Tuberculosis epidemiology in the Asia–Pacific region

Tuberculosis epidemiology in the Asia–Pacific region

Toru MORI

Leprosy Research Center, National Institute of Infectious Diseases, Tokyo, Japan

Tuberculosis epidemology in the Asia–Pacific regionMORI T. Respirology 2008; 13: S56–S64Abstract: The Asia–Pacific region accounts for about 20% of the global burden of tuberculosis (TB).However, there are a wide variety of TB problems between countries and areas. This variety could bedescribed in three dimensions: (i) historical trends of the TB epidemics, closely related to the adventof industrialization or urbanization; (ii) success in modern TB control in the early days; and(iii) expansion of the directly observed therapy, short course (DOTS) strategy during the past 20 years.Moreover, these dimensions have been subject to the ‘health infrastructure’ based on such socialgoods as people’s education, economic standards, and social security or stability. The Asia–PacificRegion offers very good examples to illustrate the roles of these factors in leading to such a variety ofTB problems as seen today. Thus, this region was the first to achieve the global target of DOTS by theend of 2005, that is to detect 70% of patients and to treat them with DOTS, and to successfully cure85% of those detected.

However, we should remember that we are currently challenged by TB combined with HIV infec-tion and AIDS; TB with drug-resistance, especially multidrug-resistant (MDR) or extensively drugresistant (XDR) forms; TB in people with special risk factors, for example diabetes and senility; andother medical and socioeconomic problems. At the same time, we have to be careful about thepremature loss of people’s interest in TB, due to illusion or unfounded optimism, especially amongmedical professionals and the government.

Key words: Asia, epidemiology, multidrug resistance, HIV, tuberculosis.

EPIDEMIOLOGICAL SIZE OFTUBERCULOSIS PROBLEM

TheWorld Health Organization (WHO)1 estimates thatthe entire Asia–Pacific region accounts for about one-fifth of the global toll of tuberculosis (TB) in terms ofestimated newTB cases of all forms, that is 1 915 000 inthe Western Pacific Region, out of 9 157 000 as of 2006,but it has just one-fourth of the global population. This

estimate is published every year, based on varioustypes of evidence that are comprehensively adjustedand validated by computer modeling.2 There is a widevariation in the incidence rate of all forms of TB in thecountries and areas in this region, from over 500 per100 000 population in Cambodia to less than 10 inAustralia. The average rate for the entire region is 110per 100 000 population. Based on these statistics, thecountries and areas of the region are roughly catego-rized into three groups, high-, intermediate- andlow-prevalence groups. The intermediate class is con-veniently defined as those ranging from 99 to 10 per100 000 population in incidence rate, and includesKorea, Macao, Hong Kong, Brunei, Singapore andJapan. Special attention will be given to this group laterin this review.

Within the Asia–Pacific Region, 65% of new casesare found in China, followed by the Philippines (13%),Vietnam (8%) and Cambodia (4%). The WHO desig-nates these four countries as high-burden countries,so that together with the other 18 countries world-wide, they account for about 80% of the global tollof new TB cases. Papua New Guinea has the thirdhighest incidence rate (250) in the region, but it con-stitutes only a small part of the pie (0.8%) because ofits small population.

Correspondence: Toru Mori, Leprosy Research Center,National Institute of Infectious Diseases, 4-2-1, Aoba-cho, Higashi-murayama, Tokyo 189-0002, Japan. [email protected]

Author’s noteIn this review, the Asia–Pacific Region is defined as thecountries and areas belonging to the Western PacificRegion of the World Health Organization, and Taiwan, ifthere is appropriate information. The Western PacificRegion has a total of 20 Pacific island countries that aresmall in population size and fortunately have no highlevel of tuberculosis rate. Therefore these countries areexcluded from consideration.

Respirology (2008) 13 (Suppl. 3), S56–S64 doi: 10.1111/j.1440-1843.2008.01335.x

© 2008 The AuthorJournal compilation © 2008 Asian Pacific Society of Respirology

mailto:[email protected]

In the countries and areas where the vital statisticssystem has been well established, tuberculosis mor-tality rates are available to delineate the long-termtrends of TB epidemics (Fig. 1). Australia3 once had afairly high TB mortality rate before World War II,which then declined slowly. After the war, the mortal-ity rate has declined steeply and continuously untilnow. Japan,4 Singapore5 and Hong Kong6 exhibit asimilar trend, each at a different level.

