Disease surveillance in China
Encyclopedia
Surveillance for communicable diseases is the main public health
surveillance activity in China
. Currently, the disease surveillance system in China has three major components:
There are 35 notifiable infectious diseases, which are divided into Classes A, B, and C. The functions of the surveillance include explaining the natural history of infectious diseases, describing the distribution of case occurrence, triggering disease-control effort, monitoring epidemic of infectious diseases during natural disasters
, predicting and controlling epidemics and providing the base of policy adjustment.
Data collected through the disease surveillance network serve as the basis for formulating health policies and devising strategies for preventing disease. A computerized reporting system for notifiable diseases has been established that links China's 30 provinces, autonomous regions, and municipalities. Mechanisms for providing timely feedback to units that report data and for systematically assessing the quality of those data are important attributes of this system.
In 1987, a Nationwide Antiepidemic Computer Telecommunication Network (NATCN) was established as an official information system for the National Disease Reporting System (NDRS). The Ministry of Public Health and the provincial centers of health and epidemic prevention support this network, which monitors disease epidemic
s at various levels within the public health system. As technical facilities of the network improve, use of the NACTN will expand into all aspects of public health surveillance.
communication network. The purpose was to link all the country's provincial centers of health and epidemic prevention in an effort to improve the system for preventing epidemics. After a year was spent establishing and modifying the system, a network that connected the capitals of 30 provinces, autonomous regions, and municipalities began operating in 1987. The primary function of the network was to collect data on the morbidity and mortality associated with reportable communicable diseases, to obtain information on outbreak
s of other types of disease, and to provide monthly and annual reports to local and national health authorities.
and Health Statistics compiles and analyzes the data, provides feedback to the provinces, and creates national summaries within one week. Copies of the MMMR are distributed regularly to health authorities at various levels.
reports to revise and update the monthly reports submitted during the previous year. Age
- and occupation
-specific reports of mortality and morbidity are also submitted at this time. In April, after the surveillance data have been reviewed at the national meeting on epidemic diseases, the MMAR and other analytical reports are distributed.
s with common analog telephone
lines had to be used. Making this large communication system run successfully posed major challenges. With some of the problems in mind, the system was designed to have strong fault-tolerant redundancy - with the capability for self-correction - to overcome the myriad of problems caused by poor-quality telephone lines and cumbersome telephone exchange
systems.
The NACTN was enhanced by incorporating the following functions.
In collaboration with the NACTN, a few provinces have established subnetworks to facilitate local communication.
. Because participation in the network was voluntary, the data collected were biased, even after attempts were made to adjust the sample to improve national representativeness. Persons covered by the DSPs tended to be from the upper-middle socioeconomic stratum.
In 1989, efforts were begun to select a new sample of surveillance points. We used stratified cluster random sampling to select 145 DSPs in 30 provinces, autonomous regions, and municipalities, which have a combined population structure similar to that shown in the national census. Data on individual births and deaths, as well as on infectious diseases and certain types of behaviors (e.g., tobacco smoking
), are recorded. At the household level, information on socioeconomic indicators, health-care conditions, and environmental factors is collected.
Information obtained from the DSPs is compared with data obtained from the National Disease Reporting System to enable policymakers to estimate more accurately the burden of morbidity and mortality associated with infectious disease. More importantly, policy makers can evaluate information from the DSPs in relation to the economic development, cultural background, and health-care-service use by the population covered by this surveillance system.
Data collected at DSPs:
Each month, data collected by the township hospitals and village prevention units are submitted to the country, which then conveys the information through the provincial centers to the Chinese Academy of Preventive Medicine. The Academy distributes monthly reports to the Ministry of Public Health, to provincial health authorities, and to all DSPs. An annual report is also published and distributed.
to address important and emerging public health issues. Issues to be addressed include a prospective study of the health consequences of smoking, an assessment of drinking-water quality and disease occurrence, an evaluation of the national "Expanded Program on Immunization
", and an epidemiologic study of hepatitis
. By selecting samples in this fashion, investigators can correlate data from these special studies with data routinely collected under the system of DSPs.
(QC) in association with data collection
(DC) has been an important component of disease-surveillance activities in China.
