The incubation period of hepatitis E genotype 1: insights from pooled analyses of travellers

Abstract

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.

Keywords: HEV; Hepatitis E; incubation period; survival analysis; travellers.

Fig. 1.

Incubation period distribution (log-normal model). (a) Shows the cumulative distribution of the incubation period (dark blue line) with bootstraps in light blue lines. (b) Shows the density function of the incubation period (black) with bootstrap estimates in light grey. Estimates of quantiles for this model are in the first row of Table 1.