Part I REVIEW OF TUBERCULOSIS EPIDEMIOLOGY 1. 2. 3. Estimated Tuberculosis Burden 7 Tuberculosis Case Notification 10 Prevalence and Tuberculin Surveys 22 PART 1 5
TABLE 1: Latest notification of tuberculosis by country Pop. Case Notification, 1994-1997 Case Notification, 1998 Estimated Case Detection Countries (x 1000) All Cases Number Rate/100 000 Incidence Rate (%) Number Number, 1998 1998 1994 1995 1996 1997 All New All New All New All New 1998 Types* Smear + Types* Smear + Types* Smear+ Types* Smear+ a d e f g h i j k b c h/b i/c American Samoa ('97) 63 6 6 6 6 10.3 10.3 56 25 12% 26% Australia 18 520 1073 1073 1145 899 203 4.9 1.1 1482 741 61% 27% Brunei Darussalam ('93) 315 160 68 58.4 24.8 183 82 101% 95% Cambodia 10 716 15 112 14 599 14 857 15 629 16 946 13 865 158.1 129.4 57 757 25 825 29% 54% China 1 255 698 363 804 335 059 469 358 418 903 457 349 214 462 36.4 17.1 1 418 938 640 406 32% 33% Cook Islands 19 4 1 0 2 1 10.4 5.2 17 8 12% 13% Fiji 796 225 203 200 171 166 74 20.9 9.3 709 318 23% 23% French Polynesia 227 89 86 91 105 34 46.2 15.0 202 91 52% 37% Guam ('94) 147 94 94 40 63.9 27.2 143 64 72% 68% Hong Kong, China 6660 6319 6212 6501 6983 7673 1869 115.2 28.1 6061 2731 127% 68% Japan 126 281 44 590 43 078 42 122 42 190 44 016 11 935 34.9 9.5 36 622 16 417 120% 73% Kiribati 81 253 253 32 276 50 340.6 61.7 72 32 383% 154% Republic of Korea 46 109 38 155 33 196 31 134 26 202 30 008 10 359 65.1 22.5 40 115 17 983 75% 58% Lao PDR 5163 1135 1307 1440 1923 2165 1508 41.9 29.2 8622 3872 25% 39% Macao, China 459 349 354 455 589 463 226 100.9 49.2 1014 454 46% 50% Malaysia 21 410 11 708 11 778 12 902 13 539 14 115 7802 65.9 36.4 23 979 10 705 59% 73% Mariana Is. 70 46 40 40 93 97 26 138.7 37.2 62 28 156% 93% Marshall Is. 60 56 49 11 81.3 18.2 54 24 91% 46% Micronesia FS 114 171 94 108 138 28 121.0 24.5 102 46 136% 61% Mongolia 2579 1730 3010 3010 2987 2915 1356 113.0 52.6 5287 2373 55% 57% Nauru ('94) 11 4 4 2 36.4 18.2 10 4 41% 45% New Caledonia 206 132 205 102 30 49.4 14.5 184 83 56% 36% New Zealand 3796 352 307 323 328 367 81 9.7 2.1 190 76 193% 107% Niue 2 2 1 2 0 1 51.4 2 1 58% Palau ('97) 19 41 19 5 15 15 7 81.0 37.8 16 7 100% 117% Papua New Guinea 4600 5335 8041 5087 7977 11 291 2107 245.5 45.8 11 499 5152 98% 41% Philippines 72 944 180 044 235 496 276 295 208 301 159 866 71 663 219.2 98.2 229 046 102 852 70% 70% Pitcairn Is. (**) 0.046 Samoa 174 45 51 37 32 22 7 12.6 4.0 155 70 14% 10% Singapore 3476 1677 1889 1889 1977 2120 480 61.0 13.8 1668 765 127% 63% Solomon Islands 417 332 352 289 318 295 140 70.7 33.6 371 167 79% 84% Tokelau ('96) 1.5 0 1 1 1 1 50.0 50.0 2 1 56% 125% Tonga 98 23 20 22 21 30 16 30.6 16.3 87 39 34% 41% Tuvalu 11 19 36 18 0 161.9 0.0 10 4 182% 0% Vanuatu 182 152 79 79 184 178 38 98.1 20.9 162 73 110% 52% Viet Nam 77 562 51 763 55 739 74 711 84 964 87 449 54 873 112.7 70.7 146 593 65 928 60% 83% Wallis & Futuna ('97) 14 11 4 4 14 14 1 93.3 6.7 13 6 105% 17% WPR TOTAL(***) 1 659 017 723 716 751 951 942 831 834 722 839 121 393 244 50.6 23.7 1 991 434 897 451 42% 44% Italic figures denote data of 1993, 1994, 1995, 1996 or 1997, which is specified in the bracket after name of country/area. * All types includes new smear-positive, relapse, smear negative and extrapulmonary tuberculosis cases. **: No data of TB is available. ***: In WPR Total, cases reported for other years than 1998 are not included in calculation. 6
1 ESTIMATED TUBERCULOSIS BURDEN WHO Western Pacific Regional Office, in collaboration with the WHO Global Tuberculosis Programme, Geneva, conducted in 1997 a workshop on tuberculosis estimates. 2 The goal of the workshop was to evaluate the availability and reliability of tuberculosis data in participating countries and derive country specific estimates of morbidity and mortality for the disease. Based on data arising out of the workshop, a report, Global Burden of Tuberculosis, was published in 1999. The estimates presented here are from that article. Global estimates The total number of tuberculosis cases was 16.2 million, while the disease claimed some 1.87 million lives that year. Table 2 shows the estimated global burden of tuberculosis in 1997. There were 7.96 million new cases worldwide, with 45% of these infectious pulmonary cases (sputum smear-positive cases). The total number of tuberculosis cases was 16.2 million, while the disease claimed some 1.87 million lives that year. TABLE 2: Estimates of tuberculosis burden worldwide, 1997 New cases (all types of tuberculosis) 7.96 million New cases (infectious pulmonary cases) 3.52 million Existing cases of tuberculosis Number of tuberculosis deaths Prevalence of M. tuberculosis infection 16.2 million 1.87 million 32% (1.86 billion) Tuberculosis/HIV situation Prevalence of tuberculosis/hiv co-infection Incident tuberculosis cases with HIV infection 0.18% of the global population 640 000 (8% of incident TB cases) Figure 3 shows the estimated incidence, prevalence and deaths from tuberculosis by WHO Region. In 1997, the Western Pacific Region ranked second globally after the South-East Asia Region in the number of tuberculosis prevalent and incident cases, and ranked third in the number of tuberculosis deaths. The Region also accounted for about 25% of global incident and prevalent tuberculosis cases, and 19% of global tuberculosis deaths. 2 Countries participating in the workshop included Cambodia, China, Japan, the Republic of Korea, Malaysia, the Philippines and Viet Nam. 7
