Serological and Molecular Detection of Anaplasma spp. in Blood From Healthy Horses: A Preliminary Study of Horses in East Texas.

This research study investigates the presence of the bacterium Anaplasma phagocytophilum, which causes the disease Anaplasmosis, in seemingly healthy horses. Scientists did this by collecting blood from horses in different locations and testing for signs of the bacterium and its antibodies. The results indicated that a large number of horses are exposed to A. phagocytophilum, especially in East Texas.

Methods and Materials

• The study involved the collection of whole blood from apparently healthy horses from four different locations; East Texas, West Texas, New York, and New Jersey.
• The researchers then conducted a series of tests on these blood samples, including an immunofluorescence antibody assay to detect any antibodies that the horses might have developed in response to a past infection with A. phagocytophilum.
• A PCR assay of white blood cell DNA was also done to detect if the bacterium was currently present.

Results

• Out of the 133 horses that were tested, 24 tested positive for the presence of A. phagocytophilum DNA, indicating current infection.
• 107 horses had antibodies present in their serum, indicating past infection with the bacterium.
• Of the 24 horses testing positive for A. phagocytophilum, 16 were positive for serum antibody presence while 8 were negative. This indicates that 8 of the horses were infected for the first time (no antibodies from past infections) while the others had previous exposure.
• Notably, 20 out of the 24 horses that tested positive were from East Texas, indicating higher exposure in this region.

Discussion and Conclusion

• The high number of horses testing positive for A. phagocytophilum DNA and its antibodies provides evidence that a large number of horses are exposed to this bacterium, particularly in East Texas.
• None of the Texas horse owners reported any treatment for anaplasmosis, and the potentially infected horses did not show any symptoms of illness at the time the blood samples were collected.
• The researchers concluded that further research is needed to understand why some horses get sick from this bacterium and others do not, and why exposure seems higher in certain regions.