Abstract
Abstract
Herein, we present a case of anaphylaxis in multiple family members after ingesting silkworms, an Asian delicacy. While food allergies, including anaphylaxis are unfortunately common, there are no previous reports of multiple family members suffering an anaphylactic reaction after eating silkworms. In addition, both family members required multiple doses of epinephrine and eventually an epinephrine infusion to improve their blood pressures. All interventions, including the epinephrine infusions, were started by emergency medical services (EMS) with on-line medical direction. Both the reaction and the required treatment are not extensively documented in the medical literature.
Key words: :
Introduction
While EMS providers and emergency physicians frequently encounter patient suffering from symptoms of an acute food allergy, the occurrence of two family members simultaneously experiencing an acute allergic reaction to ingested food product is exceedingly rare. Herein, we report on the case of a father and son who experienced simultaneous anaphylactic reactions from the first time consumption of silkworm pupae Bombyx mori, a species of domesticated silkworm that was first selectively bred in China from Bombyx mandarina over 5000 years ago and has found many uses around the world today.1,4 Most involve the use of the silk thread that makes up the cocoon of its larva to create clothing, suture, or even protective armor or scaffolds for human tissue growth.2 In addition, the silkworm itself is high in protein and is often eaten. The consumption of silkworm pupae is considered a delicacy in several Asian cultures, including China and Korea. They may be consumed raw, boiled, or oil-fried.3
However, on rare occasions, the consumption of silkworms can cause allergic reactions, including severe anaphylactic reactions. It is estimated that at least 1,000 people in China develop reactions after eating them every year, resulting in approximately 50 yearly that are significant enough to require urgent treatment in an emergency department. These reactions can occur without any prior known sensitization to silkworms or silkworm products.3
Case Report
On a summer afternoon in a mid-sized New England city, paramedics were called to a home for a report of a person suffering from food poisoning. Upon their arrival, the paramedics found two individuals, a 44-year-old Nepalese man with a history of hypertension and being treated for latent TB infection, and his 18 year old previously healthy son, both complaining of feeling unwell about one hour after eating silkworms for the first time.
The older patient initially appeared more ill, with generalized urticaria, flushed and dry skin, a heart rate of 142 with no radial pulses. Paramedics were unable to obtain a manual blood pressure. He was found lying on a couch in moderate distress, and was unable to even sit without experiencing symptoms of near syncope. He had clear breath sounds, normal mental status, and an oxygen saturation of 97% prior to transport. He had no airway or facial swelling. However, because of his poor circulatory status, he was given a fluid bolus of 250 mL of normal saline and a dose of 0.3 mg epinephrine via auto injector, along with 50 mg of IV diphenhydramine. Ten minutes later, the patient's blood pressure was 60/42 mmHg with no clinical improvement. A second 0.3 mg dose of epinephrine was administered intramuscularly via autoinjector, also with no improvement. After consultation with an online medical control physician, paramedics mixed an epinephrine infusion of 1 mg of epinephrine in 500 mL of normal saline and titrated it to effect. The patient began to show rapid improvement with intravenous epinephrine and was transported to the hospital with his son. His blood pressure just before arrival was 90/50 mmHg, and improved to 129/73 mmHg once in the emergency department.
The younger patient appeared less ill. On initial exam, he was found to have skin flushing and facial edema, but no urticaria. He denied shortness of breath or dysphagia, and had clear breath sounds with an oxygen saturation of 98%. His heart rate was 124 with a blood pressure of 104/68. While one paramedic attended to the older patient, the second paramedic and firefighter first responders brought the son to the ambulance. Shortly after removal from the house, he became acutely lightheaded, with urticaria and was found to have a blood pressure of 64/40. A 250-cc bolus of normal saline, diphenhydramine 50 mg IV and 0.3 mg of epinephrine via auto injector were administered. With minimal or no response noted, a second subcutaneous injection of 0.3 mg of epinephrine was given four minutes later. The son also showed no improvement with these two doses of epinephrine and required epinephrine infusion (using the same dosing as for his father) ten minutes after the first epinephrine was given. After initiation of the epinephrine infusion, the patient did show improvement with a blood pressure on arrival to the hospital of 100/56 and improved symptoms.
