A child presents with irritability, agitation, muscle pain, and cramping in the large leg muscles. Exam reveals a target lesion with an erythematous ring around a pale center. The child was playing in a garage and does not recall insect bites. What is the most likely cause?

A child presents with irritability, agitation, muscle pain, and cramping in the large leg muscles. Exam reveals a target lesion with an erythematous ring around a pale center. The child was playing in a garage and does not recall insect bites. What is the most likely cause?

• A. Allergic reaction to flea bites
• B. Black widow spider bite
• C. Brown recluse spider bite
• D. Ingestion of weed pods

Answer: (B)

Neurotoxic envenomation from a black widow spider produces prominent systemic and neuromuscular symptoms, especially severe muscle cramps and pain in large muscle groups, along with autonomic symptoms such as irritability or agitation. In a child who was playing in a garage—an exposure setting for spiders—these neuromuscular findings fit the toxin’s effect on nerve terminals, leading to cramping and restlessness. Local bite sites from black widows can be minimal or nonspecific, so a dramatic skin lesion isn’t required for the diagnosis. The target lesion with a pale center points more toward brown recluse bites, which classically cause a necrotic skin lesion rather than marked systemic muscle cramping or agitation. Flea bites typically cause itching and wheals rather than systemic neuromuscular symptoms, and ingestion of weed pods would present with different systemic or gastrointestinal features.

Neurotoxic envenomation from a black widow spider produces prominent systemic and neuromuscular symptoms, especially severe muscle cramps and pain in large muscle groups, along with autonomic symptoms such as irritability or agitation. In a child who was playing in a garage—an exposure setting for spiders—these neuromuscular findings fit the toxin’s effect on nerve terminals, leading to cramping and restlessness. Local bite sites from black widows can be minimal or nonspecific, so a dramatic skin lesion isn’t required for the diagnosis.

The target lesion with a pale center points more toward brown recluse bites, which classically cause a necrotic skin lesion rather than marked systemic muscle cramping or agitation. Flea bites typically cause itching and wheals rather than systemic neuromuscular symptoms, and ingestion of weed pods would present with different systemic or gastrointestinal features.