Malaria and Rome: A History of Malaria in Ancient Italy (23 page)

¹⁷⁰ North (1896: 145–7); Bellincioni (1934). Hay
et al
. (2000) observed a three-year cycle of P. falciparum
epidemics which could not be correlated with climatic trends in a highland region of western Kenya, and suggested that intrinsic population dynamics offer the most parsimonious explanation of the intervals between epidemics. However the evidence from Italy strongly supports climatic explanations for malaria epidemiology in Europe in the past.

¹⁷¹ Pliny,
Ep
. 2.17.25.

¹⁷² Dennis (1878: 222–34) on Rusellae, which is situated about 170 metres above sea level, while Vetulonia is around 300 metres above sea level.

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Ecology of malaria

developed and then gradually became cut off from the sea.¹⁷³ The flood plain of the river Ombrone was too flat for drainage purposes, like the Pontine plain. In the early modern period the increasing use of quinine played a more important role in reducing malaria in the province of Grosseto than the bonifications.¹⁷⁴ However, the final blow to malaria in Italy as a whole was delivered by the insecticides DDT (against adult mosquitoes) and Paris Green (against mosquito larvae) during and after the Second World War, for example during the operations to defeat the terrible epidemic in the Monte Cassino region. Consequently the balance of probability is that drainage operations in Roman times, when quinine and DDT were not available, had limited effects on malaria, just like their early modern counterparts.
Anopheles
mosquitoes still exist in the Maremma in spite of the bonifications.¹⁷⁵

Besides deforestation in the uplands, intensive farming in the vicinity of Rome to feed the burgeoning urban population also played a role in soil erosion, which increased enormously in Roman times. The rate of soil erosion in Latium increased
ten times in the second century  compared to its previous rate. This may be attributed to dense settlement around the city of Rome, as suggested by the Capena and Veii archaeological field surveys, and intensive market gardening to produce food for the increasing urban population.¹⁷⁶ We shall see in Chapter 8 below that there was a strong causal connection between gardening and malaria.

¹⁷³ Pinto (1982: 13–14).

¹⁷⁴ Ciuffoletti and Guerrini (1989: 67, 95, 136).

¹⁷⁵ Raffaele and Coluzzi (1949); Garaci (1947); Merzagora, Corbellini, and Colluzi (1996).

Alberto Coluzzi led the operations against this epidemic. Malaria epidemics are attested in the Monte Cassino region and the valley of the River Liri towards Frosinone as far back as the early medieval period:
e.g.
chronica monasterii Casinensis
1.22, ed. H. Hoffmann (1980),
Die Chronik von Montecassino
(
Monumenta Germaniae Historica
.
Scriptores,
xxxiv):
Qui videlicet sanctus vir cum depositus fuisset septimo idus Octobris, in loco, quo reconditus est, multos febre detentos diversisque lan-guoribus oppressos, ex fide poscentes ad suos cineres precibus ac meritis suis pristine saluti restituit
(This undoubtedly holy man [sc. abbot Deusdedit], when he was buried on 9 October [834 ], in the place, in which he rests, restored to their previous good health many people gripped by fevers and oppressed by various kinds of weariness, who in accordance with their faith invoked his ashes with prayers and their own services.); 2.96
Sed cum predictus apostolicus Romana febre iam dudum langueret, circa ipsam natalis Domini festivitatem adeo graviter infirmatus est, ut pro certo se mori putaret
[December  1057] (However since the above-mentioned bishop had already long been severely afflicted by Roman fever, he was so ill about the time of the festival of the birth of Christ that he thought that it was inevitable that he was going to die.), cf.

2.88, 90.

¹⁷⁶ Judson (1968); Potter (1979: 120–37) recorded large numbers of villas by
c
. 100 (with slave labour forces), but few significant towns occupied by a free population.

Ecology of malaria

113

Substantial erosion and redeposition of sediments has also occurred since the classical period. The consequence is that the modern landscape is quite different from the ancient one. Recent research in the Fiora, Marta, Treia, and Valchetta river valleys has drawn a very sharp contrast between the ancient and the modern river systems:

The sedimentology of the coarse deposits suggests that Roman rivers and floodplains were very different to those existing today. They were characterized by shallow channels, actively migrating, depositing bars of gravel.