Several countries in the region have conducted theprevalence survey to determine the size and trends ofthe tuberculosis problem more precisely than esti-mates.7 As depicted in Figure 2, the level of prevalencerate reflects the incidence rate, and in these countriesthe rate has been declining; slowly at 2–3% per year inthe Philippines in the 1980s and early 1990s,8 andslightly faster in China in the 1990s.9,10 In Korea thespeed of decline of prevalence was still faster at 6–8%per year during the same period, though with someirregularity.11 Cambodia conducted its first nationwide

survey in 2002–3,12 and has confirmed its very highlevel of TB prevalence. If the survey were repeated inthe future in Cambodia, the epidemiological changedue to the control efforts would be made clear. Japanrepeated the survey at 5-year intervals from 1953through to 1973, and the decline of the prevalence ratewas steep and almost parallel with that of the notifica-tion rate during the same period.13 There is a report ofa small survey from an area of Vietnam.14

CHARACTERISTICS OF EPIDEMICS

Apart from the level of epidemics, the characteristicsof epidemics, such as the patterns of age-specificincidence rates of these countries and areas, arecompared. Figure 3 presents the age-specific case-notification rates from various countries1 and areas ona relative rate scale with the rate for age 35–44 being1.0. There is a striking difference between such coun-tries as Mongolia or the Philippines (group C) andother countries such as Japan, Singapore and Vietnam(group A). In the group C countries, the peak rates areseen in young or middle ages, while in group A there isa simple, continuous rise of the rate with age. Severalcountries and areas (group B, including Hong Kong,China, Korea) exhibit a pattern somewhat betweenthese two, that is having a plateau in young adults tomiddle age, and then peaking in the older ages.

The difference in this age pattern could be inter-preted as reflecting the history of TB epidemics of thepopulation, which is explained well with the idea ofthe cohort. Figure 4 illustrates the transition of theage-specific notification rate in Japan from 1918 until1970, from the extremely high-prevalence era to thelow-prevalence era.4 A remarkable shift of peak ofrates from adolescence to the elderly generations hasoccurred together with the passing of epidemics. Asimilar theoretical explanation can be applied toHong Kong, using birth-year cohorts.15,16 The changein the age-specific incidence rate from 1958 to 1993 isexplained by the fact that the age-specific incidencerate curve for the cohort born in 1909 to 1913 shrank

0.1

10

1000

0 10 2 0 30 4 0 50 60 70 80 90 100

Year (19_)

Rat

e pe

r 10

0,00

0 po

pula

tion

Hong Kong

Japan

Singapore

Australia

1

100

Flu pandemic End of war

Figure 1 Secular trends of tuber-culosis mortality in selected coun-tries and areas.

10

100

1000

10000

Year

Japan

Cambodiasmear+

Vietnam,Hanoi

China

Korea

Philippines Cambodiaculture+

200019951990198519801975197019651960

Rat

eper

100,

000

Figure 2 Survey-defined prevalence rates of tuberculosis.Bacteriologically confirmed cases; dotted line, smear +cases.

Tuberculosis in Asia S57


with the lapse of time, resulting in the cohort curve ofthose born in 1929 to 1933.

As a result, the age composition of TB patientsvaries greatly among countries and areas (Fig. 5).1 Ofcourse, this is complicated by the difference in the agecomposition of the population and differential case-finding intensity according to age. In Japan 60% ofpatients are over 60 years old, while in Papua NewGuinea and Mongolia, most of the patients areyounger than 60 years old. The impact of aging of TBpatients has profound implications for clinical TBmanagement, with many cases having underlyingconditions such as diabetes, malignancy, use ofimmunosuppressive agents, and others. In Japan theTB patient case-fatality rate, that is TB death within 1year of diagnosis and start of chemotherapy, hasrecently been increasing. More than 5% of TB patientsof all forms die of TB within 1 year, while it was only1.9% in 1987.4 In Hong Kong, where 36% of TB

patients were 65 years old or over as of 2001, 16% of allTB patients had comorbidity, and 3.8% died from allcauses within 2 years.17 These statistics indicate one ofthe consequences of ageing of both the populationand TB epidemics.

