The role of animals in emergence and spread of the currently occurring SARS –CoV-2 pandemics is largely unknown. The definitive answers regarding the infectivity and clinical picture of SARS-CoV-2 in animals have been difficult to find (Abdel-Moneim and Abdelwhab 2020). It is suspected that SARS-CoV-2 began in animals and was passed to humans, where it was subsequently spread from human to human (Ji et al. 2020). SARS-CoV-2 infection has been recorded in several animal species. The fact that SARS-CoV-2 can infect a wide range of animals suggests that the virus is capable of crossing the species barrier (Leroy et al. 2020). As a result, many wild and domestic animals may be infected with SARS-CoV-2 and serve as intermediate hosts for the virus (Tiwari et al. 2020, Zhao et al. 2020). The natural host of SARSCoV-2 has been proposed to be the bat (Wong et al. 2020). SARS-CoV-2 infection in cats, dogs, minks, tigers, and lions has recently been documented (Abdel-Moneim and Abdelwhab 2020, Oreshkova et al. 2020). Mice, hamsters, cats, ferrets, non-human primates, and tree shrews have been shown to be susceptible to SARS-CoV-2 in experimental infections (Chan et al. 2020, Shi et al. 2020, Zhao et al. 2020). The binding mechanism of SARS-CoV-2 RBD and ACE2 receptors has been studied structurally, and it appears that ACE2 from fish, amphibians, birds, and mammals can bind to SARS-CoV-2 RBD, making them potential natural hosts for SARSCoV-2 (Chen et al. 2020). A recent study used a SARS-CoV-2 ELISA kit to identify SARS-CoV-2-specific antibodies in blood samples from 35 different animal species (Deng et al. 2020). Serum was collected from poultry (chicken, duck, and goose), experimental animals (mice, rat, and rhesus monkey), companion animals (cat and dog), domestic animals (sheep, pig, horse, and cow), and wild animals (leopard cat, masked civet, mink, ferret, jackal, fox, alpaca, camel, eagle, bamboo rat, peacock, tiger rhinoceros, porcupine, bear, giant panda, red pandas, pangolin, weasel, yellow-throated marten, and wild boar). There were no SARSCoV-2-specific antibodies in any of the blood samples tested, ruling out the idea of these animal species serving as intermediate hosts for SARS-CoV-2 (Deng et al. 2020).
In the current study, we attempted to clarify the involving of animals in spread and transmission of SARS –CoV-2 among Egyptians. RT-PCR could be a useful, rapid and of reasonable cost tool for screening of the virus infection in different populations of animal species. The primers of the used PCR assay target the RNA dependent RNA polymerase gene of CoVs. The polymerase gene is a much conserved region in the coronavirus genome. Therefore, the percentage sequence similarity will be high among different coronavirus members belonging to the same group. Nevertheless, this sequence information allows a primary identification of the coronavirus type that is present in a given sample (Vijgen et al. 2008).
In spite of the numbers of individual animals sampled per species were relatively low (Table 1), our results revealed that no evidence for circulating of SARS –CoV-2 among animal populations in Egypt. Depending on the host and pathogen species, viral prevalence might vary significantly. We could have increased our detection rate in the species where no CoVs were discovered by targeting more host species and using bigger sample sizes. The same diagnostic technique, on the other hand, was able to detect all probable clinical cases in people. These findings could support the hypothesis that the animals at the present time are not the original source for infection for the human and most animal cases have had known or suspected exposure to human COVID-19 patients, indicating that human-to-animal infection is the primary cause of spread among domestic animals. The live-wild animal markets not famous in Egypt, therefore the possibility of inter-species contact between wild and domestic animal species is very low. Hence, the possibility of inter-species transmission of CoV infections need to be confirmed by future studies, and these studies are required to understand if and how different animals could be affected by SARS-CoV-2.
To summarize, basic hygiene precautions should be used to limit contact between sick people and pets. Several animal models have been proposed for evaluating the effectiveness and safety of antiviral medicines as well as testing investigational vaccinations against SARSCoV-2. To limit the spread of SARS-CoV-2, coordinated activities from several disciplines such as public health, veterinary medicine, environmental sciences, and social sciences are critical. These investigations will aid in the understanding of the virus's possible hosts, the process of transmission, and the creation of vaccines. Furthermore, public health measures for workers who work with animals and animal byproducts are suggested, in addition to the use of basic hygiene procedures.