Sexually transmitted hepatitis A outbreak reported in London

An outbreak of hepatitis A in gay men in southeast London has been identified by the Health Protection Agency (HPA). So far, nine cases have been reported, all with symptom onset dates between mid-August and mid-September 2004.

Five of the affected men reported visiting a gay pub in Southwark, southeast London, in the two months before they became unwell. One of the nine patients is a secondary case, who has a history of household contact with one of the five patients who had visited the pub. The pub is, in effect, a public sex environment that includes a ‘dark room’ where sexual activities that carry a high risk of hepatitis A transmission occur. Of the eight patients whose vaccination status is known, none had previously been vaccinated against hepatitis A.

The local health protection unit is working with a number of agencies (including local health authorities and social and health groups that work with gay men) to advise gay men locally of the risk, and how this might be minimised, including advice on immunisation. Increasing community outreach work at this and similar venues, and actions to improve hygiene at the pub are being considered.

Transmission risks

Although some studies have associated having a greater number of sex partners, frequent oral-anal contact, insertive anal intercourse, or serologic evidence of other sexually transmitted infections with hepatitis A infection, other studies have not found specific risk factors for infection.

However, many sexual practices facilitate faecal-oral transmission of hepatitis A, and inapparent faecal contamination is commonly present during sexual intercourse. Measures typically used to prevent the transmission of other sexually transmitted infections (e.g., use of condoms) do not prevent hepatitis A transmission, and maintenance of "good personal hygiene" has not been successful in interrupting outbreaks of hepatitis A.

Prevention

Vaccination is the most effective means of preventing hepatitis A transmission among people at risk for sexual transmission of this virus and among those who use injection and non-injection recreational drugs.

In HIV-negative people, the vaccine is almost always successful after a standard course. However, the response in people who are HIV-positive with low CD4 cell counts is poor. In one study, 77% of HIV-infected persons had protective antibody levels after completing the vaccine series. Among HIV-infected men, those who responded to hepatitis A vaccination had significantly more CD4 T-cells at baseline (540 cells/mm³) compared with those who did not respond (280 cells/mm³).

HIV/hepatitis A co-infection

A recent study found that co-infection of HIV and hepatitis A leads to higher and longer lasting levels of hepatitis A viraemia. Although the duration of symptoms was unaffected by HIV status, HIV-infected patients exhibited hepatits A viraemia for a median of 53 days, compared with 22 days among the previously healthy individuals. The hepatitis A viral load was significantly higher among those with HIV, regardless of HIV viral load or CD4 cell count.

Past oubreaks

Outbreaks of hepatitis A in men who have sex with men (MSM) were reported from Denmark and the Netherlands in May 2004, and in France in 2000. Following a series of outbreaks of hepatitis A amongst MSM in the United Kingdom, including a large outbreak in London in 1997, national recommendations for hepatitis A vaccination were extended to include MSM whose sexual behaviour is likely to put them at risk.

The provision of hepatitis A vaccination for MSM at genitourinary medicine (GUM) clinics and outreach services appears to have been successful in controlling the 1997 outbreak. The outbreak reported here may indicate the need to increase hepatitis A vaccination offered to MSM through these services in order to prevent a more wide-scale problem.

The outbreak investigation team is interested in hearing about cases which may be related to this outbreak. Please contact Donal O’Sullivan at donal.osullivan@lambethpct.nhs.uk.