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possible death of a buffalo calf (syncercus caffer) due to suspected heartwater (ehrlichia ruminantium).rickettsial organisms resembling ehrlichia ruminantium (the causative organism of heartwater) were demonstrated in brain smears and formalin-fixed brain sections derived from a buffalo calf that died on a private game reserve in northern kwazulu-natal. the possibility that the tick-free environment of a quarantine boma may have affected the calf's immunity, is discussed. these findings suggest that monitoring heartwater in wild ruminants and making brain smears as a routine during post mortem ev ...200415214698
analysis of ehrlichia ruminantium-specific t1/t2 responses during vaccination with a protective killed vaccine and challenge of goats.ehrlichia ruminantium is an obligate intracellular bacterium that causes heartwater in ruminants and for which t-cell-mediated immunity is believed to play an important role in protection. to better characterize protective cellular immunity, e. ruminantium-specific ifn-gamma and il-4 recall responses in major t-cell subsets were analysed by flow cytometry during immunization of goats with a killed vaccine and following a virulent challenge. the killed vaccine elicited both cd8+ and cd4+ subsets ...200415225296
characterization of the pcs20 region of different ehrlichia ruminantium isolates.heartwater is a serious tick-borne disease of ruminants caused by the rickettsial organism ehrlichia (cowdria) ruminantium. a diagnostic test, targeting the pcs20 genomic region and using pcr amplification and probe hybridization, detects e. ruminantium infection in ticks and animals. however, only the pcs20 sequence of the crystal springs e. ruminantium isolate is available and the existence of sequence variation amongst different e. ruminantium isolates has not been determined. primers were de ...200415262001
artificial feeding of ixodid ticks.ixodid ticks are economically important as they cause direct damage to livestock and are vectors of several pathogens that cause diseases in humans and animals. some of the important tick-borne pathogens of livestock are theileria parva, t. annulata, babesia bigemina, b. bovis, anaplasma marginale and cowdria ruminantium. these pathogens are responsible for causing enormous losses in livestock. identification of factors that influence transmission and development of these pathogens in ticks will ...199615275192
the epidemiology of heartwater: establishment and maintenance of endemic stability.although heartwater (cowdria ruminantium infection) is one of the most economically important tick-borne diseases of sub-saharan africa, its epidemiology he's remained poorly understood until recently. new data, suggesting that heartwater is present in an endemically stable state in much of sub-saharan africa and demonstrating vertical transmission of cowdria ruminantium in the field, have altered previously accepted views on heartwater epidemiology. in this paper, sharon deem and colleagues pre ...199615275292
exotic animal disease bulletin. 200415359955
the pcs20 pcr assay for ehrlichia ruminantium does not cross-react with the novel deer ehrlichial agent found in white-tailed deer in the united states of america.white-tailed deer are susceptible to heartwater (ehrlichia [cowdria] ruminantium infection) and are likely to suffer high mortality if the disease spreads to the united states. it is vital, therefore, to validate a highly specific and sensitive detection method for e. ruminantium infection that can be reliably used in testing white-tailed deer, which are reservoirs of antigenically or genetically related agents such as ehrlichia chaffeensis, anaplasma (ehrlichia) phagocytophilum (hge agent) and ...200415373331
some observations on the sero-prevalence of heartwater and tick infestation in zambian goats.a survey was carried out to define the distribution of heartwater in goats that originated from six districts in communal grazing semi-arid areas of zambia. a total of 181 samples (40.1%) out of 451 serum samples from adult goats were positive for ehrlichia ruminantium antibodies after screening using indirect map-1b antigen elisa technique with statistically significant differences (p < 0.01) between the six districts. out of 1 036 adult goats examined for tick infestation, 105 were infested by ...200415373339
ehrlichia ruminantium seroprevalence in domestic ruminants in ghana. ii. point prevalence survey.serum samples collected on a single occasion from cattle, sheep and goats at sites in all 10 regions of ghana were tested for antibodies to ehrlichia (previously cowdria) ruminantium, the causative agent of heartwater, by polyclonal competitive elisa (pc-elisa). the survey revealed the presence of heartwater-exposed ruminants throughout the country, with local seroprevalence up to 100%. seronegative, and therefore presumably susceptible, animals were also present in all regions, in some areas in ...200415504589
nested pcr for detection and genotyping of ehrlichia ruminantium: use in genetic diversity analysis.ehrlichia ruminantium, the agent of cowdriosis transmitted by amblyomma ticks, presents an extensive genetic and antigenic diversity of key importance for vaccine formulation. two means of nested polymerase chain reaction (pcr) targeting were developed to conduct molecular epidemiology studies in the caribbean and africa. the first used a conserved dna fragment for detection of the pathogen in animals and vectors, and the second relied on the polymorphic map1 gene for genotyping. as compared to ...200415604477
the genome of the heartwater agent ehrlichia ruminantium contains multiple tandem repeats of actively variable copy number.heartwater, a tick-borne disease of domestic and wild ruminants, is caused by the intracellular rickettsia ehrlichia ruminantium (previously known as cowdria ruminantium). it is a major constraint to livestock production throughout subsaharan africa, and it threatens to invade the americas, yet there is no immediate prospect of an effective vaccine. a shotgun genome sequencing project was undertaken in the expectation that access to the complete protein coding repertoire of the organism will fac ...200515637156
an attenuated ehrlichia ruminantium (welgevonden stock) vaccine protects small ruminants against virulent heartwater challenge.heartwater is a tick-borne disease of ruminants caused by the intracellular rickettsia ehrlichia ruminantium. the only commercially available immunization procedure involves infecting animals with cryopreserved sheep blood containing virulent e. ruminantium organisms, followed by treatment with tetracyclines when fever develops. the virulent welgevonden stock of e. ruminantium was attenuated by continuous propagation of the organisms in a canine macrophage-monocyte cell line (dh82), followed by ...200515705474
