Chalmers R.M.,Cryptosporidium Reference Unit |
Katzer F.,Moredun Research Institute
Trends in Parasitology | Year: 2013
The protozoan Cryptosporidium is a major public and animal health concern. Young children, immunocompromised people, and pre-weaning animals are especially vulnerable, but treatment options are limited and there is no vaccine. A laboratory diagnosis is required to confirm cases of cryptosporidiosis, and species and genotype determination is essential in distinguishing human from non-human sources, understanding transmission, and strengthening the epidemiological evidence for causative links in outbreaks. However, testing is not consistent, as demonstrated by investigation of a significant increase in cases in some European countries during 2012. Many methods employed are laborious and time-consuming; recent advances, translated into diagnostic assays, can improve testing and facilitate typing to support clinical and environmental investigations. © 2013 Elsevier Ltd.
Matthews J.B.,Moredun Research Institute
International Journal for Parasitology: Drugs and Drug Resistance | Year: 2014
Anthelmintics have been applied indiscriminately to control horse nematodes for over 40. years. Three broad-spectrum anthelmintic classes are currently registered for nematode control in horses: benzimidazoles (fenbendazole, oxibendazole), tetrahydropyrimidines (pyrantel) and macrocyclic lactones (ivermectin, moxidectin). Generally, control strategies have focused on nematode egg suppression regimens that involve the frequent application of anthelmintics to all horses at intervals based on strongyle egg reappearance periods after treatment. The widespread use of such programmes has substantially reduced clinical disease, especially that associated with large strongyle species; however, high treatment frequency has led to considerable selection pressure for anthelmintic resistance, particularly in cyathostomin species. Field studies published over the last decade indicate that benzimidazole resistance is widespread globally in cyathostomins and there are also many reports of resistance to pyrantel in these worms. Cyathostomin resistance to macrocyclic lactone compounds is emerging, principally measured as a reduction in strongyle egg reappearance time observed after treatment. Ivermectin resistance is a further concern in the small intestinal nematode, Parascaris equorum, an important pathogen of foals. These issues indicate that horse nematodes must now be controlled using methods less dependent on anthelmintic use and more reliant on management practices designed to reduce the force of infection in the environment. Such strategies include improved grazing management integrated with targeted anthelmintic administration involving faecal egg count (FEC)-directed treatments. The latter require that the supporting diagnostic tests available are robust and practically applicable. Recent research has focused on maximising the value of FEC analysis in horses and on optimizing protocols for anthelmintic efficacy testing. Other studies have sought to develop diagnostics that will help define levels of pre-patent infection. This review describes recent advances in each of these areas of research. © 2014.
Knox D.,Moredun Research Institute
Advances in Experimental Medicine and Biology | Year: 2011
Parasitic nematodes express and secrete a variety of proteases which they use for many purposes including the penetration of host tissues, digestion of host protein for nutrients, evasion of host immune responses and for internal processes such as tissue catabolism and apoptosis. For these broad reasons they have been examined as possible parasite control targets. Blood-feeding nematodes such as the barber-pole worm Haemonchus contortus that infect sheep and goats and the hookworms, Ancylostoma spp. and Necator americanus, affecting man, use an array of endo- and exopeptidases to digest the blood meal. Haemoglobin digestion occurs by an ordered and partly conserved proteolytic cascade. These proteases are accessible to host immune responses which can block enzyme function and lead to parasite expulsion and/or death. Thus they are receiving attention as components of vaccines against several parasitic nematodes of social and economic importance. © 2011 Landes Bioscience and Springer Science+Business Media, LLC.
Innes E.A.,Moredun Research Institute
Zoonoses and Public Health | Year: 2010
Summary Toxoplasma gondii was discovered by scientists working in North Africa and Brazil around 100 years ago. The parasite has since been found to be capable of infecting all warm-blooded animals including humans making it one of the most successful parasitic organisms worldwide. The pathogenic potential of T. gondii was recognized in the 1920s and 1930s, in congenitally infected children presenting with the classic triad of symptoms, namely hydrocephalus, retinochoroiditis and encephalitis. In addition, around the same time T. gondii parasites were found to be associated with severe intraocular inflammation. In the 1980s, T. gondii emerged as a major cause of death in patients with acquired immunodeficiency syndrome, illustrating the importance of the immune system in controlling T. gondii infection. T. gondii was reported as a major cause of abortion in sheep in New Zealand in the 1950s, which raised questions about potential new transmission routes for the parasite. The discovery of the cat as the definitive host in the 1960s was a very important finding as it helped to complete our understanding of the parasite's life cycle, and the oocyst stage of T. gondii shed in the faeces of infected cats was found to be an important source of infection for many intermediate hosts and helped to explain infection in herbivorous animals and people with a vegetarian diet. In addition, this stage of the parasite was very robust and could survive in the environment, depending on the climatic conditions, for up to 12-18 months. Knowledge of the parasite's lifecycle, transmission routes, risk groups and host immune responses has helped in the development of strategies to control the disease, reduce transmission of the parasite and limit environmental contamination. © 2009 Blackwell Verlag GmbH.
Fitzpatrick J.L.,Moredun Research Institute
Veterinary Parasitology | Year: 2013
Global food security will require the production of more food using resources including land more efficiently, and with less waste. This goal must be achieved within the context of climate change and while ensuring minimal adverse environmental impact from both crop and livestock production. Disease, especially infectious disease, is a main constraint of biologically efficient livestock production and both endemic and exotic disease results in mortality and morbidity and hence less food than should ideally be available in current farming systems. A significant proportion of diseases affect the safety of food supplies, in addition to or instead of, their effect on volume and quality of food products. Parasitological diseases including those caused by nematodes, trematodes, protozoa and ectoparasites, have widely differing effects on meat, milk and fibre production and many new technologies have been developed in order to prevent or treat them. Approaches to developing better control of parasites have included livestock breeding strategies, improved nutrition and management, and the development of new drugs, diagnostic tests and vaccines. Some of the most important examples include both the development of new anthelmintic products, and better means of using existing drugs in order to maximise their effectiveness in the face of rapidly increasing parasite resistance; diagnostic tests which are able to detect low levels of nucleic acids or proteins from infectious agents rapidly; and vaccines derived from either native or recombinant proteins and designed to stimulate the most appropriate protective response from livestock species. Some of the parasitic diseases affect restricted regions around the world, however most affect very large global populations. The development of technologies of suitable and affordable livestock products for use in developing countries where most pressure on increased production for food will occur, provides a particular challenge. Most if not all new technologies form part of integrated management schemes on farms and these vary hugely in differing systems and geographical regions of the world. If the benefit of improved technologies for optimal health, welfare and biological efficiency of livestock is to be realised, then the veterinary, farming, commercial animal health and public service communities need to learn lessons from past successes and failures in the delivery of newly developed technologies to the farmer. The combination of technology and rural development in the veterinary parasitological field has played a key role in current food production and is well placed to continue this trend to help in ensuring future food requirements for the world. © 2013.