Cysticercosis in Bears

• Larval cestode infection

See also: Sparganosis in Bears

• Unidentified Taenia sp. (not Taenia solium). (J410.42.w1)
• Taenia solium. (J91.55.w1)
  • Note: Humans are the definitive hosts for Taenia solium. Infection in the bears is presumed to result from infected humans defecating within the bears' habitat and passing proglottids containing ova onto the ground. (J91.55.w1)

• Unidentified Taenia sp. (Taeniidae - (Family))
• Taenia solium (Taeniidae - (Family))

A female Ursus americanus - American black bear shot as a nuisance bear was found to have severe larval cestode infection. (J410.42.w1)

• The bear was in poor condition with a lusterless coat. (J410.42.w1)

Three male Ursus americanus - American black bears from different counties of California, killed by hunters in 1990, 1993 and 1994, were found to have large numbers of cysticerci grossly visible in their skeletal muscles and in cardiac muscle. (J91.55.w1)

Gross pathology:

In a female Ursus americanus - American black bear shot as a nuisance bear: (J410.42.w1)

• General:  
  • In a female Ursus americanus - American black bear shot as a nuisance bear, lusterless coat, scanty fat. (J410.42.w1)
• Muscular:  
  • In a female Ursus americanus - American black bear shot as a nuisance bear, in practically all skeletal muscles, numerous cysts in the fascia. These varied in size, 2-16 mm in length. (J410.42.w1)
    • Each cyst was made up of a host connective tissue capsule enclosing a cysticercus. (J410.42.w1)
      • Fully developed cysticerci measured 2-5 mm. (J410.42.w1)
      • Cysticerci had irregular, convoluted walls. Some scolices were inverted, others, which were everted, had well-developed neck regions. (J410.42.w1)
      • On each scolex were four muscular suckers (oval to circular, 0.209-0.268 mm, average 0.245 mm by 0.238-0.283 mm, average 0.263 mm) and a rostellum (low, flat, about 0.268 mm diameter) with two rows of hooks. Generally, large and small hooks alternated with one another. There were up to 34 hooks per rostellum. The smaller hooks measured 0.110-0.159 mm (average 0.129 mm), the larger hooks measured 0.180-0.198 mm (average 0.190 mm). The distance form the base to the tip pf the curved portion of the hook was for the smaller hooks 0.060-0.071 mm, average 0.066 mm and for the larger hooks 0.081-0.092 mm, average 0.087 mm. (J410.42.w1)
      • The species was not identified but was thought not to be Taenia solium. (J410.42.w1)
  • In three male  Ursus americanus - American black bears from different counties of California, large numbers of cysticerci were clearly visible in their skeletal muscles and in cardiac muscle. Each mature cysticercus measured about 9 mm long by 6 mm wide and consisted of a fluid-filled sac containing an opaque scolex. (J91.55.w1)
    • The rostellum was armed, with two rows of characteristic taeniid hooks, totalling 26-27 hooks. The outer row contained 13 or 14 hooks, each 100-123 µm long, while hooks in the inner row of 13 hooks measured 164-171 µm long. (J91.55.w1)

• Taenia solium was confirmed in three male Ursus americanus - American black bears from different counties of California. (J91.55.w1) 
  • The morphological features of the scolices match those of Taenia solium.
  • DNA extracted from larvae from each of the three bears and examined using PCR produced 280 +/- 4 bp length products, which matched one another and the products from known Taenia solium larvae. Restriction enzyme analysis gave further confirmation. (J91.55.w1)

Occurrence:

• There is a report of the heart of a bear [species not specified] with numerous cysticerci present. (J410.42.w1)
• Taenia sp. cysticerci in the muscles of a female Ursus americanus - American black bear from California. (J410.42.w1)
• Taenia solium cysticerci were confirmed in three male Ursus americanus - American black bears from different counties of California, killed by hunters in 1990, 1993 and 1994. (J91.55.w1)

• History & Documentation
• Physical Examination of Mammals
• Necropsy of Mammals
• Environmental Assessment
• Treatment and Care
• Environmental and Population Management
• Preventative Medicine for Mammals
• Chapter 2 - B36 Field Manual of Wildlife Diseases - Specimen Collection and Preservation
• Chapter 3 - B36 Field Manual of Wildlife Diseases - Specimen shipment
• Appendix A - B36 Field Manual of Wildlife Diseases - Sample specimen history form

• Bears (Ursidae - Bears (Family))
• Ursus americanus - American black bear

(List does not contain all other species groups affected by this disease)