Bacterial Diseases of Chicken

List of thirteen major bacterial diseases of chicken:- 1. Escherichia Coli Infections: Omphalitis 2. Salmonelloses 3. Paratyphoid Infections 4. Fowl Cholera 5. Acute Fowl Cholera 6. Chronic Fowl Cholera 7. Riemerella Anatipestifer Infections 8. Mycoplasma 9. Necrotic Enteritis 10. Cholangiohepatitis in Broiler Chickens 11. Gangrenous Dermatitis 12. Botulism 13. Avian Tuberculosis.

Bacterial Disease # 1. Escherichia Coli Infections: Omphalitis (Navel Infection):

It is characterized with reddening and tissue oedema in the umbilical region. Escherichia coli infections are widely distributed among poultry of all ages and categories. They are primarily related to poor hygienic conditions, neglected technological requirements or to respiratory and immunosup­pressive diseases.

A common sequel of navel infec­tions is local or diffuse peritonitis. Preventive mea­sures should aim at minimizing the probability of faecal contamination of eggs. This implies the main­tenance of clean nests, discarding floored eggs and removal of eggs that are cracked or contaminated with faeces.

Breeder eggs should be fumigated or disinfected in the farm prior to their transportation in the storage premise. The treatment is effective if initiated soon after testing the antibacterial sensitivity of isolates.

Bacterial Disease # 2. Salmonelloses:

Pullorum disease is an acute systemic disease in chickens and turkey. The infec­tion is transmitted with eggs and is commonly characterized by white diarrhoea and high death rate, whereas adult birds are asymptomatic earners. The morbidity and the mortality rates increase about the 7th – 10th day after hatching.

The affected chickens appear sleepy, depressed and their growth is retarded. The feathers around the vent in many chickens is stained with diarrhoeic faeces or pasted with dry faeces. The edema of tibiotarsal joints is a frequent associated sign. Pullorum disease is widely distri­buted among all age groups of chickens and turkeys. The highest losses are in birds under the age of 4 weeks.

Bacterial Disease # 3. Paratyphoid Infections:

Fowl paratyphoid is an acute or chronic disease in domestic fowl and many other avian or mammalian species, caused by some motile Salmonella serotypes that are not host- specific. The highest morbidity and death rates are usually observed during the first 2 weeks after hatching.

The chickens are drowsy with eyes closed, ruffled feathers and grouped near the sources of heat. Diarrhoea, dehydration and pasted down appearance around the vent are observed. Arthritis and peri­arthritis are encountered in broilers as well as in growing birds.

Tibiotarsal joints are most commonly affected. The skin and the mucous coats are the entrance door of the infection. The prevention is based upon detection and elimination of the causative agent.

Strict hygiene in hatcheries and throughout the injection of birds is essential for the prevention of Pseudomonas infection. The test of sensitivity is of most importance for the treatment, because the micro-organism is resistant to a high number of antimicrobial drugs.

Bacterial Disease # 4. Fowl Cholera:

Fowl cholera is an infectious disease in domestic fowl, waterfowl and other avian species. It is manifested either in acute septicaemic form with a high morbidity and death rates or as chronic local forms (independently or secondary to acute ones).

Bacterial Disease # 5. Acute Fowl Cholera:

The sudden and unexpected death could be the first sign of the disease. In this form, the lesions are predominantly related to vascu­lar injuries. Commonly observed signs are anorexia, ruffled feathers, oral and nasal mucus discharge, cyanosis and white or greenish watery mucoid diarrhoea.

Frequently, subserous petechial or ecchymosed haemorrhages in the anterior part of the small intestine, the gizzard or the abdominal fat are discovered. Congestion (overfilling of blood vessels with red blood cells) of the liver is seen as an initial manifestation of E. coli septicaemia in a broiler chicken.

Bacterial Disease # 6. Chronic Fowl Cholera:

It is characterised by local inflammations. The periorbital sinuses are frequently affected by a serofibrinous inflammation. It is pos­sibly spread from sinuses to adjacent air-filled skull bones with subsequent necrosis and onset of neurological signs (opisthotonus and torticolis).

The diagnosis is made on the basis of disease history, clinical signs, the lesions and the results of bacte­riological studies. The immunization of birds at the age of 8 -12 weeks gives very promising results. Many antibiotics and sulfonamides could lower death rate, but at discontinuation of the treatment, the disease could recur. Sulfonamides are appropriate for treatment, but they inhibit egg-laying.

Bacterial Disease # 7. Riemerella Anatipestifer Infections:

Riemerella anatipestifer (RA) infection is a contagious disease in domestic ducks, turkeys and other fowl. It is encoun­tered as acute or chronic septicaemia and is chara­cterised with serous fibrinous polyserosites. The respiratory tract could also be affected. The duck­lings at the age of 18 weeks are especially susce­ptible.

