Communicable Diseases Parasitic Diseases

Ankylostomiasis and Ascariasis. Estimates of the 1945-59 period suggest that up to 100 million people in China have had intestinal infestation with parasites causing ancylostomiasis (the hookworm)

or ascariasis (the roundworm). Ancylostomiasis remains prevalent in 14 southern provinces, and ascariasis is widespread in most of China. Improved environmental sanitation and night soil management have reduced the prevalence of both parasites, but the limited information available indicates that both remain a public health concern.

Filariasis. In the 1950s, filariasis, transmitted by a mosquito vector, was said to have affected between 20 million and 30 million people. By 1958, more than 700,000 patients had been treated, and the Patriotic Health Movement led to major improvement of environmental sanitation in many localities and to widespread extermination of mosquitoes. Shandong Province, with a population of 75 million, had eradicated the disease by 1983, and by 1985 about 76 percent of China's endemic areas were essentially disease free. In the mid-1980s filariasis was prevalent in 864 counties and cities in 14 provinces, autonomous regions, and municipalities. Slightly over half of the jurisdictions were endemic with Bancroftian filariasis, about one-fourth were endemic with Malayan filariasis, and the rest had mixed infections.

Leishmaniasis (Kala-Azar). A 1951 survey showed the area of China endemic for visceral leishmaniasis to be entirely north of the Yangtze River, covering 1.2 million square kilometers. Prevalence was 1 to 5 per 1,000, with an estimated 530,000 cases, most of whom were children. Destruction of dogs and treatment of human cases with a specially produced antimony drug played a major role in decreasing transmission. Reduction in incidence may also have resulted from a decline in the sandfly vector due to insecticide spraying for both sandflies and malarial mosquitoes. Since 1958, kala-azar outbreaks have become sporadic, with fewer than 100 cases reported every year.

Malaria. Prior to 1949, malaria incidence in China was estimated at more than 30,000,000 new cases annually (5 per 100 people), with 300,000 deaths (a 1 percent case-fatality rate). Seventy percent of China's counties were endemic for malaria in the early 1950s. Surveys in 1957 reported 70 percent prevalence among children in Guangdong and 48 percent in counties in Yunnan. Vigorous efforts to control mosquito breeding sites - consisting of environmental management, mass chemo-prophylaxis during the transmission period, and mass treatment - caused disease rates to fall rapidly in the 1950s.

Since 1974, the five provinces of Jiangsu, Shandong, Henan, Anhui, and Hubei, which together account for about 80 percent of the national total of malaria cases and which represent the main tertian malaria areas, have worked jointly to bring the disease under control. In 1985, the number of new cases in the five provinces was 350,000, compared to the 14 million cases recorded in 1973 before the joint prevention and control measures were taken. Overall, approximately one third of China's population is now living in malaria-free areas, another third in areas with minimum risk, and the remaining third in endemic areas. The 563,400 cases reported for all of China in 1985 represent an incidence of approximately 5 per 10,000 population, close to the goal of under 1 per 10,000 by the year 2000.

Schistosomiasis. Schistosomiasis japónica, the form of the disease found in China, is prevalent in the provinces of Shanghai, Jiangsu, Zhejiang, Anhui, Fujian, Guangdong, Guangxi, Hunan, Hubei, Yunnan, Sichuan, and Jiangxi. It is carried by snails and is endemic in three types of environments: water courses, hilly regions, and lakes and marshlands. Water courses account for 8 percent of the endemic areas and 33 percent of the patients; comparable values are 10 and 26 percent for hilly regions, and 82 and 41 percent for the lake and marshlands areas.

Control efforts have been deployed on a large scale. In December 1955, China set up prevention and control stations in epidemic areas, and by 1958, 197 stations were staffed by more than 1,200 medical teams and 17,000 specialized personnel (Chien 1958). By 1985, there were only 371 endemic counties with a total of 11.6 million cases and 14,000 square kilometers of snail-infested areas. During the early stage of the nationwide prevention and control program, infestation rates typically ranged from 20 to 30 percent and in some areas reached 40 percent. Of those affected, about 40 percent were symptomatic and about 5 percent evidenced advanced illness. Cattle and other domestic animals were also seriously afflicted by the disease.

