eChapters

Ornithosis

Ornithosis is caused by Chlamydia and characterized by enlargement of liver and spleen, serofibrinous pericarditis, air sacculitis and enteritis. This is also known as chlamydiosis, psittacosis and is more common in parrots, pigeons and other psittacine birds.

Etiology

• Chlamydia psittaci group B

• Size 0.3 to 1.5 m

• Disease spreads from wild birds

Aspergillosis

Aspergillosis is a fungal disease of poultry caused by different species of Aspergillus sp and characterized by granulomatous nodules in lungs, thickening of air sacs and presence of fungal growth in lungs and air sacs in early age of chicks. It is also known as Brooders pneumonia (Fig.8.1).

Etiology

• Aspergillus fumigatus

• A. flavus

• A. nidulans

• A. glaucus

• A. niger

• A. candidus

The genus Clostridium consists of gram positive, spore forming anaerobic bacilli. The spores are wider than the bacillary bodies, giving the bacillus a swollen appearance, resembling a spindle. Hence, the name clostridium (Kloster- meaning spindle) was given.
Systematics
Domain : Bacteria
Phylum : Firmicutes
Class : Clostridia
Order : Clostridiales
Family : Clostridiaceae
Genus : Clostridium
The clostridia can be divided into four major groups according to the kind of
disease they produce. They are as follows.

Kingdom: Protozoa
Phylum: Euglenozoa
Class: Kinetoplasta
Order: Trypanosomatida
Family: Trypanosomatidae
Genus: Trypanosoma
Members of the genus Trypanosoma are responsible for trypanosomosis in animals and human beings and are found in the blood vascular system and tissues all over the world. All the species of trypanosomes are transmitted biologically or mechanically through an arthropod vector except T. equiperdum, which is transmitted through coitus in equines.

• Avian Inflammation

Inflammation is a process which begins following a sublethal injury to tissue and ends with complete healing or death. It is characterized by five cardinal signs. Cardinal signs of inflammation are:

• Redness

• Heat

• Swelling

• Pain

• Loss of function

• Inflammation is beneficial in most of cases expect

• In prolonged or unending process

• In inflammation of immunological origin i.e. hypersensitivity and autoimmunity.

• It provides basic foundation of pathogenesis and pathology.

• It is now said that immunity is the resistance of body, while inflammation is the process by which the immune mechanism are implemented.

• The basis of inflammation remains same be it mammal or birds. For details, one can refer the chapter inflammation and heading in book “Illustrated Veterinary Pathology”. However, there are some differences in reaction in birds which are briefly listed below:

Pathology of nutritional deficiency diseases are described in chapter etiology of this book. However, specific deficiency of nutrition that leads to development of clinical signs and lesions in poultry are summarized as under (Fig.2.1 & Fig.2.2):

Vitamin Deficiency

1. Hypovitaminosis A

• Vitamin A is considered infection resisting vitamin because it facilitates the proper development of bursa, immunity and epithelium on mucosal and skin surfaces.

• Deficiency of vitamin A leads to swollen glands in oesophagus i.e. nutritional roup.

Ranikhet Disease

Ranikhet disease is a contagious viral disease of poultry characterized by high mortality petechial hemorrhage in proventriculus, ulcers and hemorrhage at caecal tonsils and pneumoencephalitis. It is also known as Newcastle disease (Fig.3.1).

Etiology

• Paramyxo virus

• RNA virus-3 types

• Lentogenic- mild virulent

• Mesogenic- moderate virulent

• Velogenic- highly virulent

Salmonellosis

Salmonellosis is caused by G-bacteria Salmonella and characterized by early chick mortality with necrosis and hemorrhage in liver, heart and spleen and enlarged bronze coloured liver with focal or diffuse necrosis, marbled spleen and/or oophoritis and salpingitis in adults (Fig.4.1).

Etiology

• Salmonella enteritidis var. Galinarum (S. Galinarum).

• G-, rod, non lactose fermenter.

• White small colonies on MLA and pink on BGA.

Chronic Respiratory Disease (CRD)

Chronic respiratory disease is caused by Mycoplasma gallisepticum and E.coli in birds under poor management and characterized by cloudy air sacs with thickening of their wall, accumulation of cheesy material in air sacs and lungs (Fig.6.1).

Etiology

• Mycoplasma gallisepticum

• E.coli

• Bad management like poor ventilation and inclement weather conditions

• Disease occurs more during winter and rainy season.

Spirochetosis

Spirochetosis is caused by a spiral shaped organism Borrelia anserina and characterized by greenish diarrhoea, enlarged and mottled spleen, small necrotic patches on liver and linear haemorrhage in proventriculus. This disease is transmitted by a tick Argas persicus and thus also known as “tick fever” or “tick paralysis”.

Etiology

• Spirochete Borrelia anserina

• Spiral shape 8-24m long and 0.2 to 0.3 m wide microorganism having 8-11 spirals.

• Stained with aniline dyes

Roundworms (Nematodes)

1. Ascaridia galli

A. galli is the common roundworm of poultry seen in intestines at the time of necropsy. This parasite may cause retardation of growth, loss of egg production, catarrhal enteritis and sometimes mortality due to obstruction of gut (Fig.9.1).

Etiology

• A. galli parasites are grey, thread like 5-10 cm in length.

• Eggs are elliptical with thick and shiny wall.

