Which communicable disease is known as "Hydrophobia"?

Question

Accepted Answer

The correct option is (3):
The communicable disease correctly known by the classical term "Hydrophobia" is Rabies. The word *hydrophobia* literally means 'fear of water' and is one of the most distinct and serious symptoms of the advanced, furious form of rabies. This symptom arises because the virus, a neurotropic *Lyssavirus*, causes painful, involuntary spasms of the muscles in the throat and larynx when the patient attempts to swallow or drink water. Even the sight or sound of water can trigger these violent spasms, causing the patient to develop a profound avoidance and fear of drinking. Rabies is almost universally fatal once these neurological symptoms, which also include anxiety and abnormal behaviour, begin to manifest, underscoring the critical need for prompt post-exposure treatment.

The incorrect options are (1), (2), and (4):
The other options are incorrect because they are associated with different pathogens and clinical pictures. **Tetanus** (Option 1) is a severe bacterial disease caused by the neurotoxin *tetanospasmin* from *Clostridium tetani*. While it involves painful muscle rigidity and spasms, the classic clinical sign is "lockjaw" (trismus), not the fear of water seen in rabies. **AIDS** (Option 2), or Acquired Immunodeficiency Syndrome, is caused by the Human Immunodeficiency Virus (HIV), which is a retrovirus that attacks and destroys the immune system's T-cells, leading to immunodeficiency. It is an immune disorder, and while it may have neurological complications, it is not known to cause hydrophobia. **Tuberculosis** (Option 4) is a serious bacterial infection caused by *Mycobacterium tuberculosis* that primarily affects the lungs; it is a respiratory disease with symptoms like a persistent cough, fever, and weight loss, and is not associated with the specific neurological phenomena of hydrophobia.