ANNUAL RISK OF INFECTION

The disease frequency parameters such as incidencerate and prevalence rate have a major problem in thatthey can be significantly influenced by artificial orsocial factors inherent to the process of determiningthem, such as intensity of case finding or accuracy ofdiagnosis. The annual risk of TB infection, that is thechance of an uninfected person being infected during1 year, is supposed to be the most valid indicator of TBepidemics that is free from such complications. Thisindicator can be determined by the tuberculin surveythat is far easier to implement than the prevalencesurvey. Japan,18 Korea11 and China9 have goodestimates of the annual risk of TB infection (ARTI)covering certain time-periods based on repeatedtuberculin surveys. Japan’s ARTI is known to havebeen over 1% before 1960 and then has graduallydecreased to the current level of 0.05%. A similartrend, though at a higher level, can be seen for Koreaand China (Fig. 6). For other countries and areas theindicator is estimated using data from tuberculinsurveys of children without Bacille Calmette-Guérin(BCG) vaccination history.19–23

Based on the long run of ARTI estimation, we cancalculate the age-specific prevalence of TB infection(Fig. 7) for Japan in 1950 and 2005 and for Korea to2000. The curve for Japan 1950 is concave, indicatingthat there was no reduction of ARTI until 1950. Incontrast the curve for 2005 is sigmoid, exhibiting asharp gap between young-age segments having justrare infections and old, densely infected ones. Korea’scurve for 2000 is somewhere between Japan’s 1950and 2005 curves. China’s curve is mostly based ondirect observation and looks irregular. The irregularity

0

0–14

15–2

4

25–3

4

35–4

4

45–5

4

55–6

4

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

65+

Laos

Vietnam

Cambodia

Malaysia

Singapore

Japan

a

0–14

25–3

4

15–2

4

35–4

4

45–5

4

55–6

465

+

China

Hong Kong

Korea

b

0–14

15–2

4

25–3

4

35–4

4

45–5

4

55–6

465

+

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

Philippines

Papua New Guinea

Mongolia

c

Figure 3 Age-pattern of notification rates of tuberculosis. Relative to 35–44 years of age levels, all forms, 2005.

0

100

200

300

400

500

600

0 10 20 30 40 50 60 70 80

19701960

1940

1918

1950

Age (years)

Figure 4 Ageing of tuberculosis epidemic. Age-specific TBmortality, Japan.

S58 T Mori


in the younger-age segments may be because of BCGvaccination, and that for the old-age segmentsmay reflect the waning of tuberculin reaction of theinfected individuals due to old age.

Similarly, the age-specific prevalence of infectionenables us to compute the age composition of theinfected persons from which TB patients develop, aswell as the population prevalence of infection. ForJapan almost 60% of the entire population had beeninfected with Mycobacterium tuberculosis in 1950,when the prevalence of TB was as high as 3.5%. Inthose days about 70% of the infected persons wereyounger than 45 years of age. Subsequently ARTIdecreased, the general aging of the population accel-erated, and the proportion of aged people among the

infected grew to more than 60% by 2000, when thepopulation prevalence of TB infection was only 20%.

A similar picture can be painted in countries withdifferent stages of decreasing tuberculosis. The situa-tions in Korea and China are similar to that in Japan inthe 1960s and 1970s. Their population prevalence ofTB infection is 42% (Korea) and 38% (China) (Fig. 8).

