Report and analysis of a scarlet fever outbreak among adults through food-borne transmission in China.
BACKGROUND
Scarlet fever is caused by group A beta-hemolytic streptococci (GAS). The clinical syndrome has receded in recent years, but occasionally explosive outbreaks do occur likely due to the emergence of GAS with virulence factors peculiar to this syndrome.


METHODS
Following the notification of an unexpectedly large number of scarlet fever cases amongst adults associated with a school in Ningbo, China, in June 2006, the epidemiological and clinical features of the outbreak were investigated. Logistic regression was conducted to investigate the risk factors of the outbreak and its transmission route.


RESULTS
Forty five individuals suffered scarlet fever with an attack rate of 4.98% (45/904). There was a single peak in the epidemic curve, with the majority of the cases occurring during the first two days of the outbreak. The median age of cases was 35.5 years (range 17-65). Most patients had fever (43/45), sore throat (40/45), scarlatinoid rash (39/45) and strawberry-like tongue (30/45). In laboratory detection, 45 cases' throat swabs samples were collected and GAS were isolated from 8 throat swabs samples. All of the cases, except for 2, had eaten the Plain Boiled Chicken (PBC) for lunch on June 6th, and teaching staff and students who had not eaten the PBC were not affected by the epidemic. Logistic regression analysis indicated that PBC was a key risk factor (OR=21.0, P<0.05). The chef of the school refectory was responsible for washing, braising, cutting, and distributing the PBC, and was identified as the likely source.


CONCLUSIONS
We describe an outbreak of scarlet fever caused by GAS-contaminated food.
Yang
Shi-Gui
SG
Key Laboratory of Infectious Diseases, Ministry of Health of China, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310003, China.
Dong
Hong-Jun
HJ
Li
Fu-Rong
FR
Xie
Shu-Yun
SY
Cao
Hong-Cui
HC
Xia
Shi-Chang
SC
Yu
Zhao
Z
Li
Lan-Juan
LJ
D000293:Adolescent; D000328:Adult; D000368:Aged; D000818:Animals; D002645:Chickens; D002681:China / Q000453:epidemiology; D004196:Disease Outbreaks; D005260:Female; D005506:Food Contamination; D005516:Food Microbiology; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D010614:Pharynx / Q000382:microbiology; D012307:Risk Factors; D012541:Scarlet Fever / Q000453:epidemiology* / Q000503:physiopathology / Q000635:transmission*; D013297:Streptococcus pyogenes / Q000302:isolation & purification*; D014059:Tongue / Q000473:pathology