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

Doni described Ravenna as afflicted with severe malaria in the seventeenth century.⁹⁵In the eighteenth century Francesco Ginanni wrote a comprehensive study of the natural history of the marshy woodlands in the vicinity of Ravenna. He noted the abundance in the woods in summer of the two species of mosquito that had been named Culex cinereus and Culex fuscus by Linnaeus, and observed that they bit humans frequently. However, it is striking that his account of the mosquitoes of Ravenna is located far away in his large book from his description of the ‘bad air’ of the region; Ginanni completely failed to connect mosquitoes with malaria. Nevertheless he ⁹³ Strabo 5.1.7.213C: πsti m†n oˆn ka≥ toıto qaumastÏn t0n ƒnq3de, tÏ ƒn 1lei toŸß åvraß åblabe∏ß e”nai.

⁹⁴ Fabbri (1991: 19) described the developments in the early Byzantine period as follows: in sostanza è una situazione di progressivo inaridimento idrico quello che la città vive nell’alto Medievo: una situazione di sempre più precarie condizioni igienico-ambientali, specialmente favorevoli allo stabilirsi della malaria in forma endemica. Già in queste condizioni si possono ricercare le premesse di fenomeni di depopola-mento e di crisi economia e funzionale. Squatriti (1992) is an interesting account of attitudes to marshes in early medieval Ravenna, but without any serious study of malaria or the relevant ancient sources. The most recent synthesis of Italian demographic history advocates a completely different view, so far as malaria in early medieval Italy is concerned: ‘ la malaria . . . si diffuse in vaste aree della penisola per effetto del degrado ambientale che trasformó in stagni e paludi gran parte delle pianure costiere e molte vallate interne’ (G. Pinto in del Panta et al. (1996: 18).

⁹⁵ Cavarra (1993) and Bio (1994) described the medical culture of Ravenna; CIL 11.10 for Theoderic’s activities at Ravenna ( sterili palude siccata); Doni (1667: 86, 89).

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Ecology of malaria

did accurately describe the environmental conditions that favoured endemic malaria, observing that the marshes of Ravenna tended to dry out in summer each year but retained some moisture, permitting plant growth.⁹⁶ Ginanni described the seasonality of malaria around Ravenna in the eighteenth century as follows:

The period of considerable danger from bad air in these pine woods usually runs from the summer solstice until the autumn equinox. However, it sometimes varies from year to year, because if the season is very hot, bad air begins as early as May and continues until the middle of October; nevertheless it regularly terminates during the first heavy and repeated autumn rains, which fill the already nearly desiccated beds of adjacent marshes with fresh water.⁹⁷

Ginanni argued that the ‘air’ of the town of Ravenna itself was healthier than its reputation suggested, although he acknowledged that ‘bad air’ was endemic in the surrounding area. Attempts to defend the reputation of settlements afflicted by malaria are frequently found in Italian local history. Ginanni observed that the unhealthiness of the air did not prevent numerous people living on the rich agricultural land in the vicinity of the Po delta. He even attempted to quantify mortality risks and concluded that the local inhabitants were much less likely to die from an infection of malaria than visitors to the area.⁹⁸ The reasons for that are now known; not only would those who survived childhood infections have developed acquired immunity, but the population of the area also has a high frequency of genetic mutations such as thalassaemia that confer some resistance to malaria (see Ch. 5. 3 below). This is evidence for intense pressure exercised by malaria as an agent of natural selection in the past in this region.⁹⁹ In fact, the distribution ⁹⁶ Ginanni (1774), ch.on Acque (pp. 105–21), chapter on Aere (pp. 122–34), section on mosquitoes (pp. 431–2). Jordanes, de origine actibusque Getarum, 57, shows that the famous pine forest along the coast south of Ravenna, described by Boccaccio, Dante, Byron, and other writers, already existed in late antiquity, since Theoderic encamped ‘about three miles from the city in the place called Pineta’ ( tertio fere miliario ab urbe loco qui appellatur Pineta).

⁹⁷ Ginanni (1774: 132): l’aere aliquanto pericoloso di queste Pinete è per l’ordinario dal solstizio di Estate infino all’equinozio di Autunno. Ma varia talora col variar delle annate, perché se calda molto è la stagione, vi principia l’aria pericolosa anche nel Maggio, e continua a mezza Ottobre; regolarmente però ella cessa d’esserlo nelle prime pioggie copiose, e replicate d’Autunno, che riempono d’acque dolci i letti, già quasi prosciugati de’vicini paduli.

⁹⁸ Ginanni (1774: 133–4 n. 3).

⁹⁹ Interpretation of the situation is complicated by the fact that the Po delta region was an area of Greek colonization. It can be difficult to disentangle evolution in situ from gene flow caused by human migrations (the same problem occurs in Sardinia, discussed in Ch. 4. 3

Ecology of malaria

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of b-thalassaemia mutations in this region closely matches the distribution of mosquito breeding habitats.¹⁰⁰ Thus Ginanni was right to argue that the local people were less likely to die in the short term from individual malarial infections. However malaria had profound long-term effects on such populations, sharply reducing overall life expectancy and distorting the age-structure of the population. These long-term effects were already obvious to Doni in the seventeenth century and will be described in more detail later on (see Chs. 5 and 11 below). Ginanni’s observations on the resistance of the local population to malaria are in fact paralleled by the situation in human populations in parts of tropical Africa today where malaria is endemic. In such African populations one is unlikely to die directly from malaria once one survives past a certain age in childhood—the precise age varies from region to region in Africa and depends on the transmission rate of malaria, in other words the frequency of infections—by which time acquired immunity has developed, but malaria nevertheless has a deep influence on age-specific life expectancy. Under such circumstances it is quite easy for both the inhabitants of