FIGURE 3: Estimated tuberculosis prevalent cases, new cases and deaths, WHO Regions 1997 9 8 Number of cases or deaths Millions 7 6 5 4 3 Deaths New cases Prevalent cases 2 1 0 AMR EUR EMR AFR WPR SEAR The Western Pacific Region The epidemiological status of tuberculosis varies among the countries in the Region. The countries can be grouped based on levels of the estimated epidemiological indicators (see Figure 4). The highest prevalence, incidence and mortality rates for tuberculosis are found in the group comprising Cambodia, the Lao People s Democratic Republic, Papua New Guinea, the Philippines, Mongolia and Viet Nam. The next highest rates are found in China, followed by the group including Brunei Darussalam; Hong Kong, China; the Republic of Korea; Macao, China; Malaysia; and Singapore; followed by the Pacific Islands (excluding Papua New Guinea). The countries with the lowest rate are Australia, Japan and New Zealand. China accounts for about 70% of prevalence, incidence and tuberculosis deaths, reflecting the large size of its population. 8
FIGURE 4: Estimated tuberculosis prevalence, incidence and mortality rates, Western Pacific Region 1997 600 500 Rate per 100,000 400 300 Mortality Incidence Prevalence 200 100 0 Aust/NZ/Japan Kor/Mal/Bru/Sin/HK/Mac Pac Isd (excl PNG) China Phil/IndCh/Mon/PNG Figure 5 shows the proportion of tuberculosis deaths to total deaths among the 15-64 age group in the Region. Tuberculosis is the leading cause of deaths among infectious diseases, accounting for 76.7% of infectious disease deaths. FIGURE 5: Estimated proportion of deaths due to infection (ages 15-64 years), Western Pacific Region 1997/98 (76.7%) Tuberculosis Hepatitis B/C Malaria (16.2%) Other (5.1%) (2.0%) References: 1) The Global Burden of Disease; Murray and Lopez. 2) Impact of Tuberculosis in the Western Region; Richard Taylor; September 1999. 9
2 TUBERCULOSIS CASE NOTIFICATION Background Definition of terms AAll types, new case and relapse: ll types refers to the sum of new pulmonary smear-positive, relapse, new pulmonary smear-negative and extrapulmonary tuberculosis cases. A new case is defined as a patient who has either never had previous treatment for tuberculosis or who has previously taken anti-tuberculosis drugs for less than four weeks. A relapse means a patient previously treated and declared cured by a medical officer but who reports back for treatment and is then determined as sputum smear-positive. A new case is defined as a patient who has either never had previous treatment for tuberculosis or who has previously taken anti-tuberculosis drugs for less than four weeks. Rates per 100 000 population: Rates are always expressed per 100 000 population. The rates for 1998 were calculated using the absolute number of cases reported from each country and the 1998 mid-year population. The data source of population in 1998 was UN World Population Prospects (1998 revision). Therefore, the rates used in this report may differ from those of other sources if different population numbers were used. Data collection Notification of tuberculosis cases during the last 5 years by each country are summarized in Table 1. Sending data for 1998 were 29 out of the 37 countries/areas of the WHO Western Pacific Region. The 8 countries/areas not sending data were American Samoa, Brunei Darussalam, Guam, Nauru, Palau, the Pitcairn Islands, Tokelau, and Wallis and Futuna, representing a total population of 791 496 and accounting for 0.05% of the Regional population. Out of these countries, 1997 data were available for American Samoa, Palau, and Wallis and Futuna; 1996 data for Tokelau; 1994 data for Guam and Nauru; and 1993 data for Brunei Darussalam. For this report, these 8 countries have been excluded from some tables and figures. When they were included, as in Table 1, they were assigned the most recent available data. China did not notify extrapulmonary cases. Malaysia did not report relapses and the Philippines included failure cases in its report. For New Zealand, 42 cases with no site classification were included in the total. Niue reported only 1 case without specifying its classification. In the tables, 0 means that zero cases were reported; a blank space means that data were not available, not reported or not applicable. 10
General considerations on tuberculosis trends Information on notification of cases has been collected over the past 21 years. These surveillance statistics provide some indication of the changing burden of tuberculosis in the Region and each county/area. However, because of the differing reporting systems and tuberculosis control policy between countries, changing definitions of a notifiable case and possible under- or over-reporting, these figures should be interpreted with caution. Case notification in the world in 1997 By 31 January 1999, 173 countries (82%) out of 212, reported case notifications for 1997. Globally, there were 3 368 879 of all types of cases and 1 292 884 new smearpositive cases notified in 1997. The Western Pacific Region accounted for 29% (375 809 cases) of the globally notified new smear-positive cases in 1997 (see Figure 6). The notification rate of new smear-positive cases was 23 per 100 000, almost the same as the global average (see Figure 7). FIGURE 6: Distribution of notified cases by Region, smear-positive cases, 1997 WPR 29% AFR 19% AMR 11% SER 28% EUR 9% EMR 4% 11
