Chronic diarrhoea

Editor – Hiner and Walters' article was a succinct and informative read, however, it was very disappointing to see that not only was HIV omitted as a potential cause of chronic diarrhoea, there was no mention of any sexually transmitted infections (STIs) or importance of sexual history taking.¹

Chlamydia (particularly serovar L1–3), lymphogranuloma venereum (LGV), gonorrhoea, syphilis, herpes and shigella all commonly present with anorectal manifestations, including chronic diarrhoea, particularly in men who have sex with men (MSM). In 2019, Public Health England recorded 77% of all sexually transmitted shigella as being in the MSM population, as well as 37% of all LGV diagnoses that year recorded as rectal infections in MSM.² However, if a sexual history isn't taken, then sexual orientation is unknown and risk stratification inaccurate.

In the UK, it's estimated that almost one in 10 of HIV positive individuals do not know their HIV status and, of those diagnosed, approximately 50% are diagnosed late (defined as a CD4 count <350 cells/mm³).^3,4 It almost goes without saying that late diagnosis of HIV is associated with increased morbidity and hospital admissions, and decreased life expectancy.⁵ In one cohort, 62% of patients who were diagnosed late with HIV had presented to secondary care prior to their diagnosis, with 26% having symptoms which were probably related to HIV but they were not tested for HIV.⁶

The Royal College of Physicians Concise guidance to good practice series outlines clinical indicator diseases for HIV infection, of which, chronic diarrhoea is highlighted.⁷ Chronic diarrhoea is also listed as one of the symptoms most associated with HIV infection, alongside weight loss and pyrexia of unknown origin.⁷

Many patients undergo endoscopic procedures as part of their work-up, however, a simple chlamydia/gonorrhoea swab typically costs less than £10, as does an HIV test. A full sexual history and STI testing could therefore be a relatively cheap way to negate the need for expensive and invasive investigations.

We have made huge progress with regards to awareness of HIV, but we must normalise testing in both primary and secondary care to decrease late and unknown HIV diagnoses.