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Prevalence of meningococcal meningitis in China from 2005 to 2010

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Junhong Li a , Yixing Li a , Zhujun Shao b , Li Li a , Zundong Yin a , Guijun Ning a , Li Xu b , Huiming Luo a,∗ a b

National Immunization Program Center, Chinese Center for Disease Control and Prevention, Beijing 10050, PR China National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 102206, PR China

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Article history: Received 5 September 2013 Received in revised form 15 October 2014 Accepted 23 October 2014 Available online xxx

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Keywords: Meningococcal meningitis Epidemiology Prevalence China.

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1. Introduction

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Background: We aimed to estimate the prevalence and epidemiologic characteristics of meningococcal meningitis (MM) in mainland China (excluding Taiwan, Hong Kong, and Macau) and to provide reference data for controlling the outbreak and prevalence of MM. Methods: Data from the National Notifiable Diseases Registry System and the MM case information reporting system from 2005 to 2010 as well as data from the MM Surveillance System were used. Results: The morbidity of MM for the whole country was, on average, 0.09 cases per 100,000 (range 0.02 [2010]–0.18 [2005] cases per 100,000) from 2005 to 2010, the incidence rate was highest in the Xinjiang autonomous region (average 0.56 cases per 100,000), and the majority of cases came from Anhui province (average 0.32 cases per 100,000). Morbidity was highest in children under 1 year old (average 0.60 cases per 100,000). The proportion of laboratory-confirmed cases of serogroups A, B, and C were 37.2, 11.5 and 42.7, respectively, from 2005 to 2010. Conclusions: The incidence level declined year-to-year in mainland China. Children and students are the most at risk groups. The proportion of serogroup C cases has increased year-to-year, and new cases of serogroup W135 have been found. Controlling the epidemic of serogroup C and preventing outbreaks of serogroup B and W135 represent major future challenges. © 2014 Published by Elsevier Ltd.

China has a high incidence of meningococcal meningitis (MM), with five pandemics recorded, once every 8 or 10 years [1,2]. The highest incidence of MM in China’s history occurred in the spring of 1967. The morbidity reached a rate of 403 cases per 100,000, with more than 3.04 million cases, greater than 160,000 deaths, and a 5.5% fatality rate [3], with a high prevalence of cases both in the city and the countryside. The next pandemic, in 1977, had a morbidity of 59.7 cases per 100,000 and a 4.0% fatality rate. Deaths from MM represented 60% of all deaths reported by the National Notifiable Diseases Registry System (NNDRS) in that year. The incidence level was highest in the provinces of middle and south China, followed by those of northeast and north China [3,4]. A serogroup meningococcal polysaccharide vaccine (MPV) was approved for use in China in 1980, and a vaccination coverage of 93.6% was reached. The Ministry of Health (MOH) of the People’s

∗ Corresponding author at: Epidemiology/Control and Prevention of Infectious Disease, National Immunization Program Center, 27 Nanwei Road, Xicheng District, Beijing 100050, PR China. Tel.: +86 1083159510. E-mail address: [email protected] (H. Luo).

Republic of China instituted a policy of widespread MPV vaccination for children. The incidence level of MM in China has shown a declining trend year-to-year, and the epidemic periodicity, the occurrence of an MM epidemic every 10 years, has disappeared following the continuous improvements in the living conditions and the health of the population [2,3]. Until the 1990s, the morbidity of MM was maintained under 1 case per 100,000, and the rate declined to 0.2 cases per 100,000 [5]. The incidence declined remarkably yearto-year, through prevention and control, to a rate of 0.09 cases per 100,000. Local outbreaks and epidemics were highly sporadic throughout the country [5,6]. MM in China occurs mainly in the winter and spring; the reported cases increase from October and reach a peak in March–April of the next year, which implies that this is an epidemic season [3,5]. Neisseria meningitidis (Nm) serogroup A has always been the dominant strain in China, with sporadic cases of Nm serogroup B and other groups [7]. Since 2004, the proportion of cases of the Nm serogroup C has increased alongside a declining trend in cases of Nm serogroup A [6,8]. At present, most provinces have detected cases of Nm serogroup C and isolated the strain, and this has increasingly become the dominant strain in some

http://dx.doi.org/10.1016/j.vaccine.2014.10.072 0264-410X/© 2014 Published by Elsevier Ltd.

Please cite this article in press as: Li J, et al. Prevalence of meningococcal meningitis in China from 2005 to 2010. Vaccine (2014), http://dx.doi.org/10.1016/j.vaccine.2014.10.072

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provinces. Recently, several new cases of Nm serogroup W135 have been reported. The data from the National Notifiable Diseases Registry System (NNDRS) show that the number of deaths and the fatality rate from MM were at the top of the respiratory infectious disease category. Although in relative terms, the number of cases of MM is low, the higher fatality rate and large number of sequelae lead to a serious disease burden for families and society. This article describes and analyses the incidence, prevalence, and challenges faced from MM in mainland China during the period from 2005 to 2010.

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2. Methods

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2.1. Data sources

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MM is a disease that is classified by law in mainland China. Both clinically confirmed and laboratory-confirmed MM cases are reported in the NNDRS; in place since the 1950s, this system reports basic epidemiologic data, including age, sex, date of disease onset, and residence of all clinically diagnosed MM cases. Hospitals report cases by posting a card to the county Center for Disease Control, and then the data are aggregated and submitted by the Center for Disease Control through prefecture and provincial Centers for Disease Control to reach the national level. In addition to the NNDRS, to promote MM control, the MOH developed national MM surveillance guidelines from 2005 and established a case-based MM Surveillance System (MMSS) in all provinces; this is parallel to the NNDRS, and detailed laboratory data of MM cases are reported by every province through the MMSS. Even so, the NNDRS remains the official source of data regarding the number of reported MM cases. We collected and analysed the reported MM incidence and mortality by time, place, and person based on the data from the NNDRS using denominators from the National Bureau of Statistics [9]. We used laboratory data from the MMSS for the period from 2005 to 2010 to analyse the serogroup distribution, variance, and proportion of MM cases. Data on healthy carriage was also derived from the MMSS; pharyngeal swabs were collected from the healthy population to detect carriage. Whole-population surveys of Nm carriage were periodically carried out for outbreak investigation, surveillance, and research. Epidemiologic analyses only included clinically confirmed and laboratory-confirmed MM cases. The data on the vaccine coverage rate was from the routine national Expanded Program on Immunization (EPI) system.