The elimination of snails has been a key objective of the program through such measures as draining marshlands, digging new ditches and filling up old ones, changing paddies into dry crops, tractor ploughing, field rolling, building snail trenches, and killing snails by chemical methods. The construction of dikes and the use of chemicals have proved very effective along the banks of the Yangtze River in Jiangsu Province.

Efforts to reduce the source of infection have included early detection and treatment of patients at all stages of the disease, with emphasis on those who handle diseased animals. People in snail-infested areas are encouraged to wear protective gear and take prophylactic medicines when coming into contact with water. Measures are also taken to ensure the safe collection and use of feces, and to encourage the use of safe water supplies.

By the end of 1985, schistosomiasis was declared officially eradicated in Shanghai and Guangdong, while Fujian, Jiangsu, and Guangxi have virtually eradicated the disease with more than 98 percent of the endemic areas cleared of snails and over 90 percent of the known patients cured. Among the 371 endemic counties and cities, 110 have been declared eradicated and 161 have almost eradicated the disease. In the remaining 100 counties and cities, more than 50 percent of the townships and about two-thirds of the villages have eradicated or almost eradicated the disease. Accomplishments by 1985 included the following: 95 percent of the 11.6 million patients were treated; 77 percent of the infested area was cleared of snails; and 92 percent of the 1.2 million head of afflicted cattle were treated or disposed of.

Despite these gains, concerns are being expressed by Chinese and foreign schistosomiasis experts about the future. UNICEF's Situation Analysis for China of 1989 estimated that schistosomiasis was still present in 12 provinces with a combined population of 50,000,000 and that the total of old cases approached 1,000,000 to which several thousand new cases were added annually (UNICEF 1989). The schistosomiasis control problem seems to have shifted over the decades from that of devising methods to control a major endemic parasitic disease to that of identifying the few lightly infected individuals in a sea of negatives, and ensuring that past gains are maintained without backsliding (Basch 1986).

Nonparasitic Diseases

Acquired Immune Deficiency Syndrome (AIDS). As of August 1989, China had reported only 22 human immunodeficiency virus (HlV)-infected individuals and three cases of AIDS. All were foreigners except for four Chinese who were infected through contaminated blood products (China Daily, Sept. 7,1989). The first indigenous case acquired through homosexual contact with a foreigner was reported in late 1989 (China Daily, Nov. 2, 1989). Persons from areas of high endemicity who wish to extend their visa stay beyond a limited period of time are required to have a test for HTV antibodies performed in China, and must leave China immediately if the test is positive. By December 1990 (China Daily, Dec. 31, 1990), China had identified a total of446 HIV-positive cases, since it started monitoring the epidemic in 1985, including 68 persons "from overseas."

Cholera. Cholera was said to be "virtually eliminated" by 1960 (Lampton 1977), and in 1985 only six cases and two fatalities were reported. More recent data from the Ministry of Public Health suggest that the disease is again of some importance, perhaps in part owing to better reporting. In 1989, the Ministry of Public Health reported that cholera still threatens residents of Hainan, Zhejiang, and Guandong provinces, a part of suburban Shanghai, and Guangxi Zhuang Autonomous Region. In 1988 more than 3,000 cholera cases were reported, but cases dropped to about 1,000 by the end of 1989 {.China Daily 1989).

