Epidemiology of emerging viruses

Newly emerging viruses such as West Nile virus, coronaviruses (SARS-CoV, MERS-CoV and SARS-CoV-2), H1N1pdm09, Ebola virus, Zika virus and Monkeypox virus are of global concern as they have caused serious public threats. Among the several outbreaks caused by emerging viruses, the worst pandemic was caused by SARS-CoV-2. The Omicron variant is the dominant variant among SARS-CoV-2 variants and the lineages BA.5.2 and BF.7 were responsible for the recent Chinese surge. Genome sequencing studies of MERS-CoV revealed that it is evolving with mutations in spike protein. West Nile virus is still circulating among birds in Europe, Mediterranean and North American countries. Several West Nile virus cases were reported from Europe and neighboring countries in 2022. The 2009 H1N1 pandemic caused by H1N1pdm09 is a variant strain evolved from H1N1 in swine. Though it caused more than 60 million infections, the mortality rate was 0.02%. Staggeringly, severe infections occurred among obese people. Zika virus has jumped borders from Africa and is adapting to become endemic in new geographical habitats such as South East Asia, India and Europe due to uncontrolled breeding of Aedes mosquitoes. Recently, autochthonous vector borne transmission of Zika virus was documented in France. During the Monkeypox pandemic, the virus demonstrated a lower infectious and mortality rate in individuals vaccinated for smallpox. A lower virulence of Monkeypox virus compared to smallpox was due to mutations in the ORF regions. Surveillance efforts and measures must be incessantly undertaken to prevent future outbreaks caused by emerging viruses.