The first seven plagues are recounted in this week’s parsha, and the last three in Parshat Bo. Today’s column looks at all the plagues together. Our Sages and secular commentators explain the sequence and nature of the plagues in a variety of ways. For example, the first nine plagues can be viewed as sets of three that demonstrated God’s dominance, respectively, over the ecosystem below the earth’s surface, over beings that walk on the earth, and finally over forces above the earth. They can also be viewed as attacks against the Egyptian deities associated with the target of each plague—the Nile, frogs, cattle, etc. And some commentators have offered natural explanations for the plagues, based on climatic, ecological and medical phenomena. This column shows that while miracles were embedded in the timing, coincidence and effects of the plagues, their nature and sequence appears to have followed an epidemiological progression. It draws from an article in the Jewish Bible Quarterly that I co-authored with epidemiologist Dr. John Marr.
Our analysis proceeded from the premise that the deaths in the last plague involved multiple epidemics occurring at the same time—known as a syndemic—and resulted from diseases inflicted in earlier plagues. The Torah leaves open the possibility that the Egyptians and animals that died in the tenth plague were first infected by earlier plagues. The 10th plague was pre-ordained by God from the very beginning—in order to punish the Egyptians for their mistreatment of the Israelites by killing their first-born (Exod. 4:22-3). Otherwise, God could have killed the first-born with a single plague, and done so immediately (Exod. 9:15). (This does not necessarily mean that God prevented the Egyptians from freeing the Israelites of their own free will, but implies that He knew that they would not do so.)
There are hints in the Torah that the 10th plague involved multiple diseases. God told Moses after the sixth plague that He was about to afflict the Egyptians with all My plagues (“mageifotai”)—using the plural form of the Hebrew mageifa, here meaning disease (Exod. 9:14). Rashi explains that a mageifa typically does not involve death (commentary on Exod. 7:27). However, when it comes to interpreting mageifot in 9:14, he concludes that it refers to the deaths in the 10th plague. Moreover, God later characterized the plagues in general as multiple diseases (Exod. 15:26; Deut. 7:15; 28:60-61). Since the only preceding plague that was manifestly a disease was the fifth plague, and only animals were the direct victims of that plague, the reference to multiple diseases seems best understood as alluding mainly to the 10th plague. In addition, it is inferable that life-threatening diseases had already taken hold among the Egyptians when Pharaoh pled for Moses to get rid of the locusts and entreat God to remove from me just this death (Exod. 10:17).
We estimate that the plagues played out over seven/eight months (early September to mid-April). Clearly, the plagues ended on the 15th day of Nissan (Exod. 12:51), generally corresponding to mid-April. As to when they began, Torah clues point to August or September. The most logical reason for Pharaoh to have been at the bank of the Nile when Moses and Aaron met with him before launching the first plague (Ibn Ezra on Exod. 7:15) was to check on its yearly flood level. (The Ancient Egyptian food supply depended on the annual flooding and recession of the Nile.) Rabbi Cassuto translates Exodus 7:19 as stating that the Nile’s water turned to blood even on trees and stones (after noting, in reflection on other commentaries, that the Egyptians generally did not have wooden or stone vessels). As such, the Torah seems to be describing the condition of parts of the Nile floodplain at full inundation in September.
The epidemiological analysis commences with the opening three-plague sequence. We infer that God wanted to progressively degrade the Egyptians’ health. To do so, He attacked the Nile, fertilizer of Egypt’s food and medicinal crops, unleashing a brief but intense contamination that killed the fish and (seven days later by Divine will) expelled the frogs. The first plague may have eliminated natural enemies of snails, carriers of schistosomiasis, predisposing victims to a far more serious disease, salmonellosis. Indeed, the frog deaths created a new breeding ground for deadly bacteria like salmonella. The lice of the third plague attacked both animals and humans (Exod. 8:14). Severe louse infestations in cattle and other livestock can produce serious secondary infections and nutritional deficiencies, compromising the animals as a source of both transportation and food.
The fourth and fifth plagues likely inflicted diseases on humans and livestock. Rabbi Nechemia held that the fourth plague, arov, sent swarms of mosquitoes, gnats and wasps against the Egyptians (Exodus Rabba 11:3); the Septuagint rendered arov as stable flies. But for various reasons, among them the statement in Ps. 78:45 that the arov “devoured” the Egyptians, many other Sages said that these were wild beasts. Perhaps, had the commentators known that flying insects could inflict an array of infectious diseases—something modern medical science did not know until the 1890s—more of them might have agreed with Rabbi Nechemia.
Malaria, which mosquitoes may transmit, and leishmaniasis, carried by infected sand flies, are among the potentially fatal diseases endemic to ancient Egypt that the arov may have inflicted. The fifth plague, a pestilence that infected animals, may have led to diseases transmittable to humans. Thus, for example, if the animals were infected with anthrax, their disease could have been transmitted to humans in a variety of ways, including contact with the animals or their products. In fact, those Egyptians who brought their livestock into their homes to protect them from the seventh plague’s hailstones (Exod. 9:20) were unknowingly increasing their own exposure to transmittable animal diseases such as anthrax.
The sixth plague brought the first clear indication of disease upon Pharaoh and his chartumim (priest/healers). It was the first launched by Moses himself (Exod. 9:10), and marked the first time that God saw the need to harden the heart of Pharaoh (Exod. 9:12), perhaps to prevent Pharaoh from releasing the Israelites out of pain and fear rather than remorse. Boils and blisters are common manifestations of many infectious diseases. Among other possibilities, they may have resulted from fly bites or penetrating schistosomal larvae; the inability of the chartumim to stand may, for example, indicate leg and foot inflammations common to schistosomiasis.
The hailstorms and locusts further degraded the Egyptians’ food and medicinal supplies by all but destroying Egypt’s vegetation and fruits (Exod. 10:15). And even though an epidemiological cause of the ninth plague is hard to discern, the abject darkness was undoubtedly horrifying and prevented the Egyptians from getting medical care as their diseases hurtled them to their deaths in the 10th plague.
The entire sequence of plagues, then, may have been a natural, epidemiological progression that unalterably led to massive deaths in the 10th plague. The timing of the plagues, and their ultimate effect in that all first-born Egyptians and animals died, however, are difficult to explain other than by attributing them to a Divine Hand.
By Ira Friedman
Ira Friedman, a retired attorney, is an independent researcher with an interest in the intersection of the Torah and ancient Egyptian history.
