The plagues of Egypt: what killed the animals and the firstborn?

The Book of Exodus, various translations, chapters 7 to 12--The plagues: 1. The river Nile turned the colour of blood, the water stank and the fish died 2. Hordes of frogs left the river, then they died and their bodies stank 3. Swarms of gnats attacked the people and their animals 4. Swarms of flies then did the same 5. An epidemic disease killed many farm animals 6. Boils and skin sores broke out on the people and their animals 7. A violent hail storm ruined the crops 8. A swarm of locusts ate what was left of them 9. Darkness blanketed the country for three days 10. The eldest child in each family died suddenly, and so did the first born animals. THE PERIOD: Uncertain, but deduced to be about 1470 BC. THE PEOPLE: The Egyptians, a population of about 2.5 million, about one million living in the Nile delta at an average density of about 90 people per km2 of cultivated land, and the Israelites, working as slave-labourers and quartered in the land of Goshen, a relatively small area probably near the margin of the north-east part of the Nile delta. THE PROTAGONISTS: Thutmosis III, Pharoah of Egypt, and Moses, leader of the Israelites. THE PLACE: The encounters between Thutmosis and Moses occurred just before each of the plagues, in or close to the Pharoah's palace. Given Moses' location, this must have been the palace at Memphis, the old capital, near the southern apex or beginning of the delta, not the one at Thebes, 600 km further to the south along the river. The Israelites' perception of the geographical extent of the plagues was therefore limited to what happened in the delta. The statements that plagues 1, 2, 3 and 8 affected "all the land of Egypt" should be interpreted as: all of the Nile delta including the land of Goshen. The other plagues affected parts neighbouring on, but not including, the land of Goshen.