The National Science Foundation's (NSF) Tokyo Office periodically receives and disseminates reports on research developments in Japan that are related to the Foundation's mission. NSF-sponsored researchers currently working in Japan prepare many of these reports. These reports present information for use by NSF program managers and policy makers; they are not statements of NSF policy.
Special Scientific Report #99-18 (November 17, 1999)
Ms. Michelle Calvarese, a Ph.D. candidate in the Department of Geography at Texas A&M University, prepared the following report. Ms. Calvarese was a participant in the 1999 Summer Institute sponsored in the United States by NSF/NIH/USDA and the Science and Technology Agency and Japan Science and Technology Corporation in Japan. Dr. Nobukatsu Ishikawa of the Research Institute of Tuberculosis at Japan Anti-Tuberculosis Association hosted Ms. Calvarese. Ms. Calvarese can be reached via email at: michelle@geog.tamu.edu
Tuberculosis in Japan: History, Trends, and Control
Acknowledgements
I would to thank the Research Institute of Tuberculosis in Kiyose-shi, Japan for allowing me to conduct research on tuberculosis in Japan during the summer of 1999. This paper could not have been written without the guidance of many staff members. I would like to thank the RIT staff for all their help and the staff who took the time to discuss their area of expertise on TB in Japan. Much of the information contained in this paper was taken from personal communications. Thank you to Dr. Ishikawa, Dr. Kimura, Ms. Ohmori, Ms. Yamashita, Dr. Shimouchi, Dr. Mori, Dr. Wada, Dr. Hoshino, Dr. Masuyama, Dr. Aoki, Dr. Shimao, and Dr. Yoshiyama. A special thanks to Dr. Ishikawa for agreeing to host me this summer. A special thanks to Dr. Kimura for taking me under her wing this summer.
Introduction
Tuberculosis is commonly thought to be a disease that has long since been eradicated. Tuberculosis however has been proven to be an ever-present problem in developing nations and rates have begun to slowly rise in some developed nations. Tuberculosis currently infects a third of the world's population. In 1995 there were approximately 9 million new cases worldwide with 3 million deaths (WHO, 1996). In most cases, treatment is available which would make such outbreaks easily eradicated, however non-compliance and apathy are making a controllable disease a serious public health threat.
Most developed nations which are experiencing either a stagnation of rates, a slowing in the declining rate, or an increase in rates can attribute this problem to a rise in tuberculosis infection in the foreign born, intravenous drug users, or those who are HIV/AIDS positive. Japan however cannot attribute this problem to such variables. Japan's foreign population is less than 1% of the total population, intravenous drug users are not common, and HIV/AIDS rates are comparably low. Japan's recent rate stagnation is mostly attributed to an aging population which contracted tuberculosis infection during wartime and are now developing disease and spreading it to younger generations.
This paper discusses various aspects of tuberculosis in Japan including past and current statistics of tuberculosis, the history of tuberculosis, causes of geographical distribution of tuberculosis rates, tuberculosis management and a comparison of tuberculosis in Japan to the United States.
What is Tuberculosis?
Tuberculosis (TB) is a bacterial disease caused primarily by Mycobacterium tuberculosis. These organisms are also known as tubercle bacilli. Tuberculosis is an airborne disease and is spread by an infected individual coughing or sneezing. Tubercle bacilli can remain dormant in tissues for many years without converting to tuberculosis disease. Infected individuals can remain disease free and asymptomatic for years, but can develop tuberculosis at any time. The vast majority of people with strong immune systems however, never develop tuberculosis disease. The only way to detect tuberculosis among these individuals is a tuberculin skin test (WHO, 1996). For those individuals who develop tuberculosis disease, long term medical treatment is necessary. According to WHO (1996) estimates, without treatment, 50% of pulmonary TB patients will be dead, 25% will be healthy (self-cured by strong immune defense), and 25% will remain ill with chronic, infectious TB.
Statistics
As of 1997 the total population of Japan was 126,166,000. The approximate total tuberculosis incidence rate of newly registered cases at that time was 34% per 100,000. This rate marks a very small decline from the 1996 rate of 33% and the 1995 rate of 34%. The total number of newly registered cases was 42,472, 43,078, and 44, 590 for 1996, 1995, and 1994 respectively.
