Thank you for your inquiry.
I am afraid I am not going to be able to give you a definitive analysis of this child's problem because, as you know, the history is somewhat unusual. Nonetheless, first it might help to take a look at the prosciutto that he ate. Prosciutto is a dry-cured ham that is usually served uncooked (prosciutto crudo), but can be cooked on occasion (prosciutto cotto). It can be prepared from the hind leg or thigh of a pig or a wild boar. This fact distinguishes it from other cuts of pork.
In most instances, prosciutto is prepared without seasoning other than salt. In some instances, however, it is cured with other seasonings as well, and it would perhaps be important to know whether the prosciutto ingested by your patient was cured with salt only or in the presence of other spices; and if so, what these spices were.
But, assuming that this was the typical "salt only" cured prosciutto, and keeping in mind that the child eats ham and is negative on testing for pork, we would have to assume that there is an ingredient in prosciutto that is not in the other pork he eats or either in sufficient amounts in prosciutto to induce a reaction, whereas it is not in other cuts of pork. The reason I mentioned the unique cuts for prosciutto is that in actuality, anaphylactic reactions to pork itself are reasonably rare and most cases that have been recently reported are actually not to the pork itself but to galactose-alpha-1,3-galactose (alpha-gal) (see abstracts copied below).
I know that this is doubtful in your case, but one of the characteristics of anaphylaxis to alpha-gal is that it does not necessarily occur consistently each time the patient eats the meat in question. The reasons for this are unknown, but may well be due to different levels of alpha-gal in different meats. So, one thing I would clearly do at this time is obtain an ELISA for IgE anti-alpha-gal.
In addition, if the responsible prosciutto was unusual in that it was cured with spices, it would be important to investigate each spice as a potential culprit.
Finally, I would probably wait until the alpha-gal returned before I would permit the child to eat red meat.
Thank you again for your inquiry and we would greatly appreciate a follow-up on your patient.
Pediatrics. 2013 May;131(5):e1545-52. doi: 10.1542/peds.2012-2585. Epub 2013 Apr 8.
Galactose-á-1,3-galactose and delayed anaphylaxis, angioedema, and urticaria in children.
Kennedy JL, Stallings AP, Platts-Mills TA, Oliveira WM, Workman L, James HR, Tripathi A, Lane CJ, Matos L, Heymann PW, Commins SP.
Division of Allergy and Immunology, Department of Internal Medicine, University of Virginia Health System, Charlottesville, VA 22908, USA.
Background and Objective: Despite a thorough history and comprehensive testing, many children who present with recurrent symptoms consistent with allergic reactions elude diagnosis. Recent research has identified a novel cause for "idiopathic" allergic reactions; immunoglobulin E (IgE) antibody specific for the carbohydrate galactose-á-1,3-galactose (á-Gal) has been associated with delayed urticaria and anaphylaxis that occurs 3 to 6 hours after eating beef, pork, or lamb. We sought to determine whether IgE antibody to á-Gal was present in sera of pediatric patients who reported idiopathic anaphylaxis or urticaria.
Methods: Patients aged 4 to 17 were enrolled in an institutional review board-approved protocol at the University of Virginia and private practice allergy offices in Lynchburg, VA. Sera was obtained and analyzed by ImmunoCAP for total IgE and specific IgE to á-Gal, beef, pork, cat epithelium and dander, Fel d 1, dog dander, and milk.
Results: Forty-five pediatric patients were identified who had both clinical histories supporting delayed anaphylaxis or urticaria to mammalian meat and IgE antibody specific for á-Gal. In addition, most of these cases had a history of tick bites within the past year, which itched and persisted.
Conclusions: A novel form of anaphylaxis and urticaria that occurs 3 to 6 hours after eating mammalian meat is not uncommon among children in our area. Identification of these cases may not be straightforward and diagnosis is best confirmed by specific testing, which should certainly be considered for children living in the area where the Lone Star tick is common.
Allergy. 2012 May;67(5):699-704. doi: 10.1111/j.1398-9995.2012.02799.x.
Anaphylaxis to pork kidney is related to IgE antibodies specific for galactose-alpha-1,3-galactose.
Morisset M, Richard C, Astier C, Jacquenet S, Croizier A, Beaudouin E, Cordebar V, Morel-Codreanu F, Petit N, Moneret-Vautrin DA, Kanny G.
Internal Medicine, Clinical Immunology and Allergy, University Hospital, Nancy, France.
Background: Carbohydrate-specific IgE antibodies present on nonprimate mammalian proteins were incriminated recently in delayed meat anaphylaxis. The aim of this study was to explore whether anaphylaxis to mammalian kidney is also associated with galactose-á-1,3-galactose (áGal)-specific IgE.
Methods: Fourteen patients with anaphylaxis to pork or beef kidney underwent prick tests to meat and kidney. Some patients also underwent skin tests to Erbitux(R) (cetuximab). IgE antibodies to áGal, swine urine proteins, beef and pork meat, serum albumin proteins, cat, and rFel d 1 were measured by ImmunoCAP(R). The áGal levels were estimated in meats and kidney by ELISA inhibition assay. Cross-reactivity between áGal and pork kidney was studied with the ImmunoCAP(R) inhibition assay.
Results: Among the 14 patients, 12 presented with anaphylactic shock. Reactions occurred within 2 h from exposure in 67% of patients. Associated risk factors were observed in 10 cases, and alcohol was the main cofactor. Three patients underwent an oral challenge to pork kidney, and anaphylaxis occurred after ingestion of small quantities (1-2 g). Prick tests to kidney were positive in 54% of patients. All tested patients showed positive skin tests to Erbitux(R). All patients tested positive for IgE to áGal, with levels ranging from 0.4 to 294 kU/l. IgE binding to áGal was inhibited by raw pork kidney extract (mean, 77%; range, 55-87%), which showed a high amount of áGal determinants.
Conclusions: Pork or beef kidney anaphylaxis is related to áGal IgE. Its peculiar severity could be due to an elevated content of áGal epitopes in kidney.
Allerg Immunol (Paris). 2001 Apr;33(4):163-5.
[Fatal anaphylaxis after eating wild boar meat in a patient with pork-cat syndrome].
[Article in French]
Drouet M, Sabbah A, Le Sellin J, Bonneau JC, Gay G, Dubois-Gosnet C.
Laboratoire d'Immuno-Allergologie-CHU-49033 Angers, France.
Crossed allergy between pork and cat epithelia was described by us in 1994. It is due to serum albumin. Nowadays, other bio-chemical observations allow "completion" of the syndrome by extension of the crossed reactivity between other mammal meats and other epithelia of dog and horse. The authors report an observation of the pork-cat syndrome (developing in the form of anaphylaxis, and then ending in the death of the patient), following consumption of wild boar meat. Co-factors, such as effort, taking alcohol or hormonal condition may complicate the picture to make diagnosis more difficult.
Phil Lieberman, M.D.