FIGURE 7: Notification rate by WHO Region, 1997 100 90 80 Smear-positive Cases All Types Rate per 100 000 70 60 50 40 30 20 10 0 11 AFR AMR EMR EUR SER WPR Global WHO Region Total Case notification in the Region Latest notification of all types of tuberculosis cases Notified all types of tuberculosis cases In 1998, 839 121 cases of tuberculosis were notified by 29 countries/areas of the Region (see Table 1). Five countries account for 94% of all notified cases, with China contributing 55%, the Philippines 19% and Viet Nam 10% (see Figure 8). These 5 countries also contain 95% of the Regional population (see Figure 2). FIGURE 8: Percentage distribution of notified cases by major countries, 1998 Republic of Korea 4% Others 6% Japan 5% Viet Nam 10% Philippines 19% China 55% Total Notified Cases = 839 121 12
Notification rate of all types of tuberculosis cases per 100 000 population The notification rate for the Region was 51 per 100 000 population, varying in individual countries/areas from 4.9 (Australia) to 340.6 (Kiribati) (see Figure 9). In Pacific Island Countries with a small population, such as Kiribati and Tuvalu, the annual numbers and rates of cases showed great fluctuation. The notification rate was lower than 25 per 100 000 in 6 countries, between 25 and 100 in 20 countries, and more than 100 in the remaining 11 countries. FIGURE 9: Latest rate of notified cases, all types, by country, 1998 Kiribati Papua New Guinea Philippines Tuvalu Cambodia Mariana Is. Micronesia FS Hong Kong, China Mongolia Viet Nam Macao Vanuatu Wallis & Futuna ('97) Marshall Is. Palau ('97) Solomon Islands Malaysia Republic of Korea Guam ('94) Singapore Brunei Darussalam ('93) Niue Western Pacific Region (*) Tokelau ('96) New Caledonia French Polynesia Lao PDR China Nauru ('94) Japan Tonga Fiji Samoa Cook Islands American Samoa ('97) New Zealand Australia 20.9 * - New bacteriologically positive cases 12.6 10.4 10.3 9.7 4.9 36.4 36.4 34.9 30.6 51.4 50.0 49.4 46.2 41.9 65.9 65.1 63.9 61.0 58.4 50.6 70.7 81.3 81.0 100.9 98.1 93.3 121.0 115.2 113.0 112.7 138.7 161.9 158.1 219.2 245.5 * Average for the Western Pacific Region. Figures are for 1998, unless another year is specified in brackets after the country name. 340.6 0 50 100 150 200 250 300 350 Rate per 100 000 13
Latest notification of new pulmonary sputum smear-positive cases Notified new pulmonary sputum smear-positive cases There were 393 244 new sputum positive cases notified in 1998 (see Table 1). China (55%), the Philippines (18%) and Viet Nam (14%) represented 87% of the Region s notified new pulmonary smear-positive cases. Notification rate of new pulmonary sputum smear-positive cases per 100 000 population The notification rate for the Region was 23.7 per 100 000 population, varying from 0 in Tuvalu to 129.4 per 100 000 in Cambodia (see Figure 10). The notification rate was lower than 25 per 100 000 in 20 countries, including Australia, China, Japan and the Republic of Korea. The rate was between 25 and 100 per 100 000 in 14 countries, including Malaysia, Papua New Guinea, the Philippines and Viet Nam. Cambodia was the only country to register a figure higher than 100 per 100 000. FIGURE 10: Latest rates of new smear-positive cases by country, 1998 Cambodia Philippines Viet Nam Kiribati Mongolia Tokelau ('96) Macao, China Papua New Guinea Palau ('97) Mariana Is. Malaysia Solomon Islands Lao PDR Hong Kong, China Guam ('94) Brunei Darussalam ('93) Micronesia FS Western Pacific Region (*) Republic of Korea Vanuatu Nauru ('94) Marshall Is. China Tonga French Polynesia New Caledonia Singapore American Samoa ('97) Japan Fiji Wallis & Futuna ('97) Cook Islands Samoa New Zealand Australia Tuvalu 9.5 9.3 6.7 5.2 4 2.1 1.1 0 15 13.8 10.3 18.2 18.2 17.1 16.3 14.5 24.8 24.5 23.7 22.5 20.9 29.2 28.1 27.2 37.2 36.4 33.6 37.8 50 49.2 45.8 52.6 61.7 70.7 98.2 * Average for the Western Pacific Region. 129.4 Figures are for 1998, unless another year is specified in brackets after the country name. 0 20 40 60 80 100 120 140 Rate per 100 000 14
Proportion of new smear-positive cases out of all new pulmonary cases The proportion of new smear-positive cases out of all new pulmonary cases was on average 51%, ranging between 0% in Tuvalu and 95% in Cambodia (see Figure 11). There were 9 countries with a proportion more than 55%. Out of these, 8 are countries implementing DOTS. In DOTS areas, the proportion of sputum smear-positive cases (62%) was higher than in non-dots areas (37%). This may reflect tuberculosis control programme improvements since sputum smear examinations are considered the standard diagnosis of pulmonary tuberculosis for less developed countries. FIGURE 11: Proportion of new smear-positive cases out of all new pulmonary cases, 1998 Cambodia Lao PDR Viet Nam Mongolia Solomon Islands Tonga Fiji Malaysia Macao, China Western Pacific Region (*) Philippines Cook Islands opy from 'ANNEX 4 (casebytype98)' China ort by key Samoa French Polynesia New Caledonia Australia Republic of Korea New Zealand Kiribati Marshall Is. Japan Papua New Guinea Singapore Mariana Is. Hong Kong, China Vanuatu Micronesia FS Tuvalu 0% 95% 77% 76% 65% 64% 64% 64% 61% 57% 51% 50% 50% 49% 47% 45% 43% 39% 37% 37% 34% 34% 34% 30% 29% 29% 28% * Average for the Western Pacific Region. 26% 25% 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 15
