Dr Julius Parker: Chicken Pox and a broken hip
Chicken pox is highly infectious; the secondary infection rate from a household contact can be up to 90%. This means your other children are very likely to catch chicken pox. You will know by the time you read this, but a short illness with fever and general malaise can precede the development of the typical rash. The incubation period can be between one to three weeks and people with chicken pox remain infectious until all the blisters are crusted and dry. Of course, some people don’t get chicken pox even when everyone around them does. This might be luck, but a more likely explanation is they have already had it, and are immune when exposed again. Some cases of chicken pox, especially in young children, are very mild and if no or only one or two blisters occur the illness may not be recognised by parents for what it is. One British study showed almost 90% of adults who reported no history of chicken pox were antibody positive, meaning they’d been infected in the past.
Antibody testing isn’t routinely needed, but if your older children have been in contact with cases of chicken pox in the past and not developed a rash this time the most likely explanation is they’ve already had the illness. This is good news, as chicken pox tends to be a more unpleasant illness in adults.

