title: Possible HIV transmission modes among at-risk groups at an early epidemic stage in the Philippines.
abstract: A concentrated human immunodeficiency virus (HIV) epidemic might have started in the Philippines. A subsequent characterization of viruses was carried out to estimate HIV transmission modes. Most HIV strains from injecting drug users belonged to subtype-B. CRF-01 was a major subtype harbored by three other at-risk populations: male visa applicants who had sex with men, "men who have sex with men," and visa applicants. An HIV phylogeny suggested that two strain groups of injecting drug users and others circulated separately. In contrast, there was substantial genetic overlap between two strain groups from "men who have sex with men" and visa applicants. Mean nucleotide distance within strains was shorter among subtype-B strains harbored by the injecting drug users (0.010) than among CRF-01 strains of the other three populations: male visa applicants who had sex with men (0.034), "men who have sex with men" (0.023), and visa applicants (0.032). Closely related strains of hepatitis C virus were derived from not only HIV-positive but also -negative individuals. These results suggest that there is potential for transmission from visa applicants to "men who have sex with men," and that once HIV occurs in injecting drug users, it spreads rapidly among them. Close contacts of hepatitis C virus carriers composed of HIV-negative and -positive individuals indicated ongoing HIV spread via blood and possible intervention points. Large-scale analysis is needed to provide more precise information on the transmission directions and to help curb the growth of this HIV epidemic in the Philippines.
authors: National Reference Laboratory, STD AIDS Cooperative Central Laboratory, San Lazaro Hospital, Manila, Philippines.
authors: Elizabeth Freda O
authors: EF
authors: Telan
authors: Genesis May J
authors: GM
authors: Samonte
authors: Noel
authors: N
authors: Palaypayon
authors: Ilya P
authors: IP
authors: Abellanosa-Tac-An
authors: Prisca Susan A
authors: PS
authors: Leaño
authors: Akeno
authors: A
authors: Tsuneki
authors: Seiji
authors: S
authors: Kageyama
mesh_terms: D060085:Coinfection; D055030:Drug Users; D005260:Female; D005843:Geography; D006678:HIV / Q000145:classification / Q000235:genetics*; D015658:HIV Infections / Q000453:epidemiology* / Q000635:transmission*; D016174:Hepacivirus / Q000145:classification / Q000235:genetics; D006526:Hepatitis C / Q000453:epidemiology; D018451:Homosexuality, Male; D006801:Humans; D008297:Male; D010679:Philippines / Q000453:epidemiology; D010802:Phylogeny; D011159:Population Surveillance; D060386:Sex Workers; D014505:Urban Population; D054302:pol Gene Products, Human Immunodeficiency Virus
chemical_list: D054302:pol Gene Products, Human Immunodeficiency Virus
keywords: HIV; hepatitis C virus; injecting drug users; men who have sex with men; sex workers; visa applicants