Chapter 3

Diseases caused by Fungi

 

 

               

Mycosis of fowls are of three sorts aspergillosis, in which the air passages are involved; favus, which affects the unfeathered portions of the head, and thrush, in which the mucous membranes of the upper digestive tract are affected. 

3.1 Aspergillosis:

a. Synonyms:

Brooder pneumonia

b. Definition:

A disease caused by fungus, characterized by respiratory distress and cheesy plagues in the lungs and air sacs.

c. Etiology:

Aspergillus fumingatus. Dark green spores in culture media.

Microscopically, the conidiphores have large terminal vesicles bearing many sterigmata from which chains of spores are produced.

d. Susceptibility:

More often in chicken, turkey, quail. However, nearly all species of birds may be affected.

e. Transmission:

  • 1. Baby chicks inhale the fungus in contaminated incubators. They are extremely susceptible up to about a week old.
  • 2. Spores can live up to 18 months in the incubator.
  • 3. Ingestion of spores

f. Symptoms:

  • 1. Age: Acute type usually occur in the first 8 weeks, with heaviest losses at about 4-5 weeks
  • 2. Action: Acute to chronic
  • 3. Difficulty in breathing, gasp without sound.
  • 4. Loss of appetite, slight darken comb.
  • 5. Cloudy eyes.

g) Lesions

  • 1 The lesion depend considerably on the site of infection. Either localization or generalization may be observed.
  • 2 The lungs are most frequently involved, small and large white or yellowish nodules noted. In some there may be localized hepatization, and in others, grossly visible mycelial masses may be present in the air passage and bronchi.
  • 3. There may be generalized involvement of the air sacs. Fibrinous, caseous exudate may be present in air sacs.

h. Diagnosis:

  • 1. No rattling with gasping.
  • 2. Liver is not involved as in pullorum.
  • 3. Have more nodules in lung than in pullorum.
  • 4. Mold growing in the trachea.
  • 5. Laboratory diagnosis: See mold in tissue sections. Cultivation of Aspergillus fumigatus.
  • 6. Histopathology: Granulomatous lesions in lung and other parts of the respiratory system.

i. Prevention

  • 1. General Good sanitation
  • 2. Eliminate the source of infection and medicating the flock with fungistat (mycostatin, myconox, mold curb) in feed and/or copper sulfate (1:2000 Solution).

Culture: Blood agar, Cornmeal Agar, sabourands glucose agar, chloramphenicol added. 

3.2 THRUSH

a. Synonyms:

Sour corp.

b. Definition:

Chronic mycosis of the upper digestive tract characterized by a sour crop and whitish necrotic membranes in the corp and esophagus.

c. Etiology:

Candida albicans (Monilia albicans) the yeast like fungus, is most frequently associated with the disturbance.

d. Occurrence:

  • 1. Occurs more frequent than brooder pneumonia, but in most cases it does not appear to be of sufficient significance to be considered seriously.
  • 2. Serious outbreaks have been reported in many species of birds.

e. Transmission:

  • 1. Through fecal material
  • 2. Contaminated egg.

f. Symptoms:

  • 1. Age: Semi mature to mature
  • 2. Action: Chronic
  • 3. Greenish, yellowish diarrhea.
  • 4. Loss of appetite.
  • 5. The symptoms are not characteristic.

g. Lesions:

  • 1. Lesion occur most frequently in the crop. Consist of a thickening of the mucosa with whitish circular, raised ulcer formation. Pseudomembranous patches and easily removed necrotic material over the mucosa are not uncommon.
  • 2. Mouth and esophagus may show ulcer-like patches.
  • 3. When the proventirculus is involved, it is swollen, the serosa has a glossy appearance and the mucosa is hemorrhagic and may be covered with a catarrhal or necrotic exudate.
  • 4. Crop contain sour material 

h. Prevention and Treatment:

  • 1. Avoid feeding moldy feed.
  • 2. Fumigate the incubator.
  • 3. Sick birds treated with CuS04 

i Diagnosis:

  • 1. Observation of the characteristic proliferative relatively non-inflamator lesions.
  • 2. Growth of Candida albicans in artificial media
  • 3. Differential diagnosis with Vitamin A deficiency. 

3.3 FAVUS

a. Synonyms:

White Comb.

b. Definition:

Chronic dermatomycosis, the comb is almost always attacked, in severe cases the disease spreads to the feather portion of the body.

c. Etiology:

Trichophyton gallinae (Achorion gallinae).

d. Symptoms and Lesions:

  • 1. Lesions usually develop first on the comb, as the fungus spreads white spots developed the surface of which scales off, and the comb may appear as through sprinkled with flour.
  • 2. Young birds with well-developed combs are most likely affected.
  • 3. The skin becomes thickened in the affected area and covered with scale and crusts especially around the feather follicles. A moldy odor may be detected.

e. Diagnosis:

  • 1. The gross lesion is characteristic should be sufficient for diagnosis.
  • 2. Microscopic examination
  • 3. Fungus cultivation.

F. Prevention:

Good management 

3.4 MYCOTOXICOSIS

a. Definition:

Diseases caused by toxins of pathogenic fungi. Characterized by hemorrhagic syndrome and aplastic anemia. Many fungi, such as Claviceps purpurea (ergot), Aspergillus favus, crotolaria could produce toxin.

b. Etiology:

Most commonly encountered toxin is produced by Aspergilla favus, (Aflatoxin).

c. Susceptibility:

Ducklings and turkey poults are more susceptible than chickens.

d. Occurrence:

World wide. 

e. Transmission:

  • 1. Molds in feed
  • 2. Toxin produced by mold ingested by animal. 

f. Symptoms:

  • 1. Acute to chronic depend upon quality and quantity of the toxin.
  • 2. Unthriftiness, pale shanks and combs or even paralysis.
  • 3. Increased capillary fragility resulting in hemorrhage and bruising.
  • 4. In mature fowl, lowered production, fertility and hatchability.
  • 5. Birds return to normal with in 7 days after removal of Aflatoxin. 

g. Lesions:

  • 1. In the day - old duckling, Aflatoxin can produce hepatic tumors.
  • 2. Hepatoma, anemia, loss of strength and integrity of muscle (bruising).
  • 3. Enteritis, hemorrhagic syndrome, and encephalitis.
  • 4. In older birds lesions are vague and less specific.
  • 5. Histopathology: Hepatocellular fatty change, necrosis. Hyplastic bile ducts.

h. Diagnosis:

  • 1. Based on flock history, symptoms, lesions, 
  • 2. Confirmation difficult.
  • 3. Culture for mold in the feed.

i. Prevention:

  • 1. Effective management of litter, feed and water.
  • 2. Avoid using moldy feed.
  • 3. Antimycotic additives are helpful.

j. Treatment:

  • 1. Removal of the source of toxin
  • 2. Treatment similar to other fungal disease.