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

that in northern Italy P. vivax infections in autumn tended to produce acute attacks immediately after the normal incubation period. In other words there was no delay of the primary attack until the spring as in Holland, for example. Consequently the spring wave of P. vivax malaria in northern Mediterranean countries was probably mainly composed of relapses, not primary attacks. The hotter the year, the more likely it was that P. falciparum would overshadow P. vivax and P. malariae in the late summer and autumn in Mediterranean countries. Sorgoni (1832) noted that pernicious symptoms were more frequent around Narni the greater the difference between the daytime and the night-time temperatures.

¹²² Maitland et al. (1997); contrast Covel and Nicol (1951) and Shute (1951).

156

Demography of malaria

the case of simultaneous infections with the two different species, P. vivax often fares poorly.¹²³ It is difficult to generalize about the demographic consequences at the population level of the P. vivax–P. falciparum interaction because of the complicated results found in individuals. Nevertheless the fact remains that the evidence from more recent periods of European history discussed in this chapter suggests that being infected with P. vivax in the past was not necessarily any better in the long run than being infected with P. falciparum. As far as antiquity is concerned, Galen’s comments in the second century  indicate that P. falciparum infections tended to occur at an early age then (Ch. 8 below). This suggests a different epidemiology from that described recently in Vanuatu. This Pacific island group seems to lack the full range of genotypes of P.

falciparum found in Africa and Eurasia, as is suggested by a greatly reduced range of polymorphism in the merozoite surface protein genes.¹²⁴ Presumably a large proportion of the organism’s range of genetic polymorphism failed to make it across the ocean during the human population movements which colonized the Pacific islands.

Alternatively they might have been eliminated when the human population of Vanuatu passed through a severe bottleneck within the last two hundred years. Either way, the evolution of malaria in Vanuatu, an example of evolution in an isolated island population, is not directly relevant to the historical situation in Europe, although it is certainly of considerable intrinsic interest.

In passing, it should be noted that P. vivax probably already existed and operated in the way described by Dobson in Britain in classical antiquity. The disease of the marshes that severely affected the army of Septimius Severus in Scotland in  208 may well have been P. vivax malaria, as Bordier suggested a long time ago.¹²⁵ In the seventeenth century Doni expressed the opinion that quartan fever was unknown in Scotland, implying that he believed that tertian fever did occur there.¹²⁶ An inscription, now lost, from Risingham ¹²³ Mason and McKenzie (1999). Bruce et al. (2000) suggested that in tropical regions where malaria is continuously active there is density-dependent regulation of infections that transcends species as well as genotype, resulting in non-independent sequential episodes of infection with each species.

¹²⁴ Maitland et al. (2000).

¹²⁵ Bordier, cited by Fraccaro (1919: 86 n. 2), drew attention to Cassius Dio 77.13.2: ËpÏ

t0n Ëd3twn dein0ß ƒkakoınto (they were badly affected by the waters). Herodian 3.14.6–8

emphasized the marshiness of Britain in the early third century .

¹²⁶ Doni (1667: 7): in Scotia quartanam febrim ignotam esse credi potest. It will be remembered that the British mosquito vector A. atroparvus is a poor carrier of P. malariae (Shute (1951) ), although it could have been transmitted by A. plumbeus instead.

Demography of malaria

157

(Roman Habitancum), a Roman fort north of Hadrian’s Wall, has been frequently cited as a dedication to the goddess of tertian fever.

Unfortunately this reading of the text is a guess made in the early seventeenth century. It appears to be unreliable.¹²⁷ Dobson noted that the opium poppy was widely cultivated in East Anglia in the early modern period to provide opium, which was used to relieve the symptoms of P. vivax malaria. It did not create addiction under those circumstances. Archaeobotanical finds of opium poppy ( Papaver somniferum) from Iron Age–Roman archaeological sites in East Anglia show that it was already being cultivated there by Roman times, probably for the same reason. Localized extreme variation in mortality patterns caused by malaria was probably already occurring in Roman Britain.¹²⁸

Although there is no direct evidence available, owing to the shortage of written sources for Roman Britain, the balance of probability is that the constant movements of soldiers, merchants, slaves, and administrators between Britain and other parts of the Roman Empire introduced malaria to Roman Britain, if it was not already present. As was seen earlier, the evidence of Gregory of Tours shows that malaria was frequent and familiar in France in the sixth century  (Ch. 4. 1 above). Moreover Pliny mentions tertian fever in the territory of the Tungri in Belgium and Holland in the first century .¹²⁹ P. vivax malaria was present in these areas by then, only a short distance from Britain. Alcuin in the late eighth century  is a specific case of an individual who travelled from Britain to Rome, became infected with ‘Roman fever’, and brought the parasites back to northern Europe with him. He contracted malaria during his visit to Rome in 798 and was severely affected by it thereafter. Alcuin presumably had mixed infections, ¹²⁷ The text Deae Tertianae sacrum Ael(ia) ( CIL 7.999) was accepted by Weinstock in Pauly-Wissowa RE s.v. Tertiana (vol. v A.1 (1934), column 822), Schaffner in Cancik and Schneider (1998), s.v. Febris, and Burke (1996: col. 455, p. 2269). However, it was rejected in favour of the alternative reading ( Deae Dianae sacrum Aelia Timo posuit votum solvens laeta libens merito) found in the manuscript tradition by Collingwood and Wright (1995: 397 no. 1209), who