Rapid, cost-effective diagnostic device for leading cause of blindness shows promising results in early tests

A researcher uses the DjinniChip system in the back of a car in Tanzania

A new study from a team involving ICEH has shown encouraging results for a new diagnostic test for bacteria that causes trachoma, the leading infectious cause of blindness worldwide. DjinniChip, a method for assessing the presence of Chlamydia trachomatis (Ct), the bacteria that causes the disease, could be used in the future to improve trachoma control in endemic areas.

Current efforts to eliminate trachoma, which currently affects around 40 million people, rely on community-based mass drug administration (MDA) coupled with facial hygiene and environmental improvements. However, even following MDA community treatment, the signs of trachoma, such as swelling and scarring of the eye, can remain, even if the disease is close to elimination in the area. This makes it hard to assess how effective treatment has been, creating a need for low-cost, simple-to-use tests for Ct.

This study, published in  Parasites and Vectors, tested DjinniChip in both laboratory settings and in conditions that mimicked field conditions for trachoma infections. Compared to similar testing methods, DjinniChip does not require specialist equipment or a strong electricity supply, meaning it can be used by people who are not trained laboratory  professionals, and in the type of low-resource settings where trachoma is found. It also costs around fives times less than other methods, making it significantly more accessible for lower-income healthcare systems.

The DjinniChip

In both the laboratory and field settings the chip showed that it was usable and applicable to the environments in which it was being tested, but while correctly diagnosing many cases and non-cases of Ct infection, it did not show as high sensitivity (the ability to detect positive cases) as expected. As the technology is in its early stages, this may have been the result of contamination within the samples being tested, especially within the field setting. The next iteration of the chip’s design will be an integrated, closed system, which will reduce the manual handling of liquids and other opportunities for mis-diagnosis of samples.

DjinniChip has proved that as a diagnostic test for Ct, it can be operated simply, produces results quickly, doesn’t require high-cost laboratory equipment, and is stable in the challenging environmental conditions associated with trachoma. Combined with upcoming improvements to the system’s accuracy, these results are extremely promising as a solution to aid elimination efforts for trachoma, potentially helping to one day defeat this avoidable cause of blindness.

Publication

Derrick TR, Sandetskaya N, Pickering H, et al. DjinniChip: Evaluation of a novel molecular rapid diagnostic device for the detection of Chlamydia trachomatis in trachoma-endemic areas. Parasites and Vectors (2020)

Contact

If you have any more questions about this study, please contact us as iceh@lshtm.ac.uk

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