20th century observations of adverse reactions to CM became more
frequent. The first reports mentioning diarrhea, growth retardation
as well as anaphylactic shock after milk consumption were mainly
published in the German literature [6–9]. The Swedish clinician
Wernstedt proposed the term ‘‘idiosyncrasy’’ for this phenomenon
[10].
1.2. Prevalence of cow’s milk allergy
Today CM is among the first foods introduced into an infant’s
diet and accordingly is one of the first and most common causes
of food allergy in early childhood. In fact, the term ‘‘allergic March’’
describes the typical early appearance of food allergy which precedes
the subsequent development of respiratory allergy in children
[11]. The reported prevalence of cow’s milk allergy (CMA)
varies dramatically between studies which may be attributable
to different methods used for diagnosis or differences in the ages
of the studied populations [12]. Furthermore, geographical factors
may influence the rates for prevalence. In general, the frequencies
of self-reported adverse reactions to CM are much higher than the
medically confirmed diagnoses, not only in children but also in
adults [13]. A meta-analysis of relevant original studies since
1990 by Rona et al. [14] showed a variation in self-reported prevalence
of milk allergy between 1.2% and 17%, whereas the prevalence
in studies using a double-blind placebo controlled food
challenge or an open challenge varied between 0% and 3% and in
studies based on skin prick testing (SPT) and IgE assessment frequencies
were between 2% and 9%.