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Persistence mechanisms in tick-borne diseases : tick-borne diseases  [cached]
A.F. Barbet
Onderstepoort Journal of Veterinary Research , 2010, DOI: 10.4102/ojvr.v76i1.65
Abstract: The use of new, highly sensitive diagnostic methods has revealed persistent infections to be a common feature of different tick-borne diseases, such as babesiosis, anaplasmosis and heartwater. Antigenic variation can contribute to disease persistence through the continual elaboration of new surface structures, and we know in several instances how this is achieved. Known or suspected mechanisms of persistence in babesial parasites include cytoadhesion and rapid variation of the adhesive ligand in Babesia bovis and genetic diversity in several merozoite stage proteins of different Babesia spp. In Anaplasma, extensive variation in the pfam01617 gene family accompanies cycling of organism levels in chronic infection. One result from the pioneering research at Onderstepoort is the definition of a related polymorphic gene family that is likely involved in immunity against heartwater disease. We are beginning to understand the sizes of the antigenic repertoires and full definition is close, with the possibility of applying simultaneous high-throughput sequencing to the order of 1 000 small genomes. We also, for the first time, can consider modifying these genomes and looking at effects on persistence and virulence. However, important biological questions remain unanswered; for example, why we are seeing a new emerging Anaplasma infection of humans and is infection of endothelial cells by Anaplasma significant to persistence in vivo.
Trends in the control of theileriosis in sub-Saharan Africa : tick-borne diseases  [cached]
D. McKeever
Onderstepoort Journal of Veterinary Research , 2010, DOI: 10.4102/ojvr.v76i1.64
Abstract: The declining efficacy of acaricide treatment as a means of reducing the prevalence of Theileria parva infections in sub-Saharan Africa has intensified efforts to achieve control through immunization of susceptible cattle. The infection and treatment method of immunization has enjoyed a resurgence with the availability of more effective cold chain facilities, although concerns remain regarding the possibility of vaccine strains spreading in local tick populations. In addition, an in-depth understanding of protective mechanisms deployed by immune cattle and the antigens targeted by them has led to substantial progress in the development of candidate subunit vaccines against both sporozoite and schizont stages of the parasite. The likely success of these vaccines, as well as infection and treatment immunization, will ultimately depend on the extent to which they disturb the endemic status of the parasite. These issues are discussed in the light of recent information on the genotypic diversity of T. parva in the field and the extent to which this is compromised by the immune response.
Tick-Borne Diseases
Irfan Nuhoglu,Murat Aydin,Suleyman Turedi,Abdulkadir Gunduz
TAF Preventive Medicine Bulletin , 2008,
Abstract: Paraziter diseases are important medical problems.There are endoparasitic and ectoparasitic diseases. Tick-borne diseases are the most common vector-borne illnesses. Ticks can spread bacteria, viruses, spiroketia, protozoa, nemadot and toxins and by so they made ectoparasitic diseases. Our country has suitable conditions to continue biologic activity of ticks acording to seasons, plants and surface forms. In this article we have tried to summary tick-borne diseases. [TAF Prev Med Bull. 2008; 7(5): 461-468]
Canine babesiosis : tick-borne diseases  [cached]
J.P. Schoeman
Onderstepoort Journal of Veterinary Research , 2010, DOI: 10.4102/ojvr.v76i1.66
Abstract: Babesiosis is a tick-borne disease affecting humans and many domestic and wild animals. Domestic animals showing appreciable morbidity and mortality include dogs, cats, cattle and horses. Both canine and feline babesiosis are diseases characterised by haemolytic anaemia, icterus and haemoglobinuria. Canine babesiosis can range from chronic or subclinical to peracute and fatal, depending on the virulence of the species and the susceptibility of the host. This paper deals with canine babesiosis with specific reference to pathogenesis, clinical findings, complications, diagnosis and treatment, as well as newly identified prognostic factors in Babesia rossi babesiosis.
Tick and tick borne protozoan diseases of livestock in the selected hilly areas of Bangladesh  [cached]
U.K. Mohanta
International Journal of Agricultural Research, Innovation and Technology : IJARIT , 2011,
Abstract: To study the tick and tick borne protozoan diseases of livestock in the hilly areas of Bangladesh, an attempt was made to collect tick and blood samples from cattle, goat and gayal (Bos frontalis) from different areas of the three hill districts. In this study, two species of ticks namely, Boophilus microplus (92%) and Amblyomma testudinarium (21.6%) and two species of blood protozoa like Babesia bigemina (16.63%) and Anaplasma marginale (14.94%) were recorded. Seasonal prevalence of ticks was highest in summer (97%) in comparison to rainy (95%) and winter (86%) season. On the other hand, the seasonal prevalence of blood protozoa was highest in rainy season (45.45%) in comparison to summer (27.87%) and winter (16.55%). Again, animals aged more than 2 (two) years of age (52%) found to be more susceptible to blood protozoan diseases than animals aged between 1-2 years of age (33.97%). But none of the animals under one year of age were found to be infected with blood protozoan diseases.
