An outbreak following importation of wild poliovirus in Xinjiang Uyghur Autonomous Region, China, 2011.

BACKGROUND: After more than 10 years without a case of wild poliovirus (WPV) in China, an outbreak occurred in 2011 in Xinjiang Uyghur Autonomous Region. METHODS: Acute flaccid paralysis (AFP) case surveillance was strengthened with epidemiological investigations and specimen collection and serological surveys were conducted among hospitalized patients. RESULTS: There were 21 WPV cases and 23 clinical compatible polio cases reported. WPV was isolated from 14 contacts of AFP cases and 13 in the healthy population. Incidence of WPV and clinical compatible polio cases were both highest among children <1 years, however, 24/44 (54.5%) polio cases were reported among adults aged 15-39 years. CONCLUSIONS: High coverage of routine immunization should be maintained among children until WPV transmission is globally eradicated. Expansion of AFP case surveillance and use of serologic surveys to estimate population immunity should be conducted rapidly to guide preparedness and response planning for future WPV outbreaks.

Sero-survey of polio antibodies during wild poliovirus outbreak in southern Xinjiang Uygur Autonomous Region, China.

BACKGROUND: After being polio free for more than 10 years, an outbreak following importation of wild poliovirus (WPV) was confirmed in Xinjiang Uygur Autonomous Region, China, in 2011. METHODS: A cross-sectional study was conducted prior to supplementary immunization activities (SIAs), immediately after the confirmation of the WPV outbreak. In selected prefectures, participants aged ≤ 60 years old who visited hospitals at county-level or above to have their blood drawn for reasons not related to the study, were invited to participate in our study. Antibody titers ≥ 8 were considered positive. RESULTS: Among the 2,611 participants enrolled, 2,253 (86.3%), 2,283 (87.4%), and 1,989 (76.2%) were seropositive to P1, P2 and P3 respectively, and 1744 (66.8%) participants were seropositive to all the three serotypes. Lower antibody seropositivities and geometric mean titers were observed in children <1 year of age and in adults aged 15-39 years. CONCLUSION: Serosurveys to estimate population immunity in districts at high risk of polio importation might be useful to gauge underlying population immunity gaps to polio and possibly to guide preparedness and response planning. Consideration should be given to older children and adults during polio risk assessment planning and outbreak response.

Identification and control of a poliomyelitis outbreak in Xinjiang, China.

BACKGROUND: The last case of infection with wild-type poliovirus indigenous to China was reported in 1994, and China was certified as a poliomyelitis-free region in 2000. In 2011, an outbreak of infection with imported wild-type poliovirus occurred in the province of Xinjiang. METHODS: We conducted an investigation to guide the response to the outbreak, performed sequence analysis of the poliovirus type 1 capsid protein VP1 to determine the source, and carried out serologic and coverage surveys to assess the risk of viral propagation. Surveillance for acute flaccid paralysis was intensified to enhance case ascertainment. RESULTS: Between July 3 and October 9, 2011, investigators identified 21 cases of infection with wild-type poliovirus and 23 clinically compatible cases in southern Xinjiang. Wild-type poliovirus type 1 was isolated from 14 of 673 contacts of patients with acute flaccid paralysis (2.1%) and from 13 of 491 healthy persons who were not in contact with affected persons (2.6%). Sequence analysis implicated an imported wild-type poliovirus that originated in Pakistan as the cause of the outbreak. A public health emergency was declared in Xinjiang after the outbreak was confirmed. Surveillance for acute flaccid paralysis was enhanced, with daily reporting from all public and private hospitals. Five rounds of vaccination with live, attenuated oral poliovirus vaccine (OPV) were conducted among children and adults, and 43 million doses of OPV were administered. Trivalent OPV was used in three rounds, and monovalent OPV type 1 was used in two rounds. The outbreak was stopped 1.5 months after laboratory confirmation of the index case. CONCLUSIONS: The 2011 outbreak in China showed that poliomyelitis-free countries remain at risk for outbreaks while the poliovirus circulates anywhere in the world. Global eradication of poliomyelitis will benefit all countries, even those that are currently free of poliomyelitis.

[Analysis of prevalence season and trend of meningococcal disease by circular distribution in China].

OBJECTIVE: To analyze the prevalence season and trend of meningococcal disease in China by epidemic years from 2004 to 2008 in order to provide scientific basis for making strategies ofmeningococcal disease prevention and control. METHODS: The incidence numbers of meningococcal disease were calculated by weeks, epidemic years and areas. The seasonality and prevalence trends of meningococcal disease were analyzed by circular distribution. RESULTS: The incidence trend of meningococcal disease had obvious seasonality in China (P < 0.01). The peak of meningococcal disease were different by epidemic years and areas (P < 0.01). There were no association between annual incidence rates and seasonality. CONCLUSIONS: We should strength meningococcal disease surveillance before epidemic peak period,and put immunoprophylaxis first and carry out comprehensive measures of prevention and control.

[Estimation on the level of birth and death rates of population in the three gorges area by means of capture-mark-recapture method].

OBJECTIVE: To evaluate quality of surveillance and emendate rates of birth and death of population of the Three Gorges area. METHODS: Data on the two samples collected were designed based on principle of capture-recapture method. An investigation of missing report of birth and death was conducted in 7061 families selected through stratified random sampling method. We collected and registered the data of birth and death in every family investigated and checked with correlative records reported in disease surveillance system of the Three Gorges area. The missing report rates and the 95% confidence intervals of birth rate and death rate were calculated. RESULTS: The underreporting rates of birth and death were 13.91% and 15.60% and death of infant was 33.33%. The emended birth rate was 8.92 per thousandth and the 95% confidence interval of birth rate was 8.38 per thousandth-9.45 per thousandth. The emended report rate of death was 6.88 per thousandth and the collectivity 95% confidence interval was 6.37%-7.38 per thousandth. CONCLUSION: Results showed that the quality of birth and death in the disease surveillance reporting system of Three Gorges area was competent to the quality level of the standard set for national disease surveillance system. The birth and death rates of population in the Three Gorges area were under 10.00 per thousandth.