Implementation of large-scale pooled testing to increase rapid molecular diagnostic test coverage for tuberculosis: a retrospective evaluation.

In 2021, only 6.4 million of the 10.6 million people with tuberculosis (TB) were diagnosed and treated for the disease. Although the World Health Organization recommends initial diagnostic testing using a rapid sensitive molecular assay, only 38% of people diagnosed with TB benefited from these, due to barriers including the high cost of available assays. Pooled testing has been used as an approach to increase testing efficiency in many resource-constrained situations, such as the COVID-19 pandemic, but it has not yet been widely adopted for TB diagnostic testing. Here we report a retrospective analysis of routine pooled testing of 10,117 sputum specimens using the Xpert MTB/RIF and Xpert MTB/RIF Ultra assays that was performed from July 2020 to February 2022. Pooled testing saved 48% of assays and enabled rapid molecular testing for 4156 additional people as compared to individual testing, with 6.6% of specimens positive for TB. From an in silico analysis, the positive percent agreement of pooled testing in pools of 3 as compared with individual testing for the Xpert MTB/RIF Ultra assay was estimated as 99.4% (95% CI, 96.6% to 100%). These results support the scale-up of pooled testing for efficient TB diagnosis.

Tuberculosis-loop-mediated isothermal amplification implementation in Cameroon: Challenges, lessons learned and recommendations.

Background: Until 2016, microscopy was the main tool for the early detection of pulmonary tuberculosis in Cameroon, especially in remote settings. Due to the poor sensitivity of microscopy, there was a need to implement a molecular assay in order to improve tuberculosis case detection. Intervention: In 2017, tuberculosis loop-mediated isothermal amplification (TB-LAMP), a molecular rapid diagnostic test recommended by the World Health Organization, was implemented in Cameroon as a replacement test of microscopy for initial diagnosis of pulmonary tuberculosis and also as a follow-on test to microscopy for smear-negative sputum specimens. A roll out plan for TB-LAMP implementation in Cameroon had been developed from January 2017 to April 2017, followed by initial implementation at four sites in May 2017. Additional sites were added progressively. Lessons learnt: The use of TB-LAMP as a follow-on test to microscopy for smear-negative sputum specimens helped in the detection of tuberculosis in 14.77% of those who were sputum-smear negative in 2019. Tuberculosis-loop-mediated isothermal amplification usage as an initial test, followed by testing with Xpert MTB/RIF for rapid tuberculosis and rifampicin resistance detection during tuberculosis mass screening campaigns, reduced the turn-around time by 73.23% as compared to when the Gene Xpert instrument was used alone. Recommendations: The implementation and scaling up of TB-LAMP in Cameroon contributed to increase access to tuberculosis molecular diagnosis in remote settings and as such improved tuberculosis case notification. However, to better enhance this notification and optimise the use of a TB-LAMP instrument, a suitable sample transport system is recommended.

Strengthening timely detection and reporting of unusual respiratory events from health facilities in Yaoundé, Cameroon.

BACKGROUND: The International Health Regulations state that early detection and immediate reporting of unusual health events is important for early warning and response systems. OBJECTIVE: To describe a pilot surveillance program established in health facilities in Yaoundé, Cameroon in 2017 which aimed to enable detection and reporting of public health events. METHODS: Cameroon's Ministry of Health, in partnership with the US Centers for Disease Control and Prevention, Cameroon Pasteur Center, and National Public Health Laboratory, implemented event-based surveillance (EBS) in nine Yaoundé health facilities. Four signals were defined that could indicate possible public health events, and a reporting, triage, and verification system was established among partner organizations. A pre-defined laboratory algorithm was defined, and a series of workshops trained health facilities, laboratory, and public health staff for surveillance implementation. RESULTS: From May 2017 to January 2018, 30 signals were detected, corresponding to 15 unusual respiratory events. All health facilities reported a signal at least once, and more than three-quarters of health facilities reported ≥2 times. Among specimens tested, the pathogens detected included Klebsiella pneumoniae, Moraxella catarrhalis, Streptococcus pneumoniae, Haemophilus influenza, Staphylococcus aureus, Pneumocystis jiroveci, influenza A (H1N1) virus, rhinovirus, and adenovirus. CONCLUSIONS: The events detected in this pilot were caused by routine respiratory bacteria and viruses, and no novel influenza viruses or other emerging respiratory threats were identified. The surveillance system, however, strengthened relationships and communication linkages between health facilities and public health authorities. Astute clinicians can play a critical role in early detection and EBS is one approach that may enable reporting of emerging outbreaks and public health events.