Pathogenesis

Transmission occurs through faecal - oral route. The eggs may survive for several months in litter and they take at least 10-15 days to develop the infective stage. The eggs of parasites hatch in proventriculus or intestine to develop fully grown parasite within 40-50 days.

Cannibalism

Cannibalism is a bad habit of birds in which the birds attack their fellow birds and eat their flesh. It is done through sharp end of beak, which causes deep wounds specially on vent. Sometimes the wounds are so deep that leads to death of affected bird. Two types of cannibalism vices are common i.e. vent pecking and feather pecking.

Cause / Predisposing Factors

• Over crowding

• Genetic predisposition

• Hemorrhage in external genitalia

• Protein deficiency (arginine and methionine deficiency)

• Loss of feathers • Wounds

• Prolapse of cloaca

Location and Layout
• As the laboratory will be handling materials hazardous to human and animal health, it must be isolated as much as possible from livestock yards, poultry farms and quarantine stations and should not function in or near establishments handling healthy animals, food products for human or animal consumption or near vaccine production laboratories.
• Animal houses, garages, workshops, stores, water tanks, residential accommodation, administrative blocks have to be constructed as per the need of ideal microbiological laboratory. Expansion possibilities should
also be kept in mind. The building can be arranged in 5 main groups:
• Administrative / laboratory rooms
• Decontamination and disposal area
• Animal house facilities
• Workshops / stores/garages and
• Residential accommodation for the staff, hospital, schools, playgrounds, parks, shops etc. • The laboratory building may be rectangular in blocks, arranged in L, T or U shapes and may be of one or several stories. The temperature, wind velocity, rainfall,

On the face of an outbreak of a disease, collection of right clinical specimens in proper preservative, their transportation to the laboratory under ideal conditions and quick processing of specimens in the laboratory to identify the causative agent are crucial to successful control of the disease. This attains more importance when a highly contagious disease appears.

Collection of specimens from a virus-infected host is the first step for demonstration or isolation of a virus. Specimens for virus isolation should be collected at the time when the maximum amount of virus can be expected to be present. i.e. collect the specimens as early as possible after the onset of clinical symptoms. In many viral diseases maximum viral production occurs before the patient becomes ill so that it is ideal to collect the specimen at an even early time.
The nature of the specimen taken in any particular instance is determined by the patient’s clinical syndrome and previous history. They are best considered under three main headings.

1. Specimen for virus isolation/antigen detection/ nucleic acid detection
2. Specimen for serological investigation
3. Specimen for direct examination

The chief functions of Clinical Microbiological laboratory are to examine and culture specimens for microorganisms, to make accurate species identification of important isolates and to perform antibiotic susceptibility tests when indicated. These tasks will assist physicians in the diagnosis and treatment of infectious diseases.

Once the specimen is received in the laboratory, the specimens are examined visually depending on the physicians order and the nature of the specimen. Wet mounts and smears may be prepared and stained for microscopic examination. Observations may or may not be immediately reported to the physicians depending on the definitiveness of the results. Timely information may often be used to establish a presumptive diagnosis and institute a specific course of therapy. Specimens that require definitive identification of potentially pathogenic microbes are processed further. All agar plates are streaked for colony isolation; then plates and broths. All cultures are placed in an incubator with appropriate temperature and environmental conditions to maximize the growth and replication of microbes. Often a presumptive microbial identificationcan be made. A final report should be delayed while subcultures and additional test procedures are performed to identify the organisms definitively.

Preliminary Identification of Unknown Bacteria
A number of techniques may be used in the direct microscopic examination of clinical specimens to demonstrate the presence of microbes The examination of wet mounts of unstained materials by phase contrast or
dark field microscopy is useful for demonstrating motility, spirochaetes and endospores. Giemsa, Wright or acridine orange stains may be helpful in observing bacterial forms that stain poorly or that have little contrast from
back ground material.

Special Staining
A. Spore stain
Spores may be spherical or oval and may be central subterminal or terminal in position within the cell. Shape, size and position of the spore in the cell are useful for the identification of sporulated organisms. Spores are difficult to stain and when once stained, they are difficult to decolourize. With Gram’s stain, mature spores remain unstained bodies. Modified Ziehl-Neelsen’s method of staining will be used for the staining of spores.
Composition
a. Concentrated carbol fuchsin
b. Sulphuric acid 0.5 % solution.
c. Loeffler’s alkaline methylene blue
Materials
Old cultures of B. subtilis and Cl. Chauvoei and staining solutions.
Procedure
1. Make smears and fix over flame.
2. Stain with carbol fuchsin and steam for 3 to 4 minutes.
3. Wash with tap water.
4. Decolourize with 0.5% sulphuric acid.
5. Wash with water.
6. Counter stain with Loeffler’s methylene blue for 2 minutes.

Antimicrobial Susceptibility Test
The routine use of the modified Kirby-Bauer method is recommended.
Material
• Sterile cotton swabs
• Soyabean – Casein digest broth or Tryptone soya broth
• Non selective agar such as nutrient agar.
• 0.5 Mc Farland turbidity standard:
Solution A
Bacl2, 2H2O. 1.75G
Make upto 100 ml with distilled water.
Solution B
H2SO4 1.0 ml
Make upto 100 ml with distilled water.
Stock Solution
0.5 ml of solution A + 99.5 ml of solution B. Dispense in 5 ml amounts.
Seal and store in dark.
• Glass vials or tubes 10 ml capacity
• Muller – Hinton agar
• Antimicrobial discs
• Sterile forceps
• Ruler or calipers