Monitoring morbidity from infectious disease during heavy flooding in 1991
When six provinces around the Yangtze River
were heavily flooded in 1991, the central government expressed serious concern about disease-prevention activities in these provinces. In response, experts were dispatched to the flooded area, and prevention guidelines were developed and distributed to the affected provinces. Simultaneously, a system for collecting daily reports of disease activity was established. Every 3 days, DSP data on infectious disease morbidity were compared with data from previous years to identify potential outbreaks. For example, rates of hepatitis during the flood were compared with rates for the comparable time periods from the preceding 2 years. Data collected from June to October 1991 indicated that infectious diseases had been controlled effectively during the flood.
Forecasting the epidemiologic transition in China
In a study sponsored by the World Bank
, data collected in DSPs in the period 1986-1989 have been used to study the epidemiologic transition in China. Mortality from leading causes of death was projected for 2010 and 2030. After risk factors were assessed and the impact of preventive programs on these chronic diseases
was estimated, mortality rates were recalculated. These analyses were used to develop recommendations for program planning to the Ministry of Health.
Prediction and control of meningitis
After surveillance data on morbidity from meningitis
in China were reviewed by empirical analysis and Boyer's Theorem, it was predicted that morbidity from this disease would peak in 1984 or 1985. Additional analyses suggested that the vaccination program that had been conducted for several years, which provided vaccination only for children <12 months of age, would not be adequate to control the predicted upsurge in disease. Therefore, a new vaccination program was adopted that expanded coverage to all children <5 years of age in areas in which surveillance data (including serum
epidemiologic data) identified a high risk of meningitis outbreaks. The results in Henan Province suggested that the intensified vaccination coverage was successful in decreasing rates of meningitis.
Strategy for vaccination for poliomyelitis
After data from 1988 to 1989 on rates of poliomyelitis
and vaccination coverage were reviewed, high-risk areas were identified. In these areas, persons received supplementary vaccination in 1989-1990. By 1991, rates of poliomyelitis had begun to fall.
Journals
Public health
Public health is "the science and art of preventing disease, prolonging life and promoting health through the organized efforts and informed choices of society, organizations, public and private, communities and individuals" . It is concerned with threats to health based on population health...
surveillance activity in China
People's Republic of China
China , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres...
. Currently, the disease surveillance system in China has three major components:
- National Disease Reporting System (NDRS): The system covers the entire population (1.3 billion persons) living in all the provinces, prefectures, and counties that make up mainland ChinaMainland ChinaMainland China, the Chinese mainland or simply the mainland, is a geopolitical term that refers to the area under the jurisdiction of the People's Republic of China . According to the Taipei-based Mainland Affairs Council, the term excludes the PRC Special Administrative Regions of Hong Kong and...
. Thirty-five communicable diseases are reportable under this system.
- Nationwide Disease Surveillance Points (DSPs): This surveillance system, comprising 145 reporting sites selected by stratifiedStratified samplingIn statistics, stratified sampling is a method of sampling from a population.In statistical surveys, when subpopulations within an overall population vary, it is advantageous to sample each subpopulation independently. Stratification is the process of dividing members of the population into...
clusterCluster samplingCluster Sampling is a sampling technique used when "natural" groupings are evident in a statistical population. It is often used in marketing research. In this technique, the total population is divided into these groups and a sample of the groups is selected. Then the required information is...
random sampling, covers a 1% representative sample of China's population.
- Surveillance system for specific infectious diseases, occupational diseases, food poisoning, etc.
There are 35 notifiable infectious diseases, which are divided into Classes A, B, and C. The functions of the surveillance include explaining the natural history of infectious diseases, describing the distribution of case occurrence, triggering disease-control effort, monitoring epidemic of infectious diseases during natural disasters
Natural disasters in China
China is one of the countries most affected by natural disasters. It had 5 of the world's top 10 deadliest natural disasters; the top 3 occurred in China: the 1931 China floods, death toll 3 million to 4 million, the 1887 Yellow River flood, death toll 0.9 million to 2 million, and the 1556...
, predicting and controlling epidemics and providing the base of policy adjustment.
