Background: In recent years, there has been an influx of young women through marriage from economically underdeveloped southwest provinces of China with high HIV-1 prevalence rate into more developed areas, such as Shandong Province. Shandong is a relatively developed coastal province in China with 17 cities, and a population of more than 91 million with very low HIV-1 incidence. Although China has shown considerable achievements in controlling HIV-1 spread into general populations, the influence of this special migrant population – “imported wives” (IWs) on HIV-1 epidemic has not been studied.

Methods: Epidemiological questionnaires and HIV-1 screening tests were conducted in more than 10,000 IWs in Shandong. Husbands and children were screened if the index IWs were HIV-1 positive. HIV-1 confirmatory tests were performed in accordance with the national standard. DNA fragments of HIV-1 env, gag and tat gene were amplified by nested PCR from infected IWs and immediate infected family members, and fragments of HIV-1 env C2-V3, gag P17/P24, 1st exon of tat and adjacent region were sequenced, followed by phylogenetic, homology and recombination analysis.

Results: We found 76 IWs were positive for HIV-1. The main risk factors were drug injection and unsafe sexual behavior in their ancestral home. Twenty-three husbands (23/76, 30.3%) and 7 children (7/69, 10.1%) were HIV-1 positive. In total, about 20% of HIV-1 cases in Shandong were contributed by the IWs, their husbands and children. HIV-1 sequences from 36 IWs, 11 husbands and 4 children were analyzed. Among the 36 IWs, 4 HIV-1 subtypes/CRFs: CRF08_BC (14/36, 38.9%), CRF01_AE (12/36, 33.3%), B' (6/36, 16.7%) and CRF07_BC (4/36, 11.1%) were identified. All the 11 husbands (CRF08_BC, 6/11, CRF01_AE, 2/11, CRF07_BC 2/11, B' 1/11) and 4 children (CRF08_BC 2/4, CRF01_AE 2/4) harbored the same subtype/strains as the corresponding IWs, and the divergence was smaller than 1 in all.

Conclusion: The prevalence of HIV-1 was significantly higher in IWs than the general population in Shandong and more than 80% HIV-1 strains harbored by the IWs were CRFs. Viral sequences from the 11 husbands and 4 children indicated transmission from the corresponding IWs. Furthermore, all mother to child HIV-1 transmissions were related to IWs. Our findings suggest an urgent need to develop a provincial and national strategy for HIV-1 monitoring in IWs and for the prevention of sexual and perinatal transmission.