When the level of ARTI is low, it is very difficultto determine the prevalence of infection accurately. Itis because it requires a huge sample of BCG-free chil-dren that is difficult to achieve when the coverage ofBCG vaccination is high everywhere. Moreover, whenthe prevalence of infection is low, the influence ofnonspecific reactions cannot be ignored. Mathemati-cal modeling24 may be useful, but it is still far from afinal solution. It is my personal hope that new tech-nologies such as interferon-gamma release assays(IGRAs) could be beneficially employed to determineARTI of the population more accurately than bytuberculin skin tests.25

0%

20%

40%

60%

80%

100%

PNG

Mon

golia

Philippin

es

Mala

ysia

Cambod

ia

LaoPDR

China

VietNam

Australi

a

Singa

pore

Korea

Hong K

ong

Japan

65+

55–64

45–54

35–44

25–34

15–24

0–14

Figure 5 Age-composition of noti-fied cases of tuberculosis. All forms,2006. Source: World Health Organi-zation, 2008.

0.01

0.1

1

10

1960

Cambodia

Singapore

China

Korea

Japan

Malaysia

Hong Kong

Philippines

Cambodia,

province

Taiwan

200520001995199019851980197519701965

Figure 6 Annual risk of tuberculosis infection in selectedcountries.

0

20

40

60

80

100

China, 2000

(observed)

Japan, 1950 Japan, 2005Korea, 2000

Japan, 2000

Age (yrs)80706050400 10 20 30

Figure 7 Estimated age-specific prevalence of tuber-culosis infection for selected countries.



MULTIDRUG-RESISTANT (MDR)TUBERCULOSIS

In order to further strengthen national tuberculosisprogram (NTP) in both coverage and quality, we have

to overcome some important barriers. One of them istuberculosis with drug resistance, especially MDR TB.Figures 9 and 10 depict the frequency of patients withresistance to any of the four first-line drugs and MDR,based on the global surveillance system26,27 and partlycited from original literature.28–33 Some areas in China,as well as Vietnam, suffer seriously from this problem.In contrast, the frequency is not so high in Singapore,Hong Kong, Japan and Cambodia where the treat-ment program has been successful before or after theadvent of DOTS.

The same is true for the frequency of MDR. Again,some parts of China and Vietnam have high preva-lence, in contrast to New Zealand, Singapore andCambodia. Needless to say, drug resistance amongnew cases is a result of transmission of resistant bacillifrom the failure cases or relapse cases havingacquired resistance, and therefore, there is a closecorrelation between the frequency of resistance innew cases and that in the previously treated cases(Fig. 11). MDR also exhibits a similar correlationbetween new and previously treated cases by country

0%

20%

40%

60%

80%

100%

65+55–64

45–54

35–4425–34

15–24

0–14

Pop. prev. 21%

ChinaKoreaJapan

38%42%

Figure 8 Age composition of persons infected with tuber-culosis. Year 2000, estimated.

5.9

9.9

10.8

10.9

10.9

11.2

14.2

22.2

24.2

31.9

32.3

43.0

44.6

0

Singapore, 2001

Australia, 2001

Hong Kong, 2001

Cambodia, 2000–1

Japan, 2002

New Zealand, 2001

Korea, 2004

Philippines, 2003–4

Hubei, China, 2001

South Vietnam, 2001

Henan, China, 2001

Ho Chi Minh, Vietnam, 1998–2000

Kiaoning, China, 2001

5040302010

Figure 9 Frequency of drug resis-tance to tuberculosis. Resistance toany four first-line drugs, new andpreviously treated cases combined.

0.0

0.4

0.5

1.3

1.6

1.9

3.8

5.4

5.5

5.7

7.0

8.6

13.0

151050

New Zealand, 2001

Cambodia, 2000–1

Singapore, 2001

Hong Kong, 2001

Australia, 2001

Japan, 2002

Korea, 2004

South Vietnam, 2001

Henan, China, 2001

Philippines, 2003–4

Hubei, China, 2001

Ho Chi Minh, Vietnam, 1998–2000

Liaoning, China, 2001

Figure 10 Frequency of drug resis-tance to tuberculosis. Multidrug-resistant, new and previouslytreated cases combined.