Trends in notification of all types and new smear-positive cases in the Region The number of notified all types of tuberculosis has fluctuated over the last 6 years. This is attributable mainly to the number of cases from China and, to a lesser extent, the Philippines. The notification rate for all types of tuberculosis varied from 45.7 in 1994 to 50.6 per 100 000 population in 1998, peaking at 58 in 1996 (see Figure 12). In contrast, the notification rate for new sputum positive cases increased steadily and continuously from 1993 to 1998 (see Figure 12). This rise is due largely to more frequent detection of sputum positive cases in China and, to a lesser extent, in Viet Nam. The rise in the number of new sputum smear-positive cases in China is mainly due to improved case finding in DOTS areas. FIGURE 12: All types and new smear-positive rate per 100 000 in the Western Pacific Region, 1993-1998 80.0 70.0 Rate per 100 000 60.0 50.0 40.0 30.0 20.0 All types New smear positive 48.2 45.7 45.5 17.5 19.6 16.6 58 21.7 50.9 50.6 22.9 23.7 10.0 0.0 1993 1994 1995 1996 1997 1998 Year Figure 13 shows the average notification rate for 1993-1994 and 1997-1998. In the countries that reported annual new smear-positive cases in excess of 500 in 1993-1994, the notification rate of smear-positive cases increased or did not decrease significantly (i.e., decreased by less than 10% per year on average between the periods in Hong Kong, China; the Republic of Korea; and Singapore). The high burden countries, with the exception of the Philippines, show an increase in rate. 16
FIGURE 13: Comparison of notification rate of new smear-positive cases in 1993/94 and 1997/98 0 20 40 60 80 100 120 140 160 Cambodia Philippines Viet Nam Mongolia Papua New Guinea Countries with High Burden of Tuberculosis Lao PDR China Macao, China Malaysia Hong Kong, China Rep. of Korea Countries with Intermediate Burden of Tuberculosis Singapore Japan Pacific Island Countries New Zealand Australia Countries with Low Burden of Tuberculosis Western Pacific Region (*) Average Rate in 1993/1994 Average Rate in 1997/1998 * Average for the Western Pacific Region. Distribution of the different types of notified cases in the Region Among the 839 121 notified cases, 393 244 (46.9%) were new pulmonary sputum smear-positive cases, 31 053 (3.7%) were relapses, 373 709 (44.5%) were new pulmonary sputum smear-negative cases and 27 072 (3.2%) were extrapulmonary new cases. The low number and percentage of extrapulmonary cases is accounted for by the fact that China and the Philippines did not report such cases. The proportion of new tuberculosis cases among all the notified cases was 96%. The proportion of new pulmonary smear-positive cases to all new pulmonary cases was 51.3% (see Annex 4). 17
Sex and age distribution of the new pulmonary smear-positive cases in the Region Information on sex and age was collected for new pulmonary smear-positive cases. Data from DOTS and non-dots areas were combined and analysed. Such information was reported by 27 countries, accounting for 310 636 patients (see Annex 5) and representing 79% of all new pulmonary sputum positive cases reported in the Region. Patients younger than 15 years of age accounted for 1% of new pulmonary smearpositive cases. The distribution reached a peak of 21% for the 25-34 age group and declined until the age of 65 or more, where it slightly increased. The 15-54 age group accounted for 69% of the cases (see Figure 14). FIGURE 14: New smear-positive pulmonary cases by age group, Western Pacific Region 1998 30% 25% 21% Percent 20% 15% 14% 18% 16% 14% 16% 10% 5% 0% 1% 0-14 15-24 25-34 35-44 45-54 55-64 65 or over Age Group Among the 27 countries that sent information, there were twice as many male tuberculosis patients reported as females. The number of patients was almost equal in females and males up to the age of 24, but after this age, male cases predominated, with the gap between the two sexes widening as the age increased (see Figure 15). 18
FIGURE 15: New pulmonary smear-positive cases by age group and sex, Western Pacific Region 1998 250 000 Male Female Notified Cases Notified Cases 200 000 150 000 100 000 50 000 00 000 0-14 15-24 25-34 35-44 45-54 55-64 >=65 Total Age Groups In contrast to the case distribution by age group, the notification rate of new smearpositive cases increased with age (see Figure 16 and Annex 6). This tendency is more significant in males, with the rate for those aged 65 and over (68.4) being four times higher than that for the 15-24 age group (17.5). The rate was almost similar in females and males until the age of 24, after which males showed a higher rate. The gap in rate between the two sexes widened as the age increased. FIGURE 16: Notification rate by sex and age group of new smear-positive cases, Western Pacific Region 1998 80 70 Rate per 100 000 Rate per 100 000 60 50 40 30 20 10 0 0-14 15-24 25-34 35-44 45-54 55-64 >=65 Year Male Total Female 19
