

Etiology Intestinal spirochetes colonise the large intestine of avian, swine and humans. Family spirochaetacae has six genera, of which Borrelia, Serpulina and Treponema have species pathogenic for animals. Avian intestinal spirochetes are grouped in four: Serpulina hyodysenteriae, S. intermedius, S. pilosicoli (Angullina coli) and an unnamed group. Chicken S. hyodysenteriae is different from porcine one. S. hyodysentriae, Angullina coli and unclassified groups are present in the USA, whereas S.intermedius is in Europe and Australia. Avian intestinal spirochetes are gram negative, stain brown with silver impregnation techniques and blue in Wright-Giemsa stain. They can be divided in 3 pathotypes 1) severely pathogenic 2) Mildly to moderate pathogenic and 3) subclinical or apathogenic.

In avian species following diseases are caused by Clostridium bacteria. Ulcerative enteritis Necrotic enteritis Gangrenous Dermatitis Botulism Yolk sac infections. Clostridia infections are not common in birds and are not a significant source of infection for man and animals.

Etiology Avibacter paragallinarum Serotype A, B and C. Based on hemagglutinin serotyping, three serotypes (A, B and C) have been recognized. Epizootiology The chicken is the natural host although the disease has occasionally been diagnosed in pheasants. All ages of chicken are susceptible but birds up to 10 weeks are less vulnerable. The chronic or healthy carrier birds serve as source of infection. Infection within farm occurs by contact with drinking water or feed contaminated by nasal discharge from sick/carrier chickens. To farms situated at a distance, infection is through air borne transmission. The disease occurs more in cold and wet conditions. The more severe disease occurs when other respiratory diseases are prevalent at the farm.

Etiology Ornithobacteriun rhinotracheale, bacteria, under phylum Cytophaga- Flavobacterium-Bacteroids. It is Gram negative non-motile, non-sporulating pleomorphic rod shaped bacteria. 18 serotypes Athrough R have been identified. Serotype A is prevalent in chicken and turkeys. Disease occurrence The disease is worldwide in distribution.

An important disease in Turkey producing areas of the world. It is reported an opportunistic pathogen to human. Bactria grows in ciliated epithelium of vertebrates. Etiology Bordetella avium, a small Gram-negative bacillus, which is motile and aerobic. Differences in pathogenicity among strains exist. Transmission Recovered birds serve as carriers. Turkey coryza is highly contagious, and transmission occurs directly through close contact and contaminated feed and water.

Etiology Genus Mycobacterium contains many pathogenic species that can cause disease in birds (M. avium, M. tuberculosis, M. genavenes, M. gordonae). Within M. avium, organisms are divided into four sub species. M. avium sp avium, M.avium sp silvaticum, M. avium sp homnissuis and M. avium sp paratuberculosis. Mycobacterium avium sp avium - has wide host spectrum; poultry, pigeons, raptors, ratites and wild birds. M. genavense- affects Psittacines and passarines. M. tuberculosis- psittacines and other cage birds, and wild birds in captivity. M.bovis- Psittacines and others. Under natural conditions, M. avium sp avium does not cause severe disease in mammals except in rabbit and pig. Majority of mycobacteriosis in pigs is by M. avium sp avium. In cattle and other mammal infection by M. avium remain localized and is known to give positive reaction to mammalian tuberculin. The disease in caged and wild birds in captivity is common with M. tuberculosis, because of its close contact with humans. Tuberculosis is a serious problem in zoological gardens. M. avium is being isolated in increasing number of immunocompromized human patients.

Chlamydial organisms are spherical 0.2-1.5 um in diameter. They can be stained and seen in the light microscope, but they grow only in living cells. Chlamydial organisms infect mammals and birds causing various disease syndromes. Chlamydiacae family has one genus; Chlamydia. C. trachomatis, C. suis and C. muridarum. They cause disease in man, swine and mice. C. psittaci, C. pneumonia, C. felis, C. Caviae, and C. abortus. cause disease in man, birds and animals. Species can be differentiated on their growth characters inside the host cell.