Clinically, sneezing, cough, trembling of the head and neck, ataxia and greenish diarrhoea could be present. The most characteristic gross lesion is the deposit of fibrinous exudate on the pericardium, the liver capsule or air sacs.

The chronic lesions affect the skin and the joints. Although a tentative diagnosis could be made on the basis of observed clinical symptoms and lesions, it is confirmed upon the isolation and identification of RA. The RA infection should be distinguished from septicaemia due to P. multocida, E. coli, Salmonella, etc.

The treatment with antibiotics (Flumequine) and sulfonamides I Jrimetoprim, Sulfadiazine has a varying success. Staphylococcus aureus infections are commonly seen in poultry. Usually, bones, tendon sheaths and joints, particularly coxofemoral and tibiotarsal joints are affected. The clinical signs include unilateral or bilateral lameness, reluctance to move and lying down.

When the tibiotarsal joints are affected, swellings, fever and sometimes necroses of overlying tissues and purulent exudation are observed. Other lesions related to endocardites are heart, liver and spleen infarctions. Liver infarctions are usually peripherally located on margins, have a pale creamy colour and are sharply demarcated.

The penetration of the infection occurs mainly via the oral or aero- genic route, but could also enter through the injured skin, especially in battery cage layer hens. The differential diagnosis includes other types of bacterial septicaemia as staphylococcosis, fowl cholera, E. coli infections, etc.

Bacterial Disease # 8. Mycoplasma:

The aetiological agent is Myco­plasmosis gallisepticum (MG). In many cases, however, the pathogenicity of the micro-organism is enhanced because of its association with any or some of the following agents: E. coli, Pasleurella multo­cida, Haemophilus paragallinarum and Infectious Bronchitis (IB) or Newcastle Disease (ND) viruses. MG is characterized by respiratory symptoms and a prolonged course of the disease. Particularly susceptible are hens and turkeys at all ages.

The most characteristic signs in adult flocks are tracheal rales, nasal discharge, and coughing, decreased egg production. Most outbreaks are in broiler chickens older than 4 weeks. The course of the disease is more severe during the winter and in cases of associated infections.

Often, conjunctivitis, facial skin oedema and profuse tear secretion could be observed. Most common gross finding is aerosacculftes, the air sacs being filled with fibrinous gaseous exudate. The majority of routine chemical disinfectants are effective against M. gallisepticum that rarely survives longer than a few days away from the host.

The birds could carry the micro-organism and be asymptomatic until the disease is triggered by stress factors such as change of the premise, the diet or weather, vacci­nations against or infections with IB or ND, increased levels of dust or ammonia. Affected birds get progressively exhausted. When the joints and tendon sheaths are open, a serofibrinous exudate is most commonly observed.

The aetiological agent is M. synoviae. The micro-organism shows a certain tropism to synovial structures as joints and tendon sheaths. An important route of dissemination of the agent is the transovarial transmission. The distribution by a horizontal route via the respiratory tract is also possible. The commonly used means of diagnostics is ELISA.

Bacterial Disease # 9. Necrotic Enteritis:

Necrotic enteritis (NE) is an acute Clostridium infection characterized by severe necrosis of intestinal mucosa. The disease begins suddenly, with a sharp increase in death rate. A strong dehydration is observed. The skin is sticked on or adhered to body musculature and is hardly removed.

Chickens at the age of 25 weeks are usually affected, NE is also encountered in hens particularly near the period of the beginning of egg laying or peak egg laying, most commonly associated with coccidiosis. In acute cases, marked congestion of liver, responsible for its dark red to black appearance.

The aetiological agent is Clostridium perfringens, which mainly forms type A and more rarely type C. They produce “a and p” toxins from C. perfringens type A and type C respectively, which are responsi­ble for the necrosis of intestinal mucosa. The small intestine is often distended with gases and the necrotic mucosa is visible through the wall. C. per­fringens is ubiquitous and normally reside into the intestinal tract.

The alterations are particularly in the jejunum and the ileum because of their higher pH and the lower oxygen content in these areas. Sometimes, haemorrhages are seen through the intestinal wall. Throughout the simultaneous occurrence of NE and coccidioses, the content of the lumen is bloody, mixed with necrotic detritus and gas bubbles.

The diagnosis is based on the distinctive gross lesions. When necessary, a histological investigation is per­formed or attempts for isolation of the causative agent. NE should be distinguished from ulcerative enteritis and some small intestinal coccidioses. The control should be aimed at predisposing factors.

An appropriate medication of feeds is recommended. A good effect is obtained with oxytetra-cyclinedi- hydrate (OTC 50% premix). NE could be effectively treated with doxy-cycline hydrochloride, amoxici­llin, etc.