Case detection in the world and in the Region The world in 1997 A global target is the detection of 70% of existing new sputum smear-positive cases. The case detection rate is defined as the ratio (%) of annual new smear-positive notifications to estimated annual new smear-positive cases. Figure 17 shows the notified cases in each WHO region in 1997. The estimated case detection rate of new smearpositive cases, based on the number of cases reported to WHO, in the Western Pacific Region, was 42.7%, almost the same as the global average (36.8%), ranking the Region third (see Figure 18). FIGURE 17: Notified number of new smear-positive cases by WHO Region, 1997 1400 000 1200 000 1000 000 Notified Cases 800 000 600 000 400 000 200 000 000 000 AFR AMR EMR EUR SER WPR Global Total WHO Region FIGURE 18: Case detection rate by WHO Region, 1997 100% 90% 80% All Cases New Smear + Case Detection Rate 70% 60% 50% 40% 30% 20% 10% 0% AFR AMR EMR EUR SER WPR Global Total WHO Region 20
The Region in 1998 In 1998, the case detection rate (new smear-positive cases) was 43.9%, showing no significant change from 42.7% in 1997, in the Western Pacific Region. Within the Region, the case detection rate varied by country. Figure 19 shows the case detection rate among the high burden countries. The Philippines and Viet Nam have a high case detection rate of new sputum positives of 70% and 83%, respectively, contrasting with a low rate in China (33%) and Papua New Guinea (41%). FIGURE 19: Case detection rate by countries 0% 20% 40% 60% 80% 100% 120% 140% 160% 180% 200% Papua New Guinea Philippines Viet Nam Mongolia China Cambodia Lao PDR Singapore Hong Kong, China Japan Brunei Darussalam ('93) All Types New SS+ Republic of Korea Malaysia Macao, China PICs New Zealand Australia Western Pacific Region 21
3 PREVALENCE AND TUBERCULIN SURVEYS Prevalence surveys measure prevalence and the prevalence rate, which are the number and rate, respectively, of tuberculosis cases existing at a certain point in time. T he notification number and rate of tuberculosis cases are influenced by National Tuberculosis Control Programme (NTP) performance, such as the NTP coverage and reporting system, as well as the epidemiological situation. Prevalence surveys and tuberculin surveys are conducted to provide epidemiological indicators, which can be directly measured. Prevalence surveys Prevalence surveys measure prevalence and the prevalence rate, which are the number and rate, respectively, of tuberculosis cases existing at a certain point in time. They are also used to derive other epidemiological indicators such as incidence of tuberculosis. Annex 8 summarizes available data on prevalence surveys. The Republic of Korea has conducted a prevalence survey every 5 years since 1965 (see Annex 8 and Figure 20a). There has been a steady decrease in the prevalence rate of X-ray active, bacillary positive and smear-positive tuberculosis cases. The pattern of prevalence rate by age group has been changing with the prevalence rate decreasing (see Figure 20b). FIGURE 20a: Tuberculosis prevalence rate trend in the Republic of Korea, 1965-1995 6000 5000 X-Ray Active Bac (+) Smear(+) 4000 Rate per 100 000 3000 2000 1000 0 1965 1970 1975 1980 1985 1990 1995 Year 22
FIGURE 20b: Prevalence of bacteriologically confirmed tuberculosis in the Republic of Korea, 1965-1995 3000 2500 Rate per 100 000 2000 1500 1000 500 1965 1970 1975 1980 1985 1990 1995 0 age5-19 20-34 35-49 50-64 >=65 65- Age Group In the Philippines, prevalence surveys were conducted in 1983/84 and 1997. Allowing for methodological differences compared with the 1983/84 survey, there were only minimal changes in the 14-year interval (see Annex 8 and Figure 21). The prevalence rate was similar in urban and rural areas (see Figure 22). In rural areas, the peak age group is 30-49 while prevalence increases with age in urban areas. FIGURE 21: Prevalence rate of tuberculosis in the Philippines, 1983 and 1997 4500 4000 3500 Rate per 100 000 3000 2500 2000 1500 1983 1997 1000 500 0 X-Ray Active Bacteriologically (+) (+) Smear(+) 23
FIGURE 22: Prevalence rate of bacteriologically confirmed cases, 1997 National Prevalence Survey, the Philippines Rate per 100 000 Rate per 100 000 3000 2500 2000 1500 1000 500 5 0 <30 30-49 50 or over Age Group Culture-positive (Metro Manila) Culture-positive (Other Urban) Culture-positive (Rural) Tuberculin surveys Tuberculin surveys are conducted to measure the annual risk of infection (ARI), which is regarded as a universal and comparable indicator for the epidemiological situation of tuberculosis. Recent data available in the Region are summarized in Annex 9. In the Republic of Korea, seven national surveys have been conducted. The annual reduction rate in the ARI has been about 7% since the first survey in 1965. The most recent data are from a 1997 National Survey in Philippines. Figure 23 shows the infection prevalence in urban and rural areas from the survey. There was no significant difference in the observed prevalence in the urban and rural population. The ARI, which was computed from the proportion of children aged 5-9 years who had a tuberculin reaction, was 2.3% (2.5% in males and 2.1% in females). There was little significant change from the ARI estimated in a 1981-1983 survey (2.5%). FIGURE 23: Age-specific prevalence of tuberculosis infection among unvaccinated persons, 1997 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Urban Rural < 5 5-9 10-14 15-19 20-29 30-39 40-49 50-59 60-69 70 or over Age Group 24
