“Nature doesn’t break, it only bends.” This quote was recently uttered on a television drama, which depicted an infectious disease clinician fighting a catastrophic epidemic that developed following a genetic mutation of a forgotten infectious disease agent.

As a pathologist and former microbiologist, this reference to the constant evolution of microbes made me ponder, once again, how such relatively simple organisms rapidly and continually adapt to their environments to survive and replicate. It is unfortunate, at least for the host, when the intricate balance between host, environment, and microbe becomes offset and results in infectious disease.

This theme was exemplified in April 2016 when equine infectious disease experts from around the world gathered for the 10th International Equine Infectious Diseases Conference in Buenos Aires, Argentina. The conference, which is held every four years, provides excellent continuing education for equine clinicians and brings together equine infectious disease researchers who share recent developments and breakthroughs. The five-day event addressed infectious diseases of continued and historical concern, newly recognized and emerging diseases, and important reemerging infectious diseases of the horse. These motifs were addressed in 11 separate sessions on biosecurity, diagnostics, diseases of working equids, emerging and reemerging diseases, gastroenterology, international equine movement, neurology, parasitology, theriogenology (reproduction), respiratory diseases, and infectious diseases of other systems.

Although I enjoyed all of the presentations, I was particularly taken with the talks on emerging and reemerging diseases. Emerging viral agents that were discussed included equine enteric coronavirus (a potential cause of necrotizing enteritis), Theiler’s disease-associated virus (the newly identified cause of equine serum sickness) and other viral causes of hepatitis (equine hepacivirus and equine pegivirus), Bunyamwera virus in Argentina (a cause of nervous disease and/or abortion), and Hendra virus (an acute fatal and zoonotic disease that frequently affects the respiratory and neurologic systems). Other interesting and noteworthy disease conditions comprised anthelmintic resistance (resistance of parasitic worms to treatment), the potential role of microbes in equine polyneuropathy, and strangles-like disease caused by Streptococcus zooepidemicus. The reemergence of West Nile virus (a cause of neurologic disease) in France and Salmonella Abortusequi (a cause of abortion and septicemia) in Argentina were also addressed. Although many of these diseases are emerging or reemerging in specific locations, one must be globally aware of them due to the increasing frequency with which equine athletes and breeding stock are transported around the world