infectious diseases
Coronaviruses and Acute Respiratory Syndromes (MERS and SARS)
Introduction
Coronaviruses are enveloped RNA viruses that cause respiratory illnesses of varying severity from the common cold to fatal pneumonia. Numerous coronaviruses, first discovered in domestic poultry in the 1930s, cause respiratory, gastrointestinal, liver, and neurologic diseases in animals. Only 7 coronaviruses are known to cause disease in humans. Four of the 7 coronaviruses most frequently cause symptoms of the Common Cold . Coronaviruses 229E, OC43, NL63, and HKU1 cause about 15 to 30% of cases of the common cold. Rarely, severe lower respiratory tract infections, including bronchiolitis and pneumonia, can occur, primarily in infants, older people, and the immunocompromised. Three of the 7 coronaviruses cause much more severe, and sometimes fatal, respiratory infections in humans than other coronaviruses and have caused major outbreaks of deadly pneumonia in the 21st century: COVID-19 is a novel coronavirus identified as the cause of coronavirus disease 2019 (COVID-19) that began in Wuhan, China in late 2019 and spread worldwide. Middle East Respiratory Syndrome (MERS) was identified in 2012 as the cause of Middle East respiratory syndrome (MERS). Severe Acute Respiratory Syndrome (SARS) was identified in 2003 as the cause of an outbreak of severe acute respiratory syndrome (SARS) that began in China near the end of 2002. These coronaviruses that cause severe respiratory infections are zoonotic pathogens, which begin in infected animals and are transmitted from animals to people. SARS-CoV-2 has significant person-to-person transmission. 