Sex-associated diarrhoea

Overview

Most infectious causes of diarrhoea can be transmitted sexually
Transmission is most likely to occur during oroanal sex, but diarrhoea-causing organisms that use fomite transmission will likely also transmit during other types of sex

Hence for people with casual sexual partners, it may be important to consider broader differential diagnoses for infectious diarrhoea, in addition to the viral causes of diarrhoea that commonly circulate in the general community. This consideration applies particularly to men who have sex with men and their sexual partners, where outbreaks have occurred.

Symptoms	Considerations
Enteritis – presents with watery diarrhoea and central abdominal cramping	Sex-associated causes include giardiasis, rotavirus, Cryptosporidium spp., and Escherichia coli
Proctocolitis - presents with dysentery (bloody diarrhoea), anal mucus and lower-abdominal pain	Sex-associated causes include Shigella spp., Campylobacter spp., Cryptosporidium spp., cytomegalovirus (CMV) - especially in people living with human immunodeficiency virus (HIV) - and Entamoeba histolytica
Distal proctitis - presents with constipation, pain on defecation and anal mucus	Sex-associated causes include Chlamydia trachomatis (especially serovar L, which causes Lymphogranuloma venereum [LGV]), Neisseria gonorrhoeae, Treponema pallidum (syphilis), and herpes simplex virus (HSV). Mycoplasma genitalium might also be associated

Consider stool microscopy, culture and sensitivity (MC&S), ova, cysts, parasites (O/C/P) and polymerase chain reaction (PCR) before administering antibiotics in cases of mild-to-moderate diarrhoea without features of sepsis

For cases of distal proctitis, additionally investigate with anal swab for PCR testing for C. trachomatis, N. gonorrhoeae, Mycoplasma genitalium, HSV and T. pallidum

Proctitis with confirmed chlamydia should be tested for LGV

Management of many of these diarrhoea-causing pathogens should be guided by local antibiotic guidelines and local public health units. It is worth highlighting that Shigella spp. infections among men who have sex with men are commonly resistant to multiple classes of antibiotics, and often have a different antibiotic resistance profile from those seen in the general community

Hence, when treating cases of shigellosis in men who have sex with men, it is important to seek advice from your local public health unit or sexual health specialists on whether to initiate empiric treatment or to delay treatment until antibiotic sensitivity results are available. This advice may depend on the severity of the patient’s symptoms, and the likelihood of onward sexual transmission

Contact tracing and exclusion periods from sexual activity and work (e.g. for food handlers, childcare workers, and healthcare workers) should be determined in consultation with state health departments or public health units, or guided by disease-specific advice in these or other guidelines