Cases rose by 1,049 in a week to a total of 7,198 since September, according to figures for 31 March to 6 April.
England is experiencing the highest weekly levels of scarlet fever in 30 years. GPs have already been warned to prepare for any uncommon complications, which can be fatal.
Now, Public Health England has released a template letter for GPs to warn colleagues about local outbreaks.
The letter lists the signs and symptoms of scarlet fever; reminds GPs of the complications, including an added risk of invasive group A streptococcus; and advises on testing and antibiotic treatment.
Similar template letters for schools and nurseries encourage parents to contact their GP if they suspect scarlet fever in their child.
Eight in 10 cases reported this season have been in children under 10 years old. Rates are highest in the East Midlands, with 30.5 cases per 100,000 population compared with the England average of 13.5.