Dengue. The first recognized dengue epidemic since 1949 occurred in Guangdong Province between June and September 1978, with an estimated 20,000 cases affecting persons of all ages. Approximately 25 percent had hemorrhagic manifestations. Because the usual vector, the Aedes aegypti mosquito, is thought to be absent from this area of China, suspicion has focused on the Aedes albopictus. Epidemiologists who investigated this epidemic assumed that refugees from Vietnam (estimated to exceed 200,000) imported the virus. Another dengue outbreak occurred on Hainan Island in 1980, and sporadic cases continued until 1982. Transmitted by the A. aegypti mosquito, the epidemic resulted in a peak morbidity rate of 2,146 per 10,000 and caused 64 deaths (Qiu Fu-xi and Zhao Zhi-guo 1988). Dengue has been added to the list of officially notifiable diseases, and no cases were reported in 1985.

Epidemic Hemorrhagic Fever. Epidemic hemorrhagic fever was first found in Heilongjiang province in the 1930s and then in the construction sites of the northeast China forest zones and the Baoji-Chengdu Railway. The disease became more common in later years as the population increased in endemic areas as a result of water conservation, land reclamation, and other construction projects.

China has three types of epidemic foci: house mouse, field mouse, and the "mixed type." Gamasid and Trombiculid mites may also carry the virus. Measures directed primarily at reducing mouse populations have been found to be effective in controlling the disease. Early diagnosis, rest, and hospital care in order to reduce the incidence of coma and renal failure have lowered the case fatality rate to about 3.2 percent in 1984 (Public Health in the PRC 1986).

Influenza. Influenza is the most frequently reported disease in China. Surveillance has been under way since 1968, yielding an epidemic pattern in south China that peaks in the summer and early fall, and an epidemic pattern in north China that peaks in the winter. As China's population ages and grows more vulnerable to influenza because of other serious chronic diseases, influenza will become more important as an immediate cause of death. An extensive immunization campaign has been carried out in recent years, resulting in a reduction from 8 million cases in 1975 to about 500,000 in 1980 and 1981. An unknown part of this decline may simply reflect the cyclic nature of the disease.

Japanese B Encephalitis. Japanese B encephalitis is a mosquito-transmitted viral disease seen throughout much of East Asia and is thought to be present in all of China except Tibet and Xinjiang. The case-fatality rate in 1949 was estimated at about 30 percent, and large epidemics were frequently seen near Shanghai, where the annual incidence was over 50 per 100,000. Since 1965 the incidence in the Shanghai area has been only 2 to 3 per 100,000. Mosquito vector control and vaccination of children have been priorities. Human cases peak at 4 to 5 years of age. About 100,000 cases are reported annually in China.

Leprosy. Leprosy has been present in China for more than 1,000 years. High prevalence areas are in southeast and southwest China; low prevalence areas are in the northeast and north. The official estimate for prevalence in China in 1951 was 1.2 million, although some international estimates placed the prevalence as high as 3 million.

Since the 1950s about 500,000 cases have been found, and more than 400,000 have been successfully treated. Methods used included specialized training for health personnel, prevention and control networks, early diagnosis and treatment, and infection control. In Shandong, the average annual incidence declined from 5.1 in the late 1950s to 0.14 per 100,000 in the early 1980s; the prevalence declined from 91 in 1950 to 2.3 per 100,000 in 1984. In 1958, 17,535 villages reported leprosy cases, this number dropping to only 1,500 villages by 1984.

Current estimates suggest a total of 100,000 to 200,000 patients and a prevalence of less than 20 per 100,000. China has recently embarked on a campaign to eliminate most leprosy by the year 2000 through intensified efforts of education, research, and early diagnosis and treatment (Pubic Health in the PRC 1986).

Measles. In 1950 the measles case-fatality rate was 6.5 percent, declining to 1.7 percent in 1956 with improved nutrition. When mass vaccination began in 1969, the incidence was estimated at about 3,000 per 100,000, but it now has dropped to below 20 per 100,000 for most big cities. The 1989 Ministry of Public Health epidemiologic report gave a time series estimate of 2.4 million cases in 1978, and 418,000, 199,000, 105,000, and 96,000 cases in 1985 through 1988, respectively. During the years 1986-8, the proportion of infants under 1 year immunized for measles rose steadily from 63 percent to 78 and 95 percent. The total annual reported deaths from measles since 1985 has been less than 1,000.

