Caterpillar Envenomation Clinical Presentation
- Author: Robert L Norris, MD; Chief Editor: Scott H Plantz, MD, FAAEM more...
History
- While the history of exposure related temporally to the onset of signs and symptoms may be clear, the diagnosis can be challenging. Maintain a high index of suspicion when patients present with unexplained acute dermatitis, rhinitis, conjunctivitis, or wheezing during months when caterpillars are numerous. In some regions of the world, the diagnosis becomes clear when clusters of seemingly unrelated cases start to present.
- Onset of acute dermatitis due to hair exposure may immediately follow exposure or may be delayed 8-12 hours and can be manifested by the following:
- Intense pruritus, local pain or soreness (less common), and erythematous raised rash, blisters, and bruising at the site may occur. Skin necrosis has occurred following prolonged exposure to toxic hairs. With most toxic caterpillars, systemic symptoms are unusual in the absence of respiratory exposure.
- Respiratory exposure may precipitate acute rhinitis, tearing, cough, dyspnea, respiratory distress, wheezing, and chest pain. This syndrome may need to be differentiated from the rare case of anaphylaxis.
- Ocular exposure may initiate an acute conjunctivitis with severe pain, tearing, and redness. Visual acuity can be reduced as inflammation progresses.
- Stings by venomous caterpillars result in immediate, localized, severe, burning pain, which can radiate proximally and be severe enough to inhibit movement of the extremity (pseudoparalysis). Redness and swelling with slight bruising may occur at the site. Over the first few days, the patient may note the development of small blisters, which can become hemorrhagic. Local findings, including pain, may persist for several days.
- Systemic complaints may occur within minutes of the sting, although they usually occur within 2 hours. These complaints include headache, dizziness, restlessness, nausea and vomiting, malaise, swollen or tender lymph nodes, muscle spasms, rapid heart rate, and, in exceptional cases, altered mental status. Systemic symptoms usually resolve in 24 hours.
- Following stings by some of the New World caterpillars in the family Saturniidae, which contain a fibrinolytic component to their venoms, patients may note scattered bruising (onset in 8-72 h) and bleeding from any of a number of sites (eg, gingival bleeding, hematuria). Intracranial bleeding and acute renal failure are possible complications. Coagulopathy can last 2-5 weeks.
Physical
- Local findings include erythematous papules that tend to congregate around the face, neck, trunk, arms, wrists, and hands and may become confluent; vesicles; local purpura; or ecchymosis.
- Systemic signs include a low-grade fever.
- Findings of respiratory exposure include acute rhinitis, tearing, respiratory distress, and wheezing.
- Ocular exposure presents as follows:
- Findings include acute conjunctivitis.
- Following penetration of the cornea, findings include keratitis, acute uveitis, and retinochoroiditis.
- Stings present as follows:
- Local findings include erythema, edema, small petechiae or hemorrhagic papules, vesicles, bullae, and pseudoparalysis of the extremity because of pain. Following M opercularis stings, the site may take on a gridlike pattern matching the distribution of the creature's spines.
- Systemic findings include restlessness, lymphangitis, lymphadenopathy, muscle spasms, tachycardia, altered mental status (unusual), seizures, and hypotension.
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