Parents are being urged to check their child is fully vaccinated after a boy died from diphtheria in London.
The Health Protection Agency said the boy was not immunised against the disease, which can cause membranes in the throat to detach and obstruct the airways, causing suffocation.
The boy is the first to die from the C diphtheriae strain in England and Wales since 1994, while between 1986 and 1997, there were eight cases of diphtheria caused by C diphtheriae.
The HPA said that the few isolated cases seen are usually in unvaccinated people who have travelled to countries where the disease is still common.
Professor Peter Borriello from the HPA said: "It is rare for people to die from diphtheria as severe infection is prevented by immunisation and the majority of children are routinely immunised against diphtheria in the UK.
"We recommend that if people are not up to date with their routine immunisations, they should contact their GP to arrange them."
Symptoms of diphtheria include a sore throat, fever and swollen lymph glands in the neck. More severe symptoms, including heart failure and paralysis, can occur if the diphtheria is caused by a strain that produces toxins.