Neonatal Tetanus. Although data for pre-1949 are unavailable, it is likely that neonatal tetanus accounted for as much as 20 percent of infant mortality, a percentage similar to that reported in the early 1980s in rural Thailand. Maternal and child health services in China now monitor more than 90 percent of deliveries in most provinces, and neonatal tetanus is now said to be a rarity. Sample surveys have detected neonatal tetanus in some of the more remote counties, with an average death rate of approximately 3 per 1,000, ranging from 0.3 to over 13. By using very fragmentary data from various sources, UNICEF has estimated that there are perhaps 10,000 neonatal tetanus deaths per year, or a rate of about 0.5 per 1,000 live births.

Plague. The earliest known outbreak of plague in China was in Lu'an County, Shanxi Province in 1644 (Public Health in the PRC 1986). A well-documented massive outbreak of pneumonic plague occurred in 1911 in Manchuria. This epidemic, in which 60,000 people were affected, led to the first international medical conference in China and to the establishment of the Manchurian Plague Preventive Service. The failure of traditional Chinese medicine to control the outbreak (practitioners of traditional medicine experienced a 50 percent case-fatality rate) and the success of Western methods (a case fatality rate of 2 percent) were important factors in the rise of Western medicine in China (Bowers 1972).

During the early phase of the antiplague campaign, the state encouraged and subsidized rat-killing drives by agricultural collectives along with programs to reduce other potential host animals. Measures were also taken to destroy the ecological environment of major hosts in the course of planting trees or in carrying out farmland improvement and water conservation projects. As a result, rodent plague has been virtually eliminated from most heretofore endemic foci, and the ground squirrel, marmot, and other host populations have been sharply reduced.

By the end of the 1950s, the annual incidence of plague in China had declined to about 30 per 100,000, and by the end of the following decade it was under 12. The number of counties reporting plague cases annually ranged from 26 to 61 in 1950-4, 6 to 15 in 1955-60, and 0 to 8 after 1961 (Public Health in the PRC 1986). There were only 6 cases of plague in 1985, and the case fatality rate in recent years has been less than 8 percent.

Poliomyelitis. Prior to 1955, epidemics of poliomyelitis were common in China. In 1959 in Nanning the incidence was 151 per 100,000, and incomplete statistics for 17 administrative jurisdictions showed an overall incidence of 5 per 100,000. There were polio epidemics early in the Cultural Revolution (1968—70), during which all immunizations were said to have been neglected. The generation of those 10 to 20 years old at that time was most affected. As a result of a vigorous live-vaccine immunization campaign, the incidence had declined to around 0.5 to 0.75 per 100,000 by the mid-1980s. About 3,600 polio cases were reported from January to September 1989 - up substantially from the approximately 700 cases during the previous year (China Daily 1989).

Smallpox. The incidence of smallpox may have been as high as 200 per 100,000 population before 1949. A massive immunization campaign was started, and by 1953 over 50 percent of China's then 600 million population had been vaccinated. The last cases, in Tibet and Yunnan, were seen in 1960 (Rung 1953).

Trachoma. Trachoma, an infectious eye disease that can cause blindness, was a major public health problem in China. Half of the population was estimated to have been affected in the mid-1950s, and in some areas the prevalence may have reached 90 percent. Trachoma was estimated to have caused 45 percent of the visual impairment and between 25

and 40 percent of the blindness in China. Although the current prevalence is unknown, trachoma is no longer a public health problem. Education against towel sharing ("one person one towel, running water for washing face") had been very important as a control mechanism.

Tuberculosis. Tuberculosis was a leading cause of death in China in the late 1940s, with a death rate of 200 per 100,000 and a morbidity rate of 5,000 per 100,000 in major cities. At that time there were only 13 prevention and control institutions and five small prevention and control stations in the country, and only 7,500 people in all of China received bacillus Calmette-Guerin (BCG) vaccine as immunization between 1937 and 1949 (.Public Health in the PRC 1986).