History of Tuberculosis in Japan
Pre-Edo Era
Archeological evidence suggests that tuberculosis existed in the
pre-edo era,
however concrete evidence of tuberculosis change was not detected
until around the 4th
century. Statistical data is nonexistent for this time period
(Aoki, 1999).
Edo Era
The Edo period is that time in Japanese history when Japan closed
its doors to outsiders. During this time period, Japan focused
heavily on development and manufacturing. Death records were not
kept very often during this period, but it is believed that tuberculosis
first began to spread during this time. It first began to spread
in urban areas such as Edo and Naniwa. Tuberculosis was more prevalent
among the upper classes and was believed to be a disease of the
rich (Aoki, 1999, Johnston, 1995).
Meiji Era
The Meiji era marks Japan once again opening its doors, the industrial
revolution, the adoption of western medicine, and the beginning
of the epidemic of tuberculosis. Japan became increasingly aware
of advancements in other countries and was eager to catch up.
In a country with little resources, catching up meant longer working
hours, poor working conditions, and bad nutritional habits (Fukuda,
1999, Johnston, 1995, Aoki, 1999, Ohmori, 1999).
Tuberculosis was especially prevalent among young women sent to work in textile factories. Twelve hours shifts and close quarter confinement were primary causes for the outbreaks. The infected were usually expelled from the factory and sent home where without adequate care, they would infect family members and neighbors (Fukuda, 1999). Extraordinarily high rates can be seen in prefectures with textile factories during this time period (Fukuda, 1999, Ohmori, 1999).
Other causes for increased rates during this period were increases in population growth, improved transportation, increased freedom of movement, and urban expansion (Johnston, 1995). Japan's total population increased between 15 and 20 percent between the early 1830s and 1870s. This led to an increase in the age groups most susceptible to tuberculosis (Johnston, 1995). Freedom of movement was somewhat restricted until after the Meiji restoration. The restoration coupled with improved transportation allowed for increased migration into the already overcrowded cities (Johnston, 1995).
Official data began being collected in 1877 and reflects that morbidity and mortality from tuberculosis increased yearly due primarily to modernization and insufficient knowledge of medical treatments (Fukuda, 1999).
Modern Period
The modern period begins with sharp increases in tuberculosis mortality around the world wars. Food shortages, poor living conditions, and general chaos made conditions ripe for tuberculosis transmission. After World War II, we finally begin to see a decline in tuberculosis cases with the advent of new tuberculosis control laws, the BCG vaccination, earlier detection methods, and case finding by x-ray.
Recently however, the rate of decline is decreasing and in some cases, stagnating. This is mostly attributed to Japan's aging population who became infected during wartime and are now developing disease due to a comprised immune system.
Management
Surveillance
In 1975 a computerized surveillance system was used in Okinawa. Okinawa was the only prefecture in which BCG vaccinations were not given, thus providing the most accurate skin testing results. In 1978 preliminary trials of surveillance of acute infectious diseases were carried out. In 1980 a similar computerized tuberculosis surveillance system as was used in Okinawa was used in Aichi and then in Shizuoka in 1981. Also in 1981 there was an expansion of the nationwide surveillance system of infectious diseases. Finally in 1987 a nationwide computerized tuberculosis and infectious disease surveillance system was implemented and it was later improved in 1992.
Three main bodies each contribute to maintaining the surveillance system. The smallest level is the health care center, which reports to the local government, which reports the Ministry of Health and Welfare. Currently there are 710 health centers located throughout Japan's 47 prefectures and metropolitan cities.
All tuberculosis cases must be reported to a local health facility within 2 days of diagnosis. Once reported, each individual receives a personal data card containing information such as gender, age, occupation, present bacteriology, and x-ray results. This information is reported to the local government by the 10th day of the following month. The local government then reports this data to the Ministry of Health and Welfare before the 15th of the month for analysis. Analysis results are then reported back the local health center and are published monthly for public distribution. Yearly results are published as the "Tuberculosis Year Book," and include data such as distribution of patient's, doctor's and total delay, duration of hospitalization, chemotherapy and registration, and treatment results.
