Malaria and Rome: A History of Malaria in Ancient Italy (20 page)

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embankments often subsequently became filled with water and provided excellent breeding sites for mosquitoes.¹³⁰

In antiquity Strabo explicitly commented on Roman road building in Latium and noted the cuttings through hills and embankments across valleys which Roman engineers designed for their roads. Similarly Pliny noted the roads cut through mountains.¹³¹

Modern experience in Italy in the nineteenth century with railways suggests that Roman (and also earlier Etruscan) road building would have played a significant role in creating favourable new breeding habitats for
Anopheles
mosquitoes. Similarly ‘road building was linked intimately with the proliferation of malaria’ in Bengal in India during the British rule in the nineteenth century .¹³² The ancient accounts of his life state that Gaius Gracchus organized a considerable volume of road construction in Italy, after his return from Sardinia. Modern historians have failed to realize the irony of his work. By having roads built, Gracchus unwittingly assisted the spread of malaria in those very same depopulated parts of Italy which he desired to rejuvenate.¹³³

The nuraghi of Sardinia served to introduce the question of the design and construction of housing, another very important topic.

As Varro put it:

The situation of villas, the size of the buildings, and the directions in which colonnades, doors, and windows face, are matters of very great interest.¹³⁴

Unfortunately, as has often been observed by modern scholars, the atrium of Roman houses contained a pool of rainwater in the impluvium, a possible habitat for mosquito larvae (so long as there were no fish in it). It is not clear if the presence of the impluvium was important in practice in relation to malaria. Eugenia Tognotti, in her book on malaria in Sardinia, noted that
A. labranchiae
likes houses which are dark inside, providing cover, with small windows, ¹³⁰ Bonelli (1966: 667 n. 11), quoting the Inchiesta Iacini; Tognotti (1992: 25); Celli (1900: 147).

¹³¹ Strabo 5.3.8.235C: πstrwsan d† ka≥ t¤ß kat¤ t¶n c*ran ØdoŸß, prÎsqenteß ƒkkop3ß te lÎfwn ka≥ ƒgc*seiß koil3dwn (they constructed roads throughout the land, with cuttings through hills and embankments across valleys); Pliny,
NH
36.24.125:
vias per montes excisas (roads cut through mountains).

¹³² Klein (1972: 140–1).

¹³³ Plutarch,
Tiberius and Gaius Gracchus
28, ed. Ziegler (1971); Potter (1979: 79–83, 101–9) on the Roman road network in south Etruria.

¹³⁴ Varro,
RR
1.4.4:
quod permagni interest, ubi sint positae villae, quantae sint, quo spectent porticibus, ostiis ac fenestris
.

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Ecology of malaria

a description which fits a lot of traditional housing in Mediterranean countries.¹³⁵ Sambon described the habits of what was then called
A. maculipennis
at Ostia at the end of the nineteenth century: The adult insects were found in great numbers in the houses and stables of the district. In stables they seemed to rest by preference on the old dusty cobwebs which heavily curtained the ceilings. In the houses they chose the darkest corners, often resting under beds, tables, and chairs, or on dark-coloured clothing, but more frequently on the ceilings, especially when these were begrimed with the smoke of winter fires and well out of the way of danger. In the bedrooms of an inn at Ostia, which had a blue stripe all round their whitewashed ceilings, the
Anopheles
seemed to settle by choice on the dark stripe for protection. It is almost ridiculous how these insects escape detection by those who are not in the habit of looking for them.¹³⁶

A. labranchiae
is a non-diapausing species of mosquito. It remains active indoors and continues to bite humans nearly all the year round, although malaria parasites cannot develop inside it in the winter when it is too cold. Consequently it was very vulnerable to the modern malaria-control strategy of spraying the interior walls of dwellings with the insecticide DDT. In contrast the other main vector of malaria in Mediterranean countries,
A. sacharovi
, hibernates outdoors in the winter cold and does not become active until May each year. The northern European malaria vector
A. atroparvus
tolerates cold temperatures well but does not hibernate completely, unlike
A. sacharovi
. Consequently it sometimes bites humans in houses in winter.¹³⁷

