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Psoroptic mange in sheep, known as scab, is caused by infestation by the astigmatid mite Psoroptes ovis (Hering). The disease has been widely prevalent and economically important in Europe for many hundreds of years. In the UK, intensive control measures over the first half of the twentieth century, involving compulsory treatment of infested flocks with organochlorine insecticides and movement controls, resulted in apparent eradication of the disease by 1952. However it was inadvertently reintroduced with imported stock in 1972. Twenty years of unsuccessful attempts to re-eradicate the disease then followed. Eventually, concern over the effects of the widespread use of acaricides on human health and the environment, and the failure of compulsory treatment programmes to control the disease, led in 1992 to deregulation of sheep scab and removal of compulsory national treatment programmes. Following this change, scab has very quickly become increasingly common and problematic. Nationally, there were estimated to be only 40 and 120 outbreaks per year in 1989 and 1992, but prevalence was estimated to have risen to 3,000 in 1997 and then 7,000 outbreaks by 2004. This has led to calls to re-impose eradication measures. Here, the biology of Psoroptes mites and the spread of the disease following reintroduction are described; the formidable obstacles to the success any proposed new eradication programme in the UK are then discussed.
Abstract
This chapter looks at the history of Maa-speaking communities in the Central Rift from the early nineteenth century to their removal in 1904 to make way for white settlement. The period is bracketed by two crises: climate change and drought in the later eighteenth century and pandemic disease and the establishment of colonial overrule a century later. During the period, the “traditional” Maasai moved from being one of several emerging Maa-speaking communities to a position of dominance before the 1890s. Their developing identity was shaped by a purposive and persuasive narrative of forward movement in both space and time. That narrative, like the narrative of white settlement which followed, has in turn influenced modern histories of the Central Rift. The chapter also considers the importance of Naivasha-Nakuru as a strategic corridor, allowing movement from the northern plains south and eastwards towards Kilimanjaro. Control of the corridor and its resources was both vital and contested.
Myiasis (the invasion of internal and external tissues by fly larvae) results in major welfare and economic problems for sheep husbandry in many areas of the world. Here myiasis of sheep is reviewed with a summary of the most important species involved and their lifecycles and a discussion of how using a One Health approach can result in a more robust and responsive industry to reduce the impact of myiasis on sheep production.