Wednesday, April 22, 2015

Getting Dogs to Take the Bait

An oral vaccine for rabies would save millions of dogs' lives and many thousands of human lives. The key is getting the dogs to take the bait.
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A commercially produced rabies vaccine
When I was attending Ohio State University in the early 1970's, I once brought a pomegranate back from California. Not a single person would even taste it. Not one! I was amazed. Pomegranates don't have a disgusting odor or a strange unappetizing color. But in those days, they were completely unknown in Ohio.

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Pomegranate
The people who rejected them weren't ignorant rednecks who'd never been outside of their rural birthplace. They were all graduate students working on masters or PhD degrees, who must surely have had some experience of the world. But none of them was willing to risk so much as a single bite.

I had more or less the same experience during an undergraduate year I spent in France in 1965. The American students put together a Thanksgiving dinner for their French hosts. We made the mistake of including sweet corn on the menu. "That's pig food!" was the universal verdict. They didn't need to taste it to know that it wasn't fit for human consumption.

I have to admit that I'm no different from my  friends in Ohio and in France. My husband, who grew up in England, loves Marmite, but hates its Australian cousin, Vegemite.. I dislike both of them.  But I like peanut butter, which he won't touch.
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I can't even stand the smell of this stuff.
Dogs, apparently, are much the same as people. They don't like unfamiliar things.

If dogs are roaming free or cannot easily be restrained, oral vaccination will not work unless most dogs take the bait. 70% of them need to be immune to rabies before the whole community will be protected from it.

In the 2001 trial of oral rabies vaccine carried out in the Philippines 96% of the dogs who were offered bait accepted it without hesitation. The study states that "Baits were quickly taken up and most were rapidly and completely consumed by the dogs." The bait was made from local materials, all things those dogs were familiar with and would have eaten before.
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Dogs in the Philippines
In contrast, in a field trial in Tunisia, where a commercially manufactured bait was used, only 44% of the dogs would touch it.
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Some Tunisian Dogs
The locally produced vaccine used in the Philippines  had another advantage. It cost only a penny per dose, as opposed to $1.30 per unit for a commercial raccoon bait in the U.S  That's a stratospheric difference for a country without much money.

It also seems to me that a bait made locally would produce some local jobs, especially if the program were ongoing--which it would need to be to provide continuing immunity to a changing dog population.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC60992/
https://books.google.com/books?id=C-U1LFK5zagC&pg=PA585&lpg=PA585&dq=field+trial+of+oral+rabies+vaccine+in+tunisia&source=bl&ots=Wea15gNlMZ&sig=5P5f58a4vIyogRItA5AL3YwSii0&hl=en&sa=X&ei=pKY3VdeYFoHpgwS6oYCQDg&ved=0CF0Q6AEwBQ#v=onepage&q=field%20trial%20of%20oral%20rabies%20vaccine%20in%20tunisia&f=false
cost of bait, p. 112:
http://www.aphis.usda.gov/wildlife_damage/nwrc/symposia/economics_symposium/kemereHR.pdf