The coronaviruses belong to the family Coronaviridae in the order Nidovirales . Coronaviruses are found globally and infect a variety of animals, causing illnesses that range from gastrointestinal tract infections, encephalitis and demyelination; and can be fatal . Humans coronaviruses (hCoVs) have traditionally been associated with self-limiting upper respiratory tract infections and gastrointestinal tract infections . In recent years, however, it has become increasingly evident that the hCoVs can cause more severe lower respiratory tract infections such as bronchitis, pneumonia and even acute respiratory distress syndrome (ARDS), and can lead to death . Seven coronaviruses are known to infect humans, with the four “ common cold ” CoVs circulating globally on a yearly basis . The remaining three are more pathogenic and have resulted in outbreaks with high mortality rates . This review focussed on the three pathogenic CoVs.