point seroprevalence survey of ehrlichia ruminantium infection in small ruminants in the gambia.using the map1-b enzyme-linked immunosorbent assay, we tested 1,318 serum samples collected from sheep and goats at 28 sites in the five divisions of the gambia to determine the ehrlichia ruminantium seroprevalence rates and to assess the risk for heartwater. about half (51.6%) of 639 sheep were positive, with seroprevalence rates per site varying between 6.9% and 100%. the highest seroprevalence was detected in the western part of the country (88.1% in the western division and 62.1% in the lowe ...200515817758
livelihood hazards. 200515818892
quantification of ehrlichia ruminantium by real time pcr.ehrlichia ruminantium (er) is the causative agent of heartwater, one of the most common tick-borne diseases affecting ruminants in african countries and west indies. although er can be used as an inactivated vaccine for wild and domestic animals, there are currently no easy and reliable methods for the quantification of this obligate intracellular bacterium. this report describes the development of a sybr green i based real time pcr protocol for the quantification of er for vaccine production pu ...200515863287
ticks and tick-borne disease in guatemalan cattle and horses.blood samples and ticks were collected from 48 cattle and 74 horses from seven sites in the peten region of guatemala. data on body condition, mucous membrane capillary refill time and tick infestation levels were recorded for each animal in the study. horses had significantly higher levels of tick infestation than cattle, as well as poorer body condition scores. seroprevalence of babesia spp. was 95.8% for b. bovis in cattle, 89.6% for b. bigemina in cattle, and 92.7% for b. equi in horses. ser ...200515936147
transcription analysis of the major antigenic protein 1 multigene family of three in vitro-cultured ehrlichia ruminantium isolates.ehrlichia ruminantium, an obligate intracellular bacterium transmitted by ticks of the genus amblyomma, causes heartwater disease in ruminants. the gene coding for the major antigenic protein map1 is part of a multigene family consisting of a cluster containing 16 paralogs. in the search for differentially regulated genes between e. ruminantium grown in endothelial and tick cell lines that could be used in vaccine development and to determine if differences in the map1 gene cluster exist between ...200515995193
characterization of ehrlichia ruminantium replication and release kinetics in endothelial cell cultures.ehrlichia ruminantium is the causative agent of heartwater, a fatal tick-borne disease affecting ruminants in african countries and west indies and can be used as an inactivated vaccine for wild and domestic animals. in order to improve e. ruminantium production yields we characterize e. ruminantium growth kinetics in terms of duplication time, maximum production yield, and peak of infectivity. after a 24 h period for e. ruminantium attachment/internalization and a lag phase of 12 h, the exponen ...200516139967
ehrlichial infection in cameroonian canines by ehrlichia canis and ehrlichia ewingii.ehrlichia chaffeensis and ehrlichia ewingii are agents of emerging human ehrlichioses in north america and are transmitted primarily by amblyomma americanum ticks, while ehrlichia canis is the globally distributed cause of canine monocytic ehrlichiosis (cme) and is transmitted by the brown dog tick, rhipicephalus sanguineus. although e. canis and ehrlichia ruminantium are endemic in africa, the presence of ehrlichial agents in dogs and ticks in cameroon has not been investigated. the objective o ...200516181750
ehrlichia ruminantium--an emerging human pathogen. 200516200992
process development for the mass production of ehrlichia ruminantium.this work describes the optimization of a cost-effective process for the production of an inactivated bacterial vaccine against heartwater and the first attempt to produce the causative agent of this disease, the rickettsia ehrlichia ruminantium (er), using stirred tanks. in vitro, it is possible to produce er using cultures of ruminant endothelial cells. herein, mass production of these cells was optimized for stirring conditions. the effect of inoculum size, microcarrier type, concentration of ...200616257480
ehrlichia ruminantium, sudan. 200516422005
ehrlichia ruminantium, an emerging human pathogen--a further report. 200516465354
ehrlichia ruminantium: a promiscuous genome.the intracellular bacterium, ehrlichia ruminantium, is the causative agent of heartwater, a tick-borne disease of livestock. because vaccines need to incorporate components from several virulent isolates, it is essential to have information on the extent of genetic variation among isolates. we therefore amplified and sequenced a panel of seven core function genes.200516481500
ehrlichia ruminantium: an emerging human pathogen? 200516481543
comparative genomic analysis of three strains of ehrlichia ruminantium reveals an active process of genome size plasticity.ehrlichia ruminantium is the causative agent of heartwater, a major tick-borne disease of livestock in africa that has been introduced in the caribbean and is threatening to emerge and spread on the american mainland. we sequenced the complete genomes of two strains of e. ruminantium of differing phenotypes, strains gardel (erga; 1,499,920 bp), from the island of guadeloupe, and welgevonden (erwe; 1,512,977 bp), originating in south africa and maintained in guadeloupe in a different cell environ ...200616547041
optimisation of the inactivated vaccine dose against heartwater and in vitro quantification of ehrlichia ruminantium challenge material.the aim of this work was to evaluate the minimal protective dose of the inactivated vaccine against heartwater. in order to conduct a reliable vaccination trial, an in vitro quantification method of ehrlichia ruminantium (er) challenge doses was developed. in experimental conditions, homologous gardel challenges with 2.1 x 10(4) to 9.4 x 10(4) live er elementary bodies were reproducible and mimicked a natural challenge. similar results were obtained when animals were challenged with 3 x 10(4) li ...200616621174
differential expression and sequence conservation of the anaplasma marginale msp2 gene superfamily outer membrane proteins.bacterial pathogens in the genera anaplasma and ehrlichia encode a protein superfamily, pfam01617, which includes the predominant outer membrane proteins (omps) of each species, major surface protein 2 (msp2) and msp3 of anaplasma marginale and anaplasma ovis, anaplasma phagocytophilum msp2 (p44), ehrlichia chaffeensis p28-omp, ehrlichia canis p30, and ehrlichia ruminantium map1, and has been shown to be involved in both antigenic variation within the mammalian host and differential expression b ...200616714578