Part II REVIEW OF DOTS IMPLEMENTATION IN THE REGION 1. 2. 3. DOTS Coverage 28 Treatment Outcome by DOTS and Non-DOTS 32 Summary of Progress of DOTS Implementation 35 in the Region PART II 25
TABLE 1b: DOTS coverage reported by country in 1998 Pop. Pop. Notified DOTS Notified DOTS Estimated DOTS Case Total Accessible All types* Enrolment New S+ Enrolment Incident Detection Rate Countries (x 1000) to DOTS DOTS Non- Rate DOTS Non- Rate New S+ New S+ (1998) (x 1000) (%) DOTS All Types DOTS New S+ (%) a b b/a c d c/(c+d) e f e/(e+f) g e/g American Samoa ('97) 58 58 100% 6 0 100% 6 0 100% 23 26% Australia 18 520 6853 37% 424 475 47% 116 87 57% 741 16% Brunei Darussalam ('93) 315 0 82 Cambodia 10 716 10 716 100% 16 946 0 100% 13 865 0 100% 25 825 54% China 1 255 698 802 391 64% 336 535 120 814 74% 191 290 23 172 89% 640 406 30% Cook Islands 19 13 70% 2 0 100% 1 0 100% 8 13% Fiji 796 796 100% 166 0 100% 74 0 100% 318 23% French Polynesia 227 227 100% 105 0 100% 34 0 100% 91 37% Guam ('94) 161 64 Hong Kong, China 6660 0 0% 0 7673 0% 0 1869 0% 2731 0% Japan 126 281 0 0% 0 44 016 0% 0 11 935 0% 16 417 0% Kiribati 81 30 37% 276 0 100% 50 0 100% 32 154% Republic of Korea 46 109 46 109 100% 30 008 0 100% 10 359 0 100% 17 983 58% Lao PDR 5163 3666 71% 2149 16 99% 1494 14 99% 3872 39% Macao, China 459 459 100% 463 0 100% 226 0 100% 454 50% Malaysia 21 410 0 0% 0 14 115 0% 0 7802 0% 10 705 0% Mariana Is. 70 0 0% 0 97 0% 0 26 0% 28 0% Marshall Is. 60 0 0% 0 49 0% 0 11 0% 24 0% Micronesia FS 114 0 0% 0 138 0% 0 28 0% 46 0% Mongolia 2579 2497 97% 2725 190 93% 1213 143 89% 2373 51% Nauru ('94) 11 4 New Caledonia 206 206 100% 102 0 100% 30 0 100% 83 36% New Zealand 3796 0 0% 0 367 0% 0 81 0% 76 0% Niue 2 2 100% 1 0 100% 0 0 0% 1 0% Palau ('97) 17 17 100% 15 0 100% 7 0 100% 6 117% Papua New Guinea 4600 414 9% 2845 8446 25% 418 1689 20% 5152 8% Philippines 72 944 12 328 17% 18 286 141 580 11% 10 292 61 371 14% 102 852 10% Pitcairn Is. 0.046 Samoa 174 174 100% 22 0 100% 7 0 100% 70 10% Singapore 3476 0 0% 0 2120 0% 0 480 0% 765 0% Solomon Islands 417 417 100% 295 0 100% 140 0 100% 167 84% Tokelau ('96) 1.5 1 Tonga 98 96 98% 30 0 100% 16 0 100% 39 41% Tuvalu 11 0 0% 0 18 0% 0 0 0% 4 0% Vanuatu 182 0 0% 0 178 0% 0 38 0% 73 0% Viet Nam 77 562 74 460 96% 84 599 2850 97% 53 147 1726 97% 65 928 81% Wallis & Futuna ('97) 15 0 0% 0 14 0% 0 1 0% 6 0% WPR Total (**) 1 659 017 961 853 58% 495 979 343 142 59% 282 772 110 472 72% 897 451 32% Italics indicate figures for 1997 or 1996, specified in brackets after country name. * All types includes new smear-positive, relapse, smear-negative and extrapulmonary tuberculosis cases. **: In WPR Total, cases reported for years other than 1998 are not included in calculation. 26
TABLE 1c: Treatment outcomes of new smear-positive cases registered in 1997 Country Control Strategy No. of Cases Registered Not Evaluated Cured Completed Treatment Outcomes of Treatment Died Failed Defaulted Transferred Out Treatment Success (%) (%) (%) (%) (%) (%) (%) (%) Australia DOTS 126 23.8 15.9 50.0 6.3 0.0 0.8 3.2 65.9 non-dots 100 31.0 21.0 32.0 11.0 0.0 0.0 5.0 53.0 Cambodia DOTS 12 278 3.7 86.2 4.5 2.2 0.4 2.5 0.6 90.7 China DOTS 166 279 0.5 96.3 0.0 1.3 1.0 0.6 0.3 96.3 non-dots 23 010 1.0 84.3 0.0 1.6 7.1 4.2 1.7 84.3 Fiji DOTS 46 0.0 84.8 2.2 6.5 0.0 6.5 0.0 87.0 French Polynesia DOTS 41 0.0 90.2 9.8 0.0 0.0 0.0 0.0 100.0 Hong Kong, China non-dots 1536 84.8 12.2 0.5 0.9 0.1 1.1 0.3 12.7 Republic of Korea DOTS 7487 0.0 79.4 2.2 1.4 2.4 3.6 11.0 81.6 Lao PDR DOTS 1234 22.6 57.1 5.3 5.1 0.8 6.7 2.4 62.4 Macao, China DOTS 325 0.0 80.6 0.0 5.2 4.6 8.0 1.5 80.6 Micronesia FS non-dots 9 0.0 77.8 0.0 0.0 0.0 11.1 11.1 77.8 Mongolia DOTS 705 0.1 82.4 3.5 3.8 2.7 3.4 4.0 86.0 non-dots 466 9.9 41.0 15.7 10.1 7.3 13.1 3.0 56.7 New Caledonia DOTS 28 35.7 53.6 0.0 3.6 0.0 7.1 0.0 53.6 Papua New Guinea DOTS 69 0.0 49.3 43.5 2.9 0.0 4.3 0.0 92.8 Philippines DOTS 4085 0.8 79.7 3.2 2.8 2.9 6.7 4.0 82.8 non-dots(*) 23 396 9.7 69.9 6.9 1.1 1.1 7.8 3.6 76.8 Solomon Islands DOTS 140 8.6 64.3 18.6 5.0 1.4 0.0 2.1 82.9 Tonga DOTS 11 0.0 27.3 54.5 9.1 0.0 0.0 9.1 81.8 Vanuatu non-dots 66 0.0 30.3 59.1 7.6 0.0 0.0 3.0 89.4 Viet Nam DOTS 46 466 0.0 88.2 3.2 2.9 1.2 2.2 2.3 91.4 non-dots 3585 0.0 79.3 8.2 3.2 2.6 5.2 1.6 87.5 WPR TOTAL DOTS 239 320 0.7 93.1 1.1 1.7 1.1 1.3 1.1 94.1 non-dots 52 168 7.4 74.8 3.9 1.6 3.9 5.9 2.5 78.7 The table includes countries/areas that submitted figures for the 1999 report. *: Reported from part of a country. 27
