RESUMO
Objective To identify the risk factors for reported sudden rise of measles incidence in November,2011,in some areas of Hubei province.Methods We analyzed all measles patients reported in the measles surveillance system from November 2011 to February 2012 in two prefectures with highest attack rates and their vaccination history by reviewing vaccination records.We interviewed patients' parents by telephone to obtain the history of visiting health care within 7 to 21 days before onset.We also used case-crossover study to estimate the relative risk (RR) of hospital acquired infection and to compare the exposure to health care between 7-21 days before onset to 37-51 days before onset among measles patients.Results Totally 140 patients were reported in the two prefectures.Reported measles incidence rates among the population aged ＜8 m (69/100 000) and 8 m to 17 m (72/100 000) were higher than other age groups (rang from 0 to 5.8 per 100 000).Among the population aged 8 m to 17 m,estimated vaccination coverage was lower than 75％,and it was lower than 90％ among those aged 18 m to 3 yrs.During 7-21 days before onset,58％(29/50) of the patients had an exposure to health care settings,compared to 14％ (7/50) of patients during 37 to 51 days before onset (MH RR=5.4,95％ confidence interval=2.1-14.0).Conclusion Under the condition of measles vaccination coverage lower than 95％,iatrogenic infection was a risk factor for measles in Hubei.