Case Histories

 

The following case histories are typical of the insect bite and sting consultations provided by the Agromedicine Program. We consult on about 10 insect and spider bites and stings every month from statewide callers.

 

Urticating Caterpillar

 

The Cooperative Extension Service referred a landscaper to the Agromedicine Program for consultation after he was 'stung' by a caterpillar. He had been working in Mt. Pleasant, S.C. trimming a holly bush when a caterpillar fell from the bush brushing the calf of his leg below the bottom of his shorts. Within 20 minutes he developed severe, burning pain from his foot to lower abdomen. The pain persisted overnight, almost to the point of seeking emergency treatment. He also reported that a clear fluid oozed from an area surrounding the sting site. The symptoms gradually resolved over 12 hours leaving him with red streaks that developed on the skin where he was stung.

 

A caterpillar was collected for identification. It was identified as the larval form of Megalopyge opercularis, commonly known as the puss caterpillar. The larva is about an inch in length, may be tan to brown in color, and is found throughout the Southeast. It is covered with hair giving it a furry appearance. There are three rows of long hairs along with shorter spines along both sides. The spines contain a toxin that is secreted when the caterpillar is handled.  The spines may break off and become embedded in the skin.

 

Pinson et al1 reported that intense local pain after initial contact with the puss caterpillar is typical followed 10 to 15 minutes later by local erythema, swelling, and severe proximally radiating pains. Pain may last up to five days and it may be associated with pruritus. Regional lymphadenopathy may develop within 45 minutes. Other symptoms include headache, fever, nausea, vomiting, muscle cramps, tachycardia, hypotension and rarely, convulsions or shock-like symptoms.

 

Treatment consists of removing embedded spines with repeated applications of adhesive tape, wound care, ice and elevation of the extremity for initial relief of pain. Administration of morphine sulfate, meperidine, or codeine may be needed for severe pain.

 

1Pinson RT et al. Envenomation by the puss caterpillar (Megalopyge opercularis). Ann Emerg Med 1991; 20:562-564.

 

 

IFA Sensitization

by Dr. William M. Simpson, Jr.2

 

A 19-year old Army active duty soldier reported to the Clark Health Clinic at Ft. Bragg, N.C. He had been stung by a fire ant during a session of physical training.

 

His symptoms included diffuse urticaria, itching of his skin and anxiety. He had had two previous reactions to fire ant stings and carried an emergency kit  containing epinephrine and benadryl for self-administration.  In the 10-15 minutes it required to get to the clinic, his symptoms had subsided almost completely except for mild anxiety and itching. 

 

He had entered the Army from his home in Ohio, having had no previous exposure to fire ants. He had no other known allergies.

 

He was observed for six hours in the clinic, had no recurrence of symptoms and was discharged with a new emergency kit, a profile which allowed him to avoid potential contact with fire ants and a consultation to an allergist for testing and possible hyposensitization (he had not previously been referred to an allergist).

 

This case illustrates several points:

 

  1. Patients without prior exposure to potential allergens can manifest symptoms at any age.

 

  1. Patients with systemic allergic symptoms should be observed for at least six hours, since medications used to control symptoms have relatively short duration of action and the allergic response may persist for several hours.

 

  1. Patients with systemic allergic reactions are “ticking time bombs” and should be referred immediately to an allergist for followup. However, diagnostic skin tests may be negative for 4-6 weeks after an anaphylactic reaction due to depletion of histamine from mast cells.

 

  1. Persons with one systemic allergy may have others.  They should also be tested for allergy to other hymenoptera venoms.

 

2Dr. Simpson was serving two weeks active duty last month at Fort Bragg when this case presented. SCAP Case File