“And Aaron lifted up the rod and struck the water of the river before the eyes of Pharaoh and before the eyes of his servants, and all the water in the river turned into blood, and the fish in the river died out, and the river stank, and the Egyptians could not drink the water from the river; and there was blood throughout all the land of Egypt” – Exodus 7:20,21.
Strange phenomena are described not only in the Bible, in other ancient sources there are also references to water that turned blood red. Modern researchers have proposed a theory that can explain what caused these strange phenomena.
According to scientists, the matter may be in microscopic organisms – protists, with the name Euglena bloody (Euglena sanguinea). With its rapid reproduction, the infected reservoir turns red. And since such water is toxic to animals, frogs and toads began to leave the poisoned water en masse.
Due to their migration and extinction, blood-sucking insects began to multiply intensively. And this directly affected the death of livestock and the presence of non-healing ulcers and abscesses in people. Insects can carry parasites, and simply weaken animals with a large number of bites.
And such a rapid increase in the population of Euglena could be caused by a rather sharp change in climate. Due to the increase in average temperature, the Nile became slower and shallower, which led to the reproduction of protists.
This does not sound as impressive as the biblical story, but it fits into the framework of modern science.