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PubMed2001

Evolution and function of tandem repeats in the major surface protein 1a of the ehrlichial pathogen Anaplasma marginale.

The major surface protein (MSP) 1a of the ehrlichial cattle pathogen Anaplasma marginale, encoded by the single-copy gene msp1alpha, has been shown to have a neutralization-sensitive epitope and to be an adhesin for bovine erythrocytes and tick cells. msp1alpha has been found to be a stable genetic marker for the identification of geographic isolates of A. marginale throughout development in acutely and persistently infected cattle and in ticks. The molecular weight of MSP1a varies among geographic isolates of A. marginale because of a varying number of tandemly repeated peptides of 28-29 amino acids. Variation in the sequence of the tandem repeats occurs within and among isolates, and may have resulted from evolutionary pressures exerted by ligand-receptor and host-parasite interactions. These repeated sequences include markers for tick transmissibility that may be important in the identification of ehrlichial pathogens because they may influence control strategies and the design of subunit vaccines.

Amino Acid Sequence↗

PubMed2002

Applications of a cell culture system for studying the interaction of Anaplasma marginale with tick cells.

A cell culture system for the tick-borne rickettsia Anaplasma marginale offers new opportunities for research on this economically important pathogen of cattle. A. marginale multiplies in membrane-bound inclusions in host cells. Whereas erythrocytes appear to be the only site of infection in cattle, A. marginale undergoes a complex developmental cycle in ticks and transmission occurs via the salivary glands during feeding. We recently developed a cell culture system for A. marginale using a cell line derived from embryos of Ixodes scapularis. Here we review the use of this cell culture system for studying the interaction of A. marginale with tick cells. Several assays were developed using the A. marginale/tick cell system. An adhesion assay was developed for the identification of proteins required by A. marginale for adhesion to tick cells. The effect of antibodies against selected major surface proteins in inhibiting A. marginale infection was tested in an assay that allowed further confirmation of the role of surface proteins in the infection of tick cells. A drug screening assay for A. marginale was developed and provides a method of initial drug selection without the use of cattle. The culture system was used to test for enhancing effects of tick saliva and saliva components on A. marginale infection. The tick cell culture system has proved to be a good model for studying A. marginale-tick interactions. Information gained from these studies may be applicable to other closely related tick-borne pathogens that have been propagated in the same tick cell line.

Anaplasma↗

PubMed1992

Single-step technique for staining Anaplasma marginale in bovine blood smears.

Three available differential stains, Camco-Quik, Diff-Quik, and Wright-Giesma were compared for detection of intraerythrocytic Anaplasma marginale in bovine blood smears. In samples where < 1% to more than 51% of the RBC were infected, statistical analysis of the data indicated no significant difference in the detection of A marginale with Camco-Quik or Diff-Quik stains. However, a significantly lower percentage of infected RBC were detected when blood smears were stained with the Wright-Giemsa stain, compared with the other 2 methods.

Anaplasma↗

PubMed2003

Molecular evidence for Anaplasma phagocytophilum and Borrelia burgdorferi sensu lato in Ixodes ricinus ticks from eastern Slovakia.

Ixodes ricinus ticks (20 males, 20 females and 20 nymphs) collected in Kosice, Slovakia were examined for the presence of Anaplasma phagocytophilum and Borrelia burgdorferi sensu lato (s.l.) by PCR. 38.3 % of the tested ticks carried single infection of B. burgdorferi s.l. and 8.3 % were infected with A. phagocytophilum. Double infection of both pathogens was detected in 5 % of tested ticks. These results indicate that both B. burgdorferi s.l. and A. phagocytophilum co-circulate in the enzootic sites of Eastern Slovakia and may cause co-infection in humans.

Anaplasma phagocytophilum↗

PubMed2003

[Prevalence of Anaplasma marginale and specific antibodies in new born calves].

