Prototheca species and Pithomyces chartarum as Causative Agents of Rhinitis and/or Sinusitis in Horses.

The research paper establishes Prototheca species and Pithomyces chartarum, both types of algae and fungi, respectively, as uncommon causes of respiratory diseases in horses.

Introduction & Methodology

• The research was conducted on two elderly horses; a 25-year-old gelding and a 23-year-old mare.
• Both horses were diagnosed with respiratory issues; The gelding suffered from pyogranulomatus rhinitis, an inflammatory condition, while the mare endured necrotizing sinusitis, a type of sinus inflammation characterized by tissue death.
• To identify the causative agents of these conditions, the scientists employed immunohistochemical analysis, a process that involves the use of antibodies to detect specific antigens in a tissue section.
• For further characterization of the organism in the gelding, the researchers used the Polymerase Chain Reaction technique followed by sequencing. PCR is a method widely used in molecular biology to make copies of a specific DNA segment, which can then be sequenced to identify the organism.
• The fungi from the mare were identified using molecular analysis, a method to study the molecular features of an organism.

Results & Conclusion

• The study found the presence of Prototheca species in both horses. In the gelding, further analysis revealed it was a specific subtype, Prototheca zopfii genotype 2.
• In the mare, the contributing pathogen was identified as the Pithomyces chartarum fungus.
• Both Prototheca and Pithomyces are classified as saprophytes and facultative pathogens. Saprophytes are organisms that thrive on dead or decaying organic matter, while facultative pathogens can switch between living as a harmless organism in a host and a disease-causing pathogen when the host’s immune system is compromised.
• The research concludes that both Prototheca spp. and P. chartarum should be considered rare yet potential triggers for respiratory diseases in horses.