Bubo characterisation project

Enlarged lymph nodes (known as “buboes”) are a common characteristic symptom of bubonic plague, occurring in 96% of patients at first presentation.

While changes in bubo size have been documented and used as an indicator of clinical recovery, the clinical evolution of the bubo has not been systematically documented and its relationship with disease severity, recovery or progression is unclear. 

To enhance our understanding of the clinical manifestations and physiology of the bubo and its role in plague, we conducted an observational cohort study using both clinical and ultrasound data. As bubo size is also used as a proxy for clinical recovery or progression, we also measured the bubo using two measurement tools to understand whether a bubo could be accurately measured using accessible, low-cost tools, such as a digital calliper. A digital calliper is an affordable, accessible tool to measure bubo size and has already been used in other research studies. As there is no validated “gold standard” measurement tool available to measure buboes, a portable ultrasound was chosen as the most accurate tool available for comparing to the calliper measurements. Before commencing the study, ultrasound training was provided to the study clinicians by two radiologists.

The study was conducted in rural health centres in two plague-endemic districts in Madagascar. Patients with an enlarged lymph node who were suspected of having bubonic plague were assessed on presentation to their health centre and at the end of treatment, with the option of a third assessment mid-way through treatment (if convenient for the patient). Clinical and sonographic data was collected at each visit. Full details about the study design can be found in the protocol.

The study completed recruitment in March 2024 having enrolled 16 patients. 

The study was conducted as a collaboration between ISARIC (University of Oxford), Institut Pasteur de Madagascar and Worldwide Radiology. Funding was provided by the Moh Family Foundation.