Some reaches of the contemporary streams are trying to re-establish this condition but only to a limited extent due to confinement by high cohesive sandy-silt banks.¹⁷⁷

The ancient fluvial regime had very important consequences for malaria. The
laterally mobile
Roman rivers in shallow channels would have been more liable than their modern counterparts in deeper channels to flood the surrounding countryside. As the flood waters retreated, leaving pools here and there, mosquito breeding sites would have been created.¹⁷⁸ Thus it is likely that the rivers of Latium and Tuscany in the Roman period had a greater propensity to create mosquito breeding sites than they do today. Tibullus was right to fear the rivers of Latium and Tuscany in summer.

The overall effect of all the landscape changes which have been described was to provide more breeding sites for mosquitoes in general in Roman times. In coastal areas, if the water was brackish, those species of
Anopheles
mosquito that are the most dangerous vectors of human malaria had an advantage over other species of Anopheles
. Even in Lazio, suitable breeding sites for mosquitoes can be scarce. In 1928–9 the lake at Nemi was partially drained to uncover Caligula’s ships, inadvertently providing new breeding sites for mosquitoes. In 1929 a sudden epidemic of
P. falciparum malaria infected over half the population of the town, which had no previous history of endemic malaria in its hilly location (320 metres above sea level). Prior to the drainage operations there were not enough mosquitoes around to sustain the transmission of malaria in Nemi, given that the chances against transmission by any individual mosquito are extremely high, since most mosquitoes do not ¹⁷⁷ Brown and Ellis (1995: 69).

¹⁷⁸ An example of periodic flooding at a specific site is the Roman mausoleum at Fosso della Crescenza along the Via Veientana in southern Etruria (S. Judson in Fentress
et al
.

(1983: 70–2) ). On the rivers of southern Etruria see also Rendeli (1993: 122–5).

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Ecology of malaria

live long enough to transmit the disease.¹⁷⁹
P. falciparum
, the most dangerous species of human malaria, is a very ancient parasite which was probably present in Mediterranean countries on a localized basis from the Neolithic period onwards, as has already been argued. It can certainly continue to exist in very small foci without spreading. It was not a new disease in classical times. Nevertheless the conclusion reached here is that the frequency of all types of malaria increased very substantially in Roman times primarily because of human modifications of the landscape which unintentionally favoured the vector mosquitoes. The demographic effects of this expansion on human populations demand detailed examination now.

¹⁷⁹ Hackett and Missiroli (1931: 64–5) on Nemi.

5

The demography of malaria

5. 1 D      

  

Bonelli rightly observed that in order to understand the impact of malaria on Italy in the past it is not enough simply to consider its demographic effects in purely quantitative terms.¹ It also influenced the entire lifestyle of people, even if it did not kill them, by forcing them to live away from the fields in which they had to work. In other words, malaria altered settlement patterns.² Old Salpi in Apulia was the most dramatic example of this in antiquity (see Ch. 10 below), but malaria also influenced settlement patterns within the city of Rome itself, as will be seen later (Ch. 8 below).

Malaria influenced agricultural systems by preventing intensive farming practices (Ch. 9 below). Nevertheless consideration of the demographic effects of malaria in purely mathematical and statistical terms is essential to understand the scale of its impact. The most fundamental weakness of nearly all recent literature on the question of the effects of malaria in Italy in antiquity is the absence of any appreciation in quantitative terms of the demographic effects of malaria on human populations in Europe in the past. This lack of knowledge about the demographic effects of malaria on human populations has permitted many researchers from different branches of scholarship to minimize the importance of malaria.

A good starting-point is the recent debate between Scheidel and Shaw concerning the explanation of excess seasonal mortality in the city of Rome in antiquity, as revealed by funerary inscriptions.³

Scheidel opted for malaria, in synergistic interactions with other diseases, as the principal cause. Shaw attempted to minimize the role of malaria. It is instructive to consider the flaws in Shaw’s argument. Shaw relied on national statistics which show that malaria ¹ Bonelli (1966: 662).

² Pinto (1982: 30) saw malaria as a determinant of settlement patterns in Tuscany in the medieval period.

³ Scheidel (1996); Shaw (1996).

