Why does an animal need to be put down before it can be tested for rabies?


I am thinking about the two grizzly bears at our local zoo that had to be killed in the 90’s because one of them scratched a child who jumped into their caged area. They could then confirm that neither animal had rabies.

Why is there not a more novel way to test for rabies? And why can’t the human be tested for it?

In: 357

Because the best test for rabies in animals, is an antibody test that requires a large portion of the animals fresh brain, and multiple areas must be tested to rule out the disease (and assess the risk to human at risk).
Even the constellation of tests the use to try to determine if a human has the disease isn’t as accurate, and since Rabies is so lethal you’re not going to risk doing a test that could say the animal is negative when it isn’t.

Because rabies principally infects the central nervous system, which means you need a portion of the central nervous system (i.e., brain tissue) to test. The standard is to sample from 2 different parts of the brain. It’s just not possible to do this and keep the animal alive.

Nowadays it’s become possible to test for rabies without killing the animal, but they haven’t been conclusively proven to be as reliable as directly testing brain tissue, and because rabies is essentially 100% fatal, the risk is too high to justify using a testing method that might not be certain.

Once you as a human show the first symptoms of having rabies YOU ARE DEAD. There is 100% chance of dead and there is nothing that can be done at that point.

About detection from [WHO (World Health Organization)](https://www.who.int/news-room/fact-sheets/detail/rabies)

>Current diagnostic tools are not suitable for detecting rabies infection before the onset of clinical disease.

So you can have it and we can’t tell until it’s too late to do anything about it.

As for why we need to kill the animal? We need to check their brain for the virus.

Rabies doesn’t raise a lot of antibodies, so blood and saliva tests are not conclusive; even CSF tests aren’t perfectly reliable. The most reliable and “gold standard” test requires sampling tissue from various regions of the animal’s brain. That process isn’t compatible with life, so the animal is euthanized in a humane manner.

The reason they test for the infection is because rabies is fatal if not treated prior to the onset of symptoms, and you don’t want to give the vaccine unnecessarily because not much is made and the treatment in humans consists of an expensive ($3,000 up to $10,000 in US) course of 3-4 inoculations, which are often painful and have strong side effects (short term).

This all makes me understand better why Great Britain had a six month quarantine even on house pets since there is zero presence of rabies in Great Britain. There is now a workaround for a chipped animal and testing them before traveling but for a long time it was six months.