Since mosquitoes dislike flying upwards, theoretically the upper storeys of multi-storey buildings in the city of Rome should have been healthier than the ground-floor levels. In the seventeenth century Doni emphasized the importance of building design and town planning.¹³⁸ There was a view in early modern literature that tall buildings with narrow streets provided protection against ‘bad air’. This point of view had antecedents in antiquity, since Tacitus reports that after the great fire in Rome in  64 some people did not like Nero’s plan to rebuild the city with lower buildings and wider streets, since they thought that the old layout was healthier:¹³⁹

¹³⁵ Jones (1908: 534) on
impluvia
; Tognotti (1996: 98).

¹³⁶ Sambon (1901
a
: 199).

¹³⁷ Coluzzi (1999); Shute (1951).

¹³⁸ Doni (1667: 18–23).

¹³⁹ Grandazzi (1997: 182) on the history of the old layout of the city, attributed in antiquity to the haste with which it was rebuilt after the sack by the Gauls in 390 .

Ecology of malaria

97

However, there were some people who believed that the old layout was more conducive to health because the narrowness of the streets and the height of buildings kept out the heat of the sun; but now the lack of shade in the broad open spaces meant that the summer heat was more intense.¹⁴⁰

However, people who lived in the upper storeys still had to go out periodically. The evidence of the ancient medical authors (discussed in detail in Ch. 8 below) indicates that malaria was common in the city of Rome both before and after the new town-planning regulations introduced by Nero, in spite of the frequency of multi-storey buildings. The hills of Rome, although healthy for those (the elite) who lived on top of them, probably had an adverse effect on those who lived below them. North made the significant observation that ‘experience shows that the benefit obtained [sc.

from living above ground-floor level] is not always as great as might be expected, and this is especially the case when the building is sheltered in any way by neighbouring hills’.¹⁴¹ He collected interesting information on housing and malaria in the Roman Campagna and followed Tommasi-Crudeli and earlier writers such as Knight in concluding that the custom of building houses around the four sides of a square or rectangle, with virtually all the windows opening internally on to the quadrangle, was intended to keep ‘bad air’ out.¹⁴² Modern experience shows that well-designed housing can help to keep mosquitoes out, although such measures may have little effect if people are in the habit of sleeping outside (at ground level) in hot weather, as frequently happens in the countryside in hot countries, to protect their crops.¹⁴³ Consequently the anecdote recounted by Varro in relation to the Pompeian forces on Corcyra during the civil war does have some plausibility, although it also ¹⁴⁰ Tacitus,
Annals
15.43:
Erant tamen qui crederent veterem illam formam salubritati magis con-duxisse, quoniam angustiae itinerum et altitudo tectorum non perinde solis vapore perrumperentur: at nunc patulam latitudinem et nulla umbra defensam graviore aestu ardescere
.

¹⁴¹ North (1896: 103–5); De Tournon (1831: i. 201–2); Baccelli (1881: 191–2). The advantages of tall buildings against ‘bad air’ might have been discussed in Rutilius’ book
de modo aedificiorum
(Suetonius,
Augustus
89). However, it should be noted that contrary views were also expressed in antiquity. The medieval Arab writer Ibn Ridwan quoted Rufus of Ephesus as recommending flight from cities with tall buildings and narrow streets because they were unhealthy (Dols (1984: 105) ). Similar sentiments were expressed by Sabinus in the second century  (Nutton (2000
b
: 69–70)).

¹⁴² Knight (1805: 33).

¹⁴³ Gamage-Mendis
et al
. (1991). The study of Barber and Rice (1935) in Greece reached inconclusive results in relation to the question of malaria and housing.