Public Health Nurses, Case Finding, and Delay
All TB cases must be reported to a Public Health Service Center (PHSC) within two days of diagnosis. It is the job of the PHSC to track and register all TB patients. Public health nurses have one of the most important jobs involving TB control in Japan. Once a case of TB has been reported, a public health nurse (PHN) will be assigned to the case. The first task is for the PHN to go to the patient's home for an initial consultation. This home or hospital first consultation is mandatory. During this consultation the PHN will attempt to collect very important information such as when the patient first started feeling symptoms, when the patient first went to the hospital, when did the patient receive a TB test, whether the patient previously had a BCG vaccination, and who the patient has been in recent contact with since symptoms began. It is very important for the PHN to develop a good relationship with the patient to insure honest answers and good medical compliance.
The PHN's next job is contact screening. Contact screening involves interviewing each of the patient's recent contacts. These contacts will be tracked for up to two years to insure that their TB status remains negative. Consultation with contacts is done using the concentric circle method. The patient is in the middle of the circle. The next ring is the patient's daily contacts. If a TB positive case is found, then contacts in the last month are consulted. If a TB positive case is found, then contacts in the past years are consulted.
Control Program
The current control program in Japan includes the following:
Comparison with United States
TB on the Rise
TB has re-emerged as a serious public health problem in the United States. In 1993 there were 23,287 active TB cases, an increase of 14% since 1985. In 1995 this number dropped to 22,860 but it is estimated that as many as 15 million people have latent TB infections in the United States. In 1997 the incidence rate was 7.4% per 100,000. Almost 54% of active cases are among African-Americans and Hispanics with an additional 17% found in Asians (Arnot Ogden Medical Center, 1998).
Drug-resistant cases have also increased dramatically. In some U.S. cities, more than 50% of patients (often homeless, drug addicts, and poverty stricken) fail to complete their prescribed course of TB therapy. MDR-TB is also on the rise with a death rate as high as 40 to 60 percent (Arnot Ogden Medical Center, 1998).
Unlike Japan, TB's resurgence in the United States is mostly attributed to the HIV/AIDS epidemic, an increased number of immigrants, increased poverty, increased drug use, increased homelessness, poor compliance, and an increased number of residents in long-term care facilities (Arnot Ogden Medical Center, 1998).
United States TB Control Laws
TB Control Laws vary greatly state by state. A survey conducted by the CDC of health facilities regarding TB control laws produced the following results:
BCG Vaccination
The concern of the public health community about the resurgence and changing nature of TB in the U.S. prompted a re-evaluation of the role of the BCG vaccination in the prevention and control of TB. Since in the U.S., the risk of infection in the overall population is low, the primary strategy for preventing and controlling TB is to minimize the risk of transmission by early identification and treatment of patients. The second strategy is the identification of persons with latent TB.
Use of BCG has been limited because a) its effectiveness in preventing infectious forms of TB in uncertain and b) the reactivity to tuberculin that occurs after vaccination interferes with the management of persons who are possibly infected. The use of BCG as a TB prevention strategy is reserved for selected persons who meet specific criteria such as infants and children who reside in settings, in which the likelihood of transmission is high, provided no other measure can be implemented. BCG vaccination may also be considered for health-care workers who are employed in settings in which the likelihood of transmission of drug resistant strains is high, provided comprehensive TB infection-control precautions have been implemented and have not been successful.
Overall, the BCG vaccination is rarely indicated and is not recommended for inclusion in immunization or TB control programs, and it is not recommended for most health-care workers.
Future Trends for TB in Japan
The main factors causing the slowing down in declining rates are the changes of prevalence of TB infection and the aging population. Regional differences are influenced by the rate of aging, past TB problems, poverty stricken areas, and migration into cities. Future projections estimate that the number of cases for those 70 years of age and older will increase and the number of cases for the 20-30 age group will increase. The possibility of increasing the speed of declining rates is likely with active contact examinations and preventive therapy.
Future Research
Future research on TB in Japan could include examining rates
on a prefectural level. These rates could be analyzed historically
by looking at past TB problems and implementation of TB control
laws. These data could then be imported into a Geographical Information
System (GIS) for visual representation and in-depth geographical
analysis.
Bibliography