![]() ![]() In view of the recurrence of epidemics caused by zoonoses, in 2018 the WHO warned of the likelyhood of a new wave of infections and postulated a disease X. It also explains the interest in vaccinating the animals ( 1, 2). The fact that dromedaries act as intermediate hosts explains the clustered occurrence of the infection in the Arab world. Young dromedaries in particular develop acute illness from MERS-CoV, while the infection is mild in Asian camels. Thus, up to 74% of the examined dromedaries were serum-positive. Rather, an intermediate host was identified, namely dromedaries (Arabian camels) and Asian camels, both carry MERS viruses. However, it is unlikely that in Arab countries, where bats are not caught for the purpose of consumption, the infection passed directly from them to humans. Regarding MERS, it is also assumed that there was an animal reservoir, and since coronaviruses are widespread in bats, bats are also considered to be the primary natural host here. This corresponds to a mortality rate of around 35%. By February 2020, 2,519 cases had been registered, of which 866 were fatal. By January 2018, the WHO registered 2,143 diagnosed patients, 750 of them died. The focus of the occurrence, however, was the Arabian Peninsula, where local outbreaks occurred repeatedly. Seriously ill patients infected with MERS-CoV were registered until 2018, with the infection not only occurring in the Arabian Peninsula, but also in South Korea and China (in hospitals, probably through travelers). The virus that caused it was named MERS-CoV (MERS for Middle East respiratory syndrome). The disease was severe, characterized by fever, coughing, shortness of breath (respiratory syndrome), and was associated with pneumonia, kidney failure and finally multiple organ failure. ![]() This is a nocturnal, tree-dwelling cat that is eaten and is also kept in farms for the purpose of coffee bean fermentation through digestive enzymes of the animal ( 1).Īnother wave of infections began in 2012, probably originating in Saudi Arabia and again caused by a virus belonging to the beta coronavirus family, albeit from a different subgroup. It is assumed that bats did not infect humans directly, but that there was an intermediate host for SARS-CoV, the Asian musang ( Paradoxurus hermaphroditus) from the subfamily of the palm roller. The natural hosts of these corona viruses are bats ( 1). The trigger was a virus from the large family of betacorona viruses. With 8,096 patients infected and 774 registered deaths (corresponding to a mortality rate of 9.7%), the infection went off lightly. Fortunately, the infection came to an end in May 2004, as declared officially by the World Health Organization (WHO). Patient zero was very likely a cook specialized in wild animals. Because of the serious symptoms affecting the respiratory tract it was referred to as SARS-CoV (CoV for corona virus). Already in November 2002, an epidemic emanated from the city of Shenzen in southern China. The SARS-CoV-2 pandemic is not the first one caused by a coronavirus, but it is undoubtly the most severe. Possible scenarios of virus evolution are discussed, with particular emphasis on the hypothesis that the virus could have emerged unintentionally through routine culture or gain-of-function experiments in a laboratory, where it was optimally adapted to human cells and caused cryptic infections among workers who finally spread the virus causing the pandemic. This article summarizes the unique properties of SARS-CoV-2 and focusses on a specific sequence encoding the spike protein. The propagation of SARS-like bat viruses in cell culture allowed experiments aimed at increasing the infectivity of the virus and adaptation to human cells. An intermediate host was postulated, but many SARS-like bat viruses have the ability to infect human cells directly, which has been shown experimentally by scientists in the Wuhan Institute of Virology using collected specimens containing virus material from horseshoe bats. It is considered certain that the virus is of animal origin and very likely passed from bats to humans in a zoonotic event. How the evolution of the virus and the transition to humans might have happened is the subject of much speculation. The origin of the virus can be reconstructed through epidemiological studies and, even more so, from genome comparisons. ![]() The COVID-19 is now spread worldwide and has tremendous socio-economic consequences. We are currently in a rapidly expanding pandemic of the SARS-CoV-2 virus, which originated in the city of Wuhan in central China. ![]()
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