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Volume 18, Number 10—October 2012

Dispatch

Scarlet Fever Epidemic, Hong Kong, 2011

Emma Y.Y. LukComments to Author , Janice Y.C. Lo, Amy Z.L. Li, Michael C.K. Lau, Terence K.M. Cheung, Alice Y.M. Wong, Monica M.H. Wong, Christine W. Wong, Shuk-kwan Chuang, and Thomas Tsang
Author affiliations: Centre for Health Protection, Hong Kong, People’s Republic of China

Main Article

Table 1

Epidemiologic characteristics, clinical features, and laboratory results for scarlet fever cases reported in Hong Kong during January–July 2011 compared with cases reported during 2008–2010

Characteristic* 2008–2010, n = 550 January 1–July 31, 2011, n = 996 p value
Epidemiology

Sex ratio, M:F

1.6:1 1.5:1 0.50

Age range (median)

9 mo–40 y (5 y) 1 mo–51 y (6 y) 0.40

Local cases

98.0 (539/550) 97.4 (970/996) 0.56
Clustering

Cases in a cluster

5.45 (30/550) 14.4 (143/996) <0.0001†

Cases in home clusters

3.3 (18/550); 9 clusters 6.5 (65/996); 31 clusters

Cases in each home cluster, range (median)

2 (2) 2–3 (2) 0.34

Cases in school clusters

2.2 (12/550); 4 clusters 7.8 (78/996); 28 clusters

Persons affected in each school cluster, no. (median)

2–4 (3) 2–7 (2) 0.42
Clinical features

Fever

95.6 (526/548) 93.2 (928/996) 0.065

Sandpaper rash

97.4 (534/548) 95.4 (950/996) 0.13

Strawberry tongue

45.1 (248/550) 51.4 (512/996) 0.020‡

Sore throat

74.4 (409/550) 78.5 (782/996) 0.073

Desquamation

27.8 (153/550) 23.7 (236/996) 0.084

Hospitalization

63.9 (351/549) 56.6 (561/991) 0.005§

Duration of hospitalization, d (mean)

1– 25 (3.8) 1–33 (3.3) 0.005¶

Concomitant chickenpox

5.5 (30/550) 1.9 (19/996) 0.0002#

Complications**

0.73 (4/550) 0.90 (9/996) 0.79

Toxic shock syndrome

0.18 (1/550) 0.60 (6/996) 0.43

Case-fatality rate

0 0.20 (2/996) 0.54
Laboratory results

Laboratory confirmation

46.0 (253/550) 51.8 (533/996) 0.0055††

Positive throat or wound culture

95.3 (241/253) 97.2 (521/533) 0.094

Antistreptolysin O titer >200 IU/mL

4.74 (12/253) 4.37 (12/533) 0.094

*Values are % (no./total no.) unless otherwise indicated. Lower denominators indicate data missing or not applicable.
†χ2 = 27.
‡χ2 = 5.40.
§χ2 = 7.85.
t = –2.8 (95% CI of difference 0.15–0.83 d).
2 = 14.
**Complications include toxic shock syndrome, septicaemia, parapharyngeal abscess, rheumatic fever, quinsy and hepatitis.
††χ2 = 7.7.

Main Article

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