Government control efforts resulted in the creation of a tuberculosis prevention and control network to find, register, and treat patients at the earliest disease stage possible. In addition, BCG immunization campaigns were launched, with emphasis on newborns and on the reinoculation of primary school students. The BCG immunization campaign began in 1950, and by 1979 an estimated 500 million immunizations had been given. A sample survey in the latter year indicated that prevalence had been reduced to 717 per 100,000, with sputum-positive cases averaging only 187 per 100,000.

Since 1984, the Ministry of Public Health has promoted the creation of tuberculosis prevention and control in existing antiepidemic stations. By the end of 1985,1,686 such institutions had been established at the county level, and there were 117 tuberculosis hospitals throughout the country. A sample survey of nine provinces and cities in 1984 found a prevalence of less than 500 per 100,000. The incidence remains high, however, in remote areas and those inhabited by minority nationalities (Public Health in the PRC 1986).

Typhoid and Paratyphoid Fevers. National data on typhoid and paratyphoid fevers were not available until recently. In 1975, Shanghai registered an estimated 600 cases of typhoid fever (Lampton 1977), and in 1985 there were an estimated 86,000 cases of typhoid and paratyphoid nationwide.

Venereal Disease. In the early 1950s, the prevalence of venereal disease in China was estimated at 3 to 5 percent in the cities, and as high as 10 percent among those who lived in the frontier areas (Lampton 1977). Extraordinary efforts were mounted to combat these diseases and were reported to have successfully "eradicated" them in China by the mid-1960s.

Patients with venereal disease, however, began to be seen again in 1984, and by 1988 "tens of thousands" of such cases had been reported. Preliminary reports from the country's 16 venereal disease inspection stations for the first 9 months of 1989 showed a 61 percent rise in new VD patients over the 1988 figure, bringing the cumulative total for the period to more than 220,000 (China Daily 1989). The highest incidence has been in coastal areas, such as Guangdong, Guangxi, and Fujian provinces, though cases have also been reported in Beijing, Shanghai, Tienjin, Harbin, and Xinjiang. More than 70 percent of the patients are male, and the most common diseases are gonorrhea, syphilis, and condyloma. According to the head of a national venereal disease prevention committee, the renewed spread "arises from the reemergence of prostitutes, the increased activities of 'sex gangs,' as well as changing attitudes toward sex on the part of some young people seeking sexual freedom" {Beijing Review 1988). In response, the State Council has issued a "strict ban" on prostitution; sex education courses have been widely introduced in middle schools; courses on venereal disease are being reintroduced at medical colleges; a national center for prevention and treatment of venereal disease has been established; and monitoring and treatment stations have been set up around the country.

Viral Hepatitis. Since the 1950s hepatitis has been increasing in many countries. In China, outbreaks have occurred in the northeast and north, with fluctuation in the incidence. In 1979-80 an extensive nationwide survey of the disease was conducted covering 277,186 people in 88 large, medium-sized, and small cities and 121 rural counties. Positive sero-reactivity to anti-HBV averaged 71.4 percent and to hepatitis B surface antigen (HBsAg), 88 percent. Infection appeared predominantly in two peak age groups, those under 10 and those between 30 and 40 years; rates for males were higher than for females. HBsAg seropositivity was higher in family groups and did not seem to be particularly correlated with occupation (Public Health in the PRC 1986).

Viral hepatitis research became a priority under the sixth five-year plan (1981-5), with particular emphasis directed toward development of a low-cost vaccine and on the improvement of prevention and control measures. Research and development of a hepatitis B hemogenetic vaccine began in 1978 and was completed in 1983. Confirmatory tests in 1985

showed that the vaccine was safe and effective, and mass production is planned.