restriction and expansion of ehrlichia strain diversity.ehrlichia are tick-borne gram negative, obligately intracellular bacteria. the 16s rrna gene dna sequences are highly conserved among strains of each ehrlichia species. the 28-kda/map-1 outer membrane protein genes are highly diversified among strains of ehrlichia chaffeensis and e. ruminantium, but are highly conserved among e. canis isolates. the diversity of the immunodominant proteins of e. chaffeensis and e. ruminantium in contrast with the conservation of the immunodominant proteins of e. ...200716996215
homologous recombination and the pattern of nucleotide substitution in ehrlichia ruminantium.patterns of nucleotide substitution at orthologous loci were examined between three genomes of ehrlichia ruminantium, the causative agent of heartwater disease of ruminants. the most recent common ancestor of two genomes (erwe and erwo) belonging to the welgevonden strain was estimated to have occurred 26,500-57,000 years ago, while the most recent common ancestor of these two genomes and the erga genome (gardel strain) was estimated to have occurred 2.1-4.7 million years ago. the search for gen ...200717005333
determination and quantification of the in vitro activity of aloe marlothii (a. berger) subsp. marlothii and elephantorrhiza elephantina (burch.) skeels acetone extracts against ehrlichia ruminantium.an ehrlichia ruminantium culture system was utilized for the anti-rickettsial evaluation of two ethnoveterinary plants, elephantorrhiza elephantina and aloe marlothii. well-established e. ruminantium cultures were incubated with the plant leaf acetone extracts and compared to oxytetracycline and untreated controls. effectivity was established by comparing the percentage parasitised cells and the calculation of both ec50 and extrapolated ec90 in microg/ml. the plant extracts were also screened fo ...200617058439
evaluation of e. ruminantium genes in dba/2 mice as potential dna vaccine candidates for control of heartwater.heartwater caused by the rickettsia ehrlichia ruminantium (e. ruminantium) is an acute and fatal tick-borne disease of domestic and some wild ruminants. a user-friendly vaccine does not exist. we selected and tested nine genes of e. ruminantium for protection against challenge in a dba/2 mouse model, in order to identify candidate genes for incorporation into a recombinant vaccine. of the nine dna vaccine constructs tested, four dna constructs 14hworf1/vr1012, 14hworf2/vr1012, 27hworf1/vr1012, a ...200617114751
new findings on members of the family anaplasmataceae of veterinary importance.members of the family anaplasmataceae are obligate intracellular gram-negative bacteria that naturally infect a variety of wild and domestic animal species, the spillover of which may lead to zoonosis. i discuss new findings on members of the family anaplasmataceae of veterinary importance and therefore, i will describe the recent findings on neorickettsia risticii in the trematode and related neorickettsia species. i also will review the recent progress on aegyptianella pullorum and other aegyp ...200617114752
understanding the mechanisms of transmission of ehrlichia ruminantium and its influence on the structure of pathogen populations in the field.the understanding of the structure of ehrlichia ruminantium stock population in the field was highlighted by experiments done in controlled conditions on the goat model. the mixture of strains observed in ticks seemed to be due to simultaneous infections rather than successive infections of the carrier. during a dual infection, the timing of ehrlichia ruminantium circulation of the two stocks in hosts influenced their selection by ticks.200617114762
ehrlichia ruminantium variants which do not cause heartwater found in south africa.in 1994 a batch of apparently healthy goats was selected for intended export to the usa from a heartwater-free and vector tick-free region of south africa. the animals were tested serologically for heartwater, using either or both an ifa and an elisa test, and 52% were found to be serologically positive. a pcr assay based on ehrlichia ruminantium 16s gene sequences gave positive results for 54% of the animals, suggesting that apparently non-pathogenic e. ruminantium variants existed in this hear ...200717123750
comparative genomics of three strains of ehrlichia ruminantium: a review.the tick-borne rickettsiale ehrlichia ruminantium (e. ruminantium) is the causative agent of heartwater in africa and the caribbean. heartwater, responsible for major losses on livestock in africa represents also a threat for the american mainland. three complete genomes corresponding to two different groups of differing phenotypes, gardel and welgevonden, have been recently described. one genome (erga) represents the gardel group from guadeloupe island and two genomes (erwo and erwe) belong to ...200617135545
emerging tick-borne disease in african vipers caused by a cowdria-like organism.heartwater is a tick-borne infectious disease caused by the rickettsial organism cowdria ruminantium, currently ehrlichia ruminantium. it poses an imminent threat to the western hemisphere, where it could cause mortality in cattle and other ruminant livestock in excess of 70%. it has been reported in the caribbean; and its vector, amblyomma sparsum, has been found on imported african spurred tortoises (geochelone sulcata) and leopard tortoises (geochelone pardalis) in southern florida in the uni ...200617135546
protection against heartwater by dna immunisation with four ehrlichia ruminantium open reading frames.we have reported previously that a recombinant dna vaccine consisting of four ehrlichia ruminantium (welgevonden) open reading frames (orfs) known as the 1h12 cocktail provided protection against a virulent e. ruminantium (welgevonden) needle challenge in sheep. in this study, we have investigated the vaccine effectiveness of two other cocktails of e. ruminantium (welgevonden) orfs, as well as single orfs from the 1h12 cocktail, to protect sheep against a virulent needle challenge with the homol ...200717224211
infection of a goat with a tick-transmitted ehrlichia from georgia, u.s.a., that is closely related to ehrlichia ruminantium.we detected a novel tick-transmitted ehrlichia in a goat following exposure to lone star ticks (amblyomma americanum) from a park in the metropolitan area of atlanta, ga, u.s.a. nineteen days after infestation with field-collected adult ticks, the goat developed a fever of two days duration, which coincided with mild clinical pathologic changes and the presence of dna from a novel ehrlichia in peripheral blood. the goat transmitted ehrlichiae to uninfected nymphal a. americanum that fed upon the ...200617249337
