Dermatitis herpetiformis is a rare disease, with a prevalence between 10 and 75 cases per 100,000 population and an incidence ranging from less than 1.0 to 3.5 cases per 100,000 inhabitants.[5]Salmi TT, Hervonen K, Kautiainen H, et al. Prevalence and incidence of dermatitis herpetiformis: a 40-year prospective study from Finland. Br J Dermatol. 2011 Aug;165(2):354-9.
http://www.ncbi.nlm.nih.gov/pubmed/21517799?tool=bestpractice.com
There is no clear sex predominance, although some studies report a slight male predominance.[5]Salmi TT, Hervonen K, Kautiainen H, et al. Prevalence and incidence of dermatitis herpetiformis: a 40-year prospective study from Finland. Br J Dermatol. 2011 Aug;165(2):354-9.
http://www.ncbi.nlm.nih.gov/pubmed/21517799?tool=bestpractice.com
[6]West J, Fleming KM, Tata LJ, et al. Incidence and prevalence of celiac disease and dermatitis herpetiformis in the UK over two decades: population-based study. Am J Gastroenterol. 2014 May;109(5):757-68.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4012300
http://www.ncbi.nlm.nih.gov/pubmed/24667576?tool=bestpractice.com
[7]Antiga E, Bonciolini V, Cazzaniga S, et al. Female patients with dermatitis herpetiformis show a reduced diagnostic delay and have higher sensitivity rates at autoantibody testing for celiac disease. Biomed Res Int. 2019 Dec 29:2019:6307035.
https://www.hindawi.com/journals/bmri/2019/6307035
http://www.ncbi.nlm.nih.gov/pubmed/32090062?tool=bestpractice.com
Dermatitis herpetiformis usually occurs during adulthood, with a higher incidence in the fourth and fifth decade.[5]Salmi TT, Hervonen K, Kautiainen H, et al. Prevalence and incidence of dermatitis herpetiformis: a 40-year prospective study from Finland. Br J Dermatol. 2011 Aug;165(2):354-9.
http://www.ncbi.nlm.nih.gov/pubmed/21517799?tool=bestpractice.com
However, several paediatric cases have been reported.[4]Antiga E, Verdelli A, Calabrò A, et al. Clinical and immunopathological features of 159 patients with dermatitis herpetiformis: an Italian experience. G Ital Dermatol Venereol. 2013 Apr;148(2):163-9.
http://www.ncbi.nlm.nih.gov/pubmed/23588141?tool=bestpractice.com
White people are more affected than other ethnicities, with northern Europe (particularly Finland) and North America being the areas with highest incidence and prevalence.[5]Salmi TT, Hervonen K, Kautiainen H, et al. Prevalence and incidence of dermatitis herpetiformis: a 40-year prospective study from Finland. Br J Dermatol. 2011 Aug;165(2):354-9.
http://www.ncbi.nlm.nih.gov/pubmed/21517799?tool=bestpractice.com
[8]Bolotin D, Petronic-Rosic V. Dermatitis herpetiformis. Part I. Epidemiology, pathogenesis, and clinical presentation. J Am Acad Dermatol. 2011 Jun;64(6):1017-24; quiz 1025-6.
http://www.ncbi.nlm.nih.gov/pubmed/21571167?tool=bestpractice.com
By contrast, dermatitis herpetiformis is extremely rare in Africans, African-Americans, and Asians. Japanese people may present with a variant, the so-called fibrillar-type dermatitis herpetiformis, that shows distinct features and seems not to be associated with coeliac disease.[9]Ohata C, Ishii N, Niizeki H, et al. Unique characteristics in Japanese dermatitis herpetiformis. Br J Dermatol. 2016 Jan;174(1):180-3.
http://www.ncbi.nlm.nih.gov/pubmed/26119216?tool=bestpractice.com
Contemporary data suggest that the incidence and prevalence of dermatitis herpetiformis are reducing; by contrast, for coeliac disease, they are increasing.[5]Salmi TT, Hervonen K, Kautiainen H, et al. Prevalence and incidence of dermatitis herpetiformis: a 40-year prospective study from Finland. Br J Dermatol. 2011 Aug;165(2):354-9.
http://www.ncbi.nlm.nih.gov/pubmed/21517799?tool=bestpractice.com
[6]West J, Fleming KM, Tata LJ, et al. Incidence and prevalence of celiac disease and dermatitis herpetiformis in the UK over two decades: population-based study. Am J Gastroenterol. 2014 May;109(5):757-68.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4012300
http://www.ncbi.nlm.nih.gov/pubmed/24667576?tool=bestpractice.com
The reason for the reduction in incidence and prevalence of dermatitis herpetiformis has not been confirmed, but may be related to earlier diagnosis and an early introduction of gluten-free diet, which may prevent dermatitis herpetiformis from developing in some patients with coeliac disease.