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Demography of malaria

accounted for 2.2% of all deaths in Italy in 1887–9. He concluded that malaria was less important in Italy than in Greece, where 5.6%

of all deaths were attributed to malaria as recently as 1921–32.⁴ The most detailed statistics can be extremely misleading if they are not handled very carefully indeed. In this particular case, there are two major reasons why these national statistics for cause of death are unlikely to give an accurate estimate of the contribution of malaria to mortality in the city of Rome or in the Roman Campagna in antiquity.

The first rather elementary reason is quite simply that these national statistics lumped together mortality data from localities with intense malaria with data from places where there was no malaria at all to yield meaningless averages which may be completely inappropriate if applied to any particular locality. It is always possible in demography to aggregate data from two or more different regions and calculate the average, but the crucial question is whether the average so obtained is meaningful. As del Panta said in an article on infant and child mortality in early modern Italy: No satisfactory explanations can be given for the evolution of child and infant mortality in Italy without considering territorial differences. In fact, national values result from quite different regional and provincial levels.⁵

In localities in Italy where malaria was endemic the proportion of deaths
which were directly attributed to malaria
(the significance of this phrase will be seen shortly) was far higher than the national statistics for mortality indicate. Bonelli gave as examples for 1882

Rossano in Calabria, Grosseto, and Paola in Calabria where 24.8%, 23%, and 19.5% respectively of all deaths were directly attributed to malaria. An earlier, less complete database of causes of death yielded a figure of 19% of all deaths directly attributed to intermittent fevers in Grosseto in 1840–1. This result is of the same order of magnitude as the result for 1882. However, it is probably an underestimate since the surviving records for 1840–1 excluded almost entirely causes of death for infants and children under the age of five, who would be expected to suffer severely from
P. falciparum
malaria when it is endemic.⁶ Bonelli stated that ‘in the 1880s ⁴ Shaw (1996: 133 and note 108); Balfour (1935: 302) on Greece.

⁵ Del Panta (1997: 10).

⁶ Bonelli (1966: 662); del Panta (1989: 48–9 n. 23), using the statistics of Salvagnoli Marchetti.

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117

it was quite common in the Mezzogiorno for malaria to account for 20–30% of all deaths . . . in numerous other localities malaria accounted for 10–15% of all deaths’.⁷

There are two lessons to be drawn from this. First, in any kind of comparative history it is essential to look for
appropriate
parallels.

Since the ancient medical authors Asclepiades and Galen provide positive evidence that
P. falciparum
, the most dangerous species of human malaria, was common in ancient Rome (see Ch. 8 below), the appropriate parallels are places in more recent periods of Italian history where malaria was common, such as Grosseto, not places where it did not occur at all. A good example of a comparison that should be used as a source of
contrasts
with the city of Rome in antiquity, not as a source of
parallels
, is Florence at the time of the famous
Catasto
in 1427.⁸ The
Catasto
is of course a very important historical document, to which further reference will be made in Chapter 11 below. However, the demographic situation in Florence then was fundamentally different from the situation in ancient Rome for (at least) two major reasons: (1) Florence in the late medieval period was affected by epidemics of bubonic plague, for which there is no evidence in Rome in antiquity; (2) Florence had no history of endemic malaria.⁹ Since there were significant differences in the causes of death between imperial Rome and late medieval Florence, there is no reason whatsoever for expecting the mortality patterns of ancient Rome and late medieval Florence to be similar. It follows that it is essential to investigate the causes of death in detail at the local level, before choosing comparisons for demographic purposes. Shaw did not consider the important evidence of Asclepiades and Galen. He stated that ‘it seems clear that it is the factor of temperature variability that marks the main separation between “northern” and “southern” regimes of seasonal mortality’, but failed to notice that out of the various diseases which he considered malaria is the only one in fact which is strongly temperature-dependent.¹⁰ Both what he termed ‘normal’ diseases, such as tuberculosis, and epidemic diseases, such as typhus, flourish equally well in Africa and in northern Europe. In 1998 there were ⁷ Bonelli (1966: 662):
negli anni ’80 era abbastanza frequente nel Mezzogiorno che il numero dei morti per malaria rappresentasse il 20–30% del totale dei morti . . . numerose altre località presentano una mortalità per malaria compresa tra il 10 e il 15% della mortalità generale
.