Infective cause of childhood leukaemia and wartime population mixing in Orkney and Shetland, UK.

In Orkney and Shetland (the UK's northernmost islands), during World War II, local people were outnumbered by servicemen stationed there in case of a northern invasion. Such rural-urban population mixing promotes contact between susceptible and infected individuals. We compared childhood leukaemia mortality in wartime and postwar cohorts of Orkney and Shetland children. Childhood leukaemia increased 3.6-fold, (p=0.001) in the wartime, but not in the postwar, cohort compared with national Scottish rates. These findings add to the evidence for infection as a cause of childhood leukaemia.