Several lines of evidence support a role for Epstein-Barr virus (EBV) in the aetiology of multiple sclerosis (MS). This includes the observation that nearly all MS patients show serological markers of past EBV infection. Given the well-known association between MS prevalence and latitude, we investigated whether EBV seropositivity also increases with distance from the equator. We found that the proportion of EBV positive individuals is positively associated with latitude independently of MS status (odds ratio = 1.06, 95% CI = 1.02-1.09, p = 0.002). Latitude-related factors may be implicated in the immune response to EBV and its role in MS aetiology.

It is critical to include a sexual and reproductive health lens in HIV programming as most HIV transmission occurs through sexual intercourse. As global attention is focusing on the sexual and reproductive health needs of women living with HIV, identifying which interventions work becomes vitally important. What evidence exists to support sexual and reproductive health programming related to HIV programmes?This article reviews the evidence of what works to meet the sexual and reproductive health needs of women living with HIV in developing countries and includes 35 studies and evaluations of eight general interventions using various methods of implementation science from 15 countries. Data are primarily from 2000-2009. Searches to identify effective evaluations used SCOPUS, Popline, Medline, websites and consultations with experts. Evidence was ranked using the Gray Scale.A range of successful and promising interventions to improve the sexual and reproductive health and rights of women living with HIV include: providing contraceptives and family planning counselling as part of HIV services; ensuring early postpartum visits providing family planning and HIV information and services; providing youth-friendly services; supporting information and skills building; supporting disclosure; providing cervical cancer screening; and promoting condom use for dual protection against pregnancy and HIV. Provision of antiretrovirals can also increase protective behaviours, including condom use.While many gaps in programming and research remain, much can be done now to operationalize evidence-based effective interventions to meet the sexual and reproductive health needs of women living with HIV.

Gene-environment interactions may shed light on the mechanisms underlying multiple sclerosis (MS). We pooled data from two case-control studies on incident demyelination and used different methods to assess interaction between HLA-DRB1*15 (DRB1-15) and history of infectious mononucleosis (IM). Individuals exposed to both factors were at substantially increased risk of disease (OR=7.32, 95% CI=4.92-10.90). In logistic regression models, DRB1-15 and IM status were independent predictors of disease while their interaction term was not (DRB1-15*IM: OR=1.35, 95% CI=0.79-2.23). However, interaction on an additive scale was evident (Synergy index=2.09, 95% CI=1.59-2.59; excess risk due to interaction=3.30, 95%CI=0.47-6.12; attributable proportion due to interaction=45%, 95% CI=22-68%). This suggests, if the additive model is appropriate, the DRB1-15 and IM may be involved in the same causal process leading to MS and highlights the benefit of reporting gene-environment interactions on both a multiplicative and additive scale.

Summary.A characteristic of African pre-transitional fertility regimes is large ideal family size. This has been used to support claims of cultural entrenchment of high fertility. Yet in Kenya fertility rates have fallen. In this paper this fall is explored in relation to trends in fertility norms and attitudes using four sequential cross-sectional surveys spanning the fertility transition in Kenya (1978, 1984, 1989 and 1998). The most rapid fall in the reported ideal family size occurred between 1984 and 1989, whilst the most rapid fall in the total fertility rate occurred 5 to 10 years later, between 1989 and 1998. Thus these data, spanning the fertility transition in Kenya, support the traditional demographic model that demand for fertility limitation drives fertility decline. These data also suggest that the decline in fertility norms over time was partly a period effect, as the reported ideal family size was seen to fall simultaneously in all age cohorts, and partly a cohort effect, as older age cohorts reporting higher ideal family sizes were replaced by younger cohorts reporting lower ideal family sizes. These data also suggest that a new fertility norm of four children may have developed by 1989 and continued until 1998. This is consistent with, and perhaps could have been used to predict, the stall in the Kenyan fertility decline after 1998.