Introduction The current outbreak of Hepatitis A and the recent Shigella outbreak in men who have sex with men (MSM) highlight the importance of faeco-orally transmitted organisms in this population. This may suggest that outbreaks could be predicted or prevented.

Methods We compared the age, sex and travel history of notifications of Hepatitis A with notifications of Shigella in South London between January 2010 and November 2016. We also reviewed documentation of previous outbreaks of Hepatitis A in MSM in London.

Results Male and female cases of Hepatitis A had similar age profiles and a similar proportion reported recent travel. In contrast, Shigella cases peaked in males aged 30–39 with no travel history. Case notes for Hepatitis A notifications since January 2013 suggested fewer than five in MSM. Although this review suggested very few cases in recent years, outbreaks of Hepatitis A among MSM in London were documented in the late 1990s and in 2003. The second outbreak was associated with strains that caused concurrent outbreaks in MSM across Europe. Public health response to these outbreaks recommended health promotion and opportunistic immunisation.

Discussion Hepatitis A outbreaks occur sporadically in a transnational population of MSM. Few cases may occur between outbreaks and preventative actions may be deprioritised. However, group immunity is likely to be highest after an outbreak and then wane in the absence of immunisation, increasing the risk of another outbreak. Health promotion and immunisation may be valuable outside of outbreak contexts.