HIV drug resistance transmission threshold survey in Bangkok, Thailand.
BACKGROUND
Antiretroviral therapy (ART) began in Thailand in the Bangkok Metropolitan Area (BMA) in 1988 and scale-up began in 2001. The national first-line regimen is stavudine, lamivudine and nevirapine in fixed-dose combination, which is a regimen with a low genetic barrier for resistance. Because viral load and resistance testing are not widely available, unidentified HIV drug resistance (HIVDR) may occur during treatment and could be transmitted.


METHODS
We undertook a threshold survey to assess HIVDR transmission in two subsets of recently infected individuals in the BMA. The first group consisted of returning blood donors tested at the Thai Red Cross National Blood Centre who seroconverted within the past 12 months. The second group comprised recently infected (as defined by BED assay) clients of the Thai Red Cross voluntary counselling and testing centre (VCT).


RESULTS
Genotyping of 50 consecutive specimens each from blood donors and VCT clients during 2005-2006 showed no mutations associated with HIVDR in the reverse transcriptase or protease regions of the HIV pol gene. These results are categorized by the WHO HIV drug resistance threshold survey method as representing a low prevalence (<5%) of transmitted HIV drug resistance.


CONCLUSIONS
Every effort should be made to minimize the emergence of resistance in treated individuals and to prevent primary and secondary HIV transmission. To continue to monitor HIVDR transmission, Thailand has planned additional surveys--including longitudinal surveys--in these and additional groups of individuals.
Sirivichayakul
Sunee
S
Department of Medicine, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand. ssunee@chula.ac.th
Phanuphak
Praphan
P
Pankam
Tippawan
T
O-Charoen
Rachanee
R
Sutherland
Donald
D
Ruxrungtham
Kiat
K
D000328:Adult; D044966:Anti-Retroviral Agents / Q000627:therapeutic use*; D023241:Antiretroviral Therapy, Highly Active; D001782:Blood Donors; D024882:Drug Resistance, Viral / Q000235:genetics*; D005260:Female; D005838:Genotype; D006678:HIV / Q000201:enzymology / Q000235:genetics* / Q000276:immunology; D015658:HIV Infections / Q000188:drug therapy / Q000453:epidemiology / Q000635:transmission* / Q000821:virology; D016333:HIV Protease / Q000235:genetics; D054303:HIV Reverse Transcriptase / Q000235:genetics; D006679:HIV Seropositivity; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D009313:National Health Programs / Q000706:statistics & numerical data; D011159:Population Surveillance; D015397:Program Evaluation; D011446:Prospective Studies; D013785:Thailand / Q000453:epidemiology; D013997:Time Factors; D016896:Treatment Outcome; D014504:Urban Health / Q000706:statistics & numerical data; D014944:World Health Organization
D044966:Anti-Retroviral Agents; D054303:HIV Reverse Transcriptase; D016333:HIV Protease