Surveillance of transmitted HIV drug resistance
Surveys to evaluate transmitted drug resistance (also called HIV drug resistance "threshold surveys") should be limited initially to geographic areas where transmitted HIVDR is likely to be seen first: cities or health planning areas where ART has been widely available for >3 years. WHO recommends genotyping remnant specimens collected from individuals <25 years of age (and, for females, without previous pregnancies) consecutively diagnosed with HIV in serosurveys or at diagnostic sites, within each area.
Separate surveys may be performed in different subgroups of interest in each area. Using a bionomial sequential sampling method, transmitted resistance to relevant drug classes and drugs is classified as <5%, 5-15%, >15% based on a small number of specimens collected from eligible individuals who are consecutively diagnosed with HIV. Site selection critieria and participant eligibility criteria are designed to minimize the likelihood that participants have been infected >3 years previously and that they are drug-experienced.
Recommendations for surveillance of transmitted HIV drug resistance in countries scaling up antiretroviral treatment
A novel sequential sampling technique for the surveillance of transmitted HIV drug resistance by cross-sectional survey for use in low resource settings
Consensus drug resistance mutations for epidemiological surveillance
HIV-1 protease and reverse transcriptase mutations for drug resistance surveillance
Table 1: Surveys of transmitted HIV drug resistance
|Country||Area||Time period||Site type||Participation||Predominant HIV-1 subtype(s)||Transmitted resistance classification|
|(% of eligible persons)|
|Ethiopia||Addis Abbaba||Apr-Aug 2005||ANC||100%||C||< 5%|
|Malawi||Lilongwe||Nov-Dec 2006||PMTCT||100%||C||< 5%|
|South Africa||Gauteng Province||Oct 2002||ANC||100%||C||< 5%|
|South Africa||Gauteng Province||Oct 2004||ANC||100%||C||< 5%|
|Swaziland||Manzini-Mbani Corridor||July-Aug 2006||ANC||100%||C||< 5%|
|Tanzania||Dar Es Salaam||Nov 2005-Feb 2006||ANC||100%||A1,C||< 5%|
|Thailand||Bangkok||July 2005- Apr 2006||BD||100%||CRF01-AE||< 5%|
|Thailand||Bangkok||July-Dec 2005||VCT||100%||CRF01-AE||< 5%|
|Vietnam||Hanoi||Feb-June 2006||VCT||99%**||CRF01-AE; CRF15-01B||< 5%|
|Uganda||Kampala||2006||ANC||100%||A, D, C||< 5%|
|Site type abbreviations: ANC: antenatal clinics; PMTCT: ANC with programme for prevention of mother-to-child transmission; VCT: Voluntary counselling and testing sites; BD: Blood donation site.|
HIV drug resistance status report 2009
HIVDR threshold surveys were implemented in Burkina Faso, Ghana, India, Indonesia, Uganda, Ukraine, South Africa, Zambia and Zimbabwe in 2008 bringing to a total of 22 countries that have implemented surveys. With technical support from WHO and financial support from other organizations, some of these countries are expanding implementation to additional geographic areas in 2009. WHO's threshold survey methodology has also been adopted in additional countries where training has been provided in regional workshops but where WHO is not providing financial support.
Eight countries have reported results from surveillance of transmitted HIVDR in geographic areas where ART was first used within the country at international conferences or in peer-reviewed journals (see link below). Data obtained from the HIVDR transmission surveys is providing information on the extent and patterns of drug resistance in newly acquired HIV infections. Thus far, recommendations to continue the use of current ART regimens have been made based on the surveys from 2007 and 2008, all of which report < 5% transmitted resistance to all drugs and drug classes in geographic areas where ART is widely available. The WHO mutations list for HIVDR transmission surveys was published in Antiviral Therapy and is also available on the Stanford website and used by several institutions in addition to WHO.