Both patients arrived simultaneously to a large tertiary care emergency department and were cared for by different teams. Both received steroids: the older patient, 50 mg of prednisone orally and the younger patient, 125 mg of methylprednisolone intravenously. The older patient had recurrent symptoms of tongue swelling and mild hypoxia about three hours after arrival, though he improved without intervention. He was observed overnight and discharged the following morning. He did not require any further medication while in the hospital. The younger patient was admitted to the pediatric intensive care unit for observation only and discharged the following day.
Discussion
There are relatively few examples of silkworm anaphylaxis described in literature able to be searched using PubMed, almost all of which are case reports from China. We could not find any other examples of multiple cases of anaphylaxis from eating silkworms occurring simultaneously, nor could we find any other examples of silkworm anaphylaxis not responding to multiple doses of intramuscular epinephrine and requiring escalation to an epinephrine drip. A 2008 case report was reviewed that detailed 14 different cases of silkworm anaphylaxis, 13 of which were from its own literature review of Chinese reports. Like this case, none of the cases reviewed showed any history of previous allergy and none had eaten silkworm in the past.3 Admittedly, our review of the literature is hindered by our inability to search for or review the original Chinese articles cited.
Immunoblot analysis has pointed to a 30-kDa protein as the major allergen in silkworm pupae.5 The familial relationship of the two patients may suggest genetic susceptibility to allergic reaction to this protein. Inherited allergy is not a new concept; in the case of peanuts, it has been shown that the risk that a child will have a peanut allergy is seven times higher if they have a parent or a sibling that has a peanut allergy, and two-thirds of the time a monozygotic twin will have a peanut allergy if their counterpart is allergic.6
While there were no specific prehospital recommendations for the use of epinephrine infusions for anaphylaxis, the World Allergy Organization has published consensus guidelines on the management of allergic reactions and anaphylaxis. Treatment includes early use of intramuscular epinephrine, with relatively few contraindications. If a patient does not respond to the initial dose of epinephrine, or if symptoms recur, additional doses are recommended. If a patient remains hypotensive, despite multiple doses of epinephrine, then providers should start an epinephrine infusion and titrate it to maintain an adequate blood pressure.7 The online medical control recommendations for the epinephrine infusion composition were based on emergency department pharmacy recommendations commonly used in the hospital.
As immigration and mixing of different cultures continues, the likelihood of an allergic reaction caused by silkworm ingestion presenting to an American emergency department will undoubtedly increase in the future. This case illustrates the need to be aware of this cultural practice, especially as the possibility of multiple simultaneous patients suffering from resulting anaphylaxis has been demonstrated. Continued monitoring for and reporting of similar cases would be prudent.
While the two patients in this case received epinephrine via the subcutaneous route, AHA guidelines recommend the intramuscular route due to variable and often poor absorption, especially for patients in anaphylactic shock who likely have impaired cutaneous circulation. This represents a change in practice for most experienced paramedics who were taught to administer epinephrine subcutaneously. EMS medical directors should stress the need for intramuscular administration of epinephrine an acute allergic reaction or anaphylaxis.8
Conclusion
While anaphylactic reactions are familiar to EMS responders, the presence of more than one patient on the single call is very unusual. Family members of the patient who initially presents with symptoms may be disinclined to bring up their own symptoms, whose onset may begin later, to the attention of responders out of concern that they might distract responders from the care of the initial patient. EMS responders should remain vigilant for the potential of more than one patient in the event that several previously unexposed family members with an unknown inherited allergy are simultaneously exposed to inciting agent. In addition, EMS providers should be cognizant of the need for repeat dosing of epinephrine, as well as the proper dose and route of administration, as well as the occasional need for epinephrine infusions in patients with refractory anaphylaxis.
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