Helicobacter pylori: Not just a Gastric Infection

Helicobacter (H) pylori is a gram negative spiral flagellated bacteria and is the most prevalent infection around the globe. Higher prevalence rates are linked to low socio-economic standards and hence it is more prevalent in the developing countries. Although this gram negative spiral bacteria inhabits the gastro-duodenal mucosa it is linked to gastric and many extra-gastric disease states. The diversity of presentations (Figure 1) among H pylori infected subjects are due to a complex interplay between bacterial, environmental, and host genetic factors [1]. The spectrum of gastro-duodenal affection mostly passes through asymptomatic infection. Furthermore, with time the infection evolve to acute and chronic gastritis, peptic ulcer, and minority of patients are prone to the most serious sequel, the gastric cancer (Figure 1).  H pylori is classified as class I carcinogen by the WHO [2] and hence identification and eradication of the infection is recommended for subgroups of patients as per the current practice guidelines [3,4].

The list of extra-gastric associations is long and diverse. In fact, H pylori have been linked to many metabolic, cardiac, neurological, allergic, ocular, haematological, dermatological, and hepatobiliary diseases and the list is extending [5].It seems that these associations have been over estimated because the evidence linking H pylori infection to these diseases depends on epidemiological studies. Consequently, the current practice guidelines recommend testing for and eradication of H pylori among subgroup of patients including patients with obscure iron deficiency anemia, primary immune thrombocytopenia (ITP), and  vitamin B12 deficiency [3,4]. Sticking to these recommendations would limit the over testing for H pylori in many diseases that lacks an etiological association with H pylori infection [6].

There is a trend among dermatologists in our community to test patients with persistent itching for HCV and H pylori after exclusion of the local and the common systemic causes owing to the high prevalence of both infections in our community. Although the mechanism of skin involvement among patients with HCV infection seems related to both direct immune mediated mechanisms and to indirect mechanisms through the development of cirrhosis [7,8], the mechanism of skin affection among patients with H pylori infection is not understood. However, the autoimmune mechanism is the most likely. It seems that following the prolonged infection with H pylori an interaction with the host immune system do occur. H pylori trigger antigens that cross-react with T cells and provoke autoantibodies with the final result loss of tolerance to self-antigens in the skin [9].

Salama et al., in the current issue of Afro-Egypt J Infect Endem Dis published an interesting article focusing the prevalence of H pylori among patients with persistent itching. The authors reported a prevalence of H pylori among 130 out of 280 patients (46.4%) of persistent itching after exclusion of the common