3. INTRODUCTION
Fungi and yeast produce disease in two ways
First, they invade and destroy body tissues
Secondly, fungi can infect growing grain or finished
feeds, and produce toxic chemicals (mycotoxins).
These mycotoxins produce disease or a decrease
in growth (mycotoxicosis) when they are consumed
4. The respiratory tract, nervous system and eyes
of poultry are commonly infected by fungi.
Infections are usually due to Aspergillus species.
Infection with other fungi are less common
5. INTRODUCTION
Fungal infections such as histoplasmosis and
cryptococcosis are not common pathogens of
poultry, but they are of public health importance.
6. AVIAN ASPERGILLOSIS
Aspergillosis is a disease caused by infection
with the genus Aspergillus.
Manifestations of aspergillosis depend upon
which organs or systems are involved and
whether infection is localised or disseminated
7. Aspergillosis in birds is usually confined to the
lower pulmonary system with florid lesions in air
sacs and lungs.
In young poultry it is referred to as brooder
pneumonia
AVIAN ASPERGILLOSIS
8. INTRODUCTION
Other synonyms are fungal or mycotic
pneumonia, pneumonomycosis, and
bronchomycosis
Less manifestations relate to infections of the
eye, brain, skin, joints, and viscera.
It usually means,” pulmonary or respiratory
aspergillosis.
9. ETIOLOGY
The two major species of fungus Aspergillus which
cause aspergillosis in poultry are,
Aspergillus fumigatus
Aspergillus flavus
Other species include A.terreus, A.glaucus, A.niger.
10. These organisms are common soil saprophytes,
occurring in decaying vegetative matter and feed
grains.
They grow on organic matter in warm humid
environments
Fungal hyphae are 4 -12 μm in diameter and
bear conidiopores producing conidia (spores) 2 -
6 μm in diameter that are easily spread in air.
11. ASPERGILLOSIS: TRANSMISSION
Infections are acquired from environmental
exposure.
Infection is by inhalation of spores that usually
originate from infected eggs.
Contamination of the equipments may result in
hatchery infection.
15. ASPERGILLOSIS - CLINICAL SIGNS IN
CHICKS
Signs are subtle even in cases in which severe
airsacculitis is present
16. Survived birds – become lethergic and stunted,
develop conjunctival swelling, blindness and
exhibit torticollis and other central nervous
system abnormalities.
Infected poultry flock – Biphasic mortality pattern.
17. Acute respiratory disease may cause 5-50%
mortality in the first 1-3 weeks of age.
Survivors usually develop chronic disease with
up to 5% mortality due to chronic pulmonary
insufficiency, ascites, blindness or neurological
fungal metastasis.
18. ASPERGILLOSIS: LESIONS
Macroscopical lesions
Lungs and air sacs
Granulomas appear as separate 1 -15 mm
diameter white plaques or caseous nodules.
Composition: Necrotic centres containing
branching, septate, 4-7 μm diameter hyphae.
27. Older lesions
Contain pleomorphic hyphae up to 12 μm in dia.
Air-filled cavities may appear green to black due
to development of pigmented conidiophores
Fungi tend to proliferate within the granuloma and
rarely invade adjacent tissue in immunocompetent
birds.
28. Trachea: Yellow caseous plaques adherent to the
mucosal surface.
Syrinx: Caseous, gelatinous, or less commonly
mucopurulent exudate.
Brain: white to yellow circumscribed areas either
in cerebellum or cerebrum.
Ocular form: Extensive keratoconjunctivitis
29.
30. Microscopical lesions
Air sacs
Thickening due to massive infiltration of
heterophils, multinucleated giant cells and other
types of leukocytes
Germinating conidia were seen in the membrane
interstitium, and lymphohistiocytic perivasculitisin
less severely affected area
31. Granulomas composing central necrotic cellular
debris and heterophils with peripheral palisade of
epitheliod macrophages and aggregates of
lymphocytes
32. DIAGNOSIS
Aspergillosis can be made on PM
lesions: Especially white caseous nodules in
lungs, or airsacs. Exudate plugs in tracheal and
bronchial lumen
Demonstration of branched, septate Aspergillus
hyphae in the lesions
Under microscopic, using impression smears of
lesions
33.
34. Using tissue sections
Routine haematoxylin & eosin
Periodic Acid-Schiff (PAS)
Grocott’s Methenamine-Silver (GMS)
Confirmation should also be made by cultural
isolation and identification of the causative fungus
35. Although A.fumigatus is the most likely agent of
avian aspergillosis, other species of fungi can
cause the disease. Therefore, isolates should be
identified
Granulomas or plaques may be cultured on
Sabouraud dextrose agar with antibiotics
Serological tests are of limited value due to non-
specific nature of the antigen.
36. DIFFERENTIAL DIAGNOSIS
The clinical signs of avian aspergillosis are dependent
upon the organ systems involved
Pulmonary aspergillosis is differentiated from other
respiratory diseases by granulamatous lesions at
necropsy
Exudative fibrinous or purulent air sacculitis and
pneumonia are also frequently seen in the following cases
Mycoplasmosis
Colibacillosis
Fowl cholera
Chlamydiosis
If granulamatous lesions predominate , the following ones
should also be considered
Mycobacteriosis
Other mycoses
37. THRUSH (CROP MYCOSIS, CANDIDIASIS)
Moniliasis, Oidiomycosis, sour crop and Mycosis
of the digestive tract.
