Rabies Series 3——Operation “Chicken Head Rain” to eliminate rabies

In the last issue, we introduced the process of Pasteur's development of rabies vaccine, which fired the first shot in humanity's fight back against the rabies virus. In the subsequent fight, the most famous one was Europe's "Chicken Head Rain" operation.

In Europe, the main animal source of rabies is the red fox. During World War II, red foxes carrying rabies first attacked Poland. Subsequently, rabies spread rapidly among fox populations in Western and Central Europe, posing a great threat to humans, livestock and wild animals.

Image source: pixabay

In the 1970s, rabies spread to Switzerland. The Swiss tried a variety of solutions, such as shooting or poisoning foxes, catching foxes, injecting them with rabies vaccines and releasing them, or simply setting traps. These traps were not designed to catch animals, but to vaccinate animals that stepped on the traps. However, after all the efforts, the results were not very good. What should they do?

At this time, someone proposed to try edible vaccines, which are vaccines that can be taken directly to produce effects. The white sugar pills we ate when we were young are a type of edible vaccine.

So scientists developed an edible vaccine for foxes. This vaccine can strengthen the fox's immune system and protect itself from rabies virus. But the question is, what kind of food should the vaccine be mixed into to achieve the best effect?

They tried eggs, dog biscuits, fried cornmeal with milk, sausages, etc., but all had little effect. Although foxes love eggs very much, they prefer to store them for later use, during which time the vaccine will gradually become ineffective. Fortunately, scientists have found the foxes' true love, which is chicken heads. Putting the vaccine in chicken heads seems to be more effective than putting it in other things.

In order to prove that chicken heads are really effective, scientists left a mark in the chicken heads - tetracycline. Tetracycline is an antibiotic that is absorbed by bones and dyes bones and teeth yellow and brown, so it is often used as a marker to study bone growth. Later, people found tetracycline in the teeth and bones of captured foxes, which proved that choosing chicken heads as bait is very effective.

Therefore, people increased the scale of the delivery of chicken head vaccine, and soon a "chicken head rain" fell in the Swiss forest. Tens of thousands of chicken heads were placed in areas frequented by foxes by helicopter or manually, and the effect was very good.

After seeing the results of Switzerland, other European countries also joined in. By the 1990s, 16 European countries had participated in the "Chicken Head Project".

Among these 16 countries, Germany has a large land area and the production of chicken heads as bait is very limited. Therefore, they came up with a new method: mash the meat into meat paste and make fish patties to use as bait instead of chicken heads, and the effect is also very good.

Other countries followed suit, and by 1996, about 74 million rabies vaccine patties had been fed throughout Europe. The European "chicken head vaccine" project reduced the number of foxes with rabies by about 90% within 10 years.

Eventually, more than a dozen European countries, including Switzerland, Germany, France, and Italy, used this method to get rid of the threat of rabies. Subsequent sporadic recurrences of rabies in wild animals were also curbed by using a similar "chicken head vaccine" method. Therefore, the "Chicken Head Rain" operation can be called one of the most successful cases of wildlife vaccination to date.

You wouldn’t have thought that chicken heads have made such a great contribution to the fight between humans and rabies.

However, although rabies is no longer as rampant as it used to be, it has not been eradicated. Moreover, once infected with rabies, the mortality rate is almost 100%. So what exactly does rabies do in our bodies? Let's go to the last stop of the rabies series to find out~

The article is produced by Science Popularization China-Starry Sky Project (Creation and Cultivation). Please indicate the source when reprinting.

Author: Science scraps popular science team

Reviewer: Wang Chuanlin, Director of Emergency Department, Peking University People's Hospital