1 DOTS COVERAGE DOTS has proved to be an effective control strategy for tuberculosis since the early 1990s. But certain factors that can aggravate the epidemiological situation of tuberculosis, such as population growth, urbanization and the HIV epidemic, are emerging simultaneously. Therefore, it is urgent to expand DOTS, especially in high tuberculosis prevalence countries. In this chapter, the progress of DOTS will be reviewed. Certain factors that can aggravate the epidemiological situation of tuberculosis, such as population growth, urbanization and the HIV epidemic, are emerging simultaneously. Therefore, it is urgent to expand DOTS, especially in high tuberculosis prevalence countries. To evaluate progress of DOTS the following indicators will be used: Proportion of population with access to DOTS (%): This is defined as the proportion of population living in the areas implementing DOTS programmes out of the total population. DOTS enrolment rate: This is defined as the proportion of notified cases, all types, and new smear-positive cases enrolled in DOTS out of the respective totals. DOTS case detection rate of new smear-positive cases: The case detection rate of new smear-positive cases is the ratio of annual new smearpositive tuberculosis case notification to estimated annual incidence. This is a stricter indicator to measure the fraction of all incident new smear-positive cases detected by the DOTS programme. The global target is 70%. Global coverage in 1997 Figure II-1 shows the proportion of population with access to DOTS by WHO Region in 1997. Some 35% percent of the global population had access to DOTS. In the Western Pacific Region, 57% percent of the population had access to DOTS and this figure was the highest of all six WHO regions. 28
FIGURE II-1: DOTS population coverage by Region, 1997 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% 57% 50% 50% 35% 18% 9% 16% AFR AMR EMR EUR SER WPR Global WHO Region Figure II-2 shows the DOTS enrolment rate of all types and new sputum smear-positive cases, which is proportion of cases enrolled in DOTS out of all reported cases. The global averages were 29% and 42%, respectively, in 1997. The Region had 46% and 60%, respectively, ranking second after the African Region, in the same year. FIGURE II-2: DOTS enrolment rate by WHO Region, 1997 100% 80% 67% 69% All Types (%) New SS+(%) 60% 60% 40% 20% 37% 39% 48% 39% 5% 5% 19% 8% 46% 29% 42% 0% AFR AMR EMR EUR SER WPR Global WHO Region Figure II-3 shows the DOTS case detection rate of all types and new smear-positive cases by WHO region The global figures were 12% and 16%, respectively. These compared with the Region s figures of 20% and 26%, respectively, ranking second behind the American Region. Compared with the population coverage, the DOTS case detection rate is still low due to low case detection and DOTS enrolment rates. FIGURE II-3: DOTS detection rate by WHO Region, 1997 100% 80% 60% 40% 20% 0% All Types (% ) New SS+(%) 30% 21% 25% 23% 26% 20% 12% 16% 8% 9% 4% 3% 4% 5% AFR AMR EMR EUR SER WPR Global WHO Region 29
Coverage in the Region in 1998 DOTS coverage in the Region Out of 29 countries/areas that submitted their figures in 1999, 18 countries/areas were classified as implementing DOTS in 1998. Two countries (American Samoa and Palau, both in 1997) were classified as implementing DOTS in a previous year. By the end of 1998, therefore, DOTS had been started in 20 countries/areas. Population coverage of DOTS (proportion of population with access to DOTS) was 58% in 1998, not a significant increase on the 57% in 1997. The enrolment rate of all types and new smear-positive cases were 59% and 72%, respectively, a significant rise from 46% and 60%, respectively, in 1997. This is mainly accounted for by increased enrolment rates in China. DOTS case detection rates of all types and new smear-positive cases were 25% and 32%, respectively, attributable to the increased enrolment rate. In both enrolment rate and DOTS case detection rate, the figure for new smearpositive cases was higher than that of all types. DOTS coverage in the high burden countries of the Region Figure II-4 shows population coverage in each of the high burden countries in the Region. The figure ranged from 100% in Cambodia to 9% in Papua New Guinea. DOTS enrolment rate of all types of tuberculosis ranged from 100% in Cambodia to 11% in Philippines (Figure II-5). FIGURE II-4: Population with access to DOTS in high burden countries, 1998 120% 100% 80% 60% 40% 20% 0% Cambodia Mongolia Viet Nam Lao PDR China Philippines Papua New Guinea Western Pacific Region 30
FIGURE II-5: Enrolment rate in high burden countries, 1998 120% 100% All types New S+ 80% 60% 40% 20% 0% Cambodia Lao PDR Viet Nam China Mongolia Papua New Guinea Philippines Western Pacific Region The DOTS case detection rate of new smear-positives was 32% in the Region in 1998. Although 58% of the Region s population has access to DOTS, the DOTS case detection rate of new smear-positive cases is still low on average in the Region as a whole. Among the high burden countries, the DOTS case detection rate ranged from 81% in Viet Nam to 8% in Papua New Guinea. Viet Nam is the only country that has achieved a 70% DOTS case detection rate with both high DOTS enrolment rate and high case detection rate. Other countries have not reached the 70% DOTS case detection due to low case detection and/or low DOTS enrolment rate. For instance, the Philippines had a high case detection rate but low enrolment rate. Cambodia, China, the Lao People s Democratic Republic and Mongolia had a DOTS