Etiology Mostly associated with bacterial infections. Salmonella sp, Escherichia coli, streptococcus fecalis, Staphylococcus aureus, Clostridia sp. (C. pefringens), Pseudomonas and Proteus spp. have been isolated from cases of omphalitis. Chilling, overheating or stress during transport may predispose for the condition. Inflammation of yolk sac, characterized by infected unhealed navels in young birds.

The diseases caused by Staphylococci are found in all avian species and reported through out the world. Etiology There are more than 45 species and 25 subspecies in the genus Staphylococcus. S. aureus is the most common species of birds causing disease. Staphylococci are Gram - positive, coccoid and when grown on solid medium, bacteria form grape like clusters.

Streptococcosis has been reported from avian species worldwide. Bacteria produce acute septicemic and chronic infection. Streptococcosis has wide range of host ranging from many avian species including wild birds. Etiology Streptococci are Gram-positive, non-spore forming, non-motile facultative anaerobes. They occur singly, in pairs or short chains. S. zoozooepidemicus is species associated with disease in avian species. Other species of streptococcus (S. bovis, S. dysgalactiae, S. pleomorphus) have occasionally been isolated from birds.

Enterococcus sp. belongs to Lancefield antigenic serogroup D. Enterococcus is considered normal flora of the chicken intestine. Etiology Enterococci bacteria are Gram positive, spherical seen in singles, pairs or chain. Enterococuus sp. Causing disease in birds include E. faecalis, E. faecium, E. durans, E. avium, E. hirae and E. cecorum. E. faecalis is most common isolate from birds.

ND is a viral disease of poultry, wild and cage birds characterized by marked variation in morbidity, mortality, signs and lesions. Reported in 235 species of birds. A disease of primary importance and concern worldwide which causes continuous massive economic loss. It is a reportable disease in many countries of the world. Occurrence Species: All birds susceptible. Temporary conjunctivitis may develop in people who come in close contact with NDV for the first time.

Etiology The subfamily Pneumovirinae includes two genera: Pneumoviruses and metapneumovirus. The later consists of both human and avian metapneumovirus (aMPV). aMPV produces turkey rhinotracheitis (TRT) in turkey and Swollen head syndrome (SHS) in chickens. aMPV has been detected in other species of birds, but the disease in those birds are not well defined. Occurrence Species A new disease of turkeys (in the UK since 1985) which is suspected to cause some lesser problems in chickens.

ILT is an acute viral disease of chickens, pheasants and peafowl characterized by marked dyspnea, coughing, gasping and expectoration of bloody exudate. The disease is worldwide. Hosts Chickens particularly susceptible; reported to occur in pheasants and peafowl. Age Range All ages susceptible but is most often found in adult (mature or nearly mature) commercial chicken layers.

IB is an acute, highly contagious, viral disease of chickens characterized by respiratory signs (gasping, sneezing, coughing, and nasal discharge), the severe renal disease associated with neurotropic strains, and a marked decrease in egg production. It is a serious cause of sub-optimal egg production and poor egg quality. This disease is worldwide in ditribution. Hosts Chickens only. Recently IBV has been detected in species other than chickens. The disease may be produced only in chickens, IBV may multiply in other species of birds and be a source of infection. Etiology IB is caused by the avian coronavirus; numerous strains of infectious bronchitis virus (IBV) exist because of high genetic diversity and cross protection between strains is not reliable.

This ‘virus’ is widespread in commercial flocks worldwide, but its taxonomic position is not determined. The disease is characterized by aplastic anaemia and generalized lymphoid atrophy with a concomitant immunosuppression. Consequently, infectious anaemia is frequently complicated by viral, bacterial, or fungal infections. Occurrence Chickens up to 3 weeks of age are most susceptible.