S60 T Mori


(Fig. 12). It is noted that Hubei’s data lie far from thecorrelational trend, and it is possible that Hubei’sobservations are biased in some way, or its drug resis-tance is of a different nature. Dye et al.34 asked whythe frequency of drug resistance can be extraordinar-ily high in some areas of the region but generallywithin a certain limit of less extent in others. Suchquestions should be addressed in the effort to moreaggressively fight the MDR problems in accordancewith the lines of the Green Light Committee and theGlobal Plan.35

COINFECTION WITH HIV/AIDS

Another serious issue complicating TB is HIV/AIDS.Although not so extensive as in sub-Saharan Africa,HIV epidemics have been widespread in many partsof the region (Fig. 13). Cambodia36 and Papua NewGuinea have generalized epidemics at the nationallevel with the seroprevalence in the age group of15–49 years in 2005 being 1.6% in Cambodia and 1.8%in Papua New Guinea.37 In Papua New Guinea, theseropositivity in TB patients was 9.7%, and in Cambo-dia, 11.8% or 9.9%. Moreover, there are some areas, orepicentres, where the problem is concentrated,having extremely higher levels of infection than otherparts of the country. One province in Cambodiareported that 38% of TB patients were HIV-positive,and 28% of the people living with HIV had active TB.38

A similar concentration of HIV infection is seen inChina and in Vietnam.39,40 The problem is also consid-erable in Malaysia41,42 as well as in Singapore (serop-ositivity among TB patients is 1.3%).37 In othercountries or areas, the problem remains rather spo-radic at the moment, but in some countries, as inJapan, HIV infection continues to spread steadily andinsidiously, so the problem will become seriousunless it is addressed more properly by both HIV/AIDS and TB medical professionals.

0

10

20

30

40

50

60

70

New cases %

Pre

viou

sly

trea

ted

case

s %

Singapore

Hong Kong

LiaoningHubei

Henan

Japan

Philippines

Cambodia

New Zealand

Korea

Ho Chi Minh

r = 0.91

454035302520151050

Figure 11 Correlation of frequency of any resist-ance between new and previously treated patients withtuberculosis.

0

10

20

30

40

510150

New cases %

Pre

viou

sly

trea

ted

case

s %

Singapore

Henan

Korea

New Zealand

Hubei

LiaoningPhilippines

Hong Kong

Japan

Cambodia

Ho Chi Minh

r = 0.72

Figure 12 Correlation of frequency of multidrug-resistanttuberculosis between new and previously treated patients.

Figure 13 HIV-seropositivity intuberculosis patients in selectedcountries in the Western Pacificregion.

9.7%

7.0%

9.9%

6.0%

0.5%

9.3%

3.0%

0.5%

1.3%

1.0%

11.8%

0%

Papua New Guinea, 2005

Malaysia, 2005

Cambosia, 2003

Cambodia, 2005

Cambodia, 2005

Ho Chi Minh, 1994

Ho Chi Minh, 2002

Vietnam, 2005

China, 2005

Singapore, 2005

WPR, 2005

12%10%8%6%4%2%



INTERMEDIATE-BURDEN COUNTRIES

There is a group of countries and areas with preva-lence levels that are not very high, but not yet lowenough to be at the level of many European industri-alized countries. In order to address the TB controlproblems in these countries and areas, the WesternPacific Regional Office (WPRO) of the WHO has des-ignated them as ‘intermediate burden countries.’Figure 14 plots trend lines of notification rates for theintermediate burden countries. Note that the figureonly illustrates the trend on a logarithmic scale, andthat the absolute level has no meaning. In manycountries represented here, there was stagnation orslowing of the decrease rate roughly after 1990, oreven a reversal of the rate. For example in Japan thedecrease rate slowed after 1980 followed by a tempo-rary reversal, and Singapore exhibited stagnationduring the late 1980s and early 1990s.

WPRO, the Research Institute of Tuberculosis, theJapan Anti-TB Association, reviewed epidemiologicaltrends and possibly related TB control problems ofthese countries and areas, in cooperation with localNTP staff (unpublished data). It was found that nosingle cause explained all trends and problems. Thecauses of the recent stagnation could differ amongcountries and areas. Japan’s stagnation could be dueto population aging and aging of the epidemics asseen above. Furthermore, that could have been aggra-vated by the urban poor issue. In 2006 Osaka City hadthe highest notification rate of 57/100 000 that wasover 2.5-times the national average, followed by Tokyo(30/100 000). There are some closer observations ofthis ‘urban poor’ issue in Hong Kong.43,44 The influ-ence of population aging and epidemics may also berelevant in Hong Kong and Singapore. In contrast, thechange in trends in Korea may be caused by an

artefact in which case notification by the privatesector has been facilitated due to medical servicereform. Malaysia may have similar complications, aswell as some HIV effects.

