Global food security: The impact of veterinary parasites and parasitologists
Section snippets
Food
“Food Security” is on everyone's agenda, and the definition of this complex construct varies according to the author and the audience. For the purpose of this review, the definition that best fits is “Food security is the sustainable production of sufficient amounts of high quality, affordable, safe food required to underpin health and wellbeing of human populations world-wide”, with the subtext “Food from livestock” being the specific focus for those involved in veterinary parasitology.
The
Climate and environmental change
The world is becoming warmer with strong evidence of increases of between 1 and 3 °C (IPCC, 2007), however some modelling predicts much greater increases of up to 8 °C, with a 2 °C generally accepted as the most likely scenario (Moss et al., 2008). In drought-prone countries such as Africa, temperature increases may result in the loss of significant amounts of land to agriculture (Fischer et al., 2005). It is estimated that there will be considerable variation in temperature globally and including
Impact of livestock disease
When considering food security two broad aspects of infectious disease are relevant to the sustainability of supply of products from livestock species.
The first category are the prevalent diseases that clearly constrain efficient productivity through the inefficient use of input resources (pasture/forages, concentrates/bi-products, energy/fuel, manpower) and/or the unnecessary production of waste, including morbidity and mortality of animals resulting in extended periods of time prior to
Finding solutions through technology
“Technology” can be seen as the first principal component of Food Security, and probably of equal importance is the second, “Rural Development”.
Arguably one of the most exciting and productive periods in veterinary parasitology was the elucidation of the epidemiology and pathogenesis of many parasite species such as Ostertagia ostertagi and Ostertagia circumcinta (now Teladorsagia circumcinta) (Anderson et al., 1969); Dictyocaulus viviparous (Jarrett et al., 1957); and Fasciola hepatica (
Anthelmintic resistance
Anthelmintic resistance (AR) is currently a major issue in small ruminant production in many countries worldwide (Besier, 2007, Kaplan and Vidyashankar, 2012) and therefore, constrains sustainable agricultural systems. This is especially true in the southern hemisphere, where parasite species have long seasonal activity and frequent dosing with anthelmintic drugs is required. Anthelmintic resistance is also recognised as an increasing problem in cattle (Sutherland. and Leathwick, 2011). Many
Nematode vaccines
The abomasal worm, Haemonchus contortus, is generally recognized as the most pathogenic of the nematode species of small ruminants, with the blood-sucking activities of adult worms often resulting in severe anaemia and death. Haemonchus contortus is particularly prevalent in the warmer, regions of the world where sheep or goat rearing is extensive, especially New South Wales/Queensland in Australia, much of South Africa, and at similar latitudes in parts of Brazil, Argentina and Uruguay. It is
Parasitic gastroenteritis
Many years of research have been undertaken to develop vaccines against the abomasal nematodes, Ostertagia ostertagi in cattle and Teladorsagia circumcincta in sheep, parasites of particular relevance in temperate regions of the world. The impact of these infections is recognised to be through losses in production caused by inappetance and hypo-proteinaemia as a result of damage to abomasal tissues (Armour and Ogbourne, 1982). Evidence of increasing resistance to anthelmintics in both sheep and
Liver fluke
Liver fluke, caused by the trematode species, Fasciola hepatica in temperate regions and Fasciola gigantica in tropical regions, is responsible for acute, sub-acute and chronic manifestations in sheep and cattle, causing both mortality and loss in production including growth, milk production and fertility (Behm and Sangster, 1999). In terms of avoiding or reducing waste under the Food Security agenda, fluke has also been identified as the most common cause of condemnation of livers in abattoirs
Protozoa causing reproductive failure
Poor reproductive efficiency of livestock is one of the most significant constraints to sustainable food production (Ferguson, 1996). In ruminant species, infertility and abortion are common, and may be attributed to infectious disease, inappropriate genetics/breeding or poor management and nutrition, or a combination of all three (Sheldon et al., 2006). Loss of embryos or foetuses during pregnancy, or birth of non-viable or weak offspring, results not just in the loss of the youngstock, but
Sheep scab
Sheep scab has re-emerged as a major problem in the UK and elsewhere. Eradication of Psoroptes ovis was achieved in the UK in the 1950s, during which time the disease was notifiable with compulsory dipping in an approved sheep dip once a year in the autumn forming part of a national eradication scheme. A significant increase in sheep scab in the UK followed deregulation in 1992 with an estimated 7000 outbreaks per year in 2003/2004 (Bisdorff et al., 2006) and broadly co-incided with the
Tick vaccines
One of the original success stories in parasite vaccination was against the cattle tick, Rhipicephalus microplus. Research focused on native proteins extracted from the gut of semi-engorged adult female Rhipicephalus microplus by Dr Peter Willadsen and colleagues (Willadsen and Kemp, 1988). The most significant antigen identified and purified was Bm86, a membrane-bound glycoprotein which was a “concealed antigen”. Antibodies raised against Bm86 interacted with and destroyed digestive cells
Finding solutions through rural development
The second principal component of Food Security is “Rural Development”. If research is to have impact on Food Security, the results (knowledge) and outputs (vaccines, diagnostics and disease control strategies) need to reach the target audiences in a timely manner and in the most appropriate formats. Over the years and decades there have been many highly successful examples of two-way knowledge exchange between parasitologists and farmers and their veterinary surgeons and advisors. In the UK,
Contributions of parasitologists to food security
Livestock parasitologists have contributed to Food Security long before the term was coined. The value of the underpinning work of delineating the life cycles of parasites, their epidemiology and interactions with varied and, in some cases multiple hosts, cannot be argued against. In a similar vein, essential research on host-pathogen interactions has led to many of the outputs and progress toward practical solutions described above. Outstanding scientists have worked as individuals and as
Conflict of interest
J.L. Fitzpatrick is Scientific Director of the Moredun Research Institute and Chief Executive Officer of The Moredun Group. She is a Director of Moredun Scientific, a fully owned commercial subsidiary of the Moredun Foundation, and Director of Inocul8 Ltd., Wormvax UK Ltd. and Wormvax Australia. She is Chair of Food Security at the University of Glasgow, and Vice-Chair, Chair of the Technical Subcommittee and Trustee of GALVmed. As part of her role at Moredun she is also a Director of the
Acknowledgements
J.L. Fitzpatrick would like to thank all the parasitologists who kindly discussed the science, themes and issues explored in this review, especially those from the Moredun Research Institute and those who provided the personal communications detailed above.
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