Another rare sexually transmitted infection oubreak in London gay men

The Health Protection Agency (HPA) has identified an outbreak of another sexually transmitted infection amongst gay men in London. This time, 14 cases of shigellosis, caused by the bacterium Shigella sonnei, have been reported. Shigellosis is highly infectious, can cause severe, prolonged and sometimes bloody diarrhoea, and can be more serious in HIV-positive people.

This is the third report of a new outbreak of an unusual sexually transmitted infection in gay men in as many weeks. Previously the HPA identified outbreaks of hepatitis A in London and lymphogranuloma venereum (LGV), an unusual form of chlamydia, throughout Europe.

The current outbreak

The HPA is currently investigating 14 cases of S. sonnei in gay men who have become ill since the beginning of August. The majority of cases have been reported by genitourinary (GUM) clinics in North London, but the men reside throughout Greater London. The HPA suggests it is likely that there could be many more men affected. Dr Paul Crook, the HPA’s Consultant in Communicable Disease Control said, “we are working closely with NHS colleagues to highlight action that can be taken to prevent this disease.”

Learning from previous outbreaks

Outbreaks of S. sonnei amongst gay men have been reported in the United States, Canada, the Netherlands, Germany and Australia.

• Reports published after outbreaks in San Francisco in 1996 and Amsterdam between 1997 and 2001 found that HIV-positive gay men were more likely to have contracted the infection.
• A report after a 2000 outbreak in Sydney found that visiting a sex venue in the two weeks before onset of illness was the only factor significantly associated with shigellosis.
• A report on the 2001 outbreak in Berlin found that almost all of the men affected reported direct or indirect oral-anal sexual contacts in the week before they fell ill.

Symptoms of Shigellosis

S. sonnei causes prolonged, sometimes bloody diarrhoea, or dysentery. Other symptoms include stomach cramps, fever, nausea and sometimes vomiting. The infection can be much more serious in those with reduced immunity to infection, including HIV-positive people. During the 2000 outbreak in Sydney, an HIV-positive man was diagnosed with reactive arthritis due to his infection with S. sonnei. In reactive arthritis, symptoms of joint inflammation can last from three to twelve months, or may develop into a long-term disease in a small percentage of people.

Avoiding S. sonnei

Shigellosis occurs usually one to three days after the ingestion of a very few (10 - 100) S. sonnei organisms, much fewer than salmonella, which is a similar food and faeces (shit)-borne bacterial infection.

Sexual infection can take place when a very small amount of faeces is ingested during oral or anal sex. This includes:

• Rimming (oral-anal contact).
• Fingering or fisting.
• Taking a condom off after anal sex.
• Touching sex toys that have been used in the anus.
• Sucking or licking the penis or scrotum (cock or balls), if there is a chance that the skin in the groin area is contaminated.
• Coming into contact with infected faeces in a backroom or toilet.

Tim Green, Camden Primary Care Trust’s Manager of HIV & Sexual Health Promotion adds, “gay men should be aware that they can get this infection from sexual contact and should remember to wash their hands, especially after sex, using the toilet and before eating or preparing food. If they have symptoms they should avoid sex and see their regular doctor.”