Editor—Our paper on Sentiweb, the French electronic sentinel system for surveillance of communicable diseases on the world wide web, was accompanied by three commentaries.1 In one of them Norman Noah was surprised by the low rate of reports, considering that (only?) 330 000 cases were notified in 12 years, leading to one case per doctor per week. Noah's calculations were not, however, appropriate. Some diseases shown on the internet (for example, chickenpox and diarrhoea) have been under surveillance for only six years. Estimates of nationwide …