Mäusezahl D (Department of Public Health and Epidemiology, Swiss Tropical Institute, Socinstrasse 57, PO Box, CH-4002 Basel, Switzerland), Cheng F, Zhang S Q and Tanner M. Hepatitis A in a Chinese urban population: The spectrum of social and behavioural risk factors. International Journal of Epidemiology 1996; 25: 1271-1279. Background Viral hepatitis is a major public health problem in China. Hepatitis A infections represent a substantial proportion of these, particularly in urban centres. Little is known about the social and behavioural factors in the urban household environment that influence the transmission of hepatitis A. Methods We conducted a register-based case-control study to investigate the risk factor patterns for hepatitis A in the general population of the City of Wuhan, in the PR China. Cases were selected from district-based health registers. One control, matched for sex and age, was identified from the case's neighbourhood. Home-based interviews combined with household observation were performed to obtain information on social, behavioural and economic risk factors and the household's indoor and outdoor environment. Analysis included conditional logistic regression. Results Hepatitis A infection was associated with a variety of social and household-related factors, like handwashing habits (after working in the garden: adjusted odds ratio [OR] = 8.24, 95% confidence interval [Cl] : 1.5-44.2, before food preparation: OR = 4.68, 95% Cl : 1.8-12.0; before eating: OR = 4.92, 95% Cl : 1.5-15.7), and the source of fresh vegetables (OR = 3.90, 95% Cl : 1.6-9.8). Hygiene in the kitchen and the household surroundings and the disposal of children's stools in vegetable gardens or refuse pits were significantly associated in the univariate analysis only. The lack of possession of luxury consumer items as a surrogate indicator for income was significantly associated with the disease (OR = 2.47, 95% Cl : 1.0-6.1). The study clearly established that exposure to health and hygiene education was less in the group of hepatitis A cases when compared to healthy controls (OR = 2.80, 95% Cl : 0.9-8.3). Conclusion The results of this study underline how social and behavioural factors are important determinants for hepatitis A in urban Chinese populations. These issues could be addressed by appropriate health and hygiene education targeted at high risk groups, and by strengthening existing procedures for monitoring and control of food hygien