Any rapidly spreading infectious disease capable of attaining epidemic proportions and of causing death. The Hebrew word for pestilence (deʹver) comes from a root meaning “destroy.” (2Ch 22:10) In numerous texts pestilence is related to the execution of divine judgment, as regards both God’s name people and their opposers.​—Ex 9:15; Nu 14:12; Eze 38:2, 14-16, 22, 23; Am 4:10; see PLAGUE.

Brought by Abandonment of God’s Law. The nation of Israel was warned that refusal to keep God’s covenant with them would result in his ‘sending pestilence into their midst.’ (Le 26:14-16, 23-25; De 28:15, 21, 22) Throughout the Scriptures, health, either in a physical or in a spiritual sense, is associated with God’s blessing (De 7:12, 15; Ps 103:1-3; Pr 3:1, 2, 7, 8; 4:21, 22; Re 21:1-4), whereas disease is associated with sin and imperfection. (Ex 15:26; De 28:58-61; Isa 53:4, 5; Mt 9:2-6, 12; Joh 5:14) So, while it is true that in certain cases Jehovah God directly and instantaneously brought some affliction on persons, such as the leprosy of Miriam, of Uzziah, and of Gehazi (Nu 12:10; 2Ch 26:16-21; 2Ki 5:25-27), it appears that in many cases the diseases and pestilence that came were the natural and inexorable results of the sinful course followed by persons or nations. They simply reaped what they had sown; their fleshly bodies suffered the effects of their wrong ways. (Ga 6:7, 8) Concerning those who turned to obscene sexual immorality, the apostle says that God “gave them up to uncleanness, that their bodies might be dishonored among them . . . receiving in themselves the full recompense, which was due for their error.”​—Ro 1:24-27.

Israel affected. Thus, God’s warning to Israel in effect told them of the many ailments that a course of disobedience to his will would inevitably produce among them. His Law given to them served as a deterrent to and a protection against disease, because of its high moral and hygienic standards (see DISEASES AND TREATMENT [Accuracy of Scriptural Concepts]), also because of its healthful effect on their mental and emotional state. (Ps 19:7-11; 119:102, 103, 111, 112, 165) Not an occasional infraction of that Law but outright abandonment and rejection of its standards is what Leviticus 26:14-16 describes, and this would certainly make the nation vulnerable to all manner of disease and contagion. History, both past and present, bears testimony to the truthfulness of this.

The nation of Israel fell into gross apostasy, and Ezekiel’s prophecy shows the people speaking of themselves as “rotting away” because of their revolts and sins. (Eze 33:10, 11; compare 24:23.) As foretold, the nation experienced “the sword and the famine and the pestilence,” this reaching a climax at the time of the Babylonian invasion. (Jer 32:24) The frequent association of pestilence with sword and famine (Jer 21:9; 27:13; Eze 7:15) is in harmony with known facts. Pestilence usually accompanies or follows in the wake of war and its associated food shortages. When an enemy force invades a land, agricultural activities are curtailed, crops are often confiscated or burned. Cities under siege are cut off from outside resources, and famine develops among the populace forced to live amid overcrowded and unsanitary conditions. Under such circumstances, resistance to disease drops and the way is open for the deadly assault of pestilence.

At “the Conclusion of the System of Things.” Jesus, when foretelling Jerusalem’s destruction and “the conclusion of the system of things,” showed that pestilence would be a notable feature of the time period preceding the “great tribulation.” (Mt 24:3, 21; Lu 21:10, 11) Written after Jerusalem’s destruction (which was accompanied by grave famine and disease), Revelation 6:1-8 pointed to a future time of sword, famine, and “deadly plague.” These would follow the appearance of the crowned rider on a white horse who goes forth to conquer, a figure precisely paralleling the one of Revelation 19:11-16, which clearly applies to the reigning Christ Jesus.

 Jehovah’s Protection. King Solomon prayed that, when menaced by pestilence, Jehovah’s people might pray to Him for relief, spreading out their palms toward the temple, and receive favorable hearing. (1Ki 8:37-40; 2Ch 6:28-31) Jehovah’s ability to protect his faithful servant also against spiritual harm, including that of the moral and spiritual “pestilence that walks in the gloom,” is comfortingly expressed in Psalm 91.