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Invisible Poison

Lately my mind keeps going back to Sept. 11, 2006. It was the first day of Virology class in the second year of vet school. We were fortunate that we were being taught by a wonderful person, talented professor, and brilliant veterinary virologist and public health expert, Dr. Chris Olsen.

Dr. Olsen presented the first lecture about viruses, exhibiting his passion about the topic. He opened the floor to questions and one of my classmates asked, "Of all the things to research and specialize in, why did you pick viruses?" He paused, smiled, and said something to the effect of, "I guess I'm fascinated in the power of the little guy, the tiniest germ, that we can't even see under a regular microscope, that can't even reproduce on its own, that we are sometimes powerless to control." He told us a quote, "Pitted against microbial genes, we have mainly our wits." - molecular biologist Joshua Lederberg

It was a great course.

We learned about how the word, virus, is Latin for "poison." How viruses are small, <300 nanometers in diameter, which is about a tenth of the size of a typical bacteria. A specialized microscope, called an electron microscope with the aid of certain stains, is required to see viruses and their fascinating shapes. Viruses are minimalists, made up of mostly genetic material and protein, which is not enough to replicate themselves (they need to find a host cell and hijack their machinery).

We learned about how the simplicity of viruses, and their lack of their own internal machinery means that there are fewer potential targets for drug therapy. Standard antibiotics which rapidly kill bacteria don't touch viruses.

We learned about viruses that are impossible to cure. Rabies, for example. Without any treatment for it, combined with it's 100% fatality rate, vaccinating your dogs, cats, and horses is so important. It's really scary and there are rabies deaths in humans regularly in underdeveloped parts of the world where vaccines are not routine.

We learned how some viruses don't necessarily kill, but they cause life-long infection with the potential to spread to other animals, even without showing any symptoms. Some of these viruses cannot be prevented with vaccines. Equine Infectious Anemia virus is like this, hence the coggins test to find carrier horses, donkeys, and mules.

We learned about how the Equine Encephalitis viruses, which a nearly 100% fatality rate, are spread by mosquitoes. Fortunately vaccines are highly effective, so vaccinate your horses every spring. West Nile Virus is also spread by mosquitoes, devastating to horses, and well controlled by well-timed vaccination.

We learned about the ubiquity and complexity of herpes viruses. The horse herpes viruses cause respiratory disease, genital lesions, a terrifying neurologic form, abortions in pregnant mares, and foal death. Vaccines reduce these.

Some viruses are very good at altering their own genetic material, or reassembling it with their relatives, to create new forms of themselves that our vaccines and our own immune systems can't protect against. Sometimes this enables them to jump species or change the body organs that it can infect.

Influenza is the classic example. Dr. Olsen talked a lot about the historical epidemics if influenza, such as the Spanish Flu of 1918 that infected a third of the human population and killed 50 million people worldwide. Influenza needs to be taken seriously. I'm a big proponent of vaccination in people and horses.

We learned about cornoviruses. We learned about a lot of coronaviruses because they are common in domestic species. Unfortunately, they have the sly ability to recombine, or exchange part of one virus's genetics with another virus's genetics when the two infect the same cell. This can explain how a virus can suddenly jump species or change it's behavior. In 2003 there was an outbreak of a coronavirus, SARS virus, that is thought to have originated from a Chinese Horseshoe Bat. The illness spread to more than two dozen countries in North America, South America, Europe, and Asia before the SARS global outbreak of 2003 was contained. I don't have to tell you about the latest cornovirus outbreak.

Today, more than ever, I understand Dr. Olsen's fascination with the power of the little guy, the invisible poison that leaves us at our wits end.

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