Chapter 36: Emerging Infectious Diseases

The chapter then explores zoonotic disease emergence, illustrating how paramyxoviruses such as Nipah and Hendra viruses cross species barriers from animal reservoirs, particularly fruit bats, through intermediate animal hosts before infecting human communities. A substantial portion addresses the coronavirus family, tracing the evolutionary trajectory from relatively benign respiratory pathogens to the severe pandemic threats represented by SARS-CoV and MERS-CoV, culminating in the analysis of SARS-CoV-2 and the global COVID-19 pandemic, which fundamentally reshaped understanding of pathogenic potential and transmission dynamics. The chapter also considers the expanding burden of tick-borne illnesses in changing climate and land-use environments. Subsequently, the material shifts focus to the phenomenon of antimicrobial resistance in both established and newly problematic pathogens, examining multidrug-resistant and extensively drug-resistant tuberculosis strains that persist despite prolonged treatment protocols, carbapenem-resistant gram-negative organisms that compromise last-resort antibiotic efficacy, and evolving resistance mechanisms in sexually transmitted pathogens. The chapter concludes by addressing emerging mycological threats including Candida auris and Cryptococcus gattii, which pose particular challenges due to environmental persistence and clinical virulence, underscoring the necessity for continued surveillance, rapid diagnostic innovation, and adaptive public health strategies in responding to the constantly shifting landscape of infectious disease threats.