differential transcription of the major antigenic protein 1 multigene family of ehrlichia ruminantium in amblyomma variegatum ticks.the rickettsial pathogen ehrlichia ruminantium causes heartwater in ruminants and is transmitted by ticks of the genus amblyomma. the map1 gene, encoding the major surface protein map1, is a member of a multigene family containing 16 paralogs. in order to investigate differential transcription of genes of the map1 multigene family in vivo in unfed and feeding ticks, rna was extracted from midguts and salivary glands of e. ruminantium-infected adult female amblyomma variegatum ticks and analysed ...200717321077
extensive genetic recombination occurs in the field between different genotypes of ehrlichia ruminantium.the intracellular bacterium ehrlichia ruminantium is the causative agent of heartwater throughout sub-saharan africa, madagascar, and some islands of the caribbean. the disease is tick-borne and causes substantial livestock losses, threatening food security and productivity in both the commercial and small-scale farming sectors in endemic areas. immunization by infection and treatment is currently practised in south africa, and it is known that a variety of immunotypes of the organism occur in t ...200717459616
molecular detection of ehrlichia ruminantium infection in amblyomma variegatum ticks in the gambia.in west africa, losses due to heartwater disease are not known because the incidence/prevalence has not been well studied or documented. to develop a diagnostic tool for molecular epidemiology, three pcr-based diagnostic assays, a nested pcs20 pcr, a nested map1 pcr and a nested reverse line blot (rlb) hybridization assay, were evaluated to determine their ability to detect infection in vector ticks, by applying them simultaneously to a. variegatum field ticks to detect ehrlichia ruminantium, th ...200717476576
effect of the purification process and the storage conditions on the efficacy of an inactivated vaccine against heartwater.this work evaluates the effect of purification process and storage conditions (buffer formulation and temperature) on the efficacy of ehrlichia ruminantium (er) elementary bodies to be used as an inactivated vaccine candidate against heartwater. in vitro assays revealed that, to avoid major losses in er integrity and corresponding antigenic properties, a buffer with ph between 5.6 and 8 and an osmolality above 100 mosmol/kg h(2)o is recommended. amongst the tested formulations, both pbs and nacl ...200717531356
differential strain-specific diagnosis of the heartwater agent: ehrlichia ruminantium.ehrlichia ruminantium is the causative agent of heartwater, a major tick-borne disease of livestock in africa introduced in the caribbean and threatening to emerge and spread in the american mainland. complete genome sequencing was done for two isolates of e. ruminantium of differing phenotype, isolates gardel (erga) from guadeloupe island and welgevonden (erwe) originating from south africa and maintained in guadeloupe. the type strain of e. ruminantium (erwo), previously isolated and sequenced ...200817644446
[sero-epidemiological study of cowdriosis in moorish zebu cattle from senegal].the seroprevalence against heartwater for maure zebus coming from mali and mauritania is analysed by indirect elisa using the major antigenic protein number 1-b (map1-b). sero-epidemiological results realized on maure zebu cattle give a good adequation between the abundance or absence of the vector tick in the two countries for 98% of prevalence in mali (infected area) and 0% of prevalence in mauritania (non infected area).200717645191
genetic diversity of ehrlichia ruminantium in amblyomma variegatum ticks and small ruminants in the gambia determined by restriction fragment profile analysis.understanding genetic diversity of ehrlichia ruminantium in host and vector populations is an important prerequisite to controlling heartwater by vaccination in traditional livestock systems in sub-saharan africa. we carried out a study in two phases: (i) evaluating the usefulness of the pcr-rflp assay based on the map1 coding sequence of e. ruminantium as a discriminatory tool to characterise genetic diversity, (ii) applying the technique to field samples from amblyomma variegatum ticks and sma ...200817646061
ehrlichia ruminantium: genomic and evolutionary features.ehrlichia ruminantium is the causative agent of heartwater, an important tick-borne disease of livestock in africa and the caribbean that threatens the american mainland. the genome sequences of three strains of e. ruminantium have recently been published, revealing the presence of specific features related to genomic plasticity. e. ruminantium strains have traces of active genomic modifications, such as high substitution rates, truncated genes and the presence of pseudogenes and many tandem rep ...200717652027
attenuated vaccines for tropical theileriosis, babesiosis and heartwater: the continuing necessity.overwhelming evidence has accumulated of the effectiveness of immunization with live attenuated vaccines to control tick-borne diseases of livestock. despite several disadvantages, vaccination with live attenuated organisms against tropical theileriosis, babesiosis and possibly heartwater constitutes one of the most cost-effective intervention strategies. although great advances have been made through genomics and proteomics research, this has not yet translated into effective non-living vaccine ...200717656155
longitudinal monitoring of ehrlichia ruminantium infection in gambian lambs and kids by pcs20 pcr and map1-b elisa.the epidemiology of e. ruminantium infection in extensively managed young animals is not adequately understood. thus in this study, we monitored the onset (age at first infection) and kinetics of e. ruminantium infection and antibody response in extensively managed newborn lambs and kids at three sites in the gambia.200717662144
the relationship of the agent of heart-water fever--rickettsia ruminantium.sera from sheep which were infected with heartwater fever from 39 to 110 days before the serum was withdrawn failed to fix complement in the presence of lymphogranuloma venereum antigen.194517730623
immunisation of sheep against heartwater in the gambia using inactivated and attenuated ehrlichia ruminantium vaccines.heartwater (cowdriosis) is a disease of ruminants caused by a rickettsial pathogen ehrlichia ruminantium and transmitted by ticks of the genus amblyomma. the purpose of this work was to evaluate the protective efficacies of inactivated and attenuated vaccines to protect sheep against heartwater in the gambia. an inactivated vaccine, prepared from e. ruminantium (gardel stock), and a live attenuated vaccine from e. ruminantium (senegal stock), were evaluated in two independent on-station trials. ...200717920167