Effects of Climate Change on Ticks and Tick-Borne Diseases in Europe  [PDF]
J. S. Gray,H. Dautel,A. Estrada-Pe a,O. Kahl,E. Lindgren
Interdisciplinary Perspectives on Infectious Diseases , 2009, DOI: 10.1155/2009/593232
Abstract: Zoonotic tick-borne diseases are an increasing health burden in Europe and there is speculation that this is partly due to climate change affecting vector biology and disease transmission. Data on the vector tick Ixodes ricinus suggest that an extension of its northern and altitude range has been accompanied by an increased prevalence of tick-borne encephalitis. Climate change may also be partly responsible for the change in distribution of Dermacentor reticulatus. Increased winter activity of  I. ricinus is probably due to warmer winters and a retrospective study suggests that hotter summers will change the dynamics and pattern of seasonal activity, resulting in the bulk of the tick population becoming active in the latter part of the year. Climate suitability models predict that eight important tick species are likely to establish more northern permanent populations in a climate-warming scenario. However, the complex ecology and epidemiology of such tick-borne diseases as Lyme borreliosis and tick-borne encephalitis make it difficult to implicate climate change as the main cause of their increasing prevalence. Climate change models are required that take account of the dynamic biological processes involved in vector abundance and pathogen transmission in order to predict future tick-borne disease scenarios.
Biological Features of Ticks, Tick Borne Diseases and Epidemiological Data in Turkey  [cached]
Gonul Tanir,Sebnem Ozgelen,Nilden Tuygun
Cocuk Enfeksiyon Dergisi , 2008,
Abstract: Ticks are blood-sucking ectoparasites that act as vectors for rickettsial, spirochetal, bacterial and parasitic infections. Tick-borne diseases continue to cause severe illness and death in otherwise healthy adults and children. Early signs and symptoms of these illnesses often mimic a benign or nonspecific viral illness, making diagnosis difficult. This difficult diagnostic dilemma warrants an understanding of ticks, their habitats, symptoms of illnesses and immediate treatment to ameliorate the severity and fatalities caused by these diseases. In the event that a patient presents with tick bite, it is important to remove and identify the type of tick and determine the classification for proper treatment.
Economic impacts of tick-borne diseases in Africa : tick-borne diseases  [cached]
B.D. Perry
Onderstepoort Journal of Veterinary Research , 2010, DOI: 10.4102/ojvr.v76i1.63
Abstract: As we join Onderstepoort in celebrating its centenary, it is worth reflecting that tick-borne infections of wildlife and livestock have been part of everyday life in Africa for many, many generations. While much has changed since Watkins-Pitchford started developing short-interval dipping trials with arsenicals to contain the new epidemic of East Coast fever in southern Africa 100 years ago, when it comes to the impacts of tick-borne infections, many of the same challenges remain.
Veterinary extension on sampling techniques related to heartwater research  [cached]
H.C. Steyn,C.M.E. McCrindle,D. Du Toit
Journal of the South African Veterinary Association , 2012, DOI: 10.4102/jsava.v81i3.140
Abstract: Heartwater, a tick-borne disease caused by Ehrlichia ruminantium, is considered to be a significant cause of mortality amongst domestic and wild ruminants in South Africa. The main vector is Amblyomma hebraeum and although previous epidemiological studies have outlined endemic areas based on mortalities, these have been limited by diagnostic methods which relied mainly on positive brain smears. The indirect fluorescent antibody test (IFA) has a low specificity for heartwater organisms as it cross-reacts with some other species. Since the advent of biotechnology and genomics, molecular epidemiology has evolved using the methodology of traditional epidemiology coupled with the new molecular techniques. A new quantitative real-time polymerase chain reaction (qPCR) test has been developed for rapid and accurate diagnosis of heartwater in the live animal. This method can also be used to survey populations of A. hebraeum ticks for heartwater. Sampling whole blood and ticks for this qPCR differs from routine serum sampling, which is used for many serological tests. Veterinary field staff, particularly animal health technicians, are involved in surveillance and monitoring of controlled and other diseases of animals in South Africa. However, it was found that the sampling of whole blood was not done correctly, probably because it is a new sampling technique specific for new technology, where the heartwater organism is much more labile than the serum antibodies required for other tests. This qPCR technique is highly sensitive and can diagnose heartwater in the living animal within 2 hours, in time to treat it. Poor sampling techniques that decrease the sensitivity of the test will, however, result in a false negative diagnosis. This paper describes the development of a skills training programme for para-veterinary field staff, to facilitate research into the molecular epidemiology of heartwater in ruminants and eliminate any sampling bias due to collection errors. Humane handling techniques were also included in the training, in line with the current focus on improved livestock welfare.
A century of tick taxonomy in South Africa : tick-borne diseases  [cached]
I.G. Horak
Onderstepoort Journal of Veterinary Research , 2010, DOI: 10.4102/ojvr.v76i1.67
Abstract: Eighty ixodid tick species, 25 argasid tick species and Nuttalliella namaqua occur in South Africa. Twenty-one of the 80 ixodid species and two of the argasid species occur only in this country, while N. namaqua is present only in South Africa and Namibia. Forty-six of the 80 ixodid species and 16 of the 25 argasid species as well as N. namaqua have been described as new species since 1908. People working in South Africa have written or contributed to the descriptions of 24 of these 63 new species, while foreign researchers have described the remainder. New species indigenous to South Africa are still being discovered, while the names of some species, well known because of their veterinary importance, have been altered.
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