Tropical and exotic infections: Proceedings of the fifth Liverpool Tropical School Bayer Symposium on Microbial Diseases held on 14 February 1998

This review article from a 1998 Liverpool Tropical School symposium commemorating the school's centenary covers tropical and exotic infections, with detailed sections on plague and melioidosis. The article opens with historical context about Liverpool's role in infectious disease control since 1847 and the founding of the Liverpool School of Tropical Medicine in 1898. It notes that despite some successes like smallpox eradication, global infectious disease threats continue to expand due to factors including urbanization, drug-resistant pathogens, and increased international travel. The plague section describes Yersinia pestis as a gram-negative rod causing bubonic, septicemic, and pneumonic forms of disease, with transmission primarily through infected fleas from rodent reservoirs. Treatment requires prompt antibiotic therapy with streptomycin, though antibiotic resistance is emerging. The melioidosis section covers Burkholderia pseudomallei, an environmental saprophyte endemic to Southeast Asia and northern Australia, primarily affecting individuals with underlying conditions like diabetes. Both sections emphasize diagnostic challenges, clinical management, and the ongoing public health importance of these diseases in tropical regions.

Key findings

• Plague remains a significant global health threat with 2,000-2,500 cases annually reported to WHO in the early 1990s, particularly affecting Asia, Africa, and the Americas, with pneumonic plague posing the greatest risk due to droplet transmission and rapid fatality
• Yersinia pestis shows concerning antibiotic resistance development, including a multidrug-resistant strain from Madagascar in 1995 carrying a conjugative plasmid that could spread resistance to rodent reservoirs
• Melioidosis caused by Burkholderia pseudomallei is vastly underdiagnosed in tropical regions, with estimated 2,000-5,000 annual cases in Thailand alone but likely much higher true incidence due to limited diagnostic facilities in affected areas
• Both diseases primarily affect impoverished populations in endemic tropical areas with inadequate healthcare infrastructure, making early diagnosis and treatment challenging
• Diabetes mellitus is a major risk factor for melioidosis, occurring in 51-83% of clinically apparent cases, suggesting metabolic factors play an important role in disease susceptibility