Adenoviruses have been found in several species of birds and animals. There are at least 12 serotypes of chicken adenoviruses. The chicken adenoviruses are host specific, meaning they will not infect other animal species. Avian adenoviruses are divided into three major groups. Members of each type may share group antigens, but there is no common antigen shared between types.

Quail bronchitis (QB) is caused by group I (aviadenovirus). QB is an acute respiratory disease of bobwhite quail, occasionally with high mortality. Disease has sporadic occurrence many parts of the world. QB virus is closely related to the prototype CELO (chick embryo lethal orphan) virus, which is cause of high mortality in chicks.

IBH is an adenovirus infection of young chickens characterized by sudden onset and sharply increased mortality, short course, anaemia, and hepatitis often accompanied by intranuclear inclusion bodies. It is described in Canada, USA and many other countries.

Etiology Group 1 adenovirus. First reported in Pakistan in 1987, where it caused a devastating effect on broiler industry. It has spread to all continents.

EDS 76 is an infectious disease of laying hens caused by hemagglutinating adenovirus and characterized by failure to achieve production targets or by the production of thin-shelled or shell-less eggs in otherwise healthy birds. This important disease caused loss of egg production for several years - vaccination introduced the disease and a new vaccine virtually eradicated it.

(Tenosynovitis; Ruptured gastrocnemius tendon; Reovirus infection) Viral arthritis is a reovirus infection primarily of broilers characterized by arthritis and tenosynovitis (primarily of the tarsus and metatarsus, the digital flexor and tarsometatarsal extensor tendons) and, occasionally, by rupture of the gastrocnemius tendon(s) resulting in lameness and condemnations at slaughter. The disease is reported worldwide.

Fowl pox is a slow spreading viral disease of chickens, turkeys and other birds characterized by cutaneous lesions on the un-feathered skin of the head, neck, legs and feet and/or by diphtheritic lesions in the upper digestive and respiratory tract. The disease is worldwide in distribution. Occurrence Among poultry chicken and turkey are more susceptible. Other birds include pigeons, canaries, psittacines and wild birds. Fowl pox has been reported from more than 200 species of birds. The incidence is severe in multiple age groups and intensive poultry farming areas.

IBD is an acute, contagious, viral disease of young chickens characterized by diarrhoea, vent pecking, trembling, incoordination, inflammation followed by atrophy of the bursa of Fabricius (BF) and by a variable degree of immunosuppression. In the USA the disease was reported in Gumboro, Delaware in 1962, hence the name. The occurrence is worldwide.

Marek’s disease is a herpesvirus-induced neoplastic disease of chickens characterized by infiltration of various nerve trunks and/or organs with pleomorphic lymphoid cells. Marek’s disease is world wide in distribution. Marek’s Disease has been named after Josef Marek who published the disease in 4 roosters in 1907. Occurrence In chickens only, however turkeys and quail have limited susceptibility. Lesions similar to MD have been seen in pheasants, ducks, pigeons, geese, canaries, budgerigars, swans and great horned owls. However, aetiology for lesions in these species has not been proved. It may appear at 3-4 weeks but usually after eight weeks, with major losses from 12-25 weeks. Morbidity and mortality varies depending on the virulence of MDV.

LL is a retrovirus-causes, neoplastic disease of semi-mature or mature chickens characterized by a gradual onset in a flock, persistent low mortality and neoplasia of, the bursa of Fabricius (BF) with metastasis to many other internal organs especially the liver, spleen and kidney.

The neoplastic disease primarily of broiler breeders and broilers causing serious economic losses in the commercial poultry industry. A case has been recorded in a budgerigar. Etiology ALV-J subgroup, identified in 1988. It became widespread in commercial meat type poultry in the 1990’s. Transmission of ALV-J is much higher than other subgroups thus making control much more difficult.

