Testing of a New Rapid Antigen Test for Plague in Ituri, Democratic Republic of the Congo.

Plague is a life-threatening infection caused by the bacterium Yersinia pestis, which is highly endemic in the Ituri Province of the Democratic Republic of Congo (DRC) and associated with recurrent risks of regional epidemic spread. Clinical presentations (bubonic and/or pulmonary) and outcome remain poorly characterised in this area, and diagnostic accuracy is limited due to absence of a local bacteriology laboratory.

A novel lateral-flow immunochromatographic duplex rapid diagnostic test (RDT) has been developed for plague, which detects both F1 and LcrV proteins, and appears superior to the current RDT detecting only F1 antigens. This index RDT (called Duplex F1V) has shown promise in detecting Yersinia pestis in various sample types, including blood, bubo aspirates, and saliva in human patients.

Cross-sectional diagnostic accuracy study in clinical suspects of plague, comparing the results of Duplex F1V RDT (index assay), with PCR (polymerase chain reaction) positivity (as reference assay) on different biological fluids and assessment of clinical outcome at the end of treatment (at day 10-14).

Nested test-negative case-control study to identify risk factors and clinical predictors in PCR-confirmed plague cases, compared to PCR-negative suspects.

The study will take place in the Ituri province of DRC, the world's largest plague focus. Participants will be recruited in health centers and reference hospitals in the health areas of Rethy, Logo and Aru where the teams of the "Centre de Recherche en Maladies Tropicales" (CRMT) of Ituri are active. Individuals ≥5 years of age presenting at the sites with clinical suspicion of plague -as per national clinical case definitions- will be enrolled after informed consent and followed-up until treatment completion.