title: A Population-Structured HIV Epidemic in Israel: Roles of Risk and Ethnicity.
abstract: BACKGROUND
  HIV in Israel started with a subtype-B epidemic among men who have sex with men, followed in the 1980s and 1990s by introductions of subtype C from Ethiopia (predominantly acquired by heterosexual transmission) and subtype A from the former Soviet Union (FSU, most often acquired by intravenous drug use). The epidemic matured over the last 15 years without additional large influx of exogenous infections. Between 2005 and 2013 the number of infected men who have sex with men (MSM) increased 2.9-fold, compared to 1.6-fold and 1.3-fold for intravenous drug users (IVDU) and Ethiopian-origin residents. Understanding contemporary spread is essential for effective public health planning.
  
  
  METHODS
  We analyzed demographic and virologic data from 1,427 HIV-infected individuals diagnosed with HIV-I during 1998-2012. HIV phylogenies were reconstructed with maximum-likelihood and Bayesian methods.
  
  
  RESULTS
  Subtype-B viruses, but not A or C, demonstrated a striking number of large clusters with common ancestors having posterior probability ≥0.95, including some suggesting presence of transmission networks. Transmitted drug resistance was highest in subtype B (13%). MSM represented a frequent risk factor in cross-ethnic transmission, demonstrated by the presence of Israeli-born with non-B virus infections and FSU immigrants with non-A subtypes.
  
  
  CONCLUSIONS
  Reconstructed phylogenetic trees demonstrated substantial grouping in subtype B, but not in non-MSM subtype-A or in subtype-C, reflecting differences in transmission dynamics linked to HIV transmission categories. Cross-ethnic spread occurred through multiple independent introductions, with MSM playing a prevalent role in the transmission of the virus. Such data provide a baseline to track epidemic trends and will be useful in informing and quantifying efforts to reduce HIV transmission.
authors: School of Public Health, Tel-Aviv University, Tel-Aviv, Israel; National Cancer Institute, Frederick, MD, United States of America.
authors: Zehava
authors: Z
authors: Grossman
authors: Crusaid Kobler AIDS Center, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel; Laboratory of Viruses and Molecular Biology, Tel-Aviv Sourasky Medical Center, Tel Aviv, Israel.
authors: Boaz
authors: B
authors: Avidor
authors: Ramla Department of Health, Ministry of Health, Ramla, Israel.
authors: Zohar
authors: Z
authors: Mor
authors: Meir Medical Center, Kfar Saba, Israel.
authors: Michal
authors: M
authors: Chowers
authors: Infectious Diseases Unit, Sheba Medical Center, Ramat-Gan, Israel.
authors: Itzchak
authors: I
authors: Levy
authors: Rambam Medical Center, Haifa, Israel.
authors: Eduardo
authors: E
authors: Shahar
authors: Soroka Medical Center, Beer-Sheva, Israel.
authors: Klaris
authors: K
authors: Riesenberg
authors: Kaplan Medical Center, Rehovot, Israel.
authors: Zev
authors: Z
authors: Sthoeger
authors: Hadassah Medical Center, Jerusalem, Israel.
authors: Shlomo
authors: S
authors: Maayan
authors: Advanced Biomedical Computing Center, SAIC-Frederick, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD, 21702, United States of America.
authors: Wei
authors: W
authors: Shao
authors: Rambam Medical Center, Haifa, Israel.
authors: Margalit
authors: M
authors: Lorber
authors: Hadassah Medical Center, Jerusalem, Israel.
authors: Karen
authors: K
authors: Olstein-Pops
authors: Kaplan Medical Center, Rehovot, Israel.
authors: Daniel
authors: D
authors: Elbirt
authors: Hadassah Medical Center, Jerusalem, Israel.
authors: Hila
authors: H
authors: Elinav
authors: Kaplan Medical Center, Rehovot, Israel.
authors: Ilan
authors: I
authors: Asher
authors: Hadassah Medical Center, Jerusalem, Israel.
authors: Diana
authors: D
authors: Averbuch
authors: Hillel Yaffe Medical Center, Hadera, Israel.
authors: Valery
authors: V
authors: Istomin
authors: Meir Medical Center, Kfar Saba, Israel.
authors: Bat Sheva
authors: BS
authors: Gottesman
authors: Rambam Medical Center, Haifa, Israel.
authors: Eynat
authors: E
authors: Kedem
authors: Crusaid Kobler AIDS Center, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel; Laboratory of Viruses and Molecular Biology, Tel-Aviv Sourasky Medical Center, Tel Aviv, Israel.
authors: Shirley
authors: S
authors: Girshengorn
authors: Rambam Medical Center, Haifa, Israel.
authors: Zipi
authors: Z
authors: Kra-Oz
authors: Soroka Medical Center, Beer-Sheva, Israel.
authors: Yonat
authors: Y
authors: Shemer Avni
authors: Kaplan Medical Center, Rehovot, Israel.
authors: Sara
authors: S
authors: Radian Sade
authors: Crusaid Kobler AIDS Center, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel.
authors: Dan
authors: D
authors: Turner
authors: National Cancer Institute, Frederick, MD, United States of America.
authors: Frank
authors: F
authors: Maldarelli
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001499:Bayes Theorem; D002648:Child; D002675:Child, Preschool; D058872:Epidemics / Q000706:statistics & numerical data*; D005002:Ethiopia / Q000208:ethnology; D005260:Female; D015658:HIV Infections / Q000453:epidemiology* / Q000208:ethnology / Q000635:transmission / Q000821:virology; D015497:HIV-1 / Q000235:genetics; D018451:Homosexuality, Male; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D018445:Infectious Disease Transmission, Vertical / Q000706:statistics & numerical data; D007557:Israel / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D010802:Phylogeny; D012307:Risk Factors; D015819:Substance Abuse, Intravenous / Q000150:complications; D055815:Young Adult