How many strains of encephalomyelitis are common to horses?

There are three common strains of equine encephalomyelitis that affect horses: Eastern, Western, and Venezuelan encephalomyelitis. These are viral diseases caused by arboviruses and are primarily transmitted by mosquitoes. Each strain varies in terms of geographical distribution and severity of the disease, with Eastern encephalomyelitis being the most severe form. Understanding the existence of these three strains is crucial for horse owners and caretakers since vaccination is available to protect against these potentially fatal diseases. This knowledge also highlights the importance of controlling mosquito populations and minimizing exposure to these vectors during outbreak seasons. The other choices do not encompass all the known strains, which is why they do not accurately reflect the situation regarding encephalomyelitis in horses.