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Review
. 2021 Apr;28(16):19589-19600.
doi: 10.1007/s11356-021-12553-1. Epub 2021 Mar 2.

Coronaviruses in humans and animals: the role of bats in viral evolution

Amr El-Sayed #  1 , Mohamed Kamel  2
Affiliations
Review

Coronaviruses in humans and animals: the role of bats in viral evolution

Amr El-Sayed et al. Environ Sci Pollut Res Int. 2021 Apr.

Abstract

Bats act as a natural reservoir for many viruses, including coronaviruses, and have played a crucial epidemiological role in the emergence of many viral diseases. Coronaviruses have been known for 60 years. They are usually responsible for the induction of mild respiratory signs in humans. However, since 2002, the bat-borne virus started to induce fatal epidemics according to WHO reports. In this year, the first serious human coronavirus epidemic (severe acute respiratory syndrome; SARS) occurred (China, 8098 cases, 774 deaths [9.5% of the cases] in 17 countries). The case fatality was higher in elderly patients above 60 years and reached 50% of the cases. SARS epidemic was followed 10 years later by the emergence of the middle east respiratory syndrome (MERS) in Saudi Arabia (in 2012, 2260 cases, 803 deaths [35.5% of the cases] in 27 countries). Finally, in December 2019, a new epidemic in Wuhan, China, (corona virus disease 2019, COVID-19) emerged and could spread to 217 countries infecting more than 86,255,226 cases and killing 1,863,973 people by the end of 2020. There are many reasons why bats are ideal reservoir hosts for viral diseases such as the tolerance of their immune system to the invading viruses for several months. They can actively shed the viruses, although they develop no clinical signs (will be discussed in details later in the review). Bats were directly or indirectly involved in the three previous coronavirus epidemics. The indirect transmission takes place via intermediate hosts including civet cats for SARS and dromedary camels in the case of MERS. Although bats are believed to be the source of COVID-19 pandemic, direct pieces of evidence are still lacking. Therefore, coronaviruses' role in epidemics induction and the epidemiological role of bats are discussed. The current work also presents different evidence (phylogenetic data, animal experiments, bats artificial infection studies, and computerized models of SARS-CoV2 evolution) that underline the involvement of bats in the epidemiology of the pandemic.

Keywords: Bats; COVID-19; Coronaviruses; MERS; SARS; Wuhan.

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Conflict of interest statement

The authors declare that they have no conflict of interest.

Figures

Fig. 1
Fig. 1
Phylogenetic tree of betacoronaviruses showing that the SARS-CoV-2 is related to the bat coronaviruses ZC45 and ZXC21
Fig. 2
Fig. 2
Coronaviruses affecting humans and animals
See this image and copyright information in PMC

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