Sexually acquired hepatitis C virus (HCV) infection remains a public health problem, with significant disease burden primarily in HIV-positive men who have sex with men (MSM). Over the past decades, the epidemic of sexually transmitted HCV infection has continued to expand and the epidemiology of HCV in HIV has changed significantly. In the post-combination antiretroviral therapy era, sexual network characteristics within the specific core group of MSM with increased sexual risk behaviours, including serosorting on the basis of HIV-positive status and intense mucosally traumatic sexual practices, confer increased HCV acquisition and transmission. This review summarizes the current epidemiology of sexually acquired HCV infection and the clinical and immunological contexts of acute HCV infection, and describes the biological, social, and behavioural factors that have facilitated permucosal transmission of HCV in MSM. While the advent of direct-acting antivirals has improved treatment responses significantly, sexually transmitted HCV reinfections occur in a substantial proportion of HIV-positive MSM following clearance of a primary infection. Effective strategies and preventive interventions that are tailored to the MSM communities to facilitate the control of sexually acquired HCV infection cannot be overemphasized.

In May 2015, South Korea reported its first case of Middle East respiratory syndrome coronavirus (MERS-CoV) infection in a 68-year-old man with a history of travel in the Middle East. In the presence of secondary infections, an understanding of the transmission dynamics of the virus is crucial. The aim of this study was to characterize the transmission chains of MERS-CoV infection in the current South Korean outbreak. Individual-level data from multiple sources were collected and used for epidemiological analyses. As of July 14, 2015, 185 confirmed cases of MERS have been reported in the Korean outbreak. Three generations of secondary infection, with over half belonging to the second generation, could be delineated. Hospital infection was found to be the most important cause of virus transmission, affecting largely non-healthcare workers (154/184). Healthcare switching has probably accounted for the emergence of multiple generations of secondary infection. Fomite transmission may explain a significant proportion of the infections occurring in the absence of direct contact with infected cases. Publicly available data from multiple sources, including the media, are useful to describe the epidemic history of an outbreak. The effective control of MERS-CoV hinges on the upholding of infection control standards and an understanding of health-seeking behaviours in the community.

To the editor—The article by Ribaudo et al. [1] and the accompanying editorial commentary [2] have come at the right time to stimulate debates on how, with a global perspective, a treatment algorithm for HAART should be strategically developed to achieve maximum effectiveness. In the not-too-distant past, HAART was an expensive commodity of the Western world. With the expansion of treatment access, patients with HIV infection from varied ethnic origins are exposed to the same efficacious therapy, which is not without harmful consequences—toxicity and resistance emergence—if managed inappropriately. The poor metabolism of efavirenz, a once-daily nonnucleoside reverse-transcriptase inhibitor, in persons with the CYP2B6 G516T allele (also termed 2B6*6) is a case in point. The allelic frequency varies from 0.16 in the Japanese [3] and 0.14 in Koreans [4] to a much higher level of 0.42 in West Africans and 0.62 in Papua New Guineans [5], compared with an allelic frequency of 0.28 in white Americans. We set out to establish the allelic frequency in Chinese persons against the background of a rising number of patients with HIV who received a diagnosis in mainland China. Buffy coat specimens from 100 Chinese persons who donated blood were collected in October 2005 at the Hong Kong Red Cross Blood Transfusion Service. Direct sequencing was performed to screen for single-nucleotide polymorphisms, and restriction fragment–length polymorphism with the BsrI enzyme (New England Biolab) was used to confirm the G516 sequence. A total of 76 samples were successfully sequenced, yielding the following results: GG alleles in 28 samples, GT in 30 and TT in 18. The allelic frequency of G516T was high, at 0.43.