We report on a lot of emerging studies here at TheHorse.com, translating them into layperson speak, and our writers and editors report on news as it happens. But we don’t always give our sources a chance to say, “Hey. Pay attention. This is important.” Or, “Keep an eye on this research avenue—it’s going to dictate how we handle this illness or that disorder.”

So, last week I got back to the heart of my early days at The Horse: I began visiting with scientists and veterinarians about care topics and research directions they deem important to our industry—whether right now or in the near future. First up as an important issue to horse owners right now? Mosquitoes.

We cannot become complacent: These little guys (well, technically, girls) are spreading disease as readily as ever, noted William (Bill) J.A. Saville, DVM, PhD, Dipl. ACVIM. Saville is professor and chair in The Ohio State University’s Department of Veterinary Preventive Medicine. I’ve worked with him on stories for almost 12 years. Dr. Bill Saville is a cowboy turned veterinarian turned researcher-and-educator (his research focus: equine protozoal encephalomyelitis, or EPM) turned administrator. He shoots from the hip, always giving me a “say it like it is” interpretation of an issue. In the early days of West Nile virus (WNV) emerging in the United States, he made it a personal mission to educate not only Ohio horse owners but also residents about mosquito reduction techniques.

What surprised me about his message about mosquitoes this time around (since this is the annual refrain—vaccinate and get rid of mosquitoes) was why he’s particularly concerned. It’s not that we’re still seeing horse cases, it’s that we’re seeing spikes in the human numbers. There have been 1,057 recorded cases in Texas alone (as of Sept. 11).

Why so many human cases? Here are four reasons he posed:

  1. Widespread drought and high temperatures. In many areas of the United States there has been little rain, and when it rains it’s a pouring rain that collects as standing water and begins to evaporate. Birds, which harbor WNV in their blood congregate around water sources. So do hungry mosquitoes. The mosquitoes feed and breed and feed, spreading the virus from birds to people and horses. There is no WNV vaccine for humans.
  2. Public health funding for WNV education and prevention has been cut in many states. Fewer people are getting the message about mosquito source reduction (i.e., getting rid of mosquitoes at their source by eliminating breeding grounds); wearing protective clothing/using DEET/avoiding being outside during peak mosquito activity; and officials have trimmed municipal spraying from budgets.
  3. Clinical signs in humans are more evident than ever. Where once a person may have had an unexplained fever they might have shrugged off as a summer virus or cold, he says it seems WNV is causing more noticeable signs, and he speculates that more people are getting diagnosed because of it. Does this mean the virus circulating is more potent than it used to be? Possible, though not proven by peer-reviewed published research. 
  4. A number of bird varieties withstand the virus and, thus, serve as dynamo “reservoirs” for the disease. These are the birds hanging out at the puddles and caught up in the cycle of disease spread. Keep in mind that certain birds such as crows and blue jays are particularly susceptible (they are more likely to die when infected), and entire populations of these species were wiped out in some areas over the past 13 years because of this.
mosquito dunk

Consider dropping mosquito dunks--solid "donuts" of Bacillus thuringiensis israelensis (BTi)--in small areas of standing water that you're unable to eliminate.

Saville said it's important to note that we’re not necessarily aware of all the equine cases; these cases were no longer considered reportable after WNV was declared endemic. Also, there are effective vaccines on the market and we might be seeing fewer cases overall; he drove home that most of the equine cases are unvaccinated horses. Sure, no vaccine is 100% effective but he stressed that horse owners at least give their horses a chance to fight the illness by keeping their WNV inoculations up to date.

You can also protect your horses using the mosquito source reduction techniques mentioned. At the heart is eliminating standing water, where mosquitoes like to breed. Last week Smart Horse Keeping blogger Alayne Blickle described some effective mosquito source reduction techniques to be used around the barn, and I encourage you to take a look. Something that bears mentioning is dropping mosquito dunks—solid "donuts" of Bacillus thuringiensis israelensis (BTi)—in small areas of standing water that you're unable to eliminate. Veterinarians have reported these products aren't harmful to horses or other animals. 

Saville also recommends taking a look at fact sheets The Ohio State University extension offers. Finally, we offer a recently updated WNV fact sheet, as well.

Your turn: How have you been addressing West Nile virus prevention in your horse(s)? How have you tackled mosquito source reduction in your barn area? Have you found areas of standing water on your property that surprised you, and how did you eliminate them?