MIN/Sp/AU/CAMH3/6 TB Page 26 5.2: TB Prevention, Treatment, Care and Support 5.2.1: Estimated Prevalence, incidence and death rates TB Prevalence and incidence measure the status of the TB epidemic with regard to existing cases and new cases occurring in a defined population at a point in time or during a defined time period. Both are directly linked to programme activity and population coverage with diagnostic and notification services. They are also directly linked to programme performance with regard to ability to successfully cure those with infectious forms of TB. Their trend provides a measure of the burden of tuberculosis on a population. Survey based accurate measures of both prevalence and incidence is the best way to determine this burden. However, these can be time consuming, costly and technically challenging such that they are beyond the routine use of most national programmes, even though they are encouraged where feasible. In the absence of such studies, proxy measures are being used by WHO to estimate prevalence, incidence and death rates. Estimated TB prevalence, Incidence and death rates have all continued to increase. Absolute notified cases and TB notification rates have also continued to increase at regional level. As a case in point, notification rates as a proxy for TB prevalence have risen from 82 per 100,000 population in 1990 (the Stop TB Partnership set reference year for measuring progress towards the MDG targets) to 160 in 2006. At this rate, the TB control MDG targets for TB incidence and prevalence are unlikely to be achieved at regional level. However, according to the WHO Global TB Report for 2008, by the end of 2006, six countries 37 had already halted and started to reverse overall and smear positive TB incidence as specified in the core MDG targets (without reference to the 1990 rates as specified by the Stop TB P[partnership operationalisation of the MDG targets). A further 6 countries 38 had already halted and started to reverse estimated TB prevalence, while four countries, namely, Angola, Comoros, Sao Tome & Principe and Seychelles had already halted and started to reverse death rates ( Table 4.2.2). 5.2.2: Status of case detection and treatment success rates Case detection rate: Case detection is a function of availability of laboratory services to diagnose TB as well as the quality of the services offered. Poorly developed laboratory infrastructure, poor equipment, poor personnel skills, poor technique and poor interpretation skills all contribute to low case detection rates. In the era of HIV/AIDS, an increasing proportion of patients with sputum smear negative TB and extra-pulmonary TB has been observed due to the effect of the coinfection. However, where available, culture and other more specific diagnostic methods exist that correct for this atypical presentation. 37 38 Comoros, Ghana, Mali, Mauritius, Sao Tome & Principe and Seychelles Angola, Benin, Cape Verde, Eritrea, Guinea Bissau and Niger