The point is that we have to monitor each country’ssituation with its unique problems and characteristicsclosely so that any new trend can be properly ana-lyzed and addressed. From this point of view, it issatisfying to see that many of these countries haveestablished a good TB surveillance system.

TARGETING THE GOALS

What are the implications of the above epidemiologi-cal observations for the national TB control programand its scaling up? We are proud that among a total ofseven WHO regions, this region is the first to achievethe global targets of DOTS, that is to detect 70% ofexisting patients and treat them with DOTS to cure85% of them. We are now targeting a new goal ofreducing the 2000 mortality and prevalence levels byhalf by 2010,37 which is far more ambitious than theStop TB Partnership target to achieve the same fromthe 1990 level by 2015, in parallel with millenniumdevelopment goals. In order to realize our goal, weshould expand quality DOTS through such efforts aspublic-private-mix DOTS and social mobilization.Formidable issues such as HIV/TB and MDR-TBshould be more aggressively addressed by assuringfunding, technology and advocacy. For intermediate-burden countries and areas, an effective pin-pointstrategy should be well organized to attack problemsconcentrated in high-risk groups, or hard-to-reachpeople, such as the urban poor or socioeconomicallymarginalized people, elderly persons, and thosehaving medical problems predisposing to TB.

For both high- and intermediate-burden countries,the strong commitment of the medical profession andthe government is very important for making progresstoward the goals. In Japan we have recently set upStop TB Partnership Japan with a coalition of suchgroups and individuals as the Japan Anti-TB Asso-ciation, the Japanese Society of Tuberculosis, theMedical Association, media, businesses and parlia-mentarian groups, for the purpose of enhancing thegovernment’s commitment to TB control both inter-nationally and domestically. I hope that this willbecome another source of energy to complement theStop TB Movement in Asia, in partnership with exist-ing powerful movements such as the PhilippineCoalition against TB (PhilCat) [http://philcat.org(Accessed: 28 March, 2008)] and others.

REFERENCES

1 World Health Organization. Global tuberculosis control:surveillance, planning, financing [WHO report]; 2008Report No.: WHO/HTM/TB/2008.393.

2 Dye C, Scheele S, Dolin P, Pathania V, Raviglione MC.Global burden of tuberculosis: estimated incidence,prevalence and mortality by country. JAMA 1999; 282:677–86.

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Hong Kong

Macao

Korea

Malaysia

Brunei

Singapore

JapanNot

ific

atio

n ra

te (

rela

tive

), lo

g sc

ale

Figure 14 Comparison of trends of notification rates oftuberculosis, intermediate-burden countries.

S62 T Mori


http://philcat.org

http://philcat.org

3 Lumb R, Bastian I, Gilpom C, Keehner T, Sievers A et al.Tuberculosis in Australia: bacteriologically confirmedcases and drug resitance, 2005. Commun. Dis. Intell.2007; 31: 80–6.

4 Ministry of Health, Labor, and Welfare. TuberculosisStatistics 2007. Japan Anti-tuberculosis Association,Tokyo, 2007 (In Japanese.)

5 Chee CBE, James L. The Singapore Tuberculosis Elimina-tion Programme: the first five years. Bull. World HealthOrgan. 2003; 81: 217–21.

6 Anonymous. Tuberculosis control in Hong Kong.[Accessed 20 March 2008.] Available from URL: http://www.info.gov.hk/tb_chest/doc/TBcon.pdf

7 World Health Organization, Regional Office for theWestern Pacific. Assessing Tuberculosis Prevalencethrough Population-Based Survey. World Health Organi-zation, Geneva, 2007.

8 Tupasi TE, Radhkrishna S, Rivera AB, Pascual MLG,Quelapio MID et al. The 1997 Nationwide TuberculosisPrevalence Survey in the Philippines. Int. J. Tuberc. LungDis. 1999; 3: 471–7.

