Last Mile connectivity and Universal access to rapid molecular TB diagnostics in Africa (1)

Last mile connectivity could be defined as access to quality testing below the district or sub-district levels, where in existing rapid and accurate molecular technologies would be difficult to reach due to resource limitations as well as technical and operational issues. The testing sputum sample needs to reach the labs for testing, timely. And results are to be conveyed back to treating clinician and patient, timely. In this post- let's discuss what the beast of universal access looks like in Africa for TB diagnostics.

Why is last mile connectivity important to achieve universal access in order to increasing the TB case notifications in Africa? Presently, molecular diagnostics (even the most simplified cartridge based diagnostics such as GeneXpert systems) are utilized only to the extent of about 35-40% across Africa due to various reasons. Tuberculosis treatment centers have been effectively decentralized in Africa with community TB treatment strategies supplementing facility level DOT services. However, molecular diagnosis needs minimal laboratory infrastructure, skilled technicians and real-time information management systems. At present, accessible and affordable point-of-care/near-to-the-patient diagnostics are not available and await more research & development efforts, globally. Extending access to existing molecular technologies up to the peripheral level of health services needs more financial resources impeding the universal access.

Conventionally, TB control programs implemented PASSIVE case finding strategies (i.e., waiting for patients to reach TB care facilities themselves with TB clinical signs and symptoms) effectively through a district as a basic management unit (directly observed treatment, short course). Diagnostic delays are expected in the Passive case finding strategy as patients suffering from TB do not comprehend early TB signs and symptoms. Comparatively lower sensitivity of sputum microscopy in TB diagnosis at early stage of disease (when bacillary load in sputum sample is low) also contributed for preference given to passive case finding strategies (‘higher yields’ of bacteriologically positive TB patients). At global level, passive case finding ideally suited policy makers, implementers' and funding donors as netting of positive patients remained high. This in turn lead to higher ‘returns on capital invested’ (low cost per TB case detected) and sustaining logical exuberance of donor agencies for investing in TB control programs (in terms of cases treated and thus lives saved). In epidemiological perspective this all worked well till the pandemic of HIV/AIDS arrived in early 1990’s and increased risk of TB in immunologically compromised people living with TB/HIV (PLHIVs), in addition to disturbing the capacities of public health systems in Africa (prevalence HIV peaked in around year 2000 in sub-Sahara Africa). TB being an infectious disease, any delay in diagnosis and treatment for TB/HIV co-infected people carries higher risk of mortality and increased transmission in community. Alternately, ACTIVE case finding strategies got emphasized and implemented in order to quickly reduce TB related deaths in people positive to HIV/AIDS by early detection of TB and prompt treatment. Increasing provision of anti-retroviral drugs also helped in this pursuit. Even though this is an effective strategy given the resource limited settings, the overall contribution of active case finding for TB control remained significantly low (extent of passive case finding in TB programs?).

The global goal for TB have shifted towards TB elimination by 2035 (TB as no more a threat to public health and zero catastrophic costs to TB-patients and families) and thus effective ACTIVE case finding strategies and universal access to TB diagnostics (including drug-susceptibility testing) are critical aspects. Last mile connectivity for molecular TB diagnostics should be achieved for reaching this goal.

How many number of diagnostic tests should be done to reach universal access and what are cost implications? Following slides are an attempt to focus on these query. The estimates are based on the following assumptions:

1. For first line DST: Let present Bacteriologically positive (B+) case notification rates estimated at 75% by 2020; 2025 target to increase it to 85%; 2035 target is to increase case detection by 95%
2. For first line DST: Let present Clinical case notification to be diagnosed as B+ at 30% in 2020; by 2025 to 60%; and by 2035 increased to 80%
3. Let per test cost of molecular Rapid test is assumed @ US$ 15 (all inclusive); second line DST Molecular test cost @ US$30 per test (all inclusive)
4. For second line DST: Let B+ second line DST based on XDR among MDR-TB positive with proportion of 5% in 2020; 7% in 2025 and 10% in 2035

Estimated number of tests required to achieve access to universal TB diagnosis (including Drug susceptibility testing (DST) is projected below:

To arrive at total tests done- we need to combine first line and second line DST tests.
Finally, the costs implication for the universal TB diagnosis (including DST) are provided below: 
 

Overall, it costs about US $ 15.2 to 21.78 million, annually, for whole of Africa in order to reach universal access. Global END TB strategy (2016-35) aims at eliminating TB as a public health threat with zero catastrophic costs to TB-affected families. Institutional and governmental funding to TB programs have achieved great successes, so far. Supplementing these efforts’ need additional participation from large number of individuals. How about crowd funding to programs? Every one of us by default carries that noble soul which aim to contribute to the society in one way or other. Let’s spread awareness on TB rededicating the noble soul within us. As we discussed, the sums of funds required here for achieving universal access to TB diagnostics across Africa and thus TB elimination are very moderate.  Ambitious goals, clear strategies and whole hearted implementation coupled with transparency and accountability would bring in noble individuals ready to contribute their part to support TB elimination programs.