Spondyloarthropathy as an Old World phenomenon

Area of Science:

• Comparative pathology
• Primate medicine
• Rheumatology

Background:

• Spondyloarthropathy is a group of inflammatory diseases affecting the spine and sacroiliac joints.
• Previous research has primarily focused on human cases, with limited understanding in non-human primates.
• Erosive arthritis in non-human primates can present diagnostic challenges.

Purpose of the Study:

• To definitively diagnose spondyloarthropathy in various primate species.
• To compare the characteristics of spondyloarthropathy in primates with human cases.
• To investigate the prevalence and distribution of spondyloarthropathy in different ape and monkey populations.

Main Methods:

• Radiological analysis of spine and sacroiliac joints.
• Examination of lesional character, distribution, and radiological appearance.
• Comparison of findings with established human spondyloarthropathy criteria.

Main Results:

• Spondyloarthropathy was definitively diagnosed in great apes (Gorilla, Pan), lesser apes (Hylobates), and Old World monkeys (Theropithecus, Papio, Cercopithecus, Macaca, Colobus, Presbytis, Erythrocebus).
• The observed features were indistinguishable from human spondyloarthropathy.
• Orangutans (Pongo) showed no reactive bone or sacroiliac involvement, suggesting a different pathophysiology.
• Prevalence varied significantly, with high frequency in great apes (20-28%) compared to humans (1-4%), Old World monkeys (2.4%), and lesser apes (2.4%).

Conclusions:

• Spondyloarthropathy is a naturally occurring disease in multiple primate species, closely resembling the human condition.
• The high prevalence in great apes and wide geographic distribution suggest a panendemic.
• This natural disease model is invaluable for studying the genetic and environmental factors contributing to spondyloarthropathy pathophysiology.