Background. The United Kingdom human immunodeficiency virus (HIV) epidemic was historically dominated by HIV subtype B transmission among men who have sex with men (MSM). Now 50% of diagnoses and prevalent infections are among heterosexual individuals and mainly involve non-B subtypes. Between 2002 and 2010, the prevalence of non-B diagnoses among MSM increased from 5.4% to 17%, and this study focused on the drivers of this change. Methods. Growth between 2007 and 2009 in transmission clusters among 14 000 subtype A1, C, D, and G sequences from the United Kingdom HIV Drug Resistance Database was analysed by risk group. Results. Of 1148 clusters containing at least 2 sequences in 2007, >75% were pairs and >90% were heterosexual. Most clusters (71.4%) did not grow during the study period. Growth was significantly lower for small clusters and higher for clusters of ≥7 sequences, with the highest growth observed for clusters comprising sequences from MSM and people who inject drugs (PWID). Risk group (P <. 0001), cluster size (P <. 0001), and subtype (P <. 01) were predictive of growth in a generalized linear model. Discussion. Despite the increase in non-B subtypes associated with heterosexual transmission, MSM and PWID are at risk for non-B infections. Crossover of subtype C from heterosexuals to MSM has led to the expansion of this subtype within the United Kingdom.
Bibliographical noteFunding Information:
This work was supported by the Pangea-HIV Consortium, which is supported by the Bill & Melinda Gates Foundation; the Biotechnology and Biological Science Research Council, and the National Institutes of Health (GM110749); the United Kingdom Medical Research Council (award 164587 to the United Kingdom HIV Drug Resistance Database); the United Kingdom Department of Health; Boehringer Ingelheim (to the United Kingdom HIV Drug Resistance Database); Bristol-Myers Squibb (to the United Kingdom HIV Drug Resistance Database); Gilead (to the United Kingdom HIV Drug Resistance Database); Tibotec (a division of Janssen-Cilag; to the United Kingdom HIV Drug Resistance Database); and Roche (to the United Kingdom HIV Drug Resistance Database).
© 2016 The Author 2015. Published by Oxford University Press for the Infectious Diseases Society of America.