Term endotheliosis designates a variety of syndrome caused by a reticuloendothelial virus (REV). REV caused syndromes have been demonstrated world wide. Etiology Based on replication of the virus in chicken fibroblast cell culture, two strains are known: replication defective T strain and the non-defective A strain. The REV manifests three distinct diseases syndromes:

Etiology Avian Nephritis Virus (ANV), an RNA virus is Astro virus under the genus Avastrovirus in Astroviridae family. Strains of ANV exist. ANV is very resistant and stable in the environment.

AI is a viral disease affecting the respiratory, enteric or nervous system of many kinds of birds. The most virulent form is an acute, generalized disease characterized in poultry by a short course and extremely high mortality.

(AE; Epidemic Tremor; Infectious Avian Encephalomyelitis) AE is a viral infection of chickens, turkeys, pheasants and cortunix quail characterized in young birds by ataxia progressing to paralysis and, usually, by tremors of the head and neck. Infected adults usually show no signs. AE is world wide in distribution.

Etiology A turkey coronavirus (TCV). Hosts Turkeys of all ages, but the disease is mostly observed in young turkeys (first few weeks old).

It is an acute disease of turkeys, occurring in 6-7 wk. -Old turkeys, but has been seen in younger and older turkeys as well. The disease is worldwide in distribution. Etiological Agent It belongs to adenovirus type II. A serologically indistinguishable virus from HE virus, causes marble spleen disease (MSD) in confinement reared pheasants (3-8 months old). The disease shows predominantly respiratory signs. A virus of the same group causes avian adenovirus group II splenomegaly (AAS) in chickens.

Etiology Herpes Virus Variation in pathogenicity of virus strains has been reported, but all strains appear identical immunologically. Occurrence The disease was first reported in the Netherlands in 1923. The disease has been confirmed in France, Belgium, Canada, India, Thailand, England, Hungary, Austria, Denmark and Vietnam, and suspected in China.

DVH is a highly fatal infection of young ducklings. Lesions are primarily in the liver.

It is an acute disease of pheasants, chukars, partridges, turkeys, ducks, pigeons and wild birds. The viruses of EEE and WEE are of public health importance as they infect humans and occasionally cause fatal disease. The disease is further significant because of its link to disease in horses. Etiology The arboviruses are grouped into 12 different families. The five arboviruses causing disease in birds are Eastern equine encephalitis (EEE) virus, Western equine encephalitis (WEE) virus, Highland J (HJ) virus, Israel turkey meningoencephalitis (IT) virus and West Nile Virus WNV. The first three are in Togaviridae, and IT and West Nile Virus (WNV) are in Flaviviridae.

WNV was first identified in the West Nile district of Uganda in 1937. Reported in Western Hemisphere for the first time in 1999, in New York City. The virus had until that time been found only in Africa, Eastern Europe, West Asia and the Middle East.

Introduction This is a disease mainly of the respiratory system affecting domestic poultry, wild birds and zoo birds. Systemic aspergillosis affecting visceral organs and other tissues of the bird’s body is also reported. Reports are also available on eye and brain infections.

Introduction Serious outbreaks of thrush have been observed in chickens, pigeons, geese, turkeys, pheasants, quail, peacock and many other species of birds. Candida albicans is the most commonly isolated fungus from the outbreak. Mucor spp. and Aspergilli were also found in some cases. The outbreaks are associated with unhygienic conditions and nutritional deficiencies. Infection is more common in young birds up to 10 weeks of age. Morbidity is very high and mortality ranges from 10-75%. Clinical signs are not specific. Poor growth and ruffled feathers are only clinical signs.

Etiology Cryptococcosis (KRIP-toe-cock-co-sis) is caused by the fungus, Cryptococcus neoformans (KRIP-toe-cock-kus knee-O-for-mans). It is found worldwide and primarily affects cats and people with weak immune systems.

It is a fungal infection of skin and the term favus is used for the disease in poultry. The disease is world wide in distribution. Etiology Microsporum gallinae, a fungus. The fungus is zoonotic. Lesions of ring worm are produced in humans in contact with infected birds.

