Epidémiologie de la tuberculose Document No. 3.1 Title Gestion des activités conjointes de lutte contre la tuberculose et le VIH: cours de formation pour responsables nationaux et subnationaux

Objectifs de la présentation Décrire l’épidémiologie de la tuberculose aux niveaux mondial, régional et national Expliquer les répercussions de la situation épidémiologique sur l’élaboration des activités conjointes de lutte contre la tuberculose et le VIH au niveau des pays (priorités, mécanismes, étapes et procédures) The slide is self-explanatory. The Objectives of the presentation are reported as presented in the participant manual.

Risque d’infection tuberculeuse dans des pays européens The Risk of TB Infection (or Annual Risk of TB Infection, often presented as ARTI) has declined over time in European Countries. Socio-economic improvement was initially the main determinant of the ARTI downward trend. Then the different interventions of TB control programmes (including chemotherapy) contributed in accelerating this downward trend. In The Netherlands, e.g. the decline exceeded 10% per annum. In several developing countries (particularly those with high prevalence of HIV) the decline of ARTI is much less evident. This topic will be further described in documents N° 3.2 and 3.3.

Prévalence de l’infection tuberculeuse par âge en Suisse, 1920–1990 The slide shows that in 1920, in Switzerland, the vast majority of individuals at the age of 20 years were already infected by M. tuberculosis. Progressively, over years, the old generations of infected individuals were followed by new generations less and less infected by M. tuberculosis, particularly in younger age groups. As a results of the diminished circulation of bacilli, the probability of becoming infected (very low in younger age-groups) increased with age, remaining much lower than that of the older cohorts. For example, in 1978, in Switzerland, at the age of 20 years the proportion of infected individuals was less than 20% and in 1990 near zero. As infection is the essential pre-requisite to develop TB disease, in low incidence countries TB is becoming more and more frequently a disease of the elderly. On the contrary, in high incidence countries the present situation is similar to that of Switzerland in 1920. In the presence of high prevalence of TB infection among young individuals and of high prevalence of HIV in the same age-groups, a rapid deterioration of the TB situation will be observed.

Cas de tuberculose rapportés en Suisse par âge, 1990 In low incidence countries less and less TB cases will be observed over time in the native population (and among them, elderly will prevail), while more and more cases will be detected among (young) immigrants from high TB prevalence countries.

Incidence rapportée de la tuberculose dans des pays d’Afrique, 1990–2002 100 1000 1990 91 92 93 94 95 96 97 98 99 2000 1 2 Taux pour 100 000 habitants BOTSWANA MALAWI MOZAMBIQUE AFRIQUE DU SUD OUGANDA TANZANIE ZIMBABWE What described above allows us to understand why TB incidence of notified cases in so dramatically increase in African countries.

Nb. De cas pour 100,000 habitants Notification des cas de tuberculose (TB) à frottis positif et de toutes formes au Kenya, 1990–2002 300 263 TB pulm. à frotis positif TB toutes formes 250 242 218 202 200 171 Nb. De cas pour 100,000 habitants 150 144 130 108 110 98 104 100 95 84 89 83 63 68 62 53 54 53 The slide shows how in Kenya the number of SS+ (Sputum Smear Positive) cases is increasing less rapidly than the total number of TB cases. This because in high-HIV prevalence countries the proportion of smear-negative cases is increasing over time, posing additional problems to the TB programme in terms, e.g., of case detection. 50 42 44 32 31 33 '90 '91 '92 '93 '94 '95 '96 '97 '98 '99 '00 '01 '02 Année

Epidémiologie mondiale de la tuberculose Un tiers de la population mondiale touché par l’infection Plus de 8,8 millions de nouveaux cas chaque année (141 pour 100 000 habitants) Plus de 2 millions de décès par an Plus de 95% des cas et des décès surviennent dans des pays en développement 75% des cas chez les 15–54 ans Coûts économiques dévastateurs Plus de 1 million de décès dus à la co-infection tuberculose/VIH La tuberculose multirésistante sévit partout The slide is self-explanatory. It should be noticed that 80% of the total burden of cases and the vast majority of deaths do occur in the 22 high burden countries.

Taux mondiaux de notification de la tuberculose, 2002 pour 100 000 habitants <10 10–24 25–49 50– 99 100 ou plus Pas de données The slide shows were the majority of TB cases are notified. Note that, comparing the map of slide 9 with that of slide 10 (estimates), the vast majority of countries are changing the colour: estimated case notification rates are, in general, higher than observed ones. Global Tuberculosis Control. WHO Report 2003. WHO/HTM/TB/2004.331

2002: les plus forts taux estimés de tuberculose par habitant se situaient en Afrique pour 100 000 habitants <10 10–24 25–49 50–99 100–299 300 ou plus Pas de données The slides is self-explanatory. The TB rates in sub-Saharan Africa are impressive. As we will see, they will drive the overall trend. Global Tuberculosis Control. WHO Report 2003. WHO/HTM/TB/2004.331

2002: la plupart des cas de tuberculose se situaient en Inde et en Chine Europe 10% Nombre de cas < 1 000 1 000 - 9 999 10 000 - 99 999 100 000 - 999 999 1 000 000 ou plus Pas de données 59% of the overall burden of cases are in Asia (mainly from China and India), 21% from Africa and 10% from Europe (Eastern Europe, mainly). Asie 59% Afrique 21% Global Tuberculosis Control. WHO Report 2003. WHO/HTM/TB/2004.331

Tendance des taux de notification dans quatre autres régions: baisses et hausses Global Tuberculosis Control. WHO Report 2003. WHO/HTM/TB/2004.331 Middle East & North Africa Industrialised countries (W. Europe, USA, Can, Aus, NZ, Japan) Pays industrialisés (Europe occidentale, Etats-Unis d’Amérique, Canada, Australie, Nouvelle-Zélande, Japon) Moyen-Orient et Afrique du Nord The slide clearly shows how TB is declining in Industrialized countries and in Middle East/ North Africa, while it is increasing in Africa (countries at high prevalence of HIV), in Former Soviet Union countries and in selected central European countries (Bulgaria and Romania). Afrique – Pays à forte prévalence du VIH Ex-Union soviétique, Roumanie et Bulgarie

Progression de la tuberculose en Afrique et en Europe orientale Afrique – forte prévalence du VIH 300 Europe orientale Afrique – faible prévalence du VIH 250 200 Taux standardisé de notification 150 v 100 The slides recalls the same concept descried in slide 12, showing how on African Countries at low incidence of HIV the growth of TB cases in much less evident. 50 1980 1985 1990 1995 2000

Ivanovo (Fédération de Russie) Prévalence de la tuberculose multirésistante (MDR-TB) parmi les nouveaux cas: 1994–2003 La MDR-TB est répandue en ex-Union soviétique et en Chine Lituanie Ivanovo (Fédération de Russie) 9.4 13.7 12.2 9 14.2 Tomsk (Fédération de Russie) 9.3 Estonie 14.2 13.2 Lettonie Kazakhstan Ouzbekistan 14.2 10.4 7.8 Israël 5 Liaoning (Chine) Henan (Chine) République dominicaine 6.6 République Islamique d’ Iran 5.3 4.9 Côte d’Ivoire Equateur The slide shows which are the areas where the prevalence of MDR is epidemiologically relevant. A special approach is necessary when, e.g., one new case out of ten is MDR, as observed in some territories of China and the former Soviet Union. Source: WHO/IUATLD Global Project on Anti-Tuberculosis Drug Resistance Surveillance. Anti-tuberculosis drug resistance in the world. Genève, Organisation mondiale de la Santé, 2004.