Hepatitis E virus genotype 1 (HEV G1) is an important cause of morbidity and mortality in Africa and Asia. HEV G1's natural history, including the incubation period, remains poorly understood, hindering surveillance efforts and effective control. Using individual-level data from 85 travel-related HEV G1 cases in England and Wales, we estimate the incubation period distribution using survival analysis methods, which allow for appropriate inference when only time ranges, rather than exact times are known for the exposure to HEV and symptom onset. We estimated a 29.8-day (95% confidence interval (CI) 24.1–36.0) median incubation period with 5% of people expected to develop symptoms within 14.3 days (95% CI 10.1–21.7) and 95% within 61.9 days (95% CI 47.4–74.4) of exposure. These estimates can help refine clinical case definitions and inform the design of disease burden and intervention studies.

There is little record of birth weight of Irish Travellers, a minority group in Ireland. Travellers are known to have higher rate of adult chronic disease and to be exposed to life-long disadvantage. The aim of this study was to establish whether the birth weight and infant mortality rate patterns in Ireland's Travellers were consistent with the developmental plasticity hypothesis. A 1-year follow-up birth cohort study was conducted with linkage data from maternity hospital records of Traveller infants born on the island of Ireland over a 12-month period to self-identifying Traveller and general Irish population mothers from the Lifeways Cross-Generation Cohort Study. The main outcome measure was the rate of birth weight <3000 g in a cohort of Traveller children. There were 987 confirmed Traveller births, 500 of whose mothers consented to linkage to their records. A social gradient was observed in the distribution of birth weight in the general population and Traveller infants constituted the highest proportion of all social classes in the birth weight range of 3 kg or less (16.3%). There was a high rate of persistent smoking among Traveller mothers (53%). After adjustment for smoking and alcohol consumption in pregnancy, the birth weight differential persisted (OR 3.5, 95% CI 1.4–8.1). Infant mortality rate at 12.0/1000 births (95% CI 5.5–19.7) was almost four times that of the general population. This analysis confirms Travellers had a greater than expected incidence of low birth weight and high infant mortality with high rates of premature adult chronic diseases from all causes already demonstrated previously.

The significant contribution of medicines in the introduction and spread of ‘modern’ medicine has, with the exception of vaccination, been neglected in historical studies, yet medicines have been a significant factor in people’s experiences of sickness and in their use and non-use of health services. Although medicines are implicitly acknowledged in the literature as important in the provision of healthcare, this article uses a case study of the Mt Everest region of Nepal during the second half of the twentieth century to argue that medicines have had an explicit and central role in the introduction and spread of modern medicine in this region. It also highlights the importance of travellers in the process. While this article focuses on biomedical products, modern medicine, as elsewhere in the wider Himalayan region, continued to be practised within a changing but plural medical environment. The first part of the article discusses medicines and travellers who, in the absence of biomedical services, were the main source of medicines prior to the mid-1960s, while the second part considers medicines and Khunde Hospital, which was built in 1966 by the area’s most famous overseas traveller and became not only the area’s main provider of modern health services but also the main source of medicines.

Dengue is the most frequent arboviral disease and is expanding geographically. Dengue is also increasingly being reported in travellers, in particular in travellers to Thailand. However, data to quantify the risk of travellers acquiring dengue when travelling to Thailand are lacking. Using mathematical modelling, we set out to estimate the risk of non-immune persons acquiring dengue when travelling to Thailand. The model is deterministic with stochastic parameters and assumes a Poisson distribution for the mosquitoes' biting rate and a Gamma distribution for the probability of acquiring dengue from an infected mosquito. From the force of infection we calculated the risk of dengue acquisition for travellers to Thailand arriving in a typical year (averaged over a 17-year period) in the high season of transmission. A traveller arriving in the high season of transmission and remaining for 7 days has a risk of acquiring dengue of 0·2% (95% CI 0·16–0·23), whereas the risk for travel of 15 and 30 days' duration is 0·46% (95% CI 0·41–0·50) and 0·81% (95% CI 0·76–0·87), respectively. Our data highlight that the risk of non-immune travellers acquiring dengue in Thailand is substantial. The incidence of 0·81% after a 1-month stay is similar to that reported in prospective seroconversion studies in Israeli travellers to Thailand, highlighting that our models are consistent with actual data. Risk estimates based on mathematical modelling offer more detailed information depending on various travel scenarios, and will help the travel medicine provider give better evidence-based advice for travellers to dengue-endemic countries.