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Ecology of malaria

indicates that the necessary precautions had not previously been taken on Corcyra (modern Corfu):

Did not our Varro here, when the army and fleet were on Corcyra and all the houses were full of the sick and dead, make his comrades and servants healthy again by constructing new windows to let in the north wind and excluding the pestilential winds, by changing [the positions of ] doors, and by other measures of this kind?¹⁴⁴

Since it is quite common for blood feeds by female mosquitoes to be interrupted and then finished on another person, it is possible for one mosquito to infect several people in a single household.¹⁴⁵

Certain houses which are particularly badly exposed to mosquitoes may become foci of malarial infection within a community. Households with children are most likely to end up playing this role, since gametocytes (the blood stage of the parasite’s life cycle which can reinfect mosquitoes) are mainly found in children in areas where malaria is endemic. The acquired immunity of those adults who survive infection in childhood reduces gametocyte production to insignificant levels in such areas. The dangerous species of mosquito either show a definite preference for human blood (so
A.

sacharovi
), or at least are as willing to bite humans as they are to bite other animals (so
A. labranchiae
). These two species enter houses or other man-made structures without hesitation. In contrast, other species of
Anopheles
mosquito in Italy which are not significant vectors of malaria prefer to bite other animals, generally cattle, and show little interest in entering houses. Hackett and his co-workers demonstrated this in their comparison of Val di Chiana in Tuscany, an area of anophelism without malaria in the early twentieth century, with Fiumicino, which had some of the most intense malaria in the world.¹⁴⁶

It is very important to bear in mind the possibility that the geographical distribution of mosquito species may change over time, following local environmental change. This is doubtless what happened at Ravenna, for example. Consequently regions with anophelism without malaria within the last hundred years were not necessarily like that in earlier periods of history. The southern end ¹⁴⁴ Varro, RR 1.4.6:
Non hic Varro noster, cum Corcyrae esset exercitus ac classis et omnes domus reple-tae essent aegrotis ac funeribus, immisso fenestris novis aquilone et obstructis pestilentibus ianuaque permuta-ta ceteraque eius generis diligentia suos comites ac familiam incolumes reduxit?

¹⁴⁵ Conway and McBride (1991).

¹⁴⁶ Missiroli
et al
. (1933); Hackett (1937: 38–41, 75–6, 209–12).

Ecology of malaria

16. The

southern end

of the Val di

Chiana and

Lago Trasimeno, viewed

from the

Fortezza

Medicea

above

Cortona.

99

100

Ecology of malaria

of the Val di Chiana (243–60 metres above sea level), particularly in the vicinity of Chiusi, was certainly unhealthy in the medieval and Renaissance periods, as Dante, Boccaccio, and other writers observed. Unfortunately there is no explicit evidence available for the health status of the area in antiquity. Dante bracketed the Val di Chiana with the Maremma and Sardinia as notoriously unhealthy regions: As the pain would be, if the diseases of the hospitals of the Val di Chiana, between July and September, and of the Maremma and Sardinia were all together in one ditch.¹⁴⁷

From the sixteenth century onwards repeated efforts were made to drain the flooded valley, especially by constructing a large canal, the Canal Maestro, to remove water to the Arno river. Leonardo da Vinci was the most famous of the numerous engineers who took an interest in the region’s problems. However, these efforts were vitiated for a long time by political rivalry between Rome and Florence as well as by the low gradient of the plain (the same problem as in the Pontine Marshes). Alexander’s detailed study of the Val di Chiana reached the conclusion that piecemeal drainage works were doomed to failure; only a grand plan dealing with the entire territory simultaneously would work, and this was not finally achieved until the late eighteenth and early nineteenth centuries by Vittorio Fossombroni. The drainage of the Val di Chiana did not eliminate
Anopheles
mosquitoes, but in some way facilitated a change in the balance between different species so that zoophilic species became prevalent. Similarly Pisa, whose territory suffered from intense malaria during the Renaissance period, had become an area of anophelism without malaria by the end of the nineteenth century, while the coastal region north of Pisa around Viareggio, which eventually became another area of anophelism without malaria, had been described as ‘marshy and pestilential’ (
paludosa e pestifera
) in the seventeenth century.¹⁴⁸