Inflammation and c-reactive protein
We learned a lot in 2012—and perhaps you did as well. A step forward was the addition of the C-reactive protein test in our work. We compared two published tests and found that the ELISA, although expensive, was superior. This is a capture ELISA, that means we capture nanomolar amounts of the protein from serum. We report a micromolar value, normal is 0-10 micrograms/ml in the serum.
The test results indicate the presence of inflammation (the source isn’t unique to S. neurona or EPM) and most important, the values change in response to treatment. We tested hundreds of horses and compared our data to other published data. The level of serum CRP measured in µg/ml in normal horses is 7.4 +/- 2, (n=10).
C-reactive protein is elevated in disease–pneumonia 19, +/- 9 (n=10), enteritis 16 +/- 6, (n=10) and arthritis 11 +/- 3, (n=10). We tested the level of serum CRP in horses. Those with a presumptive diagnosis of EPM (n=183) and found the value ranged between 11µg/ml-35µg/ml. We determined that 63% of horses with a provisional diagnosis of EPM have an elevated CRP. Currently we are evaluating the relationship between a drop in CRP and clinical signs post treatment by pre-and post treatment sampling.
Further analysis reveals a statistically good "normal" cut off is 16 µg/ml in a population of "EPM" suspect horses. Other associated disease, polyneuritis equi, is linked to a value of 39 µg/ml. These last two observations were added in 2017.
We learned that horses can be re-infected, the re-infection is consistent with a rise in antibody titer before the clinical signs appear. If a horse had, and is treated for the infection, a second exposure induces a quick antibody response. An inflammatory response can accompany the humoral (B-cell antibody response), and the inflammation causes clinical signs.
In order to prevent EPM there are several requirements. the horse has to be exposed to oocysts shed by the opossum. Exposure is detected by a rise in antibody titer, usually in the spring and the fall. Monitoring the SAG 1, 5, 6 antibody levels, and if indicated, a C-reactive protein, can indicate a horse that is at risk and a candidate for palliative treatment. While it is possible that horses could harbor encysted S. neurona (this makes them a definitive host) there is little published evidence in support of this theory. Experiments feeding infected horse muscles to opossums—never published to the best of my knowledge, were unfruitful, or logic says the data would have been published or discussed. Horses can harbor S. fayeri, that is another story revealed in 2016.
We found video sent via email very helpful to us. (2017 update: use the GaitScore app available from the Apple Store or Google Play). Video illustrates the degree of the neurological signs. It is also satisfying to see the progress made in positive outcomes. We are considering using email video as part of our analysis for our FDA programs, but for now getting a completed submission form is a worthy goal.
S. neurona in dogs and cats,
We published our data on S. neurona antibody found in dogs early in the year. There is no doubt there is disease due to S. neurona in both dogs and cats. We are testing samples that come in, however there is a lot of research that needs to be completed before much interpretation can be made on a serum sample test result.
Another area of our current investigations are the association between encysted small strongyles and clinical signs of inflammatory encephalitis. It’s a complicated scenario and we are trying to reduce everything down to a couple of tests—for now we offer C-reactive protein testing to monitor sub-clinical and clinical inflammation. I anticipate enough meaningful data in the next three months so that we can make interpretations and recommendations that are useful in the field. For now, it’s on a case-by-case basis.
Continuing Education for Veterinarians
An exciting part of EPM is our CE program. Pathogenes is a certified State of Florida CE provider, we offer 3 hours of CE’s to veterinarians. Our goal is to shift the paradigm, we want to change the conversation from “EPM, the disease” to “EPM, the syndrome”. The EPM syndrome is composed of infection and inflammation, both need to be treated effectively. We hope for no less than veterinarians discussing inflammatory encephalitis with their clients. In 2013, we will visit several states to meet with veterinarians and share our knowledge about EPM. Our hope is to meet some of our horse friends as well.
Hot off the press…
And, after so long a wait–our FDA EPM treatment is bagged and ready to go. The tablets are certified, pressed, and tested. This formulation will allow us to make some more discoveries. This is a product that is made specifically for horses suffering from the effects of EPM. The stability of the drug components is a big advancement in the treatment of EPM. Obtaining our license for both drugs (INAD 012092 and INAD 012219) will still be a large, time consuming hurdle, the paperwork is mind numbing—but we are committed to the task. We have some in-house experiments to conduct and field data to collect. We have to challenge horses and show how each active drug component works in the horse; our understanding of the pathogenesis of disease in the horse allows us to design such a study. Uniquely, we have the tools to prove our ideas and theories.
And finally, thank you Carine, Carine Barrs sent us a holiday picture of Romeo, wishing us a Merry Christmas, Joyeaux Noel, and Happy Holidays. We wish the same to all of you.