Surveillance of transmitted HIV drug resistance in the Manzini-Mbabane corridor, Swaziland, in 2006.

Background: In resource-limited settings where antiretroviral treatment (ART) is being scaled-up, the World Health Organization (WHO) recommends the surveillance of transmitted HIV drug resistance (HIVDR). We used the WHO's HIVDR threshold survey method to assess transmitted HIVDR in three antenatal clinic (ANC) sites along the corridor between the two most populous cities in Swaziland, where ART was introduced in 2003.

Methods: From July-August 2006, remnant sera were aliquoted from HIV serosurvey specimens collected from 70 primagravidas <25 years old attending ANC during the national HIV serosurvey. Genotyping was performed at the National Institute for Communicable Diseases, South Africa. Transmitted resistance was defined by the WHO's surveillance list of mutations. HIVDR prevalence was categorized using the WHO's threshold survey binomial sequential sampling method.

Results: Among the 70 eligible specimens, 61 were sequenced--60 (98%) were identified as subtype C and one as subtype B. No major nucleoside or non-nucleoside reverse transcriptase inhibitor mutations occurred among the first 34 consecutive specimens, which supported a transmitted resistance categorization to these drug classes as <5%. One protease inhibitor mutation, M461, was seen among the first 44 specimens, supporting a categorization of PI resistance as <5%.

Conclusion: Our survey indicates that prevalence of transmitted HIVDR among recently infected pregnant women along the Manzini-Mbabane corridor is low (<5%). Surveys will be carried out in this area biannually and may be extended to other areas. Surveys for transmitted resistance make up one element among a spectrum of activities to assess and support minimization of HIVDR.