Malaria and Rome: A History of Malaria in Ancient Italy, Robert Sallares [reading a book TXT] 📗

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The first millennium  witnessed a substantial shift away from the closed forests of the Neolithic period towards the modern open countryside. Dionysius of Halicarnassus described one famous closed forest, the Sila in Bruttium, which he regarded as a source of timber for the whole of Italy.¹⁶⁶ Such forests were under attack in Roman times. Deforestation in upland areas of central Italy led to increased run-off of rainwater. Pliny the Younger noted that at Tifernum in Umbria perennial streams watered beautiful meadows full of flowers, but the ground, because it was sloping, was not marshy, as water drained off into the Tiber. The water ended up elsewhere. A long series of major floods occurred in the city of Rome in antiquity, recalling the catastrophic flood of November 1966 at Florence, Grosseto, and elsewhere in Tuscany, which occurred after forty consecutive days of heavy rainfall. The construction of the Cloaca Maxima suggests that a need for drainage was already felt from the very beginning of Roman history. Strata dating to the imperial period in the Roman Forum are now covered by six or seven metres of alluvial deposits and are themselves several metres above the levels of the archaic period.¹⁶⁷ Pliny the Elder states that the Tiber floods were nowhere worse than in the city of Rome itself, and Pliny the Younger gives a graphic description of the effects of a Tiber flood. Orosius mentions a devastating flood in 241 . Cassius Dio recorded that the lower parts of Rome were completely flooded by the Tiber in 54 , causing severe damage to buildings. He attributed the flood to very high rainfall upstream, or to the sea driving back the river water. Both explanations are possible. Another Tiber flood made the city of Rome navigable by boat for three days in 23 . The following year, Rome was yet again submerged. Tacitus mentioned a severe flood in  15, which again caused severe damage to buildings and loss of life, and described an interesting debate in the Senate about these problems. In the end the Senate, whether because of the difficulty of water-management enterprises, or the inevitability of protests from communities liable to be affected by river diversions, or because of superstitious beliefs, decided to do nothing. This illustrates the large degree of helplessness of the Romans in the face of ¹⁶⁶ Dionysius Hal., AR 20.15, ed. C. Jacoby (1891): lh skierÏn åpoteloısa di’ Òlhß Ómvraß tÏ Ôroß (the forest keeps the mountain shaded throughout the day). Douglas (1955: 228–30) described the Sila forest as it is now, and Béal (1995) reviewed all the evidence from antiquity.

¹⁶⁷ Quilici (1979: 69–70).

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Ecology of malaria

these ‘natural’ (albeit unintentionally partly man-made) phenomena. The flood in  15, the year after the death of the emperor Augustus, shows that the measures which he is said to have taken to control the Tiber were completely ineffectual. Tacitus records another severe flood in  69. Terrible floods also occurred in Rome in the reigns of Nerva, Trajan, and Marcus Aurelius. Cassius Dio mentions another flood in  217, and there were doubtless others which have gone unrecorded.¹⁶⁸

The records of the worst floods in Rome during the last millennium show that they principally occurred during the months of September to February. As Rome gradually dried out after these great floods, mosquitoes would have found countless ideal breeding sites within the perimeter of the city of Rome itself. Literature from the early modern period shows that Tiber floods were regarded as a very important factor in the generation of malaria in the city of Rome. The Tiber was not enclosed by the Lungotevere river walls then as it is today. A huge flood in late December 1870, a few weeks after Rome had become the capital of the newly unified Italian state, put the question of taming the river Tiber at the top of the political agenda for the new government. The districts of the city worst affected by malaria were along the river. Floods in September and October increased mosquito populations and the intensity of malaria immediately. Floods later in winter would drench the ground and make it more suitable for mosquito breeding purposes in the following summer. A description of a medieval flood in December  791 makes it clear that much water remained in the city long after the Tiber had ceased to flow through it. It was not coincidence that pestilence accompanied the floods of 23–22

, according to Cassius Dio, although many other diseases besides malaria would have been active as well, especially waterborne intestinal diseases, which can interact with malaria in ways which will be described later (see Ch. 5. 2 below).¹⁶⁹

¹⁶⁸ Le Gall (1953: 29–34) discussed the evidence for Tiber floods in antiquity. The following sources are noteworthy: Pliny, Ep. 5.6.11–12; Pliny, NH 3.5.55; Pliny, Ep. 8.17; Orosius, Hist. 4.11.5–7, ed. Arnaud-Lindet (1991); Cassius Dio 39.61.1–2, 53.33.5, 54.1.1, also 56.4 for a flooding of the Campus Martius by the Tiber in  12, and 79.25.5; Suetonius, Augustus 30; Tacitus Annals 1.76, 79 (with LeGall (1953: 120–5) ); Tacitus Histories 1.86; epitome de Caesaribus 13.12–13, ed. Pichlmayr (1911); scriptores historiae Augustae Hadrian 21.6, Antoninus Pius 9.3 and Marcus Aurelius 8.4; Claudian, de bello Gildonico 39–43; Quilici (1979: 66–8).

¹⁶⁹ Bocquet (1998) described the events of 1870. A. Betocchi Del fiume Tevere in Monografia (1881: 244–5) listed the heights and months of the worst Tiber floods in the last eight hundred years. Baccelli (1881: 156, 159–60) regarded Tiber floods as very important in generating Ecology of malaria

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Besides floods, heavy rainfall in winter and spring was also beneficial for mosquito breeding. A correlation between heavy rainfall in winter or spring and an elevated frequency of malaria was observed in Rome in the last century. North described as an example the events of 1879, when exceptionally high rainfall