9 Ministry of Health. Report of the Nationwide TuberculosisPrevalence Sampling Survey, 2000. People’s Health Pub-lishing Company, Beijing 2002 (In Chinese.)

10 China Tuberculosis Control Collaboration. The effect oftuberculosis control in China. Lancet. 2004; 364: 417–22.

11 Hong YP, Kim SJ, Kew WJ, Lee EK, Han YC. The seventhnationwide tuberculosis prevalence survey in Korea,1995. Int. J. Tuberc. Lung Dis. 1998; 2: 27–36.

12 Anonymous. Report of Tuberculosis Prevalence Survey.Ministry of Health, Cambodia, 2002.

13 Ministry of Health & Welfare. Report of Nationwide TBPrevalence Survey. Ministry of Health and Welfare, Tokyo,1973.

14 Horie T, Lien LT, Tuan LA, Sakurada S, Yanai H et al. Asurvey of tuberculosis prevalence in Hanoi, Vietnam. Int.J. Tuberc. Lung Dis. 2007; 11: 562–6.

15 Wu P, Dowling BJ, Schooling CM, Johnston JM, Leung CCet al. Age-period-cohort analysis of tuberculosis notifi-cations in Hong Kong from 1961 to 2005. Thorax 2007;63: 312–6.

16 Tocque K, Bellis MA, Tam CM, Chan SL, Syed Q et al.Long-term trends in tuberculosis. Comparison of age-spedific data between Hong Kong and England andWales. Am. J Respir. Crit Care. Med. 1998; 158: 84–8.

17 Tam CM, Leung CC, Noertjojo K, Chan SL, Chan-YeungM. Tuberculosis in Hong Kong. Patient characteristicsand treatment outcome. Hong Kong Med.J. 2003; 9: 83–90.

18 Mori T. Recent trends in tuberculosis in Japan. Emerg.Infect. Dis. 2000; 6: 566–8.

19 Leung CC, Yew WW, Tam CM, Chan CK, Chang KC et al.Tuberculin response in BCG vaccinated schoolchildrenand the estimation of annual risk of infection in HongKong. Thorax. 2005; 60: 124–9.

20 Tuapsi TE, RadhakrishnaS Pascual ML, Quelapio MID,Villa ML et al. BCG coverage and the annual risk of tuber-culosis infection over a 14-year period in the Phillipinesassessed from the Nationwide Prevalence Surveys. Int. J.Tuberc. Lung Dis. 2000; 4: 216–22.

21 Norval PY, Roustit C, San KK. From tuberculin to preva-lence survey in Cambodia. Int. J. Tuberc. Lung Dis. 2004;8: 299–305.

22 Leung CC, Yew WW, Chang KC, Tam CM, Chan CK et al.Risk of active tuberculosis among schoolchildren

in Hong Kong. Arch. Pediatr. Adolesc. Med. 2006; 247–51.

23 Yu MC, Suo J, Huang C, Bai KJ, Lin TP et al. Annual risk oftuberculous infection in Taiwan, 1996–1998. J. Formos.Med. Assoc. 1999; 98: 496–9.

24 Neuenschwander BE, Zwahlen M, Kim SJ, Engel RR,Rieder HL. Trends in the prevalence of infection withMycobacterium tuberculosis in Korea from 1965 to 1995:an analysis of seven surveys by mixture models. Int. J.Tuberc. Lung Dis. 2000; 4: 719–29.

25 Mori T, Harada N, Higuchi K, Sekiya Y, Uchimura K et al.Waning of the specific interferon-gamma response afteryears of tuberculosis infection. Int. J. Tuberc. Lung Dis.2007; 11: 1021–5.

26 Aziz MA, Wright A, Laszlo A, Muynck AD, Portaels F et al.Epidemiology of antituberculosis drug resistance (theGlobal Project on Anti-tuberculosis Drug ResistanceSurveillance): an update analysis. Lancet 2006; 368:2142–54.

27 WHO/IUATLD Global Project on Anti-tuberculosisDrug Resistance Surveillance, 2002–2007. Anti-tuberuclosis Drug Resistance in the World, 4th GlobalReport. WHO/HTM/TB/2008.394 World Health Organi-zation.