host cell-specific protein expression in vitro in ehrlichia ruminantium.ehrlichia ruminantium, a tick-transmitted pathogen, is the causative agent of heartwater in ruminants. in this study, a proteomic approach was used to identify host cell-specific e. ruminantium proteins encoded by the map1 multigene family, expressed in vitro in bovine endothelial and tick cell cultures. two-dimensional gel electrophoresis combined with mass spectrometry analysis was used to establish the identities of immunodominant proteins. proteins extracted from e. ruminantium-infected endo ...200818006251
climate changes and suitability for the ticks amblyomma hebraeum and amblyomma variegatum (ixodidae) in zimbabwe (1974-1999).the spread of amblyomma hebraeum has been reported in zimbabwe. at the same time there was little or no spread in the distribution of amblyomma variegatum. this paper examines the climatic cycles and their trends in the period 1974-1999 with a view to explaining the abiotic causes of this spread, and of forecasting the likely tendency in climate suitability for both tick species. an annual data-set of rainfall and air temperature was used as a source for climate, together with a habitat-modeling ...200818083309
amblyomma variegatum in cattle in marie galante, french antilles: prevalence, control measures, and infection by ehrlichia ruminantium.we report marie galante as one of the caribbean islands most heavily infested by the tropical bont tick (tbt) amblyomma variegatum which is associated with two major diseases of ruminants: heartwater and dermatophilosis. in 2005, a survey was undertaken to assess the prevalence of tbt infestation in cattle, the prevalence of ehrlichia ruminantium infection in tbts, and the tick control measures implemented by livestock owners. a random sample of 195 cattle herds out of 1885 recorded on the islan ...200818406061
geographic distribution and genetic diversity of the ehrlichia sp. from panola mountain in amblyomma americanum.a novel ehrlichia, closely related to ehrlichia ruminantium, was recently discovered from panola mountain state park, ga, usa. we conducted a study to determine if this agent was recently introduced into the united states.200818433500
natural and experimental infection of white-tailed deer (odocoileus virginianus) from the united states with an ehrlichia sp. closely related to ehrlichia ruminantium.an ehrlichia sp. (panola mountain [pm] ehrlichia sp.) closely related to ehrlichia ruminantium was recently detected in a domestic goat experimentally infested with lone star ticks (lsts, amblyomma americanum) collected from georgia, usa. the infected goat exhibited pyrexia and mild clinical pathologic abnormalities consistent with ehrlichiosis. at least two other ehrlichia species (ehrlichia chaffeensis and ehrlichia ewingii) are maintained in nature by a cycle involving lsts as the primary vec ...200818436670
a quantitative real-time pcr assay for ehrlichia ruminantium using pcs20.heartwater is a tick borne disease that affects ruminants and wild animals in africa south of the sahara. it is caused by ehrlichia ruminantium and transmitted by the tick amblyomma hebraeum. the protocols currently used to detect heartwater take several days to complete. here, we describe the development of a pcs20 quantitative real-time pcr taqman probe assay to detect e. ruminantium in livestock blood and ticks from the field. the assay is based on the conserved pcs20 gene region of e. rumina ...200818511221
a heterologous prime/boost immunisation strategy protects against virulent e. ruminantium welgevonden needle challenge but not against tick challenge.heterologous prime/boost immunisation strategies using the ehrlichia ruminantium 1h12 pcmviubs_orfs [pretorius a, collins ne, steyn hc, van strijp f, van kleef m, allsopp ba. protection against heartwater by dna immunisation with four ehrlichia ruminantium open reading frames. vaccine 2007;25(12):2316-24] were investigated in this study. all the animals immunised twice with a recombinant (r) dna cocktail of four 1h12 pcmviubs_orfs followed by a r1h12 protein and those immunised 3x with 1h12 plas ...200818602727
in vitro isolation of ehrlichia ruminantium from ovine blood into ixodes scapularis (ide8) cell cultures.four stocks of ehrlichia ruminantium (welgevonden, ball3, nonile and blaauwkrans), the causative agent of heartwater in domestic ruminants, were isolated into ixodes scapularis (ide8) tick cells using the leukocyte fraction of the blood of infected sheep. organisms of two of the e. ruminantium stocks (welgevonden and blaauwkrans) propagated in ide8 cells were also successfully used to infect bovine endothelial cells. all stocks were successfully propagated in ide8 cells using dulbecco's modified ...200818788205
the prevalence of serum antibodies to ehrlichia ruminantium infection in ranch cattle in tanzania: a cross-sectional study.serum samples collected in a cross-sectional survey of grazing cattle on manyara ranch, monduli district, tanzania, were tested by indirect major antigenic protein 1 fragment b (map 1-b) elisa to determine the seroprevalence of ehrlichia ruminantium and to assess ranch-level risk factors for heartwater. heartwater-exposed cattle were widespread on the ranch and overall seroprevalence was 50.3% (95% ci, 44.9-55.6), enough to indicate an endemically unstable situation. multivariate logistic regres ...200818846851
serological survey of antibodies to ehrlichia ruminantium in small ruminants in tanzania.sera from 497 sheep and 555 goats collected in a cross sectional study from different geographical locations in north-eastern tanzania were examined for antibodies to ehrlichia ruminantium using map 1-b elisa technique. e. ruminantium antibodies were found in 68.6% (341/497) of sheep and 64.7% (359/555) of goats. overall seroprevalence was 66.5% (700/1052). infection rates were higher in sheep than goats (p < 0.05), in pastoral than in agro-pastoral production systems (p < 0.05) and in female sh ...200919067218
amblyomma variegatum ticks and heartwater on three caribbean islands.amblyomma variegatum tick infestation, tick infection by ehrlichia ruminantium (er), and er genetic diversity were studied in the caribbean islands of guadeloupe, marie-galante, and antigua between 2003 and 2005. nested pcr for pcs20 was used to detect er, while er strains were characterized by sequencing or by restriction fragment length polymorphism (rflp) profiles of map-1 pcr products. in 2003 in guadeloupe, the prevalence of tick-infested herds was 35.6%. in marie-galante 79.1% of herds in ...200819120208
toward prevention of cowdriosis.mass production of ehrlichia ruminantium variants from different regions of sub-saharan africa is one of the difficulties that must be overcome in producing a heartwater vaccine. vaccine productivity can be limited by endogenous induction of interferon (ifn), which inhibits the propagation of ehrlichia ruminantium (er) in cell culture. different kinds of endothelial cells, in which er multiply efficiently, could be grown in a scalable way in vuelife teflon bags on cytodex 3 microcarriers where b ...200819120230
