Practice Essentials
Approximately 3500 species of centipedes are found in the class Chilopoda, phylum Arthropoda. They are among the less well-studied arthropods. Centipedes are elongated multisegmented arthropods with a single pair of legs on each body segment. They are distributed widely, being present on every continent except Antarctica, and are especially common in warm temperate and tropical regions. Centipedes spend much of their time underground or in rock piles and usually come out at night to actively hunt their prey. They are capable of very fast movement when exposed. The most dangerous species belong to the genus Scolopendra, with the largest members (Scolopendra gigantea) reaching lengths of 26 cm. See the image below.
Giant desert centipede. Photo by Michael Cardwell.
History
The history of a centipede sting is usually straightforward. The sting is distinguishable by the presence of 2 distinct, parallel puncture wounds. [1] The victim (frequently a gardener) typically sees the creature. Patients may note the following:
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Severe pain (worse with larger specimens)
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Local tissue swelling
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Redness
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Swollen, painful lymph nodes
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Headache
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Chest pain
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Palpitations
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Nausea and/or vomiting
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Anxiety
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Local pruritus
Diagnostics
The following laboratory studies may be appropriate for centipede envenomation:
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A bedside urine test for proteinuria is reasonable. [2] The same test can detect myoglobinuria secondary to rhabdomyolysis in patients with significant swelling and pain of the affected extremity.
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If evidence of rhabdomyolysis is present, serum electrolytes, creatine phosphokinase (CPK), and renal function studies should be obtained.
A complete blood cell count, if done, may reveal a neutrophilic leukocytosis.
An echocardiogram should be obtained if the patient has a history of cardiac disease, chest pain, palpitations, or if there is any evidence of hemodynamic instability following centipede sting.
If the ECG is abnormal in the setting of chest pain following centipede sting, serum cardiac biomarkers (eg, troponins) should be checked.
If swelling of the affected extremity is severe and a compartment syndrome is suspected, intracompartmental pressures should be objectively assessed.
If a compartment syndrome is diagnosed, the limb should be elevated and plans should be made for fasciotomy. A brief trial of intravenous mannitol can be instituted in an effort to reduce pressures before surgery.
Treatment
No specific first aid measures are available for centipede stings. Seek medical care if pain persists or systemic symptoms occur. Local application of ice may reduce some of the discomfort; however, others have anecdotally found that local heat application or immersion in hot (nonscalding) water is more comforting. [3, 4] This may reflect the thermolabile properties of a number of centipede venom constituents.
See Emergency Department Care.
Prevention
Advise patients to never touch or handle centipedes and use caution when gardening, turning soil, or picking up rocks. Work gloves may be very helpful in preventing stings.
Long-term monitoring
Observe patients for evidence of infection or necrosis. Manage local necrosis by sound conservative wound care.
Pathophysiology
The venom delivery apparatus consists of a modified pair of front legs (ie, forcipules) just behind the mandibles. Venom is produced in a gland, generally located at the base of each forcipule, and is injected through ducts when the forcipules are driven into the victim's tissues.
Centipede venoms have not been studied as extensively as many spider and scorpion venoms, but they do contain a wide array of components, including 5-hydroxytryptamine (serotonin), histamine, metalloproteases, hyaluronidase, pore-forming toxins, catabolite activator proteins (CAP), and ion channel modulators. [5, 6] In addition, some centipede venoms may cause endogenous release of histamine.
Centipede venoms may have myotoxic, cardiotoxic, and neurotoxic effects. Active components are selective and often potent. These components may target a range of cellular pathways, leading to a wide variety of pathophysiologies in patients. [7]
In addition to venom, some species exude defensive substances from glands found along the body segments. These secretions are usually nontoxic to humans, although at least 1 species of the genus Otostigmus secretes a vesicating substance.
Epidemiology
While good data are sparse, in some regions of the world, centipede stings are not infrequent. Medeiros et al reported 98 such stings presenting to Hospital Vital Brazil, Butantan Institute, São Paulo, Brazil, between 1990 and 2007. [8]
From 2000-2009 in Venezuela, centipede envenomation was responsible for 106 deaths, representing 14.0% of all reported envenomation-related deaths in the nation for this time period. [9]
Prognosis
Prognosis is excellent in the vast majority of cases of centipede envenomation. Most species are relatively innocuous.
