Infection of the colon of the rhesus monkey by spiral-shaped organisms

Area of Science:

• Microbiology
• Veterinary Pathology
• Primate Research

Background:

• Intestinal spirochetosis is characterized by spiral-shaped organisms infecting the intestinal mucosa.
• Understanding its prevalence and host interaction in non-human primates is crucial for comparative pathology.

Purpose of the Study:

• To investigate the incidence and ultrastructural characteristics of intestinal spirochetosis in clinically normal rhesus monkeys.
• To determine the precise location and host-cell interaction of spiral organisms within the colonic epithelium.

Main Methods:

• Histological examination using hematoxylin and eosin (HE) and Warthin-Starry stains.
• Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) for ultrastructural analysis.
• Evaluation of 221 clinically normal rhesus monkeys (Macaca mulatta).

Main Results:

• Intestinal spirochetosis was detected in 42% of the studied rhesus monkeys.
• Spiral organisms appeared as a basophilic haze on the colonic surface, strongly positive with Warthin-Starry stain.
• Two distinct types of spiral organisms, spirochetes and flagellated microbes, were identified, primarily colonizing the brush border of the large intestine's surface epithelium, absent in crypts and small intestine.
• No significant alterations in host cytocomponents were observed.
• Infrequent penetration into epithelial cytoplasm and lamina propria occurred without eliciting an inflammatory response.

Conclusions:

• Intestinal spirochetosis is a common finding in clinically normal rhesus monkeys.
• The identified spiral organisms colonize the colonic brush border without inducing significant host tissue damage or inflammation, even upon limited invasion.