attenuated vaccines for animal diseases. 200819178885
experimental use of the attenuated ehrlichia ruminantium (welgevonden) vaccine in merino sheep and angora goats.the attenuated ehrlichia ruminantium (welgevonden) stock provides protection against a virulent homologous needle challenge in merino sheep and boer goats against heartwater. in this study, cryopreserved stabilates were tested for their suitability as a vaccine in merino sheep. vaccination did not produce disease and upon challenge with the virulent homologous stock all animals were fully protected. the vaccination protected all except one animal out of 5 challenged 12 months after immunization. ...200819178891
diversity of ehrlichia ruminantium major antigenic protein 1-2 in field isolates and infected sheep.proteins expressed from the map1 multigene family of ehrlichia ruminantium are strongly recognized by immune t and b cells from infected animals or from animals that were infected and have recovered from heartwater disease (although still remaining infected carriers). analogous multigene clusters also encode the immunodominant outer membrane proteins (omps) in other ehrlichial species. recombinant protein analogs of the expressed genes and dna vaccines based on the multigene clusters have been s ...200919307215
new approaches to detection and identification of rickettsia africae and ehrlichia ruminantium in amblyomma variegatum (acari: ixodidae) ticks from the caribbean.imported from africa in the 1700s and despite frequent modern eradication efforts, amblyomma variegatum (f.) spread through the caribbean by cattle transport, small ruminants, and migrating birds. a. variegatum is a vector for rickettsia africae, the causative agent of african tick bite fever, and ehrlichia ruminantium, the causative agent of heartwater. we examined 95 a. variegatum and six rhipicephalus (boophilus) microplus (canestrini) collected from cattle at an abattoir in antigua. engorged ...200919645301
mlst scheme of ehrlichia ruminantium: genomic stasis and recombination in strains from burkina-faso.heartwater, caused by the intracellular bacterium ehrlichia ruminantium, is a major tick-borne disease of livestock in africa also introduced in the caribbean. the main problem encountered with the control of this disease is the lack of efficient vaccine in the field. this is thought to be related to the high genetic diversity of strains circulating in a same area. a set of eight circulating strains was isolated from a herd of cows in a small locality in burkina-faso and analyzed along with two ...200919712754
seroprevalence of tick-borne diseases in communal cattle reared on sweet and sour rangelands in a semi-arid area of south africa.a survey was conducted to determine the seroprevalence of tick-borne diseases (tbd) in nguni and non-descript cattle on the sweet and sour communal rangelands across seasons. body condition scores, bodyweights, packed cell volume (pcv) and antibodies to b. bovis, b. bigemina, ehrlichiaruminatium and anaplasma marginale were determined seasonally in 144 cattle raised on communal rangelands from august 2007 to april 2008. approximately 45% of the cattle were seropositive for b. bovis, 46% for b. b ...201019733490
mining the genetic diversity of ehrlichia ruminantium using map genes family.understanding bacterial genetic diversity is crucial to comprehend pathogenesis. ehrlichia ruminantium (e. ruminantium), a tick-transmitted intracellular bacterial pathogen, causes heartwater disease in ruminants. this model rickettsia, whose genome has been recently sequenced, is restricted to neutrophils and reticulo-endothelial cells of its mammalian host and to the midgut and salivary glands of its vector tick. e. ruminantium harbors a multigene family encoding for 16 outer membrane proteins ...201019819629
natural history of ehrlichia ruminantium.ehrlichia ruminantium is an obligately intracellular proteobacterium which causes a disease known as heartwater or cowdriosis in some wild, and all domestic, ruminants. the organism is transmitted by ticks of the genus amblyomma, and it is of serious economic importance wherever the natural vectors occur, an area which includes all of sub-saharan africa, and several islands in the caribbean. the disease was first recognized in south africa in the 19th century, where its tick-borne nature was det ...201019836892
studies on the etiology of heartwater : i. observation of a rickettsia, rickettsia ruminantium (n. sp.), in the tissues of infected animals.a gram-negative, intracellular, coccus-like microorganism was found in cases of heartwater in the three species which are susceptible to the disease; namely, goats, sheep, and cattle. it was absent in the case of control animals, both normal ones and those dying of some. other diseases. the presence of this microorganism was definitely related to the febrile reaction. it was most easily detected in the renal glomeruli and in the small capillaries of the cerebral cortex but probably occurred thro ...192519869049
studies on the etiology of heartwater : ii. rickettsia ruminantium (n. sp.) in the tissues of ticks transmitting the disease.the evidence offered in the first of these studies indicative of a causative relationship between rickettsia ruminantium and heartwater is supplemented by the following observations concerning the ticks which carry the disease. when larvae, which had taken no food since hatching, were allowed to feed upon cases of heartwater, they acquired rickettsioe which appeared to be identical with those in the tissues of animals suffering from heartwater, whereas control larvae hatched from eggs deposited ...192519869050
studies on the etiology of heartwater : iii. the multiplication of rickettsia ruminantium within the endothelial cells of infected animals and their discharge into the circulation.the rickettsiae of heartwater are more definitely restricted to the vascular endothelial cells of infected animals than are those of typhus or rocky mountain spotted fever. they likewise form more pronounced spherical colonies within the cells. their presence does not injure the endothelial cells to a degree at all comparable with that caused by the other pathogenic rickettsiae. the rupture of endothelial cells and discharge of rickettsiae, which are apparently viable, into the circulation const ...192619869225
infection of the endothelium by members of the order rickettsiales.the vascular endothelium is the main target of a limited number of infectious agents, rickettsia, ehrlichia ruminantium, and orientia tsutsugamushi are among them. these arthropod-transmitted obligately-intracellular bacteria cause serious systemic diseases that are not infrequently lethal. in this review, we discuss the bacterial biology, vector biology, and clinical aspects of these conditions with particular emphasis on the interactions of these bacteria with the vascular endothelium and how ...200919967137
