Curable but Unconfirmable

Buruli ulcer, caused by *Mycobacterium ulcerans*, is a neglected tropical disease reported in 33 countries that causes progressive skin destruction and disability if untreated. A paradigm shift to simple 8-week oral antibiotic treatment (rifampicin + clarithromycin) has made the disease curable without surgery — but the only reliable confirmatory test is PCR, which requires centralized laboratory infrastructure unavailable in the rural African communities where >90% of cases occur. Samples must be shipped to reference laboratories, with turnaround times of days to weeks. Meanwhile, a Ghana study showed that >50% of clinically diagnosed Buruli ulcer cases were actually misdiagnosed, leading to inappropriate treatment. The WHO's 2022 TPP calls for a rapid test usable at primary health care level, but none exists.

Approximately 50% of affected individuals are children under 15. Diagnostic delay is statistically associated with progression to ulcerative forms and osteomyelitis, causing permanent disability. WHO programmatic targets set in 2013 for PCR confirmation rates, Category III lesion reduction, and disability prevention were largely unmet by 2019. The reported case count (~2,200/year) substantially underestimates the true burden due to diagnostic and surveillance gaps in remote endemic areas. The irony is stark: we now have an effective, affordable oral treatment but cannot confirm who needs it.

Microscopy (Ziehl-Neelsen staining) has only 30-40% sensitivity — it misses the majority of cases. Culture of the extremely slow-growing *M. ulcerans* takes weeks to months and requires specialized media and temperature conditions (30-32 degrees C). IS2404-targeted PCR is the most sensitive method (54-84% depending on sample type) but requires trained technicians, equipment, stable electricity, and quality-assured reagents — none reliably available at primary care level in endemic regions. The WHO Buruli Ulcer Laboratory Network for Africa (established 2019) has strengthened PCR capacity in 9 countries, but specimens still must be transported to reference sites, creating delays that undermine the benefit of having a simple oral cure.

Three approaches are closest to meeting the TPP requirements: (1) LAMP (loop-mediated isothermal amplification) targeting IS2404, achieving 84-87% sensitivity and 100% specificity at ~$1-2/reaction with electricity-independent versions under development; (2) recombinase polymerase amplification (RPA) in a mobile suitcase laboratory format, delivering results in ~40 minutes with 88% sensitivity; and (3) a lateral flow assay targeting mycolactone, the unique toxin of *M. ulcerans*, which would be the first true rapid diagnostic but remains in prototype stage. A student team could contribute to the RPA or LAMP platform optimization for field conditions.

A team could optimize a battery-free isothermal amplification protocol (LAMP or RPA) for *M. ulcerans* detection from skin swabs, focusing on the sample preparation step — which is the primary bottleneck for field deployment of molecular assays. The engineering challenge is extracting sufficient DNA from swab specimens without centrifugation, pipetting, or cold reagents. Alternatively, a team could evaluate the diagnostic accuracy of mycolactone detection via lateral flow using synthetic mycolactone analogs as positive controls. Relevant disciplines: biomedical engineering, microbiology, tropical medicine, point-of-care diagnostics.