Bats harbor many types of coronaviruses and were probably the original source of the new coronavirus that appeared in the Middle East. iStockphoto.com hide caption

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Two men from northwestern Missouri became ill after tick bites infected them with a previously unknown virus. iStockphoto.com hide caption

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Health Department officials cull birds and put them in sacks after bird flu virus was detected in Bhubaneswar, India. Biswaranjan Rout/AP hide caption

itoggle caption Biswaranjan Rout/AP