Transmission dynamics among participants initiating antiretroviral therapy upon diagnosis of early acute HIV-1 infection in Thailand

Eugene Kroon*, Phuc T. Pham, Sunee Sirivichayakul, Rapee Trichavaroj, Donn J. Colby, Suteeraporn Pinyakorn, Nittaya Phanuphak, Eric Sanders-Buell, Frits Van Griensven, Gustavo H. Kijak, Jerome H. Kim, Nelson L. Michael, Merlin L. Robb, Jintanat Ananworanich, Mark S. De Souza, Sodsai Tovanabutra

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


Objective: To assess transmission characteristics in a predominantly MSM cohort initiating antiretroviral therapy (ART) immediately following diagnosis of acute HIV-1infection (AHI). Methods: A longitudinal study (2009-2017) was performed in participants with AHI (n 439) attending a single clinic in Bangkok. Plasma samples obtained prior to ART were used to obtain HIV-1 pol sequences and combined with clinical and epidemiologic data to assess transmission dynamics (cluster formation and size) using phylogenetic analysis. Clusters were estimated using maximum likelihood, genetic distance of 1.5% and visual inspection. The potential transmitter(s) in a cluster was determined using time to viral suppression and interview data. Results: The cohort was predominantly MSM(93%) and infected with HIV-1 CRF01-AE (87%). Medians (ranges) for age and viral load prior to ART were 26 (18-70) years and 5.9 (2.5-8.2) log10 HIV-1 RNA copies/ml. Median time from history of HIV-1 exposure to diagnosis was 19 (3-61) days. Viral suppression was observed in 388 of 412 (94%) participants at amedian timeof 12weeks followingART.Twenty-six clusters withmedian cluster size of 2 (2-5) representing 62 of 439 (14%) participants were observed. Younger age was associated with cluster formation: median 28 versus 30 years for unique infections (P 0.01). A potential transmitter was identified in 11 of 26 (42%) clusters. Conclusion: Despite high rates of viral suppression following diagnosis and treatment of AHI within a cohort of young Thai MSM, HIV-1 transmission continued, reflecting the need to expand awareness and treatment access to the entire MSM population.

Original languageEnglish
Pages (from-to)2373-2381
Number of pages9
Issue number16
StatePublished - 2018
Externally publishedYes


  • Bangkok
  • HIV-1 transmission
  • MSM
  • acute HIV infection
  • phylogenetic analysis


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