Bacterial Disease # 10. Cholangiohepatitis in Broiler Chickens:

Cholangiohepatitis (CAH) in broiler chickens is characterized by inflammatory proliferative and dystrophic necrobiotic alterations in bile ducts and the liver parenchyma. Usually, no clinical signs are observed. The increased daily mortality is insigni­ficant, although in some chickens, a retarded growth and dehydration could be present.

Pathoanatomically, the liver is enlarged and with paler yellow colour. In some cases, its surface has a characteristic acinous appearance and in others is mottled with multiple small greyish-white or greenish foci. Clostridium perfringens is the aetiological agent.

CAH is experimentally reproduced in broilers by ligation of bile ducts and inoculation with C. perfringens. The gall bladder is filled with a thick bile secretion or a dense matter with a creamy colour. Some cases, haemorrhages with various intensities are detected in the mucous coat of the gizzard.

Pre­vention- separate housing of the different age groups of birds, avoiding the contact with other avian species. The premedication of forages with some antibiotics and their rotation would prevent the reproduction of C. colinum. A good effect is achie­ved with oxytetra-cyclinedihydrate (OTC 50% premix). UE could be effectively treated with doxycycline hydrochloride, amoxycillin, etc.

Bacterial Disease # 11. Gangrenous Dermatitis:

The gangrenous dermatitis (GD) is a disease affecting fattening and growing birds, characterized with necrotization of different skin areas and a severe cellulitis of the subcutaneous tissue. The sudden and quick increase in death rates is often the first signal for the incidence of GD. The affected birds die after less than 24 h. The death rate is from 1% to 60%.

The lesions are dark red to blue green macerated skin areas, usually featherless, beginning generally from wings and the adjacent areas. Most outbreaks are encountered in broilers at the age of 4-8 weeks. The disease is also observed in stock layer hens at the age of 6-20 weeks and broiler parents at the age of 20 weeks.

The outbreaks are frequently observed in extremely wet and warm premises. The gangrenous dermatitis affects birds while still alive. In more severe cases, the gangrene could begin and involve the skin of the head, neck and the breast. Affected skin is macerated or totally necrotic, resulting in exposure of underlying tissues in a number of cases.

Microscopic lesions are characterized by oedema, emphysema, hyperaemia, haemorrhages and necroses in the subcutaneous tissues. GD could be effectively treated by tetracyclines: doxyxycline hydrochloride, erythromycin thiocyanate, chlortetracycline and copper sulfate in the water.

Bacterial Disease # 12. Botulism:

Botulism is an intoxication caused by the toxins of Clostridium botulinum. With the exceptions of vultures, most birds are susceptible. The clinical signs appear within a few hours to several days. Flaccid paresis of legs, wings, necks and eyelids is observed. The paresis is rapidly progressing to paralysis and the birds fall into a deep coma with neck and head typically extended forward.

There are no typical gross lesions. The treatment with selenium, vitamins A, D and E as well as with some antibiotics as chlortetracycline, bacitracin, etc. could reduce mortality rate. Spirochaetosis is a septicaemic disease characterized by depression, progressive paresis, paralysis and inflammatory necrobiotic changes in parenchymal organs and the gastrointe­stinal tract.

The birds are depressed, cyanotic; greenish diarrhoea with considerable amounts of urates is observed. After removal of plumage, the ticks, adhered to the skin, are discovered. The aetiological agent is Borrelia anserina, a highly motile spirochaete with 5-8 coils.

The organism is not resistant outside the host and could exist only in some vector. The liver is often enlarged, mottled with necroses of various sizes and marginal infarctions. Usually, bile-coloured mucoid enteritis is observed.

The arsenics as well as some antibiotics including tylosin, tetracycline and penicillin are effective for treatment of infected birds. The application of vaccines is successful, but the acquired immunity is short and revaccinations are needed.

Bacterial Disease # 13. Avian Tuberculosis:

Avian tuberculosis is a chronic infectious disease characterized by the formation of granulomatous lesions in viscera, a progressive weight loss and death. It is usually encountered sporadically in birds reared in small yards, zoos and is a problem among caged exotic birds. The aetiological agent is Mycobacterium avium, a very resilient and acid-resistant micro­organism.

It is resistant to temperature changes, drying, pH changes, to many disinfectants and survives in the soil for years. Along the small inte­stine, single or multiple sub-serously prominating tubercles are detected. In advanced cases, tubercles could be observed along the bone marrow of the femur or the tibia.

Characteristic features of avian tuberculosis are conglomerate tubercles (gross and histological appearance). The diagnosis is based upon the complex evaluation of history, persisting lethality in adult flocks and the patho-anatomical findings.

Avian tuberculosis should be differentiated from neoplastic diseases, coligranuloma (Hjarre’s disease), pullorum disease, etc. The treatment is not advised, as the disease is contagious for men.