Anaplasma marginale is an intraerythrocytic rickettsia that affects the cattle and constitute a constraint for its production. The transplacental transmission of A. marginale could be of importance under field conditions, but until now no data is available to interpret its relevance in Venezuela. The goal of this work was to evaluate both the presence of A. marginale and the antibody response against the rickettsia in new born calves. Fourteen calves, one week old, were simultaneously bled for parasitological tests, packed cell volume measurement and to obtain sera for immunoenzymatic assays. All the animals showed parasitemia between seventeen and thirty days old. The antibody IgM and IgG response at this time was low. Probably, these calves acquired A. marginale infection through transplacental route and a very low level of immunity by the colostrum.

Anaplasma marginale↗

PubMed2004

Acute recumbency associated with Anaplasma phagocytophilum infection in a horse.

An 11-year-old Hanoverian-cross gelding was evaluated because of acute onset of ataxia, recumbency, and fever. At the stable, this and other horses had recently been infested with ticks. Results of analysis of a sample of CSF were within reference limits, but hematologic abnormalities included lymphopenia, thrombocytopenia, mild anemia, and intracytoplasmic inclusion bodies in neutrophils that were consistent with Anaplasma phagocytophilum (previously Ehrlichia equi). Results of serum biochemical analyses were characteristic of infection and included high, unconjugated bilirubin concentration. Other common causes of recumbency in horses, such as equine protozoal myeloencephalitis, infection with eastern or western equine encephalitis viruses and equine herpesvirus-1, West Nile viral encephalitis, trauma, and metabolic disease, were ruled out. The horse responded quickly to i.v. administration of oxytetracycline and recovered fully within 6 days.

Acute Disease↗

PubMed2004

Ixodes ricinus as a vector of Borrelia burgdorferi sensu lato, Anaplasma phagocytophilum and Babesia microti in urban and suburban forests.

In the suburban and urban forests in the cities of Gdansk, Sopot and Gdynia (northern Poland), Ixodes ricinus ticks should be considered as the vector of pathogenic microorganisms that may cause significant diseases in wild and domestic animals and humans. These microorganisms include etiologic agents of Lyme disease, human anaplasmosis (HA) and babesiosis: Borrelia burgdorferi sensu lato, Anaplasma phagocytophilum and Babesia microti, respectively. DNA extracts from 701 ticks collected in 15 localities were examined by PCR for the simultaneous detection of these 3 pathogens. Overall, 14 % were infected with A. phagocytophilum followed by 12.4 % with B. burgdorferi s.l. and 2.3 % with B. microti. In total, the percentage of infected females (32.9 %) was 2.4 times higher than in males (13.7 %) and 3.2 times higher than in nymphs (10.3 %). Among adult ticks (n = 303), 8.3 % were dually infected with A. phagocytophilum and B. burgdorferi s.l., 2.0 % with the agent of human anaplasmosis and B. microti and 0.3 % with borreliae and B. microti.

Anaplasma phagocytophilum↗

PubMed2004

Ecology of Anaplasma phagocytophilum and Borrelia burgdorferi in the western United States.

We discuss the ecology of Anaplasma phagocytophilum and Borrelia burgdorferi in the western U.S. These agents, while emerging in the eastern U.S., remain stable or rare in the west. In the western U.S., tick vectors and mammalian hosts for B. burgdorferi and A. phagocytophilum are distinct from those in the eastern U.S. and considerably more variable. Spatial complexity, local extinctions, and low levels of movement among foci may determine the distribution and prevalence of these agents. High-prevalence A. phagocytophilum patches may be transient, possibly as host individuals become immune. Thus, A. phagocytophilum in California could exist in a metapopulation of interacting patches. Local dynamics are sensitive to host population sizes and minimum tick infestation levels. Determining critical values for these key factors and their interactions will be important for predicting the level and distribution of future infections in the western U.S.

Anaplasma phagocytophilum↗

PubMed2004

Prevalence of antibodies to bluetongue virus and Anaplasma marginale in Montana yearling cattle entering Alberta feedlots: Fall 2001.

