Ingenious and bizarre way the US Government is preventing a rabies outbreak: Planes drop bait laced with vaccines for racoons to munch on

American health officials are preventing an outbreak of rabies by dropping vaccines from planes as part of a half-billion-dollar federal program.

Over 9 million ketchup packet-sized pieces of food containing vaccines are scattered all over the Eastern United States to suppress the deadly neurological virus in raccoons and keep it from killing humans.

The packets come in two flavors especially designed to appeal to the trash-diving mammal — vanilla and fishmeal — but 'packet thieves' who don't need the rabies vaccine, like gray squirrels and opossums, do make off with a few morsels.   

The annual airdrop, run by the US Department of Agriculture since 1997, has stopped the spread of rabies westward across the US, but now hopes to eradicate the disease in racoons in the east as well.

The news comes amid warnings from scientists that rabies-infected vampire bats are creeping up North America via Mexico, as habitats shift due to climate change. 

'What we haven't been able to do,' according to Charles Rupprecht, a former head of the US Centers for Disease Control and Prevention's (CDC) rabies program, 'is eliminate it from any state where raccoon rabies currently exists.'

The USDA has renewed testing of a newer vaccine with a new flavor this year, in its effort to entice more raccoons: marshmallow with icing sugar, vegetable oil and a dark-green food dye.

'Our feelings are absolutely not hurt if skunks, foxes or coyotes pick them up. And they do,' said wildlife biologist Jordona Kirby, a field coordinator for the USDA's National Rabies Management Program.

'So, although raccoons are the reservoir and spread rabies primarily in the east,' Kirby told NPR, 'those other animals, just like any mammal, can contract rabies.'

Last year, in fact, researchers working with the University of Georgia's Savannah River Ecology Laboratory determined that 'competition with opossums,' at least, was not holding raccoons back from getting their dose of the vaccine. 

The researchers' proposed two solutions to get more raccoons vaccinated, as published this year in the Journal of Wildlife Management, focused less on the competition and more on the raccoons. 

The first suggestion was 'altering the bait matrix to make it more attractive to raccoons,' meaning even more design and flavor experimentation. 

Their second new proposal: drop the oral vaccine packets in winter months, when food is more scarce, 'to promote bait acceptance by raccoons.'

Up to the present, the USDA's oral vaccine airdrops have typically occurred between the months of July and October.  

Starting last July, the USDA's Animal and Plant Health Inspection Service (APHIS) began the next phase of their marshmallow trials — which distributes approximately 3.5 million of the new oral vaccine baits, called ONRAB ORV, across parts of Vermont, New Hampshire, Maine, New York, Ohio, Pennsylvania, and West Virginia.

One other area, however, will be the focus of their data collection for this field test.  

'APHIS is conducting the final year of a small-scale project during October in Chattanooga,' USDA officials announced, 'to evaluate the effectiveness of ONRAB’s distribution methods.' 

Wildlife biologists working for APHIS in Chattanooga, Tennessee will catch and test a random sampling of raccoons and skunks following this year's bait distribution to track their vaccination rates.

Low flying planes are used in rural areas to scatter these oral vaccines from the air, equipped with a convey belt inside the aircraft to automate and evenly distribute the vaccines at roughly 75 baits per square kilometer (29 per square mile). 

In truly remote areas where raccoons are less likely to live, including the spruce forests of northeastern Vermont, the USDA only drops about 37 baits per square kilometer (14 per square mile).

But in more urban areas, the USDA's distribution hopes to hit as much as 150 oral vaccines per square kilometer (58 per square mile), dropped on the suburbs via helicopter and tossed out the back of vans in cities. 

Bushes, sewer drain pipes under roads and bridges, and strip mall restaurant dumpsters are all prime locations. 

'Any area that looks like a raccoon habitat, we stop there,' wildlife biologist Kathy Nelson, who oversees the USDA's National Rabies Management Program told Wired.

Nelson said the USDA estimates that only 30 percent of raccoons in a region need to be vaccinated to stop the spread of the disease, and 60-percent vaccination rate could eliminate rabies from an entire area. 

She hopes new techniques can entice more of the creatures to do so. 

Rabies is a neurological virus transmitted through saliva that kills approximately 59,000 people each year, worldwide, but only two to three deaths annually in the US — thanks to the USDA's multimillion dollar program and other national efforts. 

In the first half of the 20th century, the majority of rabid animals in the US were dogs, both pets and strays, until vaccine efforts targeting the disease in pooches succeeded in dropping those numbers in the 1950s and '60s.

Today the most common carriers are raccoons, skunks, foxes and bats, with the winged creatures increasingly becoming the main cause of rabies deaths in the US.

As the vaccine bait drops continue, a statement from the USDA advises, 'Humans and pets cannot get rabies from contact with the bait but are asked to leave the bait undisturbed if they encounter it.'

'An intact bait is harmless, but it’s difficult to know if the bait was leaking vaccine while on the ground,' department officials said. 'If contact with bait occurs, the contact area should be immediately rinsed with warm water and soap.'

'Each bait carries a toll-free number that people can call if they have additional questions concerning a bait contact.'