Responsibility for hepatitis prevention and control is vested in the sanitation and antiepidemic stations at all administrative levels. Stations collect and analyze morbidity data, conduct epidemiologic studies, and provide assistance to medical units, to patients' families, and to organizations on such matters as patient isolation, sterilization, food and water management, environmental sanitation, and personal hygiene. They also provide regular medical examinations to food industry and nursery personnel.

Strengthened hygienic legislation, standards, and administrative guidelines have also contributed to a reduction in the spread of both hepatitis A and B. For example, many hospitals have set up hepatitis wards to prevent hepatitis B from spreading. Special attention has been given to screening blood donors and to the strict management of blood products. Most health facilities now use disposable needles and syringes and have tightened the control and disposal methods of blood stained water and objects.

Chronic Diseases

Chronic diseases now account for almost two-thirds of all mortality in China and are expected to become even more significant in the future, owing to an aging population and to changing environmental and life-style factors. This section considers briefly the three main chronic disease categories: heart disease, stroke, and cancer.

Heart Disease. Heart disease is now the leading cause of death in China. Among the deaths from heart disease the causes are, in declining order of frequency, hypertensive heart disease, cor pulmonale, rheumatic heart disease, and coronary heart disease. The importance of coronary heart disease is, however, increasing rapidly.

Hypertension's contribution to stroke and renal disease as well as to hypertensive heart disease probably makes this condition the largest single risk factor for death in China. Based on age-specific hypertension rates observed in a 1979 national hypertension sample survey, by 2010 China could have more than 110 million cases of hypertension. With rising incomes, however, and a probable parallel rise in age-specific rates, this may be a low estimate.

Cor pulmonale, manifested by right ventricular hypertrophy and decreased output, appears to be linked to the high prevalence of chronic obstructive lung disease (COLD). This condition is most often the end result of pneumoconiosis secondary to air pollution from factories, transport, home cooking over open stoves, and, with increasing frequency, cigarette smoking. Although national statistics are still inadequate to distinguish between cor pulmonale and COLD, data from the Disease Surveillance Point (DSP) system covering a population of about 10 million will soon be able to provide better estimates of the magnitude of these and other health problems. COLD morbidity has been estimated at 20 times COLD mortality and appears to affect rural residents substantially more than those in urban areas.

Rheumatic heart disease has accounted for a major portion of heart disease morbidity and mortality in the past, but today, with the widespread use of antibiotics, its significance is on the decline. In 1986, an estimated 50,000 deaths resulted from this disease, with perhaps some 1 million infected.

Coronary heart disease, the main form of heart disease in the industrialized countries, is in fourth place in China but is expected to gain rapidly in importance as a result of the delayed effects of richer diets and more cigarette smoking. In four urban districts of Beijing, for example, the coronary heart disease death rate doubled from 71 per 100,000 in 1958 (10.8 percent of all deaths), to 141 per 100,000 in 1979 (25 percent of all deaths).

Cerebrovascular Disease. More commonly known as stroke, cerebrovascular disease is most often a complication of hypertension and is currently the third leading cause of death in China. In the same four urban districts of Beijing mentioned above, stroke was responsible for 152 deaths per 100,000 population in 1979 (27.3 percent of all deaths), as compared to 107 per 100,000 in 1958. The ratio of stroke to coronary heart disease mortality (a relatively small part of all heart disease mortality) in China is about 4:1 as compared with about 1:3 in the United States, though this is expected to change rapidly as the effects of dietary and smoking habits come to be fully manifest.

Cancer. Cancer has become one of China's top three causes of death. According to 1986 Disease Surveillance Point mortality data, the five leading cancers in men were, in rank order, lung, stomach, liver, esophagus, and colorectal, while for women cervix cancer replaced colorectal in fifth place. Those who live in urban areas have a 50 percent higher cancer mortality rate than do rural residents, and men are about 50 percent more at risk than are women, regardless of location. When compared with the results of a retrospective survey of all deaths in mainland China for the years 1973-5, these data suggest that overall cancer mortality rates are rising, lung cancer is gaining in relative importance, and esophageal cancer may be declining.