A serologic survey was conducted in yearling cattle imported into Alberta feedlots from Montana during October 2001 to estimate the prevalence of antibodies to bluetongue virus (BTV) and Anaplasma marginale in Montana yearling cattle. The apparent prevalence of antibodies to BTV when the competitive enzyme-linked immunosorbent assay (cELISA) was used was 0.37% (21/5608). Test positive cELISA samples were also all positive when tested by virus neutralization (VN) and they reacted to 1 or more BTV serotypes, including 2, 10, 11, 13, and 17. The apparent prevalence of antibodies to A. marginale when a recombinant cELISA (rcELISA) was used with a positive cutoff at 30% inhibition was 1.93% (108/5608). When the rcELISA positive cutoff was at 42% inhibition, the apparent prevalence was 0.73% (41/5608). After the reported sensitivity and specificity of the test had been accounted for, the A. marginale antibody results were consistent with a population that was either free of exposure or had a very low prevalence for A. marginale.

Alberta↗

PubMed2004

Use of imidacloprid-permethrin to prevent transmission of Anaplasma phagocytophilum from naturally infected Ixodes scapularis ticks to dogs.

One group of eight beagles was treated with a combination of imidacloprid and permethrin 7 days before exposure to Ixodes scapularis ticks that were naturally infected with Anaplasma phagocytophilum. A second group of eight beagles was not treated and was also exposed to infected ticks. Seven of eight non-treated dogs--but none of the treated dogs--developed specific antibodies to A. phagocytophilum. Results of this study indicate that a combination of imidacloprid and permethrin can prevent transmission of A. phagocytophilum to dogs if administered before exposure to infected ticks.

Anaplasma phagocytophilum↗

PubMed2005

[Babesia microti and Anaplasma phagocytophilum: two emerging zoonotic pathogens in Europe and Hungary].

Babesia microti and Anaplasma phagocytophilum was recently reported with a minimum prevalence of 0.9 and 1.3% in Hungary based on the PCR-sequencing analysis of 452 European sheep ticks (Ixodes ricinus). These results and the epidemiological data of the neighbouring countries indicate that human cases caused by these pathogens may occur in the country. The aim of the present paper is to summarise the current knowledge on the morphology, life cycle and distribution of B. microti and A. phagocytophilum, and the epidemiology, clinical features, diagnosis, treatment and control of babesiosis and granulocytic anaplasmosis.

Anaplasma phagocytophilum↗

PubMed1992

Development of Anaplasma marginale in male Dermacentor andersoni transferred from parasitemic to susceptible cattle.

The development and transmission of Anaplasma marginale was studied in Dermacentor andersoni males. Laboratory-reared male D andersoni were allowed to feed for 7 days on a calf with ascending A marginale parasitemia. The ticks were then held in a humidity chamber for 7 days before being placed on 2 susceptible calves. Anaplasmosis developed in the calves after incubation periods of 24 and 26 days. Gut and salivary glands were collected from ticks on each day of the 23-day experiment and examined with light and electron microscopy. Colonies of A marginale were first observed in midgut epithelial cells on the sixth day of feeding on infected calves, with the highest density of colonies found in gut cells while ticks were between feeding periods. The first colonies contained 1 large dense organism that subsequently gave rise to many reticulated organisms. Initially, these smaller organisms were electron-lucent and then became electron-dense. On the fifth day after ticks were transferred to susceptible calves for feeding, A marginale colonies were found in muscle cells on the hemocoel side of the gut basement membrane. A final site for development of A marginale was the salivary glands. Colonies were first seen in acinar cells on the first day that ticks fed on susceptible calves, with the highest percentage of infected host cells observed on days 7 to 9 of that feeding. Organisms within these colonies were initially electron-lucent, but became electron-dense.

Anaplasma↗

PubMed2005

Prevalence of infection with Francisella tularensis, Borrelia burgdorferi sensu lato and Anaplasma phagocytophilum in rodents from an endemic focus of tularemia in Bulgaria.

