Earliest Known Infectious Diseases

In all likelihood, infectious diseases of humans and animals have existed for as long as humans and animals have inhabited the planet. We know that human pathogens have existed for thousands of years because damage caused by them has been observed in the bones and internal organs of mummies and early human fossils. By studying mummies, scientists have learned that bacterial diseases, such as tuberculosis, leprosy, and syphilis, malaria, hepatitis, and parasitic worm infections, such as schistosomiasis, dracunculiasis (guinea worm infection), hookworm, and fluke and tapeworm infections, have been around for a very long time.

The earliest known account of a “pestilence” occurred in Egypt about 3180 bc. This may represent the first recorded epidemic, although words such as pestilence and plague were used without definition in early writings. Around 1900 bc, near the end of the Trojan War, the Greek army was decimated by an epidemic of what is thought to have been bubonic plague. The Ebers papyrus, describing epidemic fevers, was discovered in a tomb in Thebes, Egypt; it was written around 1500 bc. A disease thought to be smallpox occurred in China around 1122 bc. Epidemics of plague occurred in Rome in 790, 710, and 640 bc, and in Greece around 430 bc.
Artist rendering of an Escherichia coli (E. coli) bacterial cell, one of the most thoroughly studied of all microbes.
Artist rendering of an Escherichia coli (E. coli) bacterial cell, one of the most thoroughly studied of all microbes.

In addition to the diseases already mentioned, there are early accounts of rabies, anthrax, dysentery, smallpox, ergotism, botulism, measles, typhoid fever, typhus fever, diphtheria, and syphilis. The syphilis story is quite interesting. It made its first appearance in Europe in 1493. Many people believe that syphilis was carried to Europe by Native Americans who were brought to Portugal by Christopher Columbus. The French called syphilis the Neapolitan disease; the Italians called it the French or Spanish disease; and the English called it the French pox. Other names for syphilis were Spanish, German, Polish, and Turkish pocks. The name “syphilis” was not given to the disease until 1530.

First Microorganisme on Earth
Perhaps you have wondered how long microbes have existed on Earth. Scientists tell us that Earth was formed about 4.5 billion years ago and, for the first 800 million to 1 billion years of Earth’s existence, there was no life on this planet. Fossils of primitive microbes (as many as 11 different types) found in ancient sandstone formations in northwestern Australia date back to about 3.5 billion years ago. By comparison, animals and humans are relative newcomers. Animals made their appearance on Earth between 900 and 650 million years ago (there is some disagreement in the scientific community about the exact date), and, in their present form, humans (Homo sapiens) have existed for only the past 100,000 years or so. Candidates for the first microbes on Earth are archaea and cyanobacteria.