Diseases caused by toxic metabolites of fungi are called mycotoxicosis. It affects man and animals including birds. Fungi which grow on feeds and grains in an unfavorable environment mostly cause mycotoxicosis in birds.

The disease is worldwide in distribution and remains the major parasitic problem in the poultry industry. The problems occur principally in poultry maintained on deep litter. Etiology Coccidiosis of all classes of poultry is caused by one or more of the many species of coccidia of Eimeria species. In chickens nine main species are encountered. Eimeria tenella, E. necatrix, E. maxima, E. acervulina, E. mitis, E. mivati, E. hagani, E. brunetti and E. preacox.

Cryptosporidiosis is a protozoan disease. Species C. meleagridis: Infects small intestine. C. baileyi: Infects digestive tract (bursa of Fabricius and cloaca), kidneys and respiratory tract.

Histomoniasis is a protozoan disease. Etiology Histomonas meleagridis. Hosts Mainly disease of turkey but has also been reported in chickens, peafowl, grouse, quail and gallinaceous birds.

Etiological Agent Trichomonas gallinae, a flagellate protozoan. Strains vary in pathogenicity. The disease continues to be of significance in pigeons and doves. It has also been reported in raptors.

Introduction Chickens are considered one of the most important hosts in the epidemiology of Toxoplasma gondii infection because they are an efficient source of infection for cats that excrete the environmentally resistant oocysts and because humans may become infected with this parasite after eating undercooked infected chicken meat. Poultry meat is an important part of cuisine, consumed widely all over the world; therefore, consumption of uncooked or not properly cooked poultry meat may pose a risk factor for T. gondii infection in humans or animals.

Introduction A. Common species of nematodes encountered in poultry are: Syngamous trachea (in the respiratory tract) large 2.00cm size live in the trachea and larger bronchi. Many species of domestic and wild birds are affected. Dyspnea, gasping and head shaking are main clinical signs. Treatment is difficult. Ascaridia galli (in the intestine) They parasitize chicken, turkey, pigeon, quail and guineas. In younger birds parasites cause enteritis. In heavily infected birds clinical signs are emaciation and diarrhea.

Introduction Various genera of tapeworms are found in poultry. They are: Raillietina spp. Choanotaenia spp. Davainea spp. Amebotaenia spp. and Hymenolepis spp. Tapeworms mainly parasitise the small intestine. Tape worms deprive the bird of its nutrition and cause weight loss and decreased egg production. Out of 3 species of Raillitina, Raillietina echinobothrida is one of the pathogenic species as it produces granuloma at its attachment site (nodular disease). They all require intermediate host for their development. Intermediate hosts are common houseflies, ants, beetles and grasshoppers, which makes control of tapeworms difficult.

HAEMOPROTEUS Host Infection with Haemoproteus species is host specific. H. meleagridis – domestic poultry and pet birds H. olumbae in pigeons H. nettionis in waterfowl.

LICE Introduction Lice are common ectoparasites of birds. There are many species of bird lice and are found on chicken, turkey, guinea fowl, duck, goose and pigeon. Lice species prefer a different part of the body. Most of them are straw colour and measure 1-10 mm. Lice from one host can parasitise another host if they are in close contact. For example, a louse from chicken can parasitise guinea fowls kept on the same premises. Hence, the species of lice is determined if cross contamination from another species is suspected. Lice are not highly pathogenic to mature birds. However, severe lousiness may lead to weight loss, as well as low production and death.

Vitamin A Source of Vitamin Berseem, legumes, alfalfa or other grass meal, fish oils, yellow corn, palm oil, commercial Vitamin A concentrate

CALCIUM & PHOSPHORUS Source of mineral Soluble grits (Limestone grits containing chiefly CaCo3) which is soluble in acid medium of crop. It differs from insoluble grits (gravel, granites, sand etc.) which acts only mechanically in the gizzard.

