METHODS: The study included 143 new cases of HIV-1 infection. Viral RNA was extracted from stocked plasma samples and sequenced for the pol and the env regions using the Sanger method. Near-full length sequencing using MiSeq was performed in 3 patients who were suspected to be infected with recombinant HIV-1. Phylogenetic analysis was performed using the neighbor-joining method and Bayesian Markov chain Monte Carlo method.
RESULTS: MSM was the main transmission route in the previous and current studies. However, heterosexual route showed a significant increase in recent years. Phylogenetic analysis documented three taxa; Mongolian B, Korean B, and CRF51_01B, though the former two were also observed in the previous study. CRF51_01B, which originated from Singapore and Malaysia, was confirmed by near-full length sequencing. Although these strains were mainly detected in MSM, they were also found in increasing numbers of heterosexual males and females. Bayesian phylogenetic analysis estimated transmission of CRF51_01B into Mongolia around early 2000s. An extended Bayesian skyline plot showed a rapid increase in the effective population size of Mongolian B cluster around 2004 and that of CRF51_01B cluster around 2011.
CONCLUSIONS: HIV-1 infection might expand to the general population in Mongolia. Our study documented a new cluster of HIV-1 transmission, enhancing our understanding of the epidemiological status of HIV-1 in Mongolia.
METHODOLOGY: Cord blood samples from a pilot screening programme for congenital hypothyroidism in 1995 at Ipoh city and surrounding district hospitals were screened anonymously for HIV 1 and 2. HIV status was determined using chemiluminescent technology. Positive samples were retested using the Genelavia Mixt assay.
RESULTS: A total of 4927 samples were tested. The ethnic breakdown included 51.7% Malays, 18.9% Chinese, 14.3% Indian, 2.3% Others and 12.9% unknown. The geographical distribution of samples was 73.9% urban, 24.2% rural and 1.9% unknown. The seroprevalence of HIV positivity was 3.25 per 1000 deliveries (95% CI: 1.92-5.16). Seroprevalence was higher for samples from rural and Malay mothers.
CONCLUSION: The high seroprevalence in this study suggests that the spread of HIV is far wider than that anticipated by mandatory national reporting. It also supports antenatal screening and the use of antiretroviral therapy as an important strategy to reduce perinatal transmission.