Dong-liang Zhang1, Jin-ren Pan2, Shu-yun Xie3, Yang Zhou2, Ling-zhi Shen2, Guo-zhang Xu4, Tao Zhang4, Rui Ma4, Zhong Ye5, Jian-rong Xu5. 1. Ningbo Municipal Center for Disease Control and Prevention, Ningbo City, Zhejiang Province, People's Republic of China; Chinese Field Epidemiology Training Program, Chinese Center for Disease Control and Prevention, Beijing, People's Republic of China. 2. Zhejiang Province Center for Disease Control and Prevention, Hangzhou City, Zhejiang Province, People's Republic of China. 3. Zhejiang Province Center for Disease Control and Prevention, Hangzhou City, Zhejiang Province, People's Republic of China. Electronic address: shyxie@cdc.zj.cn. 4. Ningbo Municipal Center for Disease Control and Prevention, Ningbo City, Zhejiang Province, People's Republic of China. 5. Xiangshan District Center for Disease Control and Prevention, Ningbo City, Zhejiang Province, People's Republic of China.
Abstract
BACKGROUND: An outbreak of measles occurred in early 2014 among individuals not targeted for vaccination-adults, and infants too young to vaccinate, in Xiangshan County, Zhejiang Province, in eastern China. OBJECTIVE: We conducted an investigation to identify risk factors responsible for this outbreak and to provide evidence-based recommendations for measles elimination strategies in China. METHODS: Measles was diagnosed using national standard case definitions. In a case-control study, 20 randomly selected measles patients were matched with controls selected from the same village or community as each case in a 1:2 case-to-control ratio. Controls were matched on age, within 5 years, and gender. We compared exposure histories during the 7-21 days before rash onset of the case and the same time period for the matched controls. We also conducted a measles antibody seroprevalence survey of a convenient sample of residual serum obtained from healthy patients during routine care in a hospital. RESULTS: The outbreak consisted of 45 measles cases, with an attack rate of 8.9/100,000 total population. Among cases, 91.1% (41/45) were adults (ranged 23-51 years) who had unknown vaccination histories; the other cases were infants younger than 8 months of age. The case-control study showed major risk factors to be a visit to Hospital X (OR(MH)=7.3, 95% CI: 1.8-30.7) and treatment in an IV room in Hospital X (OR(MH)=11.0, 95% CI: 1.3-96.1). The seroprevalence survey showed that 88.8% of adults had measles IgG antibodies, and that 100% of children 2-19 years of age were seropositive. CONCLUSIONS: The outbreak was primarily among age groups not targeted for vaccination-primarily adults, but with some children too young to vaccinate. Visiting a hospital was the major risk factor for measles transmission. We conclude that in addition to maintaining high 2-dose coverage with measles vaccine, working with hospital infection control programs to implement evidence-based strategies to prevent or limit hospital transmission is an important action for eliminating measles in eastern China.
BACKGROUND: An outbreak of measles occurred in early 2014 among individuals not targeted for vaccination-adults, and infants too young to vaccinate, in Xiangshan County, Zhejiang Province, in eastern China. OBJECTIVE: We conducted an investigation to identify risk factors responsible for this outbreak and to provide evidence-based recommendations for measles elimination strategies in China. METHODS: Measles was diagnosed using national standard case definitions. In a case-control study, 20 randomly selected measles patients were matched with controls selected from the same village or community as each case in a 1:2 case-to-control ratio. Controls were matched on age, within 5 years, and gender. We compared exposure histories during the 7-21 days before rash onset of the case and the same time period for the matched controls. We also conducted a measles antibody seroprevalence survey of a convenient sample of residual serum obtained from healthy patients during routine care in a hospital. RESULTS: The outbreak consisted of 45 measles cases, with an attack rate of 8.9/100,000 total population. Among cases, 91.1% (41/45) were adults (ranged 23-51 years) who had unknown vaccination histories; the other cases were infants younger than 8 months of age. The case-control study showed major risk factors to be a visit to Hospital X (OR(MH)=7.3, 95% CI: 1.8-30.7) and treatment in an IV room in Hospital X (OR(MH)=11.0, 95% CI: 1.3-96.1). The seroprevalence survey showed that 88.8% of adults had measles IgG antibodies, and that 100% of children 2-19 years of age were seropositive. CONCLUSIONS: The outbreak was primarily among age groups not targeted for vaccination-primarily adults, but with some children too young to vaccinate. Visiting a hospital was the major risk factor for measles transmission. We conclude that in addition to maintaining high 2-dose coverage with measles vaccine, working with hospital infection control programs to implement evidence-based strategies to prevent or limit hospital transmission is an important action for eliminating measles in eastern China.
Authors: Abram L Wagner; Matthew L Boulton; Brenda W Gillespie; Ying Zhang; Yaxing Ding; Bradley F Carlson; Xiaoyan Luo; JoLynn P Montgomery; Xiexiu Wang Journal: PLoS One Date: 2017-09-26 Impact factor: 3.240