The prevalence of Francisella tularensis, Borrelia burgdorferi and Anaplasma phagocytophilum in rodents is a determinant for their role in maintaining pathogens in the environment. A total of 169 rodents, trapped in an endemic focus of tularemia, were examined by PCR to asses the frequency of infection with the etiological agents of tularemia, Lyme borreliosis and human granulocytic anaplasmosis. The overall prevalence of F. tularensis was 22 %. In 6 % of the black rats, F. tularensis was identified in coinfection with B. burgdorferi and in 3 % in coinfection with A. phagocytophilum. B. burgdorferi and A. phagocytophilum were detected in 26 % and 8 % of the trapped rodents. Results obtained show the existence of an active natural focus of tularemia. The high level of coinfections indicated that the endemic focus is mixed and generates risk for multiple infections in humans. Further investigations are needed to reveal interactions between the pathogens in the infected animals.

Anaplasma phagocytophilum↗

PubMedDate not supplied

[Evaluation of diagnostic tests in the absence of a gold standard using an Anaplasma marginale field data set].

The evaluation of newly developed diagnostic tests (tests) commonly involves the comparison of the test outcomes (pos/neg.) of a sample of animals to those of a reference test (gold standard) in order to derive sensitivity and specificity estimates. Often, however, new tests have to be evaluated against an imperfect reference test since a true gold standard test is either too expensive or too costly to apply. This results in bias in the test characteristic estimates. To solve this problem, latent class and Bayesian models can be used to estimate sensitivity and specificity when evaluating a diagnostic test in the absence of a gold standard. They require at least two imperfect reference tests applied to all individuals in the study. In our approach we used a two-test two-population scenario. Both the gold standard and these modelling approaches rely on various assumptions. When violated, biased results will be obtained. The analysis of field data from an Anaplasma marginale outbreak in cattle in Switzerland with four diagnostic procedures (detection of the agent, serology, PCR and hematocrit measurements) was used as a practical example to demonstrate and critically discuss the approaches taken. In this relatively small data set (n = 275) the estimates for the test characteristics obtained by the different methods were quite similar. Overall, the bias in the point estimates depended mainly on the chosen estimation approach. All tests showed a non-negligible correlation mainly in the test sensitivities. This emphasizes the importance of taking into account test dependence even if it seems not biologically plausible at first thought.

Anaplasma marginale↗

PubMed2005

Anaplasma phagocytophilum infection (granulocytic anaplasmosis) in a dog from Vancouver Island.

A 7-year-old Labrador retriever had nonspecific clinical signs that included lethargy, malaise, and difficult ambulation. The dog was native to Vancouver Island, British Columbia, and had never left this area. Morulae were identified in polymorphonuclear cells. Serologic studies and polymerase chain reaction (PCR) testing confirmed canine anaplasmosis caused by Anaplasma phagocytophilum. The dog recovered after treatment with tetracycline.

Anaplasma phagocytophilum↗

PubMed2005

[Prevalence of antibodies against Anaplasma phagocytophilum, Babesia microti i Borrelia burgdorferi in adults in North-Eastern Poland].

