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PubMed2003

Enzootic transmission of the agent of human granulocytic ehrlichiosis among cottontail rabbits.

To determine whether the agent of human granulocytic ehrlichiosis (HGE) (Anaplasma phagocytophilum) may be maintained in a parallel enzootic cycle between cottontail rabbits and their ticks, we sampled these hosts from a zoonotic site during five transmission seasons. Evidence of infection was sought by microscopy and polymerase chain reaction from rabbit blood or splenic tissue, and from ticks collected from rabbits or from vegetation. Approximately 27% of all rabbits sampled contained evidence of active infection, and 66% were seropositive. The vectorial capacity of Ixodes dentatus was demonstrated by xenodiagnosis studies; in addition, 2% of host-seeking nymphs were infected. Haemaphysalis leporispalustris was not a competent vector. Because of their propensity to densely inhabit peridomestic sites, and because I. dentatus may be transported by birds, a parallel cycle of transmission in cottontail rabbits would facilitate introduction and perpetuation of the agent of HGE.

Anaplasma phagocytophilum↗
PubMed2004

[Detection of anti-Ehrlichia antibodies and direct demonstration of Ehrlichia nucleic acid using the polymerase chain reaction (PCR) in patients in the Czech Republic].

PURPOSE OF THE STUDY: In patients presenting symptoms with a suspicion of ehrlichiosis we determined antiehrlichia antibodies and investigated the presence of Ehrlichia nucleic acid in the plasma. MATERIAL AND METHODS: In our group were 46 patients with tick sucks in their case history, who presented symptoms compatible with ehrlichiosis. Anti-Ehrlichia antibodies were determined by an indirect immunofluorescent test with a commercial kit from MRL Diagnostics. Ehrlichia DNA was detected using a nested PCR - the target sequence was a part of the antigen Anaplasma phagocytophilum. RESULTS: Antibodies against HGE agents were demonstrated in 28 % of the patients; 10.5 % of the patients had in their serum antibodies reacting to the Ehrlichia chaffeensis antigen. The nucleic acid of A. phagocytophilum was detected in 11 % of the patients. CONCLUSIONS: The Czech population is relatively often exposed to Ehrlichia infections. Although most cases are asymptomatic, we should bear in mind this diagnosis, especially in immunodeficient patients, where early treatment may prevent a complicated course of the disease.

Adult↗
PubMed2004

Human anaplasmosis in north-eastern Poland: seroprevalence in humans and prevalence in Ixodes ricinus ticks.

Sera of 500 inhabitants of north-eastern Poland, 450 suspected for Lyme borreliosis and 50 blood donors (control group), were analysed for the presence of IgG antibodies against Anaplasma phagocytophilum, the causative agent of human anaplasmosis (HA), known so far as human granulocytic ehrlichiosis (HGE). Forty one (9.1 %) sera of the study group and one serum (2 %) of the control group were positive using indirect fluorescence assay (IFA). The seropositivity tended to be more frequent among males (10.3 %) than females (7.6 %) and among the rural (10.3 %) than urban population (7.5 %); however, differences were of no statistical significance (p = 0.4). No age difference was found between the seropositive and the seronegative individuals (p = 0.77). The only factor increasing the risk of HA seropositivity found was forestry employment (p < 0.05). Additionally, a total of 559 Ixodes ricinus ticks, collected in the same area as sera, were investigated for the presence of A. phagocytophilum by the polymerase chain reaction (PCR) and 41 (8.7 %) of them were found to be positive. The infection level ranged from 2.3-13.7 %, depending on the area studied. Bacteria were significantly less frequently detected in nymphs - 2.1 % (5/235) than in adult ticks - 13.6 % (44/324) and in males--4.2 % (74/165) than in females--23.3 % (37/159) (p < or = 0.05). The obtained results confirm both the occurrence of HA foci in north-eastern Poland with I. ricinus as the principal vector of the A. phagocytophilum infection, and forestry workers as the main group at risk.

Adult↗
PubMed2004

[Ixodes ricinus, transmitted diseases and reservoirs].