Pododermatitis or bumble foot has many causes including excess weight bearing from obesity or unequal weight bearing between the two feet as a result of lameness of one foot, causing less weight to be placed on that foot and more on the contralateral foot, or from abnormal abrasions of the plantar surface from inappropriate substrate (too sharp or rough, wire, etc.), decreased blood supply to the foot (sometimes from lack of exercise), trauma, or standing for prolonged periods of time, especially in ducks that are not provided with adequate swimming opportunities. Bumble foot is commonly seen in waterfowl under one or more of the following conditions; obesity, hard substrate, lack of access to water to swim in, malnutrition and underlying disease. This is localized infection of the feet. It is seen as bulbous swelling of the footpad and surrounding tissues. It appears usually after an injury to the foot pad and causes lameness in one or both feet. Pododermatitis is divided into varying grades depending on the literature source used, but generally includes mild, moderate, and severe grades with the severe grades including osteomyelitis. Infection by various bacteria commonly occurs and superficial wounds may not be present. Sometimes ulcers are formed on the planter surface of the foot. The layers become lame and production lowers, sometimes completely stops. On opening the swelling a foul smelling thick pus is found. The condition is more common in heavy breeds. Early surgery and antibiotic therapy may control the condition. Removal of high roosts reduces the incidence.

Cage layer fatigue is a term used to describe leg weakness and acute deaths in chickens in cages, and is caused by inadequate calcium, phosphorus and Vitamin D levels in the blood stream. Calcium is required for muscle function, bone formation, and egg shell formation. This condition may be seen even in floor birds under certain conditions. It is seen most often in young hens early in production.

Introduction Although the causative agent for the condition has not been identified, experimental studies indicate the association of parvovirus and or Astrovirus. Under experimental conditions, the virus induces clinical signs onlyin fast growing broiler chickens. The clinical signs, based on experimental inoculation of chickens, consist of watery or mucoid mustard yellow colour diarrhoea within 3-5 days after infection. Chickens become stunted, and a variable number of such chickens die during 10 and 20 days. Pronounced weight loss is in around four week’s age. The mortality is low (5 - 10%) however, the morbidity is very high (50 - 80%).

Introduction The condition has been reported the world wide in growing broiler chickens. The affected birds show clinical signs usually during 4 - 5 weeks of age. The clinically affected birds are smaller, listless with ruffled feathers, pale head and shrunken comb. Severely affected birds have distended abdomen, which restricts their normal movement. Death may occur suddenly, and not all the broilers which die of the condition have ascites. The incidence of the disease varies between 2 to 20%.

Introduction Hypoglycemia Spiking mortality syndrome is a disease in broilers, characterized by low mortality with sudden onset of high mortality. The affected birds are clinically hypoglycemic. There is no known aetiology.

The condition is characterized by proventriculitis and dilatation of proventriculus. Etiology The cause of transmissible viral proventriculitis (TVP) is a birnavirus referred as Chicken proventricular necrosis virus (CPNV). TVP is a disease of 3-8 week-old broiler.

Seen in mature chickens. Condition results from myocardial degeneration which causes bilateral ventricular hypertrophy and dilation. Etiology is not known. Round heart disease in turkey causes mortality in 1-4 weeks of age. Lesions are severe cardiomyopathy, ascites, hydropericardium and generalized congestion of tissues. No aetiology is known.

Index A Adenovirus Infections 131 Aflatoxicosis 215 Arizonosis 42 Arthritis 32, 59, 65, 103, 105, 145, 146, 147 Ascites 1, 72, 95, 261, 262, 267 Aspergillosis 42, 205, 206, 207 Avian Chlamydiosis 93 Avian Encephalomyelitis 112, 165, 183 Avian Influenza 112, 124, 179, 181 Avian Intestinal Spirochetosis 77 Avian Leukosis 167 Avian Mycoplasmosis 44 Avian Nephritis 177 Avian Salmonellosis 31