persistence mechanisms in tick-borne diseases.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 ...200919967928
trends in the control of heartwater.heartwater is an economically serious tick-borne disease of ruminants caused by the intracellular bacterium ehrlichia ruminantium. the disease has traditionally been controlled by four different approaches: controlling the tick vector by dipping, establishing endemic stability, performing immunisation by infection and treatment, and preventing the disease by regular administration of prophylactic antibiotics. the first three of these methods are subject to failure for various epidemiological rea ...200919967932
innovative approach for transcriptomic analysis of obligate intracellular pathogen: selective capture of transcribed sequences of ehrlichia ruminantium.whole genome transcriptomic analysis is a powerful approach to elucidate the molecular mechanisms controlling the pathogenesis of obligate intracellular bacteria. however, the major hurdle resides in the low quantity of prokaryotic mrnas extracted from host cells. our model ehrlichia ruminantium (er), the causative agent of heartwater, is transmitted by tick amblyomma variegatum. this bacterium affects wild and domestic ruminants and is present in sub-saharan africa and the caribbean islands. be ...200920034374
science and popular participation in the investigation of heartwater in south africa, c. 1870-1950.during the late nineteenth century, settler farmers in southern africa identified heartwater as a damaging disease of small stock and cattle. they advanced various explanations of the disease, including the theory that it was caused by the bite of ticks. around 1900, the american entomologist c.p. lousbury demonstrated that heartwater was transmitted by the bont tick. he also worked out the life cycle and life habits of the tick. subsequently, farmers developed methods of controlling ticks by di ...200820055238
studies of a polymorphic ehrlichia ruminantium gene for use as a component of a recombinant vaccine against heartwater.a previously identified polymorphic ehrlichia ruminantium gene, erum2510, was investigated to determine its ability to induce protective immunity in ruminants following two different dna immunisation strategies; dna-only and a dna prime/recombinant protein (rprotein) boost immunisation. the dna-only vaccine was also compared to a cocktail of three polymorphic e. ruminantium (welgevonden) open reading frames (orfs) adjacent to erum2510 in the genome. weak protection was observed in animals immuni ...201020338214
use of geographic information systems to identify areas at risk of introducing amblyomma variegatum and a. hebraeum to italy.tick-borne diseases are one of the most important obstacles to the development of livestock breeding in africa. among these diseases, heartwater is of significant importance, second in rank to east coast fever. heartwater affects wild and domestic ruminants and is caused by a micro-organism belonging to the order rickettsiales, previously called cowdria ruminantium and recently renamed ehrlichia ruminantium. the disease is transmitted solely by ticks. although the aetiology and the clinical sign ...200720422545
heartwater: an abridged historical account.heartwater was first recognised and recorded in south africa as early as 1838. since then the disease has been described from almost all the countries in africa south of the sahara, from certain islands around africa and from a number of islands in the caribbean. most of the research on the disease, at least until fairly recently, was conducted in south africa. progress in research on the disease has been slow but a few important findings are highlighted in this paper.200920458858
efficiency of inactivated vaccines against heartwater in burkina faso: impact of ehrlichia ruminantium genetic diversity.in order to identify the appropriate strains to use in vaccination trials against heartwater in burkina faso, the protective effect of gardel and welgevonden strains was assessed against local strains on sheep vaccinated by infection-and-treatment method: gardel protected significantly against burkina faso strains tested (survival rate 59% for immunised sheep vs 13% for control sheep) while welgevonden did not (survival rate 45% for immunised sheep vs 25% for control sheep). the efficacy of the ...201020470791
clonal origin of emerging populations of ehrlichia ruminantium in burkina faso.cowdriosis or heartwater is a major tick-borne disease on ruminants in africa and the caribbean. the causative agent is ehrlichia ruminantium, an intracellular bacterium. development of vaccines against heartwater has been hampered the limited efficiency of vaccine in the field, thought to be a consequence of the high genetic diversity of strains circulating in a same area. a sampling scheme was set to collect ticks over 2 years in a delimited area and well identified flock. prevalence was low a ...201020553966
in vitro and in vivo evaluation of five low molecular weight proteins of ehrlichia ruminantium as potential vaccine components.low molecular weight (lmw) proteins of e. ruminantium can induce proliferation of immune peripheral blood mononuclear cells (pbmcs) and the production of interferon-gamma (ifn-gamma) by cd4+-enriched t-cells. in this study, a reverse vaccinology approach was applied to identify additional vaccine candidates focusing on genes that encode lmw proteins smaller than 20 kda. five open reading frames (orfs) were selected from the e. ruminantium genome and their corresponding recombinant (r) proteins w ...201020566221
a novel ehrlichia genotype detected in naturally infected cattle in north america.during a research investigation to determine if cattle from british columbia (bc), canada were infected with anaplasma marginale or other related rickettsial blood parasites, a novel ehrlichia genotype was revealed. blood from seven bc source cattle was bioassayed by intravenous inoculation into naïve splenectomised calves. additional splenectomised calves were used as uninoculated negative control or a. marginale-inoculated positive control. newly designed sets of primers specific for the msp5 ...201020663613
recognition of the threat of ehrlichia ruminantium infection in domestic and wild ruminants in the continental united states. 201020807129
