acute urticaria is caused by various factors including foods , chemical agents , infections , and insect bites .
when a clinician is trying to determine the cause of a patient 's urticaria , it is important to ask about the patient 's food intake , possible chemical agent exposure , and symptoms that may indicate an infection . here , we report the cases of five patients with acute urticaria .
although four of the patients did not describe experiencing a bee sting at their presentation , the subsequent examination detected anti - bee - specific ige antibodies .
the ages of the five japanese patients ranged from 33 to 86 years ( median : 61 ) .
the onset of urticaria was 614 days ( median : 10 ) after a bee sting .
all five patients presented at our hospital in the 3-month period from july to september .
only one patient had a local skin reaction at the sting site , 2 days before the onset of urticaria .
the type of bee involved was paper wasp in three cases and yellow jacket in two cases .
venom - specific iges for paper wasp , yellow jacket and honeybee were examined in four cases .
the three patients stung by a paper wasp were positive for paper wasp and yellow jacket but not for honeybee .
the urticaria was well controlled by a type 2 antihistamine antagonist in three patients ; the other two patients required oral prednisone .
although most anaphylactic reactions caused by insect stings occur shortly after the sting , they occasionally have a delayed onset . in the study by the american academy of allergy and immunology committee , there were only three patients in whom the reaction started more than 48 h after the sting in the recorded 2,219 patients with allergic reaction by insect sting .
so , it may be difficult to suspect bee sting as cause of allergic reaction if it shows a delayed onset .
four of our five patients took no notice of a relationship between their acute urticaria and their bee sting history .
importantly , an examination detected ige antibodies for bees in all four examined cases with a cross - reactivity between paper wasp and yellow jacket in three of them .
a history of a bee sting should thus be part of the medical interview sheet for patients with acute urticaria , especially in the summer to early autumn .
if a patient has incurred a bee sting within 2 weeks prior to his or her presentation , an examination of ige for bees may help prevent a severe bee - related anaphylactic reaction in the future .
moreover , individuals who are stung by a bee should be advised that their antibodies for bees should be examined if a general or local eruption with pruritus occurs within approximately 2 weeks after the sting .
a question is raised regarding the mechanism of late onset of acute urticaria in our cases .
reisman and livingston   reported 10 patients with allergic reactions 12 weeks after bee stings .
four of them had serum sickness - type reactions with joint swelling , arthralgia and urticaria , three had only generalized urticaria , two had severe symptoms of anaphylaxis with urticaria and the remaining one had a large local swelling .
all patients had venom - specific ige and four had serum venom - specific igg which relates to serum sickness reaction .
however , sickness - type reactions were observed only in one of four patients with venom - specific igg .
reisman and livingston   suggested that the late reaction ranges from typical anaphylaxis to serum sickness , probably related to simulation of ige antibodies and subsequent reaction with persisting venom antigen . although the mechanism of late onset of acute urticaria without rapid reaction is unclear , our cases might show delayed urticaria caused by a reaction of the bee antigen - specific ige antibody to the antigens remaining in the body , after the first sensitization .
it suggests that bee antigens can remain for 12 weeks in the body after a bee sting , because the bee antigen - specific ige antibody can not react without bee antigens .
 here we report the cases of five patients with a late onset of acute urticaria after a bee sting . 
 the ages of the five japanese patients ranged from 33 to 86 years ( median : 61 ) . 
 all patients had no history of an allergic reaction to bee stings . 
 the onset of urticaria was 614 days ( median : 10 ) after a bee sting . 
 although four of the patients did not describe experiencing a bee sting at their presentation , the subsequent examination detected anti - bee - specific ige antibodies . 
 so , we think a history of a bee sting should thus be part of the medical interview sheet for patients with acute urticaria , and an examination of ige for bees may help prevent a severe bee - related anaphylactic reaction in the future . 
Introduction
Case Presentation
Discussion
Statement of Ethics
Disclosure Statement