In the Western world we think of tuberculosis (TB) as a disease of the Victorian age, something from the past, but there are many countries where the disease is a devastating killer, and worldwide it claims 4500 lives each day. This curable and preventable infectious disease affects mainly the lungs and can exist in the body without symptoms, but once someone becomes ill they can easily pass it on through coughing and sneezing. To coincide with the End TB campaign and World TB Day 2018 on 24 March, we take a look at the diagnostics in use and the plans to wipe it out.
The numbers for TB are shocking – an estimated 10.4 million new cases in 2016 leading to around 1.7 million deaths. People with HIV are particularly susceptible. There has been significant progress, however. The Bill & Melinda Gates Foundation, which is actively involved in tackling common infectious diseases such as TB, says, “Between 1990 and 2014, TB mortality fell by 47 percent, and 66 million TB patients were successfully treated between 1995 and 2014 thanks to coordinated global efforts and the use of the recommended treatment.”
Diaceutics and TB diagnostics
Diaceutics works with pharma to ensure that companion diagnostics are developed alongside a targeted therapy and that patients are tested at the right time for the right drug. We believe that in all disease areas better testing equals better outcomes for patients. We are proud to have had the opportunity to work with the Bill & Melinda Gates Foundation and advise on its efforts to improve access to available TB diagnostics and “address the key gaps on the patient pathway”.
Diagnostics for TB
There has been worryingly little development in diagnostics and drugs for TB although more effective use is saving many lives. The World Health Organization (WHO) says, “Research and development are severely underfunded with at least additional USD 1.2 billion per year needed to accelerate development of new, innovative tools.” To make matters worse, two strains of drug-resistant TB have emerged, which increases the urgent need for research into new treatments. As TB can be difficult to diagnose accurately and rapidly, the speed of diagnosis is particularly important for the drug-resistant strains.
- Skin and sputum tests are the most common TB diagnostics and look for Mycobacterium tuberculosis, while a chest x-ray can confirm the damage caused.
- Other tests for TB, such as the culture test, offer greater accuracy but are costly and results can take weeks when effective treatment relies on early and accurate diagnosis.
- Interferon gamma release assays (IGRAs) are blood tests that diagnose latent TB in 24 hours, however, the sample must be analysed quickly in a laboratory and may not provide accurate results for people with HIV.
- New molecular tests are becoming available but again are proving expensive for such widespread testing.
- WHO has endorsed the GeneXpert molecular test to diagnose TB and drug resistance, the main feature being that results are ready in two hours. It was initially thought that similar tests would follow and thereby reduce costs, but developments here have been slow. The device has been rolled out across relevant countries and many now consider this the first choice for testing. It has the advantage of speedy diagnosis but still presents practical challenges around power supply, recalibration, temperature limits and shelf life. However, the manufacturer, Cepheid, is developing an updated version.
Plans for eradication
Given that the only vaccine (BCG) was developed nearly 100 years ago, and is far less effective for adults infected with the most common strain than children, the Bill & Melinda Gates Foundation believes that a “more effective vaccine would be the single most powerful tool to reduce the incidence of TB. Even a partially effective new vaccine introduced in 2024 could, by some projections, decrease TB incidence by up to 70 percent by 2050.”
WHO has established a Strategy to End TB for good. It is aiming for:
- 80% drop in new TB cases by 2030
- 90% drop in people dying of TB by 2030
- 100% of TB-affected families protected from catastrophic costs by 2030
Elsewhere, there are developments in delivering vaccines in tablet form rather than by needle, which would make storage and transport much easier as pills would not require refrigeration.
On diagnostic strategy for TB, WHO says, “Uptake of TB diagnostic technologies requires appropriate laboratory infrastructure, sufficient human resources and adequate policy reform at country level to enable their effective use in TB screening and diagnostic algorithms.” The Bill & Melinda Gates Foundation also believes diagnostics lie at the heart of plans to tackle the disease and is supporting “less expensive, more effective diagnostic tools that can reach more people with TB” along with “the use of data and analytics to drive policy and funding decisions”.
Diaceutics fully supports the WHO campaign to end TB and save millions of lives.