Scarlet fever has exhibited an “unprecedented” resurgence in England since 2014, with incidence rates in the country at a 50-year high, according to findings recently published in The Lancet Infectious Diseases.
The illness was previously one of many diseases that had declined steadily throughout the last century without the aid of antibiotics.
“Whilst current rates are nowhere near those seen in the early 1900s, the magnitude of the recent upsurge is greater than any documented in the last century,” Theresa Lamagni, PhD, epidemiologist with Public Health England, told Infectious Disease News.
The law in the U.K. requires medical practitioners to notify authorities whenever certain diseases are diagnosed. Scarlet fever has remained on the list of notifiable diseases despite the steady decrease in cases.
“Within this context of overall diminishing incidence of scarlet fever, a sudden rise was noted during 2014, with early indications suggesting a doubling in case numbers across England, Wales and Northern Ireland,” Lamagni and colleagues wrote.
The researchers performed a population-based surveillance study, evaluating scarlet fever notifications in England and Wales from 1911 to 2016. Lamagni and colleagues assessed the characteristics of cases and outbreaks, such as the frequency of hospital admissions and complications, as well as isolates from throat swabs.
Rates of scarlet fever increased from 8.2 cases per 100,000 population in 2013 to 27.2 per 100,000 in 2014, the researchers reported (rate ratio, 3.34; 95% CI, 3.23-3.45). Rates increased again in 2015, to 30.6 cases per 100,000, and once more in 2016, to 33.2 per 100,000. That same year, the country saw 19,206 cases — the highest since 1967.
Young children were hit particularly hard. Patients had a median age of 4 years in 2014, and the incidence among children aged younger than 10 years was 186 per 100,000, Lamagni and colleagues wrote.
The incidence of scarlet fever rose in every part of England, the researchers said, with 620 reported outbreaks in 2016. Between 2013 and 2016, hospital admissions for scarlet fever rose by 97%. One in every 40 patients was admitted for management of either the condition or possible complications, Lamagni and colleagues wrote.
When the researchers analyzed a total of 303 strains, they reported multiple emm types, with emm3 (43%), emm12 (15%), emm1 (11%) and emm4 (9%) being the most common.
They also wrote that “the magnitude of the recent upsurge in scarlet fever was unique, suggesting the current phenomenon is not explained by the usual cyclical patterns in disease incidence.”
“Notifications so far for 2017 suggest a slight decrease in numbers, but we continue to monitor the situation carefully,” Lamagni said. “Guidance on management of outbreaks in schools and nurseries has just been updated, and research continues to further investigate the rise. We encourage parents to be aware of the symptoms of scarlet fever and to contact their general practitioner if they think their child might have it.”
In an accompanying editorial, Mark J. Walker, PhD, and Stephan Brouwer, PhD, both from The University of Queensland, Brisbane, Australia, wrote that the upswing in the U.K. mirrored increases in northeast Asia, particularly one in Hong Kong. Both outbreaks have shown low mortality.
“Further research needs to be done to better understand the causes of scarlet fever resurgence,” Walker and Brouwer wrote. “Scarlet fever epidemics have yet to abate in the U.K. and northeast Asia. Thus, heightened global surveillance for the dissemination of scarlet fever is warranted.” – by Andy Polhamus
Editor’s note: This article has been updated with the correct rate of scarlet fever in 2015. The editors regret the error.
Disclosures: The authors report no relevant financial disclosures.