the gulf coast tick: a review of the life history, ecology, distribution, and emergence as an arthropod of medical and veterinary importance.the gulf coast tick, amblyomma maculatum koch (acari: ixodidae), is a unique univoltine ectoparasite of seven vertebrate host classes in the western hemisphere that is increasingly recognized as a pest of livestock and wildlife, a vector of pathogens to humans and canines, and a putative vector of ehrlichia ruminantium, the causal agent of heartwater, a fatal foreign animal disease of ruminants resident in the caribbean. this review assembles current and historical literature encompassing the bi ...201020939363
haemoparasite prevalence and theileria parva strain diversity in cape buffalo (syncerus caffer) in uganda.cape buffalo (syncerus caffer) are considered to be an important reservoir for various tick-borne haemoparasites of veterinary importance. in this study we have compared the haemoparasite carrier prevalence in buffalo from four geographically isolated national parks in uganda [lake mburo national park (lmnp), queen elizabeth national park (qenp), murchison falls national park (mfnp) and kidepo valley national park (kvnp)]. differences were seen in haemoparasite prevalence in buffalo from the fou ...201021074945
development of loop-mediated isothermal amplification (lamp) assays for rapid detection of ehrlichia ruminantium.the rickettsial bacterium ehrlichia ruminantium is the causative agent of heartwater, a potential zoonotic disease of ruminants transmitted by ticks of the genus amblyomma. the disease is distributed in nearly all of sub-saharan africa and some islands of the caribbean, from where it threatens the american mainland. this report describes the development of two different loop-mediated isothermal amplification (lamp) assays for sensitive and specific detection of e. ruminantium.201021087521
thoughts on the threat of ehrlichia ruminantium infection. 201021090154
epidemiological analysis of tick-borne diseases in zambia.tick-borne diseases are a constraint to livestock production in many developing countries as they cause high morbidity and mortality, which results in decreased production of meat, milk and other livestock by-products. the most important tick-borne diseases of livestock in sub-saharan africa are east coast fever (caused by theileria parva), babesiosis (caused by babesia bigemina and b. bovis), anaplasmosis (caused by anaplasma marginale) and heartwater (caused by ehrlichia ruminantium). despite ...201021106294
treatment and control of chlamydial and rickettsial infections in sheep and goats.small ruminants are susceptible to several chlamydial and rickettsial infections. some of them, such as ehrlichia ruminantium, have a great impact on the sheep and goat industry while others, such as coxiella burnetii, are important zoonotic agents. this review focuses on measures of treatment and control for the following organisms: chlamydophila abortus (formerly chlamydia psittaci immunotype 1), coxiella burnetii, anaplasma ovis, anaplasma phagocytophilum, and ehrlichia ruminantium.201021215905
veterinary extension on sampling techniques related to heartwater research.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 cros ...201021247042
ehrlichia ruminantium in amblyomma variegatum and domestic ruminants in the caribbean.the highly sensitive nested pcs20 polymerase chain reaction assay for ehrlichia ruminantium was negative on 506 amblyomma variegatum from caribbean islands where clinical heartwater has not been reported, mainly the united states virgin islands (18), dominica (170), montserrat (5), nevis (34), st. kitts (262), and st. lucia (17). positive results were obtained with positive controls (crystal springs strain) and a. variegatum from countries in africa where infections are endemic, mainly tanzania ...201121485394
tick-borne bacteria in free-living jaguars (panthera onca) in pantanal, brazil.abstract tick-borne bacteria were investigated in 10 free-living jaguars and their ticks in the pantanal biome, brazil. jaguar sera were tested by indirect fluorescent antibody assays using rickettsia rickettsii, rickettsia parkeri, rickettsia amblyommii, rickettsia rhipicephali, rickettsia felis, rickettsia bellii, ehrlichia canis, and coxiella burnetii as crude antigens. all 10 jaguar sera reacted (titer ≥64) to at least one rickettsia species; 4 and 3 sera reacted with e. canis and c. burneti ...201121612532
an alternative approach to multiple genome comparison.genome comparison is now a crucial step for genome annotation and identification of regulatory motifs. genome comparison aims for instance at finding genomic regions either specific to or in one-to-one correspondance between individuals/strains/species. it serves e.g. to pre-annotate a new genome by automatically transfering annotations from a known one. however, efficiency, flexibility and objectives of current methods do not suit the whole spectrum of applications, genome sizes and organizatio ...201121646341
multi-locus sequence typing of ehrlichia ruminantium strains from geographically diverse origins and collected in amblyomma variegatum from uganda.abstract: background: the rickettsial bacterium ehrlichia ruminantium is the causative agent of heartwater in ruminants. a better understanding of the population genetics of its different strains is, however, needed for the development of novel diagnostic tools, therapeutics and prevention strategies. specifically, the development of effective vaccination policies relies on the proper genotyping and characterisation of field isolates. although multi-locus sequence typing (mlst) has been recently ...201121762509
preparation and in vitro characterisation of ehrlichia ruminantium plasmid dna and proteins encapsulated into and dna adsorbed onto biodegradable microparticles.four e. ruminantium 1h12 open reading frames and their proteins known to protect sheep against heartwater needle challenge were encapsulated into, or adsorbed onto poly(d,l-lactide-co-glycolide) microparticles. microspheres with smooth surface and smaller than 5 ++m diameters were produced, with high adsorption and encapsulation efficiencies. gel electrophoresis showed that neither encapsulation nor adsorption affected the stability of the dna or proteins. cationic microparticles released ôê+40% ...201021771527
Development of multiple-locus variable-number tandem-repeat analysis for rapid genotyping of Ehrlichia ruminantium and its application to infected Amblyomma variegatum collected in heartwater endemic areas in Uganda.SUMMARYThe rickettsial bacterium Ehrlichia ruminantium is the causative agent of heartwater, a serious tick-borne disease in ruminants. The genetic diversity of organisms in the field will have implications for cross-protective capacities of any vaccine developed, and for an effective vaccine design strategy proper genotyping and understanding of existing genetic diversity in the field is necessary. We searched for variable-number tandem-repeat (VNTR) loci for use in a multi-locus VNTR analysis ...201122008706
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