Fatalities are extremely rare following centipede stings. A death was reported in a 7-year-old Filipino girl who was stung on the head by a centipede of the large species Scolopendra subspinipes, which may reach 23 cm in length.
A case of electrocardiographic (ECG) changes suggestive of ischemia has been reported in a 60-year-old man after a sting by a 12-cm centipede in Turkey. [10] While there was a slight associated elevation in serum CK-MB and myoglobin, troponin I, troponin T, and delayed exercise stress testing were all normal, and the ECG returned to normal a few hours later. Another 20-year-old man in Turkey presented to an emergency department with chest pain approximately 24 hours after a reported centipede sting. [11] His ECG revealed inferior ST-segment elevation, and he had a positive rise in his CK-MB and troponin T levels. His echocardiogram was normal, and he did well after conservative therapy (without thrombolysis or angioplasty). Delayed coronary angiography revealed normal coronary arteries. The patient was noted to be "completely symptom free" at 17 months. He was felt to have suffered a myocardial infarction, possibly related to coronary vasospasm, inflammatory changes, or multifactorial effects.
A 22-year-old man without cardiac risk factors suffered an apparent ST elevation myocardial infarction following a purported centipede sting in India. [12] The victim was stung on the finger, had immediate pain and swelling, and, 2 hours later, developed chest pain with nausea, vomiting, and diaphoresis. On presentation to the hospital 14 hours after the injury, his ECG was consistent with anterior ST elevation myocardial infarction. He was treated with nitrates and morphine. His creatine kinase MB level was elevated and his troponin-I was 13.2 µg/L. Echocardiography revealed anterior wall hypokinesis. Cardiac catheterization revealed normal coronary arteries. Three days later, his ECG and echocardiography returned to normal.
A 31-year-old man in Turkey was stung on the foot by a 10-12 cm golden-colored centipede. [13] He presented to an emergency department approximately 1 hour after the sting, complaining of foot pain and swelling. Shortly after arrival, he developed squeezing chest pain radiating to his left arm. While an electrocardiogram was being obtained, he went into cardiac arrest. He was successfully resuscitated within 5 minutes and was treated with aspirin, heparin, and intravenous nitroglycerin. His ECG demonstrated inferior-posterior acute myocardial infarction, and an echocardiogram revealed akinesis in the inferior and posterior segments of his left ventricle, as well as hypokinesis of the lateral wall. As he continued to have chest pain and ST elevations despite conservative treatment, the decision was made to administer 100 mg of tissue plasminogen activator (t-PA). After 90 minutes, the patient’s symptoms resolved and his ECG normalized. His troponin I peaked at 7.23 ng/mL at 12 hours. He was transferred to a facility capable of performing a cardiac catheterization, which revealed normal coronaries. Follow-up echocardiogram demonstrated only slight hypokinesis of the inferior wall of the left ventricle and an ejection fraction of 65%. His only cardiac risk factor was a smoking history. The authors of this report suspect his myocardial infarction and arrest were due to venom-induced coronary vasospasm leading to an acute coronary thrombosis.
A 63-year-old man suffered a Scolopendra subspinipes sting to the right upper extremity, initially experiencing only pain and edema localized to the hand and forearm. He was started on analgesics and prednisone. After medical noncompliance, the patient re-presented with an amoxicillin-sensitive Staphylococcus aureus superinfection. Intravenous amoxicillin/clavulanic acid was started, and 2 separate surgical debridements were necessary. The patient eventually made a good recovery after a prolonged course. [14]
A case of rhabdomyolysis complicated by compartment syndrome and acute renal failure requiring temporary hemodialysis has been reported following the sting of the giant desert centipede, Scolopendra heros. [15] Prolonged, isolated proteinuria without any other evidence of renal dysfunction has also been reported in a young female following Scolopendra sting.
Langley reported 5 centipede-related deaths recorded in the National Center for Health Statistics [16] CDC Wonder database in the United States between 1991 and 2001, though he had no supporting documentation to confirm that these deaths were truly due to centipedes.
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Giant desert centipede. Photo by Michael Cardwell.
