Rabies vs Tetanus
How to tell Rabies and Tetanus apart when a board question makes them look alike.
Rabies is bite/bat encephalitis with hydrophobia; tetanus is contaminated wound toxin causing lockjaw and spasms.
Side by side
Rabies follows animal bite or bat exposure with paresthesias at bite site, fever, anxiety, agitation, hydrophobia, aerophobia, dysphagia, hypersalivation, encephalitis, and near-universal fatality after symptoms.
Tetanus follows wound contamination with Clostridium tetani spores and causes trismus, risus sardonicus, dysphagia, painful muscle spasms, opisthotonos, and autonomic instability without sensory loss.
Rabies virus travels retrograde along peripheral nerves to the CNS, causing encephalitis; Negri bodies can appear in neurons.
Tetanospasmin blocks release of GABA and glycine from inhibitory interneurons, causing disinhibited motor neuron activity.
Animal bite, bat exposure, hydrophobia, aerophobia, encephalitis, nuchal skin biopsy/saliva PCR, and prevention with vaccine plus immunoglobulin support rabies.
Dirty wound, uncertain immunization, lockjaw, generalized spasms triggered by stimuli, and treatment with wound care, metronidazole, TIG, and vaccination support tetanus.
The trap
Both can follow animal or environmental exposure, but rabies changes behavior/swallowing from encephalitis while tetanus causes rigid spasms from disinhibition.
The repair move
For exposure-related neurologic disease, separate viral encephalitis/hydrophobia from toxin-mediated spastic paralysis.
Try a free question
CoreA patient bitten by a bat weeks ago develops fever, bite-site paresthesia, agitation, dysphagia, hypersalivation, and spasms triggered by attempts to drink water. Which diagnosis is most likely?
Show answer and explanation
Answer: A. Rabies. Bat exposure followed by encephalitis, dysphagia, hypersalivation, and hydrophobia supports rabies.
Why the other choices are tempting
- B. Tetanus causes lockjaw and painful spasms after contaminated wounds.
- C. Botulism causes descending flaccid paralysis.
- D. Polio causes asymmetric flaccid paralysis.
- E. West Nile can cause encephalitis but not classic hydrophobia after bat bite.
Flashcards
Tap a card to flip it.
What exposure supports rabies?
Animal bite or bat exposure supports rabies risk.
What symptom strongly supports rabies?
Hydrophobia with encephalitis strongly supports rabies.
Quick answers
What is the fastest way to tell Rabies from Tetanus?
Rabies is bite/bat encephalitis with hydrophobia; tetanus is contaminated wound toxin causing lockjaw and spasms.
What is the key clue for Rabies?
Rabies follows animal bite or bat exposure with paresthesias at bite site, fever, anxiety, agitation, hydrophobia, aerophobia, dysphagia, hypersalivation, encephalitis, and near-universal fatality after symptoms.
What is the key clue for Tetanus?
Tetanus follows wound contamination with Clostridium tetani spores and causes trismus, risus sardonicus, dysphagia, painful muscle spasms, opisthotonos, and autonomic instability without sensory loss.
What is the common trap with Rabies vs Tetanus?
Both can follow animal or environmental exposure, but rabies changes behavior/swallowing from encephalitis while tetanus causes rigid spasms from disinhibition.