Why person having rabies become hydrophobic?

The virus causing rabies leads to an infection or inflammation in the brain known as encephalitis. The central nervous system is severely affected, and the limbic system, which controls emotions and behaviours, is also profoundly affected.

There is an inflammatory response involving the central nervous system during the encephalitic stage. The virus is known to have an affinity for the neural tissue and the neurotransmitter receptors in the brain, which could be a reason for the inflammation and the consequent clinical signs of the disease.

Hydrophobia or water aversion is a sign that the human nervous system has been compromised. The infected person often experiences difficulty in swallowing due to intense muscular spasms in the throat and respiratory tract. These spasms occur in response to stimuli like attempting to drink water, which is why it looks like a hydrophobia (fear of water) when in reality it is a reflex response to swallowing anything.