| Description:
|
Aspergillus is a filamentous,
cosmopolitan and ubiquitous fungus found in nature.
It is commonly isolated from soil, plant debris, and
indoor air environments. The genus Aspergillus includes
over 185 species. Approximately 20 of these species
have been reported as causative agents of opportunistic
infections in man. Infection caused by the fungus is
known as aspergillosis. Aspergillosis is a zoonotic
infection and can be transmitted to humans from animals.
Infection has been observed in dogs, cats, reptiles
and avian species. In dogs and cats, the organism generally
causes either nasal or pulmonary and disseminated infections.
Nasal infection is most commonly associated with A.
fumigatus while dissemination is associated with A.
terreus. Nasal aspergillosis in dogs usually remains
confined to the nasal cavity or paranasal sinus, but
marked destruction of turbinate mucosa and bone is nearly
always seen. Canine nasal aspergillosis usually occurs
without concurrent immunosuppressive disease, and affected
dogs are usually in excellent health. The main clinical
features of disease in canines include profuse nasal
discharge, nasal pain, ulceration of the external nares,
and frontal sinus infection.
In avian species, aspergillosis is usually contracted
by the inhalation or oral ingestion of spores after
exposure to moldy food or contaminated bedding. Many
sources report aspergillosis as the most frequently
occurring fungal infection in birds. Aspergillosis spores
are widespread in the environment and many birds may
carry them in their lungs and air sacks until immunosuppression
or stress triggers clinical disease. Typically, A. fumigatus
is the most common Aspergillus species responsible for
infection in birds. Symptoms range from respiratory
distress, gasping, accelerated breathing, voice changes,
abnormal droppings, emaciation, regurgitation, and lesions
(yellow or grey nodules and/or plaques in the lungs,
air sacs or trachea). |
| Diagnosis: |
Early diagnosis of
aspergillosis is important because early treatment may
resolve this potentially fatal infection. Serological
tests such as those involving the detection of antibodies
are less helpful because of the poor antibody responses
in immunosuppressed animals. In addition, the methods
used for detecting circulating Aspergillus antigens,
such as radioimmunoassay, immunoblotting assay, enzyme
immunoassay, and the latex agglutination test, have
poor sensitivity. PCR-based testing for the detection
of DNA specific for the fungus is a highly sensitive
method to confirm infection. This method is even suitable
for immunocompromised animals since detection of antibodies
is avoided.
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