The tick Ixodes ricinus has been recorded in most Italian regions especially in thermo-mesophilous woods and shrubby habitats where the relative humidity allow the tick to complete its 3 year developmental cycle, as predicted for the European climatic ranges. This tick acts both as vector and reservoir for a series of wildlife zoonotic pathogens, especially the agents of Lyme diseases, Tick borne encephalitis and Human Granulocytic Ehrlichiosis, which are emerging in most of Europe. To assess the spatial distribution of these pathogens and the infection risk for humans and animals within the territory of the Province of Trento, we carried out a long term study using a combination of eco-epidemiological surveys and mathematical modelling. An extensive tick collection with a GIS based habitat suitability analysis allowed us to identify the areas where tick occurs at various density. To identify the areas with higher infection risk, we estimated the values of R0 for Borrelia burgdorferi s.l., TBE virus and Anaplasma phagocytophila under different ecological conditions. We assessed the infection prevalence in the vector and in the wildlife reservoir species that play a central role in the persistence of these infections, ie the small mammals A. flavicollis and C. glareolus. We also considered the double effect of roe deer (Capreolus capreolus) which act as reservoir for A. phagocytophila but is an incompetent host for B. burgdorferi and TBE virus, thus reducing the infection prevalence in ticks of these last two pathogens. Infection prevalence with B. burgdorferi and A. phagocytophila in the vector was assessed by PCR screening 1212 I. ricinus nymphs collected by dragging in six main study areas during 2002. The mean infection prevalence recorded was 1.32% for B. burgdorferi s.l. and 9.84% for A. phagocytophila. Infection prevalence in nymphs with TBE virus, as assessed in a previous study was 0.03%. Infection prevalence in rodents was assessed by screening (with ELISA and PCR) tissues and blood samples collected from 367 rodent individuals trapped extensively during 2002 within 6 main study areas. A. flavicollis (N=238) was found to be infected with all three pathogens investigated, with infection prevalence ranging from 3.3% for TBE virus to 11.7% for A. phagocytophila, and 16.6% with B. burgdorferi s.l. C. glareolus (N=108) showed an infection prevalence of 6.5% with A. phagocytophila and 12.7% with B. burgdorferi s.l., while no individuals were infected with TBE virus. We also screened 98 spleen samples collected from roe deer with PCR, resulting in a mean prevalence of infection with A. phagocytophila of 19.8%. Using a deterministic model we explored the condition for diseases persistence under different rodent and roe deer densities. R0 values resulted largely above 1 for B. burgdorferi s.l. in the vast majority of the areas classified as suitable for I. ricinus occurrence in Trentino, while the condition for TBE persistence appeared to be more restricted by a combination of climatic condition and host densities.

Anaplasma phagocytophilum↗
PubMed2005

Clinical, epidemiologic, and environmental surveillance for ehrlichiosis and anaplasmosis in an endemic area of northern California.

Two forms of tick-borne leukocytotropic rickettsioses have been recognized in California since the mid-1990s: human monocytic ehrlichiosis (HME) caused by Ehrlichia chaffeensis and human granulocytic anaplasmosis (HGA) caused by Anaplasma phagocytophilum. Between 1997 and 1999, two cases of HME and four cases of HGA were diagnosed in residents of southern Humboldt County, California. Environmental followup at case-patients' residences revealed dense populations of Ixodes pacificus ticks, particularly in grassy roadside areas. PCR evidence of A. phagocytophilum was detected in approximately 2.0% of I. pacificus; E. chaffeensis was not detected in any of 625 ticks tested. Serologic antibody to A. phagocytophilum was detected in two of 54 participants in a community epidemiologic study; one of these also had antibody to E. chaffeensis. Over 85% of study participants reported finding a tick on themselves in the preceding 12 mo. Residents of southern Humboldt County are at significant risk of tick bites and should take appropriate prevention measures to avoid infection with rickettsia and other tick-transmitted pathogens.

Adolescent↗
PubMed2006

Role of reactive nitrogen species in development of hepatic injury in a C57bl/6 mouse model of human granulocytic anaplasmosis.

Human granulocytic anaplasmosis (HGA), caused by the granulocytic rickettsia-like organism Anaplasma phagocytophilum, is the 3rd most frequent vector-borne infection in North America. To understand the disease mechanisms of HGA, we developed a murine model that lacks clinical disease yet exhibits characteristic histopathologic and immunologic changes. Because the degree of hepatic histopathology is unrelated to high bacterial numbers, tissue injury in HGA is thought to occur due to products of innate immunity, such as nitric oxide (NO) and reactive nitrogen species (RNS) from cytokine-activated macrophages. To test the hypothesis that RNS cause hepatic tissue damage, mice received either water treated with a nonspecific inhibitor of inducible nitric oxide synthase, L-NAME, or untreated water for 7 to 10 d before infection and continuing thereafter. Mice were euthanized for tissue harvest at 0, 7, 14, or 21 d after infection to assess differences in histopathology, hepatic bacterial load, RNS quantity in urine and liver, and serum chemistry values. Overall, L-NAME treatment had a beneficial effect, resulting in lower histopathology scores and RNS levels compared with those of untreated mice. There were no significant differences in hepatic bacterial load among treatment groups of infected mice. The observed increases in serum glucose and alanine aminotransferase levels on day 14 appear to be unexpected side effects of L-NAME administration. HGA is best characterized as an immunopathologic disease rather than one caused by direct bacterial injury to the host. Therefore, human and animal patients with HGA likely would benefit from therapy targeting reduced inflammation to supplement anti-infective modalities.

Anaplasma phagocytophilum↗
PubMed2005

[Diagnostics of human granulocytic anaplasmosis].

Diagnostics of human granulocytic anaplasmosis. Human granulocytic anaplasmosis is one of recently emerging tick-borne diseases. The paper summarizes current opinions on diagnostics of this zoonosis, including the recent recommendations of ESCAR (European Society of Clinical Microbiology and Infectious Diseases Study Group on Coxiella, Anaplasma, Rickettsia and Bartonella).

