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Caterpillar Envenomation: Follow-up

Author: Robert L Norris, MD, Associate Professor, Department of Surgery; Chief, Division of Emergency Medicine, Stanford University Medical Center
Contributor Information and Disclosures

Updated: Nov 19, 2008

Follow-up

Further Inpatient Care

• The vast majority of victims of erucism or lepidopterism are treated as outpatients. The rare patient with significant anaphylaxis following exposure should be admitted to the hospital for further standard monitoring and management.
• Victims of stings by the South American Lonomia caterpillars should be admitted to the hospital and observed for development of coagulopathy.

Further Outpatient Care

• Victims of caterpillar stings can be observed for 2 hours in the ED to ensure that they do not develop significant systemic toxicity.
• Although uncommon, secondary infection can occur following erucism or lepidopterism. Instruct patients to follow up immediately if any signs or symptoms of infection occur. Patients with particularly severe exposures should have scheduled follow-up care to exclude infection or necrosis.
• All patients with ocular exposures to caterpillar or moth hairs or setae should receive early ophthalmologic follow-up care to exclude retained fragments, which can lead to catastrophic complications.
• Following caterpillar stings, local findings, including pain, may persist for several days. Systemic symptoms usually resolve in 24 hours.
• Patients who experience a significant allergic reaction to caterpillar exposure (eg, hypotension, bronchospasm) should receive a prescription for an epinephrine self-administration device prior to discharge from the hospital and should be instructed in its use. They also should consider obtaining and carrying medical alert identification of this history. Unlike therapy for hymenoptera-induced anaphylaxis, there is no desensitization therapy for patients highly allergic to caterpillars.

Deterrence/Prevention

• All caterpillars should be considered potentially toxic, and contact should be avoided. Children particularly should be warned in this regard. When working outdoors during peak caterpillar seasons, individuals should wear long-sleeved shirts, long pants with the cuffs tucked into their socks, and work gloves. Collars should be close fitting to avoid having a caterpillar fall into one's shirt. When working in an area where airborne caterpillar debris is a problem, a tight-fitting face mask and eye protection should be used. Laundered clothing should not be hung outdoors to dry as it may collect airborne caterpillar debris.
• Insecticides can be used to control caterpillar populations. A professional pest specialist or entomologist should be consulted before applying such agents because many caterpillar species are beneficial to agricultural and ornamental plants.
• If a caterpillar is found on one's body, it should be gently lifted off with a stick to avoid contact with potentially toxic hairs, setae, or hemolymph.

Complications

• The wounds or dermatitis that follow exposures to irritant or toxic caterpillars and moths can become secondarily infected, which can lead to scarring and permanent dysfunction. The risk is increased when hairs or spines are retained or in patients with severe pruritus that leads to excessive scratching. In rare cases, necrosis can result from prolonged exposure to caterpillar or moth setae.
• Ocular exposures can cause development of keratitis, acute uveitis, retinochoroiditis, endophthalmitis, and ophthalmia nodosa in the setting of retained hairs that tend to migrate into the eye. The ultimate outcome may be permanent blindness.
• An uncommon but very concerning complication following caterpillar or moth exposures is the development of anaphylaxis in sensitized individuals.

Prognosis

• The prognosis is generally excellent.

Miscellaneous

Medicolegal Pitfalls

• Since secondary infection or necrosis following erucism or lepidopterism is possible, wound care instructions and follow-up care are necessary.
• The risk of major complications following retained, fine setae in the eye dictates that all patients with ocular exposure to caterpillar or moth hairs be referred to an ophthalmologist for further examination and follow-up care.
• Patients who have experienced an anaphylactic reaction following any form of arthropod sting or exposure should receive an appropriate field epinephrine kit and instruction in its use at the time of discharge.

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