Three examples from the 1973-5 survey illustrate the wide regional variations that can be observed in cancer mortality according to site, variations that have recently been mapped by the government's National Cancer Control Office. Nasopharyngeal cancer is virtually limited to south China, with the highest incidence in Guangdong Province, from which it decreases in concentric bands. Mortality due to cancer of the esophagus varies more than sixfold across China's counties, with higher prevalence locations often separated by long distances. Liver cancer tends to be concentrated in coastal plains in the southeast.

The diverse patterns in the geographic distribution of cancer have led to epidemiological research on selected cancers (see, e.g., Armstrong 1982). With 60 percent of all fatal cancers originating in the upper alimentary tract, particular attention has been given to the role of diet and food hygiene. Cancer epidemiology has also focused on trend analysis. Through such studies it has been found that whereas the incidence of stomach cancer in China has been decreasing in recent years, that of lung cancer has increased rapidly. This latter trend had been especially pronounced in urban areas and is presumably associated with rising levels of smoking, as shown by studies such as that by Y. T. Gao and colleagues (1988). High lung cancer rates have also been found in rural areas subject to serious problems of indoor air pollution (Chapman, Mumford, and Harris 1988).

Chinese authorities have recently begun to address the public health hazards of smoking. Surveys have found that some 69 percent of Chinese men and 7 percent of women above the age of 20 smoke, and, although the rate for women is still low, this is likely to increase rapidly in the future. Antismoking measures - including education, cigarette price increases, limits on tobacco production, and banning of smoking in certain locations - have not had much effect thus far. Rather, cigarette production increased 9-fold between 1949 and 1980. Chinese cigarettes have about double the world average of tar, and now with the government deriving significant revenues from the sale of cigarettes, and the sudden increase in the importation of foreign brands, the potential for a rapid increase in tobacco consumption is great indeed.

Occupational Diseases

The safety of the workplace has received increasing attention since the first industrial health organization was established in 1950. By 1985 there were more than 170 such organizations and industrial health sections at more than 3,300 sanitation and antiepidemic stations, and about 25,000 persons were employed in this field. Starting with the promulgation of regulations on the control of silicon dust at the workplace in 1956, health authorities have extended industrial health regulations until by 1985 there were 122 industrial health standards and 16 standards for diagnosing occupational diseases. The decline in the incidence of silicosis documents both what has been accomplished and what remains to be done. According to a recent study of silicosis in 26,603 dust-exposed workers at seven mines and industrial plants, the 8-year cumulative incidence of silicosis declined from 36.1 percent among workers employed before 1950 to 1.5 percent for those employed after 1960 (Lou and Zhou 1989). During the same period, the cumulative incidence of tuberculosis decreased from 54.7 to 16.7 percent, and the silicosis case-fatality rate declined from 53.9 to 18.3 percent. The average age at the detection of silicosis increased from 41.3 to 52.7 years from the 1950s to the 1970s, while the average survival times of silicosis patients increased from 2.0 to 12.2 years.

Nutritional Diseases

Endemic Fluorine Poisoning. Endemic fluorine poisoning is a chronic disease caused by an excess in intake of fluorine. On the basis of epidemiological surveys, it is currently estimated that in all areas of endemicity there are some 21 million people suffering from fluoride-caused mottled enamel and 1 million from bone disease caused by fluorine poisoning (.Public Health in the PRC 1986). Efforts to control the disease include the use of rainwater, along with wells and other low-fluorine water sources, for drinking purposes, and treating water supplies to reduce the fluorine content. The provision of fluorine-free drinking water became one of China's projects in a 10-year world program for attaining a safe drinking-water supply and environmental hygiene.

