Emerging Infectious Diseases Are Virulent Viruses—Are We Prepared? An Overview

“

TL;DR

This narrative review summarizes emerging and re-emerging viruses (Ebola, Marburg, Zika, dengue, MERS, SARS, SARS-CoV-2, avian influenza, mpox), their clinical features, treatments, and surveillance tools. It highlights that while mRNA and other vaccines have been developed rapidly, vaccine hesitancy and viral mutations continue to challenge public health preparedness. The paper emphasizes the need for improved bioaerosol surveillance systems and international collaboration to detect and respond to future outbreaks.

Full summary

3,908 CHARS

**Background:** The COVID-19 pandemic exposed global vulnerabilities in preparedness and response systems, highlighting the increasing frequency of emerging and re-emerging viral outbreaks driven by international travel and climate change. This narrative review provides an overview of several virulent viruses, their transmission, clinical manifestations, available treatments, vaccination strategies, and surveillance tools, with the aim of informing future prevention and control strategies.

**Methods:** The authors conducted a narrative review of the literature, summarizing information on Filoviridae (Ebola and Marburg viruses), Flaviviridae (Zika and dengue viruses), coronaviruses (MERS-CoV, SARS-CoV, SARS-CoV-2), avian influenza (H5N1, H7N9), and monkeypox virus. They also reviewed vaccination history, vaccine development, clinical management, and surveillance methods including bioaerosol monitoring and viral detection techniques.

**Key Results:** - Ebola virus disease (EVD) has a case fatality rate (CFR) ranging from 25% to 90%, while Marburg virus CFR ranges from 24% to 88%. The largest EVD outbreak (2014–2016) involved >28,000 cases. FDA-approved treatments for EVD include the triple monoclonal antibody REGN-EB3 (Inmazeb) and ansuvimab (Ebanga). No approved treatment exists for Marburg virus disease. - Zika virus infection is mostly asymptomatic but can cause microcephaly in 5–15% of infants born to infected mothers. Vertical transmission was 65% or higher in one cohort. No approved vaccine or antiviral is available; management is supportive. - Dengue cases increased from >500,000 in 2000 to 5.2 million in 2019, with the largest outbreak in 2019 (3.1 million cases in the Americas). - MERS-CoV has a high mortality rate but limited person-to-person transmission. SARS-CoV was contained after 2004. COVID-19 (SARS-CoV-2) has an incubation period of 14 days (most cases 4–5 days); 20% of patients developed ARDS after 8 days, and 12.3% required mechanical ventilation. WHO-recommended treatments include Remdesivir, Nirmatrelvir, corticosteroids, IL-6 receptor blockers, and Baricitinib. - Avian influenza H5N1 has a mortality rate up to 50%; H7N9 has a 78% ICU admission rate and 28% death rate. Oseltamivir and peramivir are recommended, but antiviral resistance is a concern. - Mpox (monkeypox) outbreaks since May 2022 have been declared a public health emergency. Tecovirimat is available for treatment; trifluridine eye drops are used for ocular lesions. - Vaccine development: The Pfizer/BioNTech mRNA vaccine (Comirnaty) was FDA-approved in August 2021, and Moderna's Spikevax in 2022. The Johnson & Johnson adenovirus vaccine was 66% effective vs. 95% for mRNA vaccines. The ERVEBO® Ebola vaccine will begin phase 4 trials in 2024. No approved vaccines exist for Marburg, Zika, or H7N9. - Surveillance: Bioaerosol monitoring methods (e.g., filters, impactors, cyclones) can detect airborne viruses. PCR is the most common detection method but requires prior sequence knowledge; next-generation sequencing (NGS) can identify unknown viruses. High-risk surveillance locations include wildlife markets, farms, and tropical regions.

**Clinical Implications:** The review underscores the need for robust surveillance systems (including bioaerosol and wastewater monitoring) to provide early outbreak warnings. Vaccine hesitancy and viral mutations threaten herd immunity, as seen with measles and polio outbreaks. Rapid vaccine development (e.g., mRNA platforms) and international collaboration are critical. Clinicians should be aware of the diverse presentations of emerging viruses (e.g., mpox with genital lesions, Zika with microcephaly) and the importance of supportive care and targeted antivirals where available. The authors conclude that proactive surveillance, rapid diagnostics, and effective communication networks are pivotal for containing future threats.