Prospective Sentinel Surveillance Of Rifampicin Resistant TB, TB/HIV Integration And Hospitalised TB In South Africa
Complementing surveillance based on reporting of routine data, an enhanced surveillance programme has been introduced to provide additional quality assured data on demographic and clinical features, as well as risk factors. In addition, a surveillance specimen is collected and is used to generate complementary microbiological data. The first TB-related surveillance established was for RR TB and this has now been implemented in seven of the nine provinces. Important findings across the sites have shown that between 38% and 50% of patients with RR TB have never had TB treatment before, while between 9% and 33% have had household contact with TB, both indicating that transmission plays an important role. Striking differences have been observed in the prevalence of rifampicin mono-resistance between sites, with higher rates seen in selected districts/sites in Mpumalanga and the Northern Cape, and a mixed pattern in the other provinces. The percentage of RR TB patients with a final baseline resistance profile of XDR TB was highest in Eastern Cape at 18% and 8% across all sites.
The most recent surveillance introduced has been clinic-based rather than laboratory-based and will monitor TB and HIV programmatically, assessing trends and relative risk factors. In addition to clinic-based surveillance, monitoring of drug resistance has also been incorporated. Since both TB and HIV use empiric regimens for treatment without primary resistance testing, except for rifampicin resistance in TB, this surveillance is critical and will provide baseline data for the monitoring of resistance to isoniazid and other first-line drugs as well as baseline data on HIV resistance in those starting treatment. Both these are important and are missed in the routine system; notably for TB where isoniazid mono-resistance (IMR) is expected at >5% but is not detected by the widely implemented Xpert MTB/RIF assay. This has been observed with IMR at 11.1% at one site and 4.6% at a second site, though numbers are relatively small at this stage.