Anaplasma phagocytophilum↗
PubMed2006

Disruption of the salivary protein 14 in Ixodes scapularis nymphs and impact on pathogen acquisition.

We previously examined the physiological role of the anticoagulant salivary protein 14 (salp14) in adult Ixodes scapularis and showed that Salp14 played a role in tick feeding and engorgement. We now analyze whether the disruption of the salp14 family expression by RNA interference affects tick weight in naïve nymph I. scapularis. Salp14 expression after dsRNA injection was significantly reduced, as shown by mRNA and protein analysis. However, nymph engorgement weight was not altered in salp9pac (salp14 paralog) dsRNA-injected ticks. We also determined Borrelia burgdorferi and Anaplasma phagocytophilum acquisition in I. scapularis nymphs that had reduced Salp14 expression. B. burgdorferi and A. phagocytophilum acquisition was not affected 72 hours after feeding. Our results suggest that different mechanisms govern nymph and adult feeding in I. scapularis.

Anaplasma phagocytophilum↗
PubMed1989

Epidemiologic investigation and control of an epizootic of anaplasmosis in cattle in winter.

An epizootic of anaplasmosis affecting 18 of 90 beef cows in winter on a western Illinois ranch was investigated to determine the probable source and mode of transmission. The cause of the epizootic was Anaplasma caudatum. Cows were classified as sick, convalescent, or carrier on the basis of blood smear, complement fixation, or modified rapid card agglutination test results. Patterns of movement did not suggest a common exposure prior to assembly of cattle at the affected ranch. The combination of clinical stages and temporal pattern of the epizootic was compatible with exposure on one or more occasions after arrival of cattle on the ranch, most likely during herd vaccination or ear tagging. A serologic testing and treatment program was initiated to rid the herd of infection. Seventeen surviving cows were treated 3 times with 20 mg of oxytetracycline/kg, IM, at 5-day intervals. At the end of the 6-month follow-up period, 1 of 17 cows was still serologically positive and was treated with a second regimen of oxytetracycline. We believe that eradication of A caudatum was successful, because no clinical cases of anaplasmosis have been reported on the ranch during the last 3 vector seasons.

Anaplasma↗
PubMed1986

Anaplasmosis of small ruminants in Nigeria: incidence and parasite identification through blood smear and latex agglutination test (LAT).

A survey was carried out on the incidence of anaplasmosis in small ruminants at Bodija abattoir, Ibadan. 100 sheep and 200 goats were examined using and comparing two methods-the Giemsa stained blood smear and serodiagnosis by Latex Agglutination Technique. The sheep and goats examined were among those brought from various parts of northern states and some neighbouring countries like Chad, Benin, Niger and Burkina Faso. 27% of the sheep and 17.5% of goats were positive for Anaplasma bodies with blood smear method while 54% of sheep and 61% of goats were sero positive with latex agglutination test (LAT). There seems to be a high incidence of anaplasmosis among sheep and goats probably due to the abundance of its arthropod vectors. The serodiagnostic method showed a high degree of specificity and sensitivity and is useful in field diagnosis.

Anaplasma↗
PubMed1986

Epidemiologic aspects of bovine anaplasmosis in semiarid range conditions of south central Idaho.

The prevalance of Anaplasma marginale-infected cows, as determined by use of the modified rapid card agglutination (MRCA) test, was measured during a 4-year period (1980-1983). The prevalence of A marginale-infected cows, defined as positive reactors on the MRCA test, remained constant (31%-37%). The apparent incidence of A marginale transmission to susceptible cows was approximately 7% from 1980 to 1981, 8% from 1981 to 1982, and no transmission from 1982 to 1983. The occasional MRCA-positive cow became negative on the MRCA test, and 1 cow was determined to be free of A marginale infection by subinoculation of 100 ml of the cow's blood into a susceptible, splenectomized calf. Dermacentor andersoni, a known vector of A marginale, was often found on the cattle and in their environment. However, A marginale was not transmitted to susceptible, splenectomized calves, using collected ticks. Of 56 calves born to MRCA-positive cows, 82% were MRCA-positive within the first 3 months of life. These calves converted to MRCA-negative status and were determined to be free of A marginale infection by subinoculation of their blood into susceptible, splenectomized calves, indicating the passive transfer of colostral antibodies.

Anaplasma↗
PubMed1979

[Preparation and comparative testing of antigens for the immunodiagnosis of anaplasmosis in cattle].

Three antigen types were produced by ultra-sound treatment of the initial material (Anaplasma marginale Theiler infected blood) and its subsequent sedimentional centrifugation from 10 000 to 100 000 G. Their specificity and susceptibility to the Reaction Complement Binding (RCB) and to the capillary agglutination (CA) serological tests was comparatively checked up. Antigens A and B were very active in RCB, while antigen B--in the CA reaction. By these qualities they meet the requirements and are suitable for the practical need of discovering animals-carriers of anaplasmosis.

Anaplasma↗
PubMed1978

Immunization against anaplasmosis and babesiosis. Part II. Evaluation of cryo-preserved vaccines using different doses and routes of inoculation.

Anaplasma marginale, Babesia argentina and Babