The Department of Health urges people with a history of unprotected sex to have an HIV test, as there may be a rapid and local HIV transmission in Hong Kong.

It has uncovered two clusters of HIV infections with similar gene sequencing affecting men having sex with men and heterosexuals, the department says.

Consultant Dr Wong Ka-hing said investigations have so far revealed that these cases may be linked. Unprotected sex is the likely cause.

Tests on the gene sequences of most confirmed HIV positive blood specimens found two separate clusters of HIV-1 subtype B infections.

The first cluster of HIV infection comprised 34 men aged 22 to 54. Of them, 27 were Chinese. All these cases were reported between November 2003 and September this year.

The second cluster comprised 12 Chinese men aged 34 to 67. These cases were reported between May 2004 and September this year.

HIV is prone to mutate during replication, and as such the gene sequencing of HIV infection in different individuals varied.

Rapid transmission

"HIV infections between closely related individuals may present with similar gene sequencing. The detection of a cluster of HIV infection suggested the presence of a rapid and local HIV transmission among the affected people," Dr Wong said.

Homosexual and bisexual contacts were the most common mode of transmission in these two clusters, which accounted for 71% of the first cluster and 83% of the second. Heterosexual contact was the risk factor reported in 20.6% and 8.3% of these two clusters.

Against the background of an increase in reported HIV cases in recent years, the identification of these two clusters of infections signified that HIV was on the rise in the city. It is anticipated that the two clusters will continue to grow in numbers as more new HIV diagnoses are made and reported.

People having anal, oral or vaginal intercourse should use condoms to reduce the risk of HIV infection. People with a history of unsafe sex should go for an HIV test. They can call the AIDS hotline 2780 2211 for a free, anonymous and confidential HIV test. Free HIV tests are also provided at the department's social hygiene clinics.

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