Oral, oesophageal or crop candidiasis occurs
quite commonly, but rarly causes clinical signs.
38. AETIOLOGY
Crop mycosis is usually caused by Candida
albicans, a dimorphic yeast. It appears as
round to oval 3-4 μm budding yeasts
(blastospores) on epithelial surfaces, or as
branching septate hyphae or pseudohyphae in
deeper tissues.
39. C. albicans is ubiquitous in the environment,
and is usually present in the upper
gastrointestinal tract of normal birds.
Candidial overgrowth occurs in prolonged
administration of antibiotics.
Antibiotics suppress normal bacterial flora, thus
allowing Candida to proliferate.
40. Other risk factors include highly contaminated
drinkers or feeders, eating litter, immuno
suppression, environmental stress, or nutritional
disease.
Infections are more common in birds under 3
weeks of age. This suggests acquired or age
resistance. Mortality directly due to candidiasis is
almost non-existent. Most signs are due to other
concurrent diseases, or reduced feed intake.
41. CLINICAL SIGNS
Infections are common, but clinical signs are
seen in only severely affected birds.
Birds with superficial oral, oesophageal or crop
infections fail to gain weight.
In rare cases there is systemic invasion, and
signs of neurological, renal, or intestinal
disease may be present
42.
43.
44.
45.
46.
47.
48.
49. PATHOGENESIS AND LESIONS
Candida are acquired by ingestion.
They then become part of the normal flora of the
mouth, oesophagus, and crop.
With inhibition of competing microflora (by
antibiotics) or immunosuppression, fungi
proliferate on the surface, and hyphae or
pseudohyphae penetrate superficial epithelial
layers.
50. This penetration stimulates epithelial
hyperplasia, and pseudomembrane or
diphtheritic membrane formation.
The membrane appears grossly as multifocal to
confluent layers of white cheesy material in the
crop and sometimes in the oesophagus and
pharynx.
51. Candidial thick tangled mass and membranes
are usualIy adherent. They cannot be washed
away like normal accumulations of mucus.
Inflammatory response to mucosal candidiasis
is mild, unless ulceration is produced.
52. DIAGNOSIS
Pseudomembranes and diphtheritic membranes
in the crop, oesophagus and mouth are highly
suggestive of candidiasis.
Wet mount by scraping.
Corn meal agar or Biggy agar
53. FAVUS INFECTION
This disease is no longer important in commercial
poultry.
Dermatophytosis, dermatomycosis, ringworm, and
favus are terms applied to the condition of fungal
infections of skin
The term favus usually is used to denote the disease
in poultry
Favus has a world wide distribution but its occurrence
is sporadic
54. The disease is contagious and is transmissible in
humans
The primary etiologic agent of favus is
Microsporum gallinae (previously, Trichophyton
gallinae)
The incidence have been reported in the
chicken, turkey, duck, quail, and canary
M.gallinae favus may be more common in
64. DACTYLARIOSIS
This is a new fungal disease of chickens
caused by the thermophilic fungus Dactylaria
gallopava.
Young chickens and turkey poults rapidly
develop neurological disease. Sometimes,
pulmonary lesions similar to those of
aspergillosis are seen
65. Usually, there is also involvement of the
nervous system. I nfected chicks and poults
develop torticollis, paresis, and incoordination.
In rare cases, pulmonary granulomas develop
and cause dyspnoea as in aspergillosis.
DACTYLARIOSIS
66. PATHOGENESIS AND LESIONS
Spores reach the brain haematogenously and
produce the main lesions of meningeal and
encephalitic necrosis. This lesion is most
common in the cerebellum, but can appear
anywhere in the brain.
67. It differs from the mycotic encephalitis of
aspergillosis by having more malacia and
haemorrhage and having far greater number of
giant cells. Grossly, ocular and pulmonary
lesions appear similar to aspergillosis, but
microscopically are less well organized and
have greater number of giant cells.
PATHOGENESIS AND LESIONS
68. DIAGNOSIS
Clinical signs and gross lesions are not
specific enough to allow diagnosis. Brain
lesions should be examined microscopically.
Those containing pigmented 2μm diameter
hyphae and large number of giant cells are
diagnostic for dactylariosis. The fungus can
be cultured from brain lesions on Sabouraud
dextrose agar with added antibiotics.
69. HISTOPLASMOSIS
This disease is not of economic importance to
the poultry industry, but it is considered because
of its public health significance.
It is caused by the fungus Histoplasma
capsulatum, and has been reported usually in
zoo birds, and sometimes, in chicken and
turkey.
It is an infectious and not contagious disease of
human and lower animals. The disease
70. Histoplasma capsulatum thrives best in soils that have
accumulated droppings from chickens, pigeons, starlings,
other birds, and bats.
71. 1. Histoplasmosis is common in bird dropings.
2. Protective equipment is necessary for cleaning the
dropings.
3. Birds dropings carries the Histoplasmosis.
4. Microscopic view of Histoplasmosis.
1 2 3 4
72.
73. CRYPTOCOCCOSIS
Cryptococcosis is a disease of humans and
animals, and It is caused by the fungus
Cryptococcus neoformans.
In humans, it is characterized by a meningitis.
Although the disease is not of economic
importance in poultry, there are many
sporadic cases from zoo birds.