Is the timing of exposure to infection a major determinant of acute lymphoblastic leukaemia in Hong Kong?
The hypothesis that protection of infants from exposure to infectious agents with delayed first exposure to one or more specific agents together contribute to the aetiology of childhood leukaemia, especially common acute lymphoblastic leukaemia (cALL), has substantial indirect support from descriptive epidemiology and case-control studies in developed Western countries. A case-control study of childhood leukaemia diagnosed at ages 2-14 years has now been conducted in Hong Kong. Cases (n = 98) formed a consecutive series of Chinese children diagnosed with acute leukaemia; controls (n = 228) were identified following a survey using random digit dialling and required to attend for medical examination by a paediatrician. Interviews with mothers were conducted in hospital by one trained interviewer using a structured questionnaire. Odds ratios (OR) and 95% confidence intervals (Cl) are reported for exposure variables capable of serving as proxies for exposure to infection in two critical ti
