Virological efficacy and emergence of drug resistance in adults on antiretroviral treatment in rural Tanzania.
BACKGROUND
Virological response to antiretroviral treatment (ART) in rural Africa is poorly described. We examined virological efficacy and emergence of drug resistance in adults receiving first-line ART for up to 4 years in rural Tanzania.


METHODS
Haydom Lutheran Hospital has provided ART to HIV-infected patients since October 2003. A combination of stavudine or zidovudine with lamivudine and either nevirapine or efavirenz is the standard first-line regimen. Nested in a longitudinal cohort study of patients consecutively starting ART, we carried out a cross-sectional virological efficacy survey between November 2007 and June 2008. HIV viral load was measured in all adults who had completed at least 6 months first-line ART, and genotypic resistance was determined in patients with viral load >1000 copies/mL.


RESULTS
Virological response was measured in 212 patients, of whom 158 (74.5%) were women, and median age was 35 years (interquartile range [IQR] 29-43). Median follow-up time was 22.3 months (IQR 14.0-29.9). Virological suppression, defined as <400 copies/mL, was observed in 187 patients (88.2%). Overall, prevalence of > or =1 clinically significant resistance mutation was 3.9, 8.4, 16.7 and 12.5% in patients receiving ART for 1, 2, 3 and 4 years, respectively. Among those successfully genotyped, the most frequent mutations were M184I/V (64%), conferring resistance to lamivudine, and K103N (27%), Y181C (27%) and G190A (27%), conferring resistance to non-nucleoside reverse transcriptase inhibitors (NNRTIs), whereas 23% had thymidine analogue mutations (TAMs), associated with cross-resistance to all nucleoside reverse transcriptase inhibitors (NRTIs). Dual-class resistance, i.e. resistance to both NRTIs and NNRTIs, was found in 64%.


CONCLUSIONS
Virological suppression rates were good up to 4 years after initiating ART in a rural Tanzanian hospital. However, drug resistance increased with time, and dual-class resistance was common, raising concerns about exhaustion of future antiretroviral drug options. This study might provide a useful forecast of drug resistance and demand for second-line antiretroviral drugs in rural Africa in the coming years.
Johannessen
Asgeir
A
Ulleval Department of Infectious Diseases, Oslo University Hospital, Oslo, Norway. asgeir.johannessen@medisin.uio.no
Naman
Ezra
E
Kivuyo
Sokoine L
SL
Kasubi
Mabula J
MJ
Holberg-Petersen
Mona
M
Matee
Mecky I
MI
Gundersen
Svein G
SG
Bruun
Johan N
JN
D000328:Adult; D019380:Anti-HIV Agents / Q000627:therapeutic use*; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D024882:Drug Resistance, Viral / Q000235:genetics*; D005260:Female; D015658:HIV Infections / Q000188:drug therapy* / Q000821:virology; D015497:HIV-1 / Q000187:drug effects / Q000235:genetics*; D006801:Humans; D008297:Male; D013636:Tanzania; D013997:Time Factors; D014766:Viremia / Q000188:drug therapy
D019380:Anti-HIV Agents