28 Wang PD, Lin RS. Drug-resistant tuberculosis in Taipei,1996–1999. Am. J. Infect. Control. 2001; 29: 41–7.

29 Kam KM, Yip CW. Surveillance of Mycobacterium tuber-culosis susceptibility to second-line drug in Hong Kong,1995–2002, after the introduction of DOTS-Plus. Int. J.Tuberc. Lung Dis. 2004; 8: 760–6.

30 Quy HT, Buu TN, Cobelens FGJ, Kan NTN, LambregtsCSB et al. Drug resistance among smear-positive tuber-culosis patients in Ho Chi Minh City, Vietnam. Int. J.Tuberc. Lung Dis. 2006; 10: 160–6.

31 Yamada N, Saorith K, Yamakami K, Onozaki I, Boran Set al. The National Tuberculosis Drug Resistance Surveyin Cambodia, 2000–2001. Int. J. Tuberc. Lung Dis. 2007;11: 1321–7.

32 Huong NT, Lan NTN, Cobelens FGJ, Duong BD, Co NVet al. Antituberculosis drug resistance in the South ofVietnam: prevalence and trends. J. Inf. Dis. 2006; 194:1226–32.

33 Bai GH, Park YK, Choi YW, Bai JI, Kim HJ et al. Trend ofanti-tuberculosis drug resistance in Korea, 1994–2004.Int. J. Tuberc. Lung Dis. 2007; 11: 571–6.

34 Dye C, Espinal MA. Will tuberculosis become resistant toall antibiotics? Proc. Biol. Sci. 2001; 268: 45–52.

35 Stop TB Partnership and World Health Organization.Global Plan to Stop TB 2006–2015. World Health Organi-zation, Geneva, 2006 (Report No.: WHO/HTM/STB/2006.35).

36 Kimerling ME, Schchter J, Chanthol E, Kunthy T, StuerF et al. Prevalence of pulmonary tuberculosis amongHIV-infected persons in a home care program inPhnom Penh, Cambodia. Int. J. Tuberc. Lung Dis. 2002;6: 988–94.

37 World Health Organization, Regional Office for theWestern Pacific. Tuberculosis Control in the WesternPacific Region—2007 Report. World Health Organiza-tion, Phillipines, 2007.

38 Cain KP, Kanara N, Lasersib KF, Vannarith C, SameournS et al. The epidemiology of HIV-associated tuberculosisin rural Cambodia. Int. J. Tuberc. Lung Dis. 2007; 11:1008–13.



http://www.info.gov.hk/tb_chest/doc/TBcon.pdf

http://www.info.gov.hk/tb_chest/doc/TBcon.pdf

39 Buu TN, Houben RMGJ, Quy HT, Lan NTN, BorgdorffMW et al. HIV and tuberculosis in Ho Chi MinhCity, Vietnam, 1997–2002. Emerg. Inf. Dis. 2007; 13:1463–9.

40 Goldfeld A, Ellner JJ. Pathogenesis and management ofHIV/TB co-infection in Asia. Tuberculosis 2008; 87: S26–30.

41 Cheong I, Lim A, Ibrahim Z, Sarvanathan K. Epidemiol-ogy and clinical characteristics of HIV-infected patientsin Kula Lumpur. Med. J. Malaysia. 1997; 52: 313–17.

42 Dony JF, Ahmad J, Yap KT. Epidemiology of tuberculosisand leprosy, Sabah, Malaysia. Tuberculosis 2004; 84: 8–18.

43 Chan-Yeung M, Yeh AGO, Tam CM, Kam KM, Leung CCet al. Socio-demographic and geographic indicatorsand distribution of tuberculosis in Hong Kong: a spatialanalysis. Int. J. Tuberc. Lung Dis. 2005; 9: 1320–6.

44 Leung CC, Yew WW, Tam CM, Chan CK, Chang KC et al.Socio-economic factors and tuberculosis: a district-based ecological analysis in Hong Kong. Int. J. Tuberc.Lung Dis. 2004; 8: 958–64.

S64 T Mori


Documents

Tuberculosis epidemiology in the Asia–Pacific region