Endemic Goiter and Endemic Cretinism. Endemic goiter is caused by lack of iodine in the diet. Surveys suggest that about 35,000,000 people in China suffered from endemic goiter and another 250,000 from endemic cretinism. However, over the past three decades more than 2,500 monitoring stations have been set up to supervise the production, marketing, and use of iodized salt. By 1985 this salt was available to about 85 percent of the counties in the endemic areas, and as a result of these and other measures, over 22,000,000 endemic goiter patients have been successfully treated. The average incidence of the disease has been reduced to under 4 percent, and few patients with endemic cretinism are now found (Public Health in the PRC 1986).

Kaschin-Beck Disease. This disease is a chronic degenerative osteoarthropathy of unknown cause. The major pathological changes include degenerative necrosis of leg and arm joints and of epiphyseal plate cartilage. The earliest written record of the disease was made in 1934, but it is believed to have existed in China for a long time.

Surveys conducted since the early 1950s show that Kaschin-Beck disease prevails in a wide area from the northeast to the southwest, covering 287 counties and cities in 15 provinces, autonomous regions, and municipalities. It is estimated that 1.6 million people suffer from the disease, 65 percent of whom are youths and teenagers. Disease incidence fluctuates substantially, and a rainy autumn usually results in an increased incidence the next year. There are three views as to the etiology of Kaschin-Beck disease: poisonous organic matter in water, the fusar-ium tox in grain, and excessive or insufficient trace elements in water, soil, and grain CPublic Health in the PRC 1986).

Several methods have been used to prevent and treat Kaschin-Beck disease. One includes the use of deep wells, alternate water sources, or water treatment with active carbon and magnesium sulfate to improve its quality. A study done in Fusong County of Jilin Province from 1972 to 1977 showed that disease incidence for people drinking water diverted from nearby springs was 1.2 percent, as compared with 13.5 percent for those who continued to drink from old sources (Public Health in the PRC 1986).

Another method is to provide grain from non-affected areas to people in affected areas. Meanwhile, efforts are made to prevent grain in storage from becoming mildewed. A 7-year study in Shuang-yashan City which compared two areas using the same water sources found no new cases in an area where outside grain was available. By contrast, the incidence continued to rise in the area using indigenous grain (Public Health in the PRC 1986).

More recent studies have demonstrated a relationship between selenium intake and Kaschin-Beck disease. Between 1974 and 1976, Gansu Province used sodium selenite and vitamin E to treat 224 children suffering from the early-stage Kaschin-Beck disease. In areas where the disease is present, the lower the ambient selenium levels, the greater the prevalence. From 1981 to 1985, Shaanxi Province experimented with use of seleniumized table salt to prevent the disease. Measures to increase selenium intake, now used among more than 8 million people, are considered a major approach to the prevention of Kaschin-Beck disease (Public Health in the PRC 1986).

Keshan Disease. Keshan disease is a myocardial disease found in a long, narrow strip of land covering 309 counties from northeast to southwest China. The disease is sudden in onset and often acute, with a high case-fatality rate of around 20 percent. Housewives and teenagers are at particular risk. Keshan disease has been endemic in China for about 100 years, and a 1935 outbreak of the disease in Keshan County, Heilongjiang Province, led to its name. Endemic areas have been found to have low selenium levels in the water, earth, grain, and vegetables, and residents suffer from a deficiency of selenium. Considerable success in reducing disease incidence has been achieved with oral sodium selenite, but selenium deficiency may not be the only cause.

Effective measures to prevent and control Keshan disease include keeping homes warm, dry, and free of smoke, ensuring safe drinking water, improved eating habits, early diagnosis, and treatment. The principal treatment methods are intravenous injection of high doses of vitamin C and blood expanders; oral selenite is used to prevent acute and subacute Keshan disease. There have been no widespread outbreaks of the disease for 15 years. In 1985, only 374 cases of acute and subacute Keshan disease were found, with 92 deaths, the lowest rates ever. The number of chronic patients has decreased from 220,000 in the early 1970s to 76,500 by the mid-1980s. A total of 4.1 million people now take oral selenite, contributing to the falling incidence (Public Health of the PRC 1986).

Your Heart and Nutrition

Your Heart and Nutrition

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