THE AIM: of the study was to evaluate the seroprevalance of antibodies against Anaplasma phagocytophilum and Babesia Microti in healthy north-eastern Poland, adult population. MATERIAL AND METHODS: The study was conducted in a group of 142 healthy adults (mean age 19-22), bitten by ticks within last 2 years. The control group consisted of 50 adults from central Poland (nonendemic area). The antibody levels for A. phagocytophilum (IgG/Ap-Ab) and B. microti (IgM/Bm-Ab) were evaluated in two series of samples from the same persons (interval 5-6 months) by immunoenzymatic tests (Borrelia Biomedica, Austria), immunofluorescence test (Human Granulotic Ehrlichiosis IFA IgG and Babesia microti IFA IgG from MRL Diagnostics). RESULTS: Positive results for A. phagocytophilum were defined as titres > or =1:256 and for B. microti > or =1:64 and B. burgdorferi > or = 11 BBU/ml. Positive results for IgG B. burgdorferi during the first collection were revealed in 16% (n=24/142) of individuals from endemic area and in 4% (n=2/50) of the control group, which was statistically relevant (p<0,05). IgG A. phagocytophilum antibodies were present in 3,5% (n=5/142) of individuals from the endemic area, but for IgG B. microti antibodies (IgG/Bm-Ab) no positive results were found. No IgG antibodies against A. phagocytophilum and B.microti, were found in individuals from non-endemic area. During the second collection, in individuals from the endemic area, the antibodies against B. burgdorferi were found in 9,8% (n=14/142), IgG A. phagocytophilum antibodies (IgG/Ap-Ab) in 4,9% (n=7/142) and against B. microti (IgG/ Bm-Ab) in 1,4% (n=2/142). The antibodies against B. Burgdorferi were found in 2% (n=1/150) of the control group during the second collection, and no IgG against A. phagocytophilum and B. microti were found. CONCLUSION: [corrected] Evaluating the seroprevalance of the studied antibodies in both collections, a conclusion was drawn that there was no significant increase of antibodies levels directly after the highest exposition to tick bites. None of individuals showed 4-fold antibody level increase between the first and second collection. The seroconversion for IgG/Bm-Ab antibodies was present in 1,4% (n=2/142) of individuals, in those 2 cases a 2-fold antibodies level increase was observed. As far as IgG/Ap-Ab antibodies are concerned the seroconversion was observed in 2,1% (n-3/142), but only one case shown a 3-fold antibodies level increase. No seroconversion of B. burgdorferi antibodies were found in the second collection.

Adult↗

PubMed2005

[An epidemiological survey of equine anaplasmosis (Anaplasma phagocytophilum) in southern France].

Anaplasmosis is caused by the bacterium Anaplasma phagocytophilum and transmitted by Ixodes spp. ticks. According to some reports the disease can be introduced into disease-free zones by migrating birds. The purpose of this study was to evaluate the seroprevalence of A. phagocytophilum in horses in the Camargue. Data concerning 424 horses were gathered and the sera were tested for A. phagocytophilum and for piroplasmoses using an enzyme-linked immunosorbent assay and a complement fixation test, respectively. The seroprevalence rates were 11.3 % for A. phagocytophilum, 64.4 % for Theileria equi and 19.7% for Babesia caballi. Stallions were less likely to produce antibodies against A. phagocytophilumthan were females or geldings (odds ratio [OR] = 0.3; p = 0.021). The presence of swallows increased the risk of infections in stables (OR = 5.18; p = 0.011). Spatial analysis showed the existence of groups of infected stables along canals and rivers (p = 0.008). These results suggest an emergence of A. phagocytophilum in the Camargue.

Anaplasma phagocytophilum↗

PubMed2004

[Prevalence of antibodies to Anaplasma phagocytophilum and Borrelia burgdorferi in forestry workers from the Lublin region].

Ticks are recently regarded as ones of the most important vectors of emerging diseases. One of these diseases is human granulocytic ehrlichiosis caused by obligatory intracellular microorganism recently named as Anaplasma phagocytophilum. 334 sera from forestry workers and 56 sera from blood donors (as a control group) were collected and examined for antibodies to A. phagocytophilum and B. burgdorferi. The antibodies were found statistically more frequently in sera from foresters compared to sera of the control group, both to A. phagocytophilum (19.8% vs. 5.4%, p < 0.001) and B. burgdorferi (32.0% vs. 7.1%, p < 0.01). Only 15 sera (4.5%) were found positive for both examined bacteria suggesting inhibition of coexistence although it was not statistically significant. No correlation was found between percentages of antibodies to A. phagocytophilum and to B. burgdorferi from different locations.

Anaplasma phagocytophilum↗