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2.2. MM case definition

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The national MM surveillance guidelines published by the MOH use the same case definition of MM as the Diagnostic Criteria for Epidemic Cerebrospinal Meningitis of Health Industry Standard of the People’s Republic of China (WS295-2008) [10], which was implemented nationally and combined with the epidemiologic history, clinical features, and results of the laboratory examination. (1) Suspected/possible cases: onset during the epidemic season of MM with clinical features of fever, headache, vomiting, and signs of meningeal irritation. Laboratory blood shows increased WBCs and neutrophil leukocytes; the appearance of cerebrospinal fluid (CSF) was purulent, pressure increased, WBCs increased significantly and were dominated by polykaryocytes, sugar and chlorides in the CSF decreased significantly; and protein levels in the CSF increased. (2) Clinical/probable cases: based on suspected case diagnosis and the simultaneous presence of a petechial rash or ecchymosis. (3) Laboratory-confirmed cases: based on suspected cases or clinical case diagnoses, with the following pathogenic evidence or serum immunological evidence: Gram-negative kidney-like diplococci could be found inter-neutrophil in the smear of a petechial rash

Fig. 1. Prevalence curve of meningococcal meningitis (MM) in China from 2005 to 2010. *The cases include both fatal and non-fatal cases.

(ecchymosis) tissue, fluids, or CSF; the culture of CSF or blood showed positive diplococci meningococcus; a specific fragment of nucleic acid of diplococci meningococcus was detected; an Nm group-specific polysaccharide antigen was detected from the CSF or blood during the acute period; a serum-specific antibody was detected during the convalescent stage; and the titre increased four times or more compared with that of the acute stage. 2.3. Clustering cases definition We defined a clustering case as one that corresponded with any of the following conditions: two or more MM cases found within 7 days in a village, school, or other collective unit; three or more cases occurring within 14 days in a township; if five or more cases detected in a county within 1 month. 2.4. Statistical analysis Microsoft Excel 2007 was used for data entry and statistical analysis, and MapInfo 7.0 was used to prepare distribution maps.

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3. Results

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3.1. Incidence level

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Since MM serogroup C became epidemic in Anhui province from 2004 to 2005, the prevention, control, and surveillance for MM have been enhanced in mainland China. From 2005 to 2010, the total number of reported cases of MM was 7057, of which 23.9% were laboratory confirmed, and the total number of deaths was 702, of which 22.6% were laboratory confirmed. The reported morbidity was on average 0.09 cases per 100,000 (range 0.02 [2010]–0.18 [2005] cases per 100,000), and the reported mortality was on average 0.009 deaths per 100,000 (range 0.003 [2010]–0.02 [2005] cases per 100,000). The morbidity in 2010 declined by 88.9% compared with that in 2005 and by 48.9% compared with that in 2009 (Fig. 1). The average fatality rate was 10.39% (range 11.9 [2008]–8.9% [2005]). 3.2. Seasonal characteristics From 2005 to 2010, most cases were reported from February to April, a few cases occurred from May to October, and there was an observable increase in cases beginning in November. In the peak prevalence from February to April during 2005–2010, the total number of reported cases reached an average of 670 (range 163 [2010]–1447 [2005]), representing 55.3% (49.8 [2007]–62.4% [2005]) of all cases from January to December (Fig. 2).

Please cite this article in press as: Li J, et al. Prevalence of meningococcal meningitis in China from 2005 to 2010. Vaccine (2014), http://dx.doi.org/10.1016/j.vaccine.2014.10.072

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A total of 31 provinces, autonomous regions, and municipalities directly under the Central Government reported MM cases (Fig. 3). Most cases were distributed in Anhui, Xinjiang, Guizhou, Hebei, and Sichuan; the cases reported in these five provinces represented 44.8% of the cases from the whole country. The three provinces with the highest reported incidence rates were Xinjiang, Anhui, and Guizhou, with incidence rates on average of 0.56 cases per 100,000 (range 0.13 [2010]–1.15 [2007] cases per 100,000), 0.32 cases per 100,000 (range 0.10 [2010]–0.43 [2004] cases per 100,000), and 0.26 cases per 100,000 (range 0.05 [2010]–0.58 [2007] cases per 100,000), respectively.

3.4. Age and occupation distribution Fig. 2. Epidemic curve of meningococcal meningitis (MM) for the epidemic seasons in China from 2005 to 2010.

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3.3. Area of distribution Historically, the areas of highest incidence were in the middle, east, and south of China [3,4]. In recent years, most reported cases occurred in the northwest and southwest of China, with a lower incidence in the middle and east of China. Areas of economic underdevelopment and weak vaccine coverage face an increased risk from MM.

The incidence rates in all age groups showed a declining trend, and in the young age group it decreased greatly. The incidence rate was higher in children (a child is

Prevalence of meningococcal meningitis in China from 2005 to 2010.

We aimed to estimate the prevalence and epidemiologic characteristics of meningococcal meningitis (MM) in mainland China (excluding Taiwan, Hong Kong,...
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