An occurrence of avian tuberculosis in hooded merganser (Lophodytes cucullatus)

Area of Science:

• Avian pathology
• Mycobacteriology
• Zoological medicine

Background:

• Hooded mergansers (Lophodytes cucullatus) are migratory birds occasionally housed in zoological collections.
• Avian tuberculosis is a chronic infectious disease caused by Mycobacterium species.

Observation:

• Two male hooded mergansers were introduced into a zoological aviary in Japan.
• One bird died 10 months post-introduction.
• Postmortem examination revealed numerous white-yellowish nodules in the liver, and nodules below the lung and on the kidney.

Findings:

• Histopathology showed numerous tubercles containing acid-fast bacilli in the liver.
• Amyloid deposition was observed in the connective tissue of the tubercles.
• Bacteriological analysis isolated Mycobacterium avium serovar 1 from the liver.

Implications:

• This case highlights the susceptibility of hooded mergansers to mycobacterial infections.
• The findings contribute to understanding avian tuberculosis in non-native species within zoological settings.
• Early detection and biosecurity measures are crucial for preventing disease spread in captive bird populations.