Abstract
Sir: We read with interest the article by Sarah Day 1 describing a young heterosexual woman presenting to an evening genitourinary (GU) medicine clinic with a ‘classic’ manifestation of nocturnal pruritis ani consistent with enterobiasis. Although enterobiasis is usually asymptomatic in adults 2 and not necessary transmitted sexually, oral–anal sexual contact may enhance the exposure rate to the partner's anal area and/or faecal material during sexual activity and consequently strengthen the possibility of sexual transmission of this parasitic infection in adults.
The sexual activity of oral–anal contact is particularly practised among men who have sex with men (MSM), and may also be practised by exclusive heterosexuals, bisexuals and lesbians. Oral–anal contact facilitates faecal-oral contamination and subsequent transmission of enteric pathogens including bacteria, viruses and parasites such as Entamoeba histolytica, Giardia intestinalis and Cryptosporidium spp. Other activities such as digital-oral contact after manual anal stimulation or digital-anal contact may also increase the probability of transmission.
The sexual transmission of intestinal parasites including enterobiasis has been well described particularly among MSM from the early 1970s. Abraham 3 published the first report on the finding of giardiasis and enterobiasis co-infection in a young homosexual man in 1972. Later Waugh 4,5 and McMillan 6 have separately described several cases of enterobiasis infestation among MSM in the UK. Reports of enterobiasis in MSM have suggested the possibility of sexual transmission of this parasite at least among those individuals who were engaged in oral–anal sex. However, many infected individuals remain asymptomatic and the true prevalence rate among MSM is unknown.
Tendency of patients to have concurrent infections with two or more parasites, 7 and the presence of asymptomatic carrier states in many infections, in combination with the variable and/or prolonged incubation period of intestinal protozoan parasites, highlights the importance of testing faecal specimens for ova, cysts and parasites in cases where sexual transmission of intestinal parasites is either clinically indicated or suspected.
Further studies should be undertaken to estimate the prevalence and incidence of sexually transmitted enterobiasis in adults who practice oral–anal sex regardless of their sexual orientation, mostly individuals attending to GU medicine clinics. This in turn, may elucidate the probable occurrence of concurrent infection(s) with other intestinal parasites particularly protozoa with the same transmission route as enterobiasis in this target population.