enrolment rate in excess of 80% but the case detection rate remained low. In Papua New Guinea, the enrolment rate and case detection rate remained low. In Figure II-6, each column indicates the case detection rate of new smear-positive cases in each country and the dark red part of the column indicates the DOTS case detection rate. The proportion of red in the column, therefore, indicates the DOTS enrolment rate. If the enrolment rate were 100% in a country, there would be no white part, indicating that the case detection rate and DOTS case detection rate are identical. FIGURE II-6: Case detection rate by DOTS and non-dots in high burden countries, 1998 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Viet Nam Philippines Mongolia Cambodia Papua New Guinea Detection by Non-DOTS Detection by DOTS (DOTS Detection Rate) Lao PDR China Western Pacific Region 31
2 TREATMENT OUTCOME BY DOTS AND NON-DOTS To evaluate the outcome of treatment in DOTS areas, the cure rate and success rate of smear-positive cases are used. Globally, treatment outcome by non- DOTS methods is poor with a treatment success rate of 38.6%, mainly due to large number of unevaluated cases. The Region has the highest DOTS treatment success rate among the WHO Regions. The cure rate is the proportion of patients who have completed treatment and had smear-negative results confirmed twice, once at the end of treatment. The treatment success rate is the sum of the cure rate and completion rate defined as a proportion of patients who completed treatment and did not register smear-positive results after 5 months of treatment or later. The global targets are an 85% cure rate and a greater treatment success rate. Global treatment outcome in 1996 (Figure II-7) DOTS treatment outcomes were reported from 72 countries worldwide. The global DOTS treatment success rate was 78.4%. Treatment outcome by non-dots methods is poor with a treatment success rate of 38.6%, mainly due to large number of unevaluated cases. The Region has the highest DOTS treatment success rate among the WHO Regions. FIGURE II-7a: Treatment outcomes under DOTS by Region, 1996 100% 90% 80% 70% 60% 50% 40% 30% 57.7% 81.5% 85.7% 71.5% 77.2% 93.1% 78.4% Not Evaluated Not Treated Successfully Treated Successfully 20% 10% 0% AFR AMR EMR EUR SER WPR Global 32
FIGURE II-7b: Treatment outcomes under non-dots by Region, 1996 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% AFR AMR EMR EUR SER WPR Global Not Evaluated Not Treated Successfully Treated Successfully Treatment outcomes in the Region in 1997 The treatment outcome of cases registered in 1997 was reported by 18 of the Region s countries/areas. In DOTS areas, 239 320 new smear-positive cases were registered in 1997, of which 99% were evaluated for treatment outcome. The cure rate and treatment success rate of new smear-positive cases under DOTS were 93.1% and 94.1%, respectively, in the Region in 1997 (see Table 1c). High burden countries (with the exception of the Lao People s Democratic Republic) had a DOTS success rate of 80% or greater. Cambodia, China, Papua New Guinea and Viet Nam achieved an 85% success rate (see Figure II-8). However, Papua New Guinea had a low cure rate of 49.3% because 43.5% of cases did not receive sputum smear examinations at the end of treatment. The success rate for the Lao People s Democratic Republic was low (62.4%) and a proportion of the unevaluated cases was high (22.6%). For non-dots areas, 8 countries reported treatment outcomes. The success rate under non-dots was 78.7%. However, it is difficult to assess the treatment outcome of non-dots cases properly because the evaluated cases represent only a small fraction of cases reported for 1997. 33
FIGURE II-8: Treatment outcomes under DOTS in high burden countries, 1997 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% China Papua New Guinea Viet Nam Cambodia Mongolia Philippines Lao PDR TOTAL Not Evaluated Not Successful Successful 34
3 SUMMARY OF PROGRESS OF DOTS IMPLEMENTATION IN THE REGION Figure II-9 shows regional DOTS implementation from 1995 to 1998. In terms of population, DOTS coverage has improved since the strategy began in 1991. The figure was 58% in 1998. The DOTS enrolment rate has also increased significantly to 59% for all types. A high treatment success rate in excess of 90% was maintained in the Region as a whole, as well as in most of the countries using DOTS. A high treatment success rate in excess of 90% was maintained in the Region as a whole, as well as in most of the countries using DOTS. However, 40% of population still did not have access to DOTS and 40% of notified tuberculosis patients did not receive DOTS in 1998. Furthermore, almost 60% of the estimated cases were not reported. Based on the reported cases, the DOTS case detection rate of new smear-positive cases was 32%, still far short of the global target of 70%. It is necessary to expand DOTS rapidly and to increase the population coverage and enrolment rate, especially in high prevalence countries. FIGURE II-9: Trends in DOTS implementation, 1995-1998 70% 60% 50% DOTS Enrolment Rate (All Types) 40% 30% 20% Population w ith Access to DOTS 10% 0% 1995 1996 1997 1998 35
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