Overview
Bubonic plague, caused by the bacterium Yersinia pestis, remains a significant public health concern, particularly in regions with historical endemicity. The global burden of plague is disproportionately concentrated in Madagascar, where it has been endemic since 1898, affecting both coastal and central highland areas, accounting for approximately 80% of reported cases [PMID:41838707]. Despite its historical association with rodent populations, outbreaks can occur in areas lacking apparent rodent involvement, as evidenced by an outbreak in Uttar Kashi, India, where no rat fleas or rodent infestations were identified, underscoring the unpredictable nature of plague transmission [PMID:16506545]. Understanding the epidemiology, clinical presentation, diagnosis, management, and prognosis of bubonic plague is crucial for effective public health interventions and clinical care.
Epidemiology
The epidemiology of bubonic plague highlights significant regional disparities, with Madagascar bearing the brunt of global cases, reflecting a long-standing endemic pattern since 1898 [PMID:41838707]. This endemic status spans both coastal and central highland regions, indicating the adaptability of Yersinia pestis across diverse ecological settings within the country. However, the disease's emergence in areas like Uttar Kashi, India, where traditional rodent vectors were not implicated, suggests that plague can spread through alternative transmission routes, possibly including human-to-human contact or other zoonotic pathways [PMID:16506545]. These findings emphasize the need for comprehensive surveillance beyond traditional rodent monitoring to detect and respond to outbreaks effectively. Public health strategies must therefore be adaptable, incorporating both environmental and human behavioral factors to mitigate the risk of plague spread.
Clinical Presentation
The clinical presentation of bubonic plague typically manifests with characteristic buboes, which are swollen and painful lymph nodes, observed in approximately 96% of cases [PMID:41838707]. These buboes are often accompanied by systemic symptoms such as fever, headache, altered mental status, and chills, reflecting the systemic inflammatory response to the infection. Inguinal lymphadenopathy is a hallmark feature, consistently reported across various age groups, including older adults, although the absence of pneumonia in reported cases suggests that pulmonary involvement may not be universal [PMID:16506545]. The absence of pneumonia in these cases does not preclude the possibility of septicemia or secondary pneumonic plague, underscoring the importance of vigilant monitoring for progression to more severe forms of the disease. Ultrasound imaging has emerged as a valuable tool in assessing bubo morphology and size, providing clinicians with a non-invasive method to track disease progression and treatment efficacy [PMID:41838707].
Diagnosis
Diagnosing bubonic plague accurately is critical for timely intervention and containment. Polymerase Chain Reaction (PCR) testing has demonstrated high sensitivity (85%) compared to culture methods (65%) in suspected cases from Madagascar, indicating its superiority in confirming infections [PMID:41389991]. Laboratory-based tests, such as the F1 Rapid Diagnostic Test (F1RDT), exhibit even greater sensitivity (91.8%) and specificity (99.1%) when conducted under optimal conditions, though these metrics drop to sensitivity of 94% and specificity of 74% in on-site settings [PMID:41389991]. This variability highlights the importance of centralized laboratory support for definitive diagnosis, especially in remote areas where access to advanced diagnostics may be limited. Serological testing, particularly through the detection of IgG F1 antibodies, can identify cases retrospectively but is less practical for acute diagnosis due to the delayed appearance of antibodies [PMID:41389991]. Therefore, a multi-modal approach combining PCR, culture, and rapid diagnostic tests, alongside clinical judgment, is recommended for comprehensive diagnosis.
Management
Effective management of bubonic plague involves both supportive care and targeted antimicrobial therapy. The containment of the Uttar Kashi outbreak within two weeks through supervised chemoprophylaxis using tetracycline, administered to approximately 1250 individuals, underscores the importance of rapid and widespread antibiotic administration in controlling localized outbreaks [PMID:16506545]. In clinical practice, defining clear endpoints for treatment efficacy, such as changes in bubo size and morphology, is crucial for assessing response to therapy [PMID:41838707]. However, the limitations of on-site diagnostic tools like the F1RDT, with lower specificity and sensitivity compared to laboratory conditions, necessitate caution in clinical decision-making and highlight the need for confirmatory testing when possible [PMID:41389991]. Supportive care measures, including fluid resuscitation, pain management, and monitoring for complications like sepsis, are essential components of managing severe cases, particularly in older adults who face a higher mortality risk, with up to 27.3% mortality observed within 48 hours in some studies [PMID:16506545].
Prognosis & Follow-up
The prognosis of bubonic plague varies significantly based on early diagnosis and prompt treatment. Multi-modal diagnostic approaches, combining PCR and culture methods, have identified 87% of confirmed cases, emphasizing the value of integrating different diagnostic techniques to enhance accuracy [PMID:41389991]. Follow-up care is critical, particularly in monitoring for potential sequelae and ensuring complete eradication of the pathogen to prevent relapse or progression to secondary pneumonic plague. Long-term follow-up should include serological testing to confirm clearance of Yersinia pestis antibodies, though the timing and practicality of such testing remain challenges due to the delayed appearance of IgG antibodies [PMID:41389991]. Regular clinical assessments and patient education on signs of recurrence are also vital components of post-treatment care.
Special Populations
Special attention is required for populations at higher risk, such as older adults, who exhibit increased mortality rates, with up to 27.3% mortality observed within 48 hours in some outbreaks [PMID:16506545]. Remote and resource-limited areas face additional challenges, including limited access to advanced diagnostic imaging like ultrasound, which is crucial for monitoring bubo evolution [PMID:41838707]. These regions necessitate innovative solutions, such as portable diagnostic tools and telemedicine support, to bridge the gap in diagnostic capabilities. Serological testing, while sensitive in identifying past infections, is less practical for acute management due to its delayed antibody response, making it less suitable for routine clinical use in these settings [PMID:41389991]. Tailored public health interventions and enhanced diagnostic infrastructure are essential to mitigate the disproportionate impact on vulnerable populations and remote communities.
Key Recommendations
References
1 Bourner J, Dwivedi R, Randremanana RV, Razananaivo LH, Pesonel E, Garcia-Gallo E et al.. A prospective cohort study to describe the morphology of buboes in patients with bubonic plague using ultrasound imaging. PLoS neglected tropical diseases 2026. link 2 Raberahona M, Rajerison M, Edwards T, Bourner J, Pesonel E, Ramasindrazana B et al.. Performance of diagnostic procedures for bubonic plague in endemic settings in Madagascar: a prospective test accuracy sub-study within the IMASOY trial. Clinical microbiology and infection : the official publication of the European Society of Clinical Microbiology and Infectious Diseases 2026. link 3 Mittal V, Rana UV, Jain SK, Kumar K, Pal IS, Arya RC et al.. Quick control of bubonic plague outbreak in Uttar Kashi, India. The Journal of communicable diseases 2004. link