In Cambodia the suffering from tuberculosis (TB) remains unacceptably high. WHO estimates that for Cambodia 36% of TB cases - a proportion almost double for drug-resistant (DR) TB - are being missed. A prevalence survey identified many symptomatic individuals who had never been screened. Access to care is an issue especially for the poor. Therefore, we questioned whether existing case-finding efforts for TB in Cambodia were sufficient.
We implemented community-based active case-finding (ACF) in poor urban settlements of the capital. A door-to-door survey by health workers included symptom screening, sputum collection in the community, sputum smear microscopy and Xpert MTB/RIF for high-risk participants, mobile phone for issuing results and early referrals. This approach proved feasible and effective for case detection and treatment uptake. Because of challenges inherent to implementing a novel strategy, we also assessed the community's perception on ACF and explored potential barriers to its success.
Early detection of TB requires appropriate diagnostic tools and effective algorithms. We have shown that in ACF a two-sputum specimen strategy (versus three), examined by fluorescence microscopy, would be rewarding provided an early morning specimen is collected. Xpert contributed to increase of bacteriologically confirmed TB and shorter time-to-diagnosis.
Given the low detection rates for DR-TB in Cambodia, the introduction of Xpert prompted us to start systematic screening for DR-TB in high-risk patients. When supported by a well-functioning health system, Xpert facilitated screening efforts and case detection, and substantially shortened time-to-treatment initiation for DR-TB. Under programmatic conditions Xpert performed well to detect rifampicin resistance. Indispensable for appropriate decision making however, was good clinical risk assessment and knowledge of the assay's performance characteristics.
In conclusion, systematic screening for both drug-susceptible and DR-TB in deprived communities in Phnom Penh provided a good opportunity to assist TB detection in high-risk populations missed under the current strategy. New and improved diagnostic tools can shorten time-to-treatment and as such curtail the risk of transmission. A comprehensive approach within a well-functioning health system can ascertain high treatment uptake and completion. More research is required to demonstrate the epidemiological impact, cost-effectiveness and affordability of systematic screening for active TB in different epidemiological settings.