The occurrence of hemotropic Mycoplasma ovis-like species in horses.

The study investigated the occurrence of hemotropic Mycoplasma ovis-like bacteria in horses and its potential impact on horse health. A small percentage of the examined horses were found to be infected by the bacteria, similar to the strain found in sheep and goats, and experienced mild anemia.

Hemotropic Mycoplasma Investigation

• The research targeted hemotropic mycoplasmas or haemoplasmas, which are bacteria lacking cell walls. In mammals, these microorganisms can cause anemia and, in worst-case scenarios, lead to death. The researchers focused on identifying the pathogen causing haemoplasma infection in horses.
• Blood samples from 133 horses in southern Iran were tested through microscopic examination and polymerase chain reaction (PCR) assay. These tests aimed to detect the presence of hemotropic Mycoplasma and equine piroplasma, specifically Babesia caballi and Theileria equi.

Molecular Characterization and Phylogenetic Analysis

• For a more in-depth understanding of the responsible infectious agents, the researchers performed molecular characterizations using 16S rDNA and 18S rDNA markers. The markers were specific to hemotropic Mycoplasma and piroplasma pathogens, respectively.
• They subsequently sequenced the PCR-positive samples for haemoplasma. Phylogenetic analysis of the resulting haemoplasma sequences was carried out to determine the relationships and history of these strains.

Prevalence of Hemotropic Mycoplasma

• In the given sample size, nine horses (approximately 6.77%) tested positive for Mycoplasma sp. using PCR. Additionally, three of these horses had co-infections with T. equi.
• According to phylogenetic and molecular analysis, the haemoplasma sequences derived from the PCR positive cases were found to be identical to the 16S rDNA in Mycoplasma ovis. This variant is primarily found in sheep and goats, making it a novel discovery in horses.

Impact on Health

• The PCR-positive horses for M. ovis-like species displayed a decrease in hematocrit (Hct), hemoglobin (Hb) concentration, and red blood cell (RBC) count as opposed to the PCR-negative ones.
• Mild anemia was also found in the haemoplasma-positive horses, demonstrating the potential health impact of this infection.
• The researchers suggest more experimental studies to explore the significance of this non-specific host infection and its pathogenicity in equine and other animal species.