title: Estimating the Impact of Earlier ART Initiation and Increased Testing Coverage on HIV Transmission among Men Who Have Sex with Men in Mexico using a Mathematical Model.
abstract: OBJECTIVE
  To estimate the impact of late ART initiation on HIV transmission among men who have sex with men (MSM) in Mexico.
  
  
  METHODS
  An HIV transmission model was built to estimate the number of infections transmitted by HIV-infected men who have sex with men (MSM-HIV+) MSM-HIV+ in the short and long term. Sexual risk behavior data were estimated from a nationwide study of MSM. CD4+ counts at ART initiation from a representative national cohort were used to estimate time since infection. Number of MSM-HIV+ on treatment and suppressed were estimated from surveillance and government reports. Status quo scenario (SQ), and scenarios of early ART initiation and increased HIV testing were modeled.
  
  
  RESULTS
  We estimated 14239 new HIV infections per year from MSM-HIV+ in Mexico. In SQ, MSM take an average 7.4 years since infection to initiate treatment with a median CD4+ count of 148 cells/mm3(25th-75th percentiles 52-266). In SQ, 68% of MSM-HIV+ are not aware of their HIV status and transmit 78% of new infections. Increasing the CD4+ count at ART initiation to 350 cells/mm3 shortened the time since infection to 2.8 years. Increasing HIV testing to cover 80% of undiagnosed MSM resulted in a reduction of 70% in new infections in 20 years. Initiating ART at 500 cells/mm3 and increasing HIV testing the reduction would be of 75% in 20 years.
  
  
  CONCLUSIONS
  A substantial number of new HIV infections in Mexico are transmitted by undiagnosed and untreated MSM-HIV+. An aggressive increase in HIV testing coverage and initiating ART at a CD4 count of 500 cells/mm3 in this population would significantly benefit individuals and decrease the number of new HIV infections in Mexico.
authors: Faculty of Medicine, Universidad Nacional Autónoma de México, Mexico City, Mexico; Department of Infectious Diseases, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubiran, Mexico City, Mexico.
authors: Yanink
authors: Y
authors: Caro-Vega
authors: Hubert Department of Global Health, Rollins School of Public Health & Emory Center for AIDS Research, Atlanta, Georgia, United States of America.
authors: Carlos
authors: C
authors: del Rio
authors: Division of AIDS, Department of Medicine, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada.
authors: Viviane Dias
authors: VD
authors: Lima
authors: Faculty of Medicine, Universidad Nacional Autónoma de México, Mexico City, Mexico.
authors: Malaquias
authors: M
authors: Lopez-Cervantes
authors: Department of Infectious Diseases, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubiran, Mexico City, Mexico.
authors: Brenda
authors: B
authors: Crabtree-Ramirez
authors: Division of Health Economics and Health Systems Innovations, National Institute of Public Health, Cuernavaca, Morelos, Mexico.
authors: Sergio
authors: S
authors: Bautista-Arredondo
authors: Division of Health Economics and Health Systems Innovations, National Institute of Public Health, Cuernavaca, Morelos, Mexico.
authors: M Arantxa
authors: MA
authors: Colchero
authors: Department of Infectious Diseases, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubiran, Mexico City, Mexico.
authors: Juan
authors: J
authors: Sierra-Madero
mesh_terms: D000328:Adult; D023241:Antiretroviral Therapy, Highly Active; D005260:Female; D006678:HIV / Q000472:pathogenicity; D015658:HIV Infections / Q000453:epidemiology / Q000628:therapy / Q000635:transmission*; D018451:Homosexuality, Male; D006801:Humans; D008297:Male; D008403:Mass Screening; D008800:Mexico; D008962:Models, Theoretical; D012309:Risk-Taking; D012725:Sexual Behavior / Q000502:physiology*