African Journal of EcologyVolume 55, Issue 4 p. 705-709 Note and Record The Italian occupation of Massawa and the supposed origin of the African rinderpest panzootic Clive A. Spinage, Corresponding Author Clive A. Spinage c.spinage336@btinternet.com orcid.org/0000-0003-4055-422X Wickwood House, Stanford Road, Faringdon, Oxon, SN7 8EZ U.K.Correspondence: E-mail: c.spinage336@btinternet.comSearch for more papers by this author Clive A. Spinage, Corresponding Author Clive A. Spinage c.spinage336@btinternet.com orcid.org/0000-0003-4055-422X Wickwood House, Stanford Road, Faringdon, Oxon, SN7 8EZ U.K.Correspondence: E-mail: c.spinage336@btinternet.comSearch for more papers by this author First published: 20 May 2017 https://doi.org/10.1111/aje.12403Citations: 1Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume55, Issue4December 2017Pages 705-709 RelatedInformation

Some consider the migration of tribes from West Africa across the centre of the continent at the turn of the first century A.D., with their cattle and iron technology, the most important event in African history, these Bantu migrants opening up equatorial Africa, displacing hunter-gathering Pygmies and San. The Pygmies retreated into the humid forests and the San were pushed into the arid Kalahari. The Bantu reached the Rift Valley and Lake Victoria and by the second century had extended to the Indian Ocean. In the fifth century they expanded south. Around A.D. 1350 two groups of Nilo-Saharan pastoralists, the Madei and Kalenjin, moved from the Sudd, the former to Lake Victoria and the latter to the Kenya highlands, shifting, it is assumed, the balance back towards pastoralism on which the Bantu would have become less dependent. Around 1600 another wave of Nilo-Saharan pastoralists, the Luo, moved up the Nile to Lake Victoria. Welburn et al. (2004) suggest these waves of pastoralists are likely to have had dramatic effects on the epidemiology of trypanosomiasis around Lake Victoria, apart from their possible role in the spread of animal diseases and effects upon grassland ecology.

For the most part which species of locust is being referred to in historical accounts is unclear but the history of locust plagues shows how pervasive plagues were, and when records are more complete in later history seemingly almost continuous in occurrence. If it was like this in Europe where the majority of historical records come from, how much more so must it have been in Africa where conditions were much more conducive to locusts?

Following 4 years of almost no rain in Angola in 1793–1794, rodents were reported as beginning to attack people (Miller 1982), indicative of a rodent outbreak. Specific rodent irruptions in Africa have been reported since 1905 beginning with Meriones shawi in Tunisia. M. shawi is the species most involved in irruptions in North Africa, with the multimammate rat Mastomys (=Praomys) natalensis and the field rat Arvicanthis niloticus in sub-Saharan Africa. Tropical rodents exhibit large but irregular intra and inter annual fluctuations, unlike the cyclic populations showing regular density fluctuations in the northern temperate zone. The years 1975–1976 witnessed a major irruption of rodents throughout the Sahel.

The definition of a zoonosis is that it must affect man but the term is used often outside of medical terminology of animal diseases where man is not involved. Zoonoses are diseases naturally transmitted between animals and man and comprise in total about 80% of all described human infections. Attempts have been made to define different classes of zoonoses according to the man-animal relationship but generally this does not seem to have been accepted. Elton in 1927 stressed the field of wild animal pathology was still virtually untouched, and in 1968 McDiarmid reiterated the view that it remained one of the most neglected aspects of animal ecology. There is now an extensive literature but it is rarely incorporated into ecological texts although disease is often the driving force in population dynamics. The primary driver of infectious disease dynamics is transmission between individuals, yet in most important respects remarkably little is known about the subject (Craft et al. 2008, Haydon 2008). Occasionally, under high population densities, an organism may infect a host outside of its normal range with highly pathogenic effect in its adventitious host.

About 50 million years B.P. in Subsaharan Africa a large turnover of bovids occurred which Vrba (1985) attributes to the spread of open grasslands, but historically recent changes in Africa's vegetation are primarily related to forests. Being generally deep-rooted, forest trees obtain their moisture from lower levels than other vegetation and transpire enormous quantities of moisture into the air. If this transpiration exceeds the normal amount of evaporation on open ground the tree growth will lower the water table, although the moisture of the surface soil in a forest is greater than that of open ground. Highly fissured rocks, such as some limestone formations, are capable of acting as important reservoirs and if penetrated by tree roots will lose far more water than if covered by shallow vegetation, but root penetration into some types of rock improves water penetration. Whether forests affect the water supply of rivers and streams depends upon the character of the soil, subsoil, and underlying rock, nature of the rainfall, slope of the land, and composition of the forest. Humus formed in forests tends to increase the moisture-absorbing capacity of the soil and although on level ground this will not affect runoff appreciably, on hill slopes it is of great importance as it allows more rain to percolate into the soil, reducing the extent of floods and causing runoff to be more regular. On dry gravelly or sandy sites forests improve the water supply, on wet sites they reduce it, while on intermediate sites there is little appreciable effect although certain water-demanding exotic species will reduce the water supply there (Nicholson 1929a).

Describing conditions similar to the twenty-first century, perhaps the earliest written record of climate in Africa is that of Theophrastus (372–287 B.C.) who wrote of the Red Sea coast that “a little north of Koptos [on the Egyptian Red Sea shore] there grows on the land no tree except that called the thirsty Acacia [A. tortilis], and even this is scarce by reason of the heat and lack of water, for it never rains except at intervals of 4 or 5 years, and then the rain comes down heavily and it is soon over” (Hort 1916–1926).

Why did Burton, writing in 1860, refer to the tsetse fly as not having died out in eastern Africa? Although in southern Africa its range retracted before the rinderpest panzootic of 1896 this was generally not commented upon until after that date, long after Burton wrote. In 1888 an article in the 9th edition of the Encyclopædia Britannica noted the tsetse fly in South Africa appeared to be gradually retreating northwards "following the big game". The northern limits of its distribution were not known.

In the past Africans were often referred to as prone to psychosomatic illness but new techniques are enabling identification of a whole host of previously unsuspected diseases ranging from debilitating to fatal. Most actual and potential human pathogens are endemic to tropical zones and Darlington (1969) considered disease had obstructed every racial and cultural development in Africa, the greater part of man’s diseases arising there where man had his origins but climatically indifferent, as they are due to viruses and bacteria which are directly infectious and contagious. Probably all are the object of genetic adaptations favouring resistance arising in populations that have long been exposed to them. But those diseases carried by, or directly due, to tropical animal parasites, have not resulted in the same, if any, genetic resistance in man. As Anderson and May (1991) pointed out, to be successful parasites need not necessarily evolve to be harmless, it depends upon the relation between virulence and transmissibility and the cost to the host of evolving resistance.

Rinderpest is a highly contagious viral disease of the myxovirus group which although convincing evidence for many species is lacking (Scott 1959), probably infects all members of the order Artiodactyla. It forms a subgroup with canine distemper and human measles and has been shown experimentally to produce resistance to canine distemper in dogs, leaving the virus with enhanced virulence for cattle. The virus is fragile, rapidly destroyed at temperatures of 56–60°C, by drying, or by exposure to ultra-violet light. It is sensitive also to pH changes and to effects of putrefaction. Infected carcasses in the tropics are thus rendered harmless within a few hours and one wonders how such a fragile organism can spread so easily, for natural infection in ungulates is airborne and requires close contact, perhaps spreading mainly at night. The role of carrion feeders and bloodsucking diptera is regarded as minimal in transmission.