Data collected through the disease surveillance network serve as the basis for formulating health policies and devising strategies for preventing disease. A computerized reporting system for notifiable diseases has been established that links China's 30 provinces, autonomous regions, and municipalities. Mechanisms for providing timely feedback to units that report data and for systematically assessing the quality of those data are important attributes of this system.
National Disease Reporting System (NDRS)
In 1959, a system for reporting infectious diseases was established. Data collected at the village level are reported to prevention units in township hospitals. From the prevention units, data are transmitted through county health and epidemic-prevention stations to provincial centers and then on to the Chinese Academy of Preventive Medicine. Since 1977, the Ministry of Public Health has convened annual meetings to analyze these data on the morbidity and mortality associated with infectious diseases.In 1987, a Nationwide Antiepidemic Computer Telecommunication Network (NATCN) was established as an official information system for the National Disease Reporting System (NDRS). The Ministry of Public Health and the provincial centers of health and epidemic prevention support this network, which monitors disease epidemic
Epidemic
In epidemiology, an epidemic , occurs when new cases of a certain disease, in a given human population, and during a given period, substantially exceed what is expected based on recent experience...
s at various levels within the public health system. As technical facilities of the network improve, use of the NACTN will expand into all aspects of public health surveillance.
Computer Network Development
After receiving approval from the Ministry of Public Health in 1986, the Chinese Academy of Preventive Medicine (CAPM) began to establish a nationwide microcomputerMicrocomputer
A microcomputer is a computer with a microprocessor as its central processing unit. They are physically small compared to mainframe and minicomputers...
communication network. The purpose was to link all the country's provincial centers of health and epidemic prevention in an effort to improve the system for preventing epidemics. After a year was spent establishing and modifying the system, a network that connected the capitals of 30 provinces, autonomous regions, and municipalities began operating in 1987. The primary function of the network was to collect data on the morbidity and mortality associated with reportable communicable diseases, to obtain information on outbreak
Outbreak
Outbreak is a term used in epidemiology to describe an occurrence of disease greater than would otherwise be expected at a particular time and place. It may affect a small and localized group or impact upon thousands of people across an entire continent. Two linked cases of a rare infectious...
s of other types of disease, and to provide monthly and annual reports to local and national health authorities.
Morbidity and Mortality Monthly Reports (MMMR)
Each month, all provinces transmit county-level summaries of the numbers of cases and deaths associated with 35 notifiable communicable diseases to the Academy of Preventive Medicine. Reports are sent on the 13th to 15th day of each month via the NACTN. At the central node of NACTN, the Academy's Center of Computer ScienceComputer science
Computer science or computing science is the study of the theoretical foundations of information and computation and of practical techniques for their implementation and application in computer systems...
and Health Statistics compiles and analyzes the data, provides feedback to the provinces, and creates national summaries within one week. Copies of the MMMR are distributed regularly to health authorities at various levels.
Morbidity and Mortality Annual Report (MMAR)
Each January, all provinces provide supplementarySupplementary
The term supplementary can refer to a number of things:* Supplementary angles* Supplementary Benefit - a former benefit, payable in the United Kingdom* Supplementary questions asked during Prime Minister's Questions...
reports to revise and update the monthly reports submitted during the previous year. Age
Ageing
Ageing or aging is the accumulation of changes in a person over time. Ageing in humans refers to a multidimensional process of physical, psychological, and social change. Some dimensions of ageing grow and expand over time, while others decline...
- and occupation
Employment
Employment is a contract between two parties, one being the employer and the other being the employee. An employee may be defined as:- Employee :...
-specific reports of mortality and morbidity are also submitted at this time. In April, after the surveillance data have been reviewed at the national meeting on epidemic diseases, the MMAR and other analytical reports are distributed.
Computer Telecommunication of Surveillance Data: Technical Issues
Until the 1980s, no public digital communications system was available in China. In establishing the nationwide communication network, modemModem
A modem is a device that modulates an analog carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information. The goal is to produce a signal that can be transmitted easily and decoded to reproduce the original digital data...
s with common analog telephone
Plain old telephone service
Plain old telephone service is the voice-grade telephone service that remains the basic form of residential and small business service connection to the telephone network in many parts of the world....
lines had to be used. Making this large communication system run successfully posed major challenges. With some of the problems in mind, the system was designed to have strong fault-tolerant redundancy - with the capability for self-correction - to overcome the myriad of problems caused by poor-quality telephone lines and cumbersome telephone exchange
Telephone exchange
In the field of telecommunications, a telephone exchange or telephone switch is a system of electronic components that connects telephone calls...
systems.
The NACTN was enhanced by incorporating the following functions.
- BreakpointBreakpointIn software development, a breakpoint is an intentional stopping or pausing place in a program, put in place for debugging purposes. It is also sometimes simply referred to as a pause....
recording with resumption of operations: When telephone lines break during data transmission, the system is designed to record the break-point status for every case. This allows data transmission to resume automatically when line connections are reestablished.
- Automatic node scanning and re-circling: This feature allows the system to scan the status of all network nodes to allocate telephone lines and thereby optimize the strategy for maintaining line connections. This important mechanism improves the efficiency of the system and makes data transmission more successful.
- Automatic sorting/batching, rescheduling, and executing of transmissions: The system can execute all necessary network commands to carry out the communication task arranged by command files of the MMMR/MMAR system. The system adjusts the path as needed in order to complete transmissions that have been delayed because of problems in the system.
- Data compressionData compressionIn computer science and information theory, data compression, source coding or bit-rate reduction is the process of encoding information using fewer bits than the original representation would use....
and securityData securityData security is the means of ensuring that data is kept safe from corruption and that access to it is suitably controlled. Thus data security helps to ensure privacy. It also helps in protecting personal data. Data security is part of the larger practice of Information security.- Disk Encryption...
: Before transmission, data are processed by a "two-phase compressing" procedure. Data file size can be compressed more than 90%, resulting in shorter onlineONLINEONLINE is a magazine for information systems first published in 1977. The publisher Online, Inc. was founded the year before. In May 2002, Information Today, Inc. acquired the assets of Online Inc....
transmission times. Thus, receiving data from the 30 provincial reporting centers on the network requires only about an hour of online operation. Compression also makes data transmission more secure.
System Support for NACTN
- Personnel: In each province, the computer divisions have selected one or two persons who are dedicated to operating the province's nodes of the NACTN. In 1987, a working group convened to coordinate computer applications and activities. Several times each year, persons from provincial centers meet to discuss network problems and to devise solutions.
- Hardware and software: Special software has been developed: YQS for collecting and processing information and producing reports and TXS for managing network communications.
Future Developments of the NACTN
- Accumulating information
- Updating techniques
- Establishing subnetworks within provinces
In collaboration with the NACTN, a few provinces have established subnetworks to facilitate local communication.
Existing Databases
- National report on infectious disease
- National disease surveillance
- National report on occupational disease
- National report on outbreaks of food poisoning
- National survey data bases: Drinking water quality; Human-parasite infections; Nutritional surveys; Nutrition for the elderly; Child-nutrition surveillance; Diarrheal disease of children; Smoking and health.
National Disease Surveillance Points (DSPs)
In the period 1980-1989, the network of DSPs covered 29 provinces, autonomous regions, and municipalities that had a combined population of 10 million persons (<1% of China's population). When the network was proposed in 1978, it was not possible to obtain a population-based random sampleRandom sample
In statistics, a sample is a subject chosen from a population for investigation; a random sample is one chosen by a method involving an unpredictable component...
. Because participation in the network was voluntary, the data collected were biased, even after attempts were made to adjust the sample to improve national representativeness. Persons covered by the DSPs tended to be from the upper-middle socioeconomic stratum.
In 1989, efforts were begun to select a new sample of surveillance points. We used stratified cluster random sampling to select 145 DSPs in 30 provinces, autonomous regions, and municipalities, which have a combined population structure similar to that shown in the national census. Data on individual births and deaths, as well as on infectious diseases and certain types of behaviors (e.g., tobacco smoking
Tobacco smoking
Tobacco smoking is the practice where tobacco is burned and the resulting smoke is inhaled. The practice may have begun as early as 5000–3000 BCE. Tobacco was introduced to Eurasia in the late 16th century where it followed common trade routes...
), are recorded. At the household level, information on socioeconomic indicators, health-care conditions, and environmental factors is collected.
Information obtained from the DSPs is compared with data obtained from the National Disease Reporting System to enable policymakers to estimate more accurately the burden of morbidity and mortality associated with infectious disease. More importantly, policy makers can evaluate information from the DSPs in relation to the economic development, cultural background, and health-care-service use by the population covered by this surveillance system.
Data collected at DSPs:
- Household information: includes data on number of members, income, health-care situation, water supply, and toilet facilities.
- Individual information: includes data on occupation, education, births, deaths, episodes of infectious diseases, pregnancy, lactationLactationLactation describes the secretion of milk from the mammary glands and the period of time that a mother lactates to feed her young. The process occurs in all female mammals, however it predates mammals. In humans the process of feeding milk is called breastfeeding or nursing...
, feeding, and vaccinationVaccinationVaccination is the administration of antigenic material to stimulate the immune system of an individual to develop adaptive immunity to a disease. Vaccines can prevent or ameliorate the effects of infection by many pathogens...
status.
Each month, data collected by the township hospitals and village prevention units are submitted to the country, which then conveys the information through the provincial centers to the Chinese Academy of Preventive Medicine. The Academy distributes monthly reports to the Ministry of Public Health, to provincial health authorities, and to all DSPs. An annual report is also published and distributed.
Surveys and Investigations
Surveys and investigations are conducted by the DSPs to improve the quality and promote the use of data collected. These surveys and investigations are designed to generate information that can be used by policymakers. At present, the following activities are being undertaken:- Characterizing risk factors and patterns of death among adults;
- Identifying factors that influence the quality of data collected by DSPs;
- Developing methods to monitor Chronic diseases in ChinaChronic diseases in ChinaChronic diseases, non-communicable diseases now account for an estimated 80% of total deaths and 70% of disability-adjusted life years lost in China...
;
- Devising approaches to promote use of data from DSPs by policymakers.
Development of the Network of Disease Surveillance Points
Samples of persons already monitored under existing DSPs will be used for data collectionData collection
Data collection is a term used to describe a process of preparing and collecting data, for example, as part of a process improvement or similar project. The purpose of data collection is to obtain information to keep on record, to make decisions about important issues, to pass information on to...
to address important and emerging public health issues. Issues to be addressed include a prospective study of the health consequences of smoking, an assessment of drinking-water quality and disease occurrence, an evaluation of the national "Expanded Program on Immunization
Immunization
Immunization, or immunisation, is the process by which an individual's immune system becomes fortified against an agent ....
", and an epidemiologic study of hepatitis
Hepatitis
Hepatitis is a medical condition defined by the inflammation of the liver and characterized by the presence of inflammatory cells in the tissue of the organ. The name is from the Greek hepar , the root being hepat- , meaning liver, and suffix -itis, meaning "inflammation"...
. By selecting samples in this fashion, investigators can correlate data from these special studies with data routinely collected under the system of DSPs.
Surveillance of Specific Infectious diseases
The following are examples of surveillance for specific infectious diseases.- For each 10-day period during the summer, cases of choleraCholeraCholera is an infection of the small intestine that is caused by the bacterium Vibrio cholerae. The main symptoms are profuse watery diarrhea and vomiting. Transmission occurs primarily by drinking or eating water or food that has been contaminated by the diarrhea of an infected person or the feces...
- diagnosed by microbiologic or clinical criteria - from all the provinces, autonomous regions, and municipalities are reported to the national level; this information is compiled and conveyed back to the provincial reporting sources.
- In eight provinces, surveillance among subgroups of the population with elevated risk for infection with human immunodeficiency virus (HIV) is conducted at the national diagnostic laboratories by using immediate reports and confirmatory testing.
- A surveillance network for epidemic hemorrhagic fever has been established for immediate reporting of cases. During the peak season, surveillance for disease among rodentRodentRodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....
s is conducted to provide an early-warning system at the local level.
Quality control of data collection
Quality controlQuality control
Quality control, or QC for short, is a process by which entities review the quality of all factors involved in production. This approach places an emphasis on three aspects:...
(QC) in association with data collection
Data collection
Data collection is a term used to describe a process of preparing and collecting data, for example, as part of a process improvement or similar project. The purpose of data collection is to obtain information to keep on record, to make decisions about important issues, to pass information on to...
(DC) has been an important component of disease-surveillance activities in China.
- In November of each year, the NDRS actively surveys hospitals and households to identify the proportion of notifiable diseases that went unreported. During a recent year, for example, the proportion of class A and B infectious diseases that was unreported was 27%; this proportion was used to correct the total annual estimate of morbidity attributable to infectious diseases.
- Disease Surveillance Points (DSPs) are surveyed annually to estimate underreporting of births, deaths, and morbidity due to infectious diseases. From 1990 to 1991, for example, reporting of morbidity from infectious diseases improved. The proportions of unreported births, age-specific deaths, and disease-specific deaths are also reported. In 1991, a team from the Chinese Academy of Preventive Medicine evaluated the quality of data reported from 18 DSPs located in nine provinces. In their study, the evaluation team identified factors that influenced data quality.
Use of surveillance data for control of disease
Surveillance data have been used to implement and evaluate public health programs.Monitoring morbidity from infectious disease during heavy flooding in 1991
When six provinces around the Yangtze River
Yangtze River
The Yangtze, Yangzi or Cháng Jiāng is the longest river in Asia, and the third-longest in the world. It flows for from the glaciers on the Tibetan Plateau in Qinghai eastward across southwest, central and eastern China before emptying into the East China Sea at Shanghai. It is also one of the...
were heavily flooded in 1991, the central government expressed serious concern about disease-prevention activities in these provinces. In response, experts were dispatched to the flooded area, and prevention guidelines were developed and distributed to the affected provinces. Simultaneously, a system for collecting daily reports of disease activity was established. Every 3 days, DSP data on infectious disease morbidity were compared with data from previous years to identify potential outbreaks. For example, rates of hepatitis during the flood were compared with rates for the comparable time periods from the preceding 2 years. Data collected from June to October 1991 indicated that infectious diseases had been controlled effectively during the flood.
Forecasting the epidemiologic transition in China
In a study sponsored by the World Bank
World Bank
The World Bank is an international financial institution that provides loans to developing countries for capital programmes.The World Bank's official goal is the reduction of poverty...
, data collected in DSPs in the period 1986-1989 have been used to study the epidemiologic transition in China. Mortality from leading causes of death was projected for 2010 and 2030. After risk factors were assessed and the impact of preventive programs on these chronic diseases
Chronic diseases in China
Chronic diseases, non-communicable diseases now account for an estimated 80% of total deaths and 70% of disability-adjusted life years lost in China...
was estimated, mortality rates were recalculated. These analyses were used to develop recommendations for program planning to the Ministry of Health.
Prediction and control of meningitis
After surveillance data on morbidity from meningitis
Meningitis
Meningitis is inflammation of the protective membranes covering the brain and spinal cord, known collectively as the meninges. The inflammation may be caused by infection with viruses, bacteria, or other microorganisms, and less commonly by certain drugs...
in China were reviewed by empirical analysis and Boyer's Theorem, it was predicted that morbidity from this disease would peak in 1984 or 1985. Additional analyses suggested that the vaccination program that had been conducted for several years, which provided vaccination only for children <12 months of age, would not be adequate to control the predicted upsurge in disease. Therefore, a new vaccination program was adopted that expanded coverage to all children <5 years of age in areas in which surveillance data (including serum
Blood serum
In blood, the serum is the component that is neither a blood cell nor a clotting factor; it is the blood plasma with the fibrinogens removed...
epidemiologic data) identified a high risk of meningitis outbreaks. The results in Henan Province suggested that the intensified vaccination coverage was successful in decreasing rates of meningitis.
Strategy for vaccination for poliomyelitis
After data from 1988 to 1989 on rates of poliomyelitis
Poliomyelitis
Poliomyelitis, often called polio or infantile paralysis, is an acute viral infectious disease spread from person to person, primarily via the fecal-oral route...
and vaccination coverage were reviewed, high-risk areas were identified. In these areas, persons received supplementary vaccination in 1989-1990. By 1991, rates of poliomyelitis had begun to fall.
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