Which insect bite is classically associated with immediate pain and paresthesia and a positive tap test?

Which insect bite is classically associated with immediate pain and paresthesia and a positive tap test?

• A. Black widow spider
• B. Scorpion
• C. Fire ant
• D. Mosquito

Answer: (B)

Immediate pain with paresthesias after a sting points to a neurotoxic envenomation. Scorpion venom contains toxins that rapidly excite sensory nerves by affecting ion channels, so the sting feels immediately sharp and can produce tingling or numbness around the site. A tap test—gently tapping the area to elicit amplified pain or tingling—reflects this nerve hyperexcitability from the venom. In contrast, a black widow sting more often causes diffuse muscle cramps and autonomic symptoms rather than focal neuropathic pain; fire ant stings are intensely painful locally but don’t typically present with persistent paresthesias or a positive tap test; mosquito bites mainly cause itching and mild swelling. Therefore, the described presentation is most consistent with a scorpion sting.

Immediate pain with paresthesias after a sting points to a neurotoxic envenomation. Scorpion venom contains toxins that rapidly excite sensory nerves by affecting ion channels, so the sting feels immediately sharp and can produce tingling or numbness around the site. A tap test—gently tapping the area to elicit amplified pain or tingling—reflects this nerve hyperexcitability from the venom. In contrast, a black widow sting more often causes diffuse muscle cramps and autonomic symptoms rather than focal neuropathic pain; fire ant stings are intensely painful locally but don’t typically present with persistent paresthesias or a positive tap test; mosquito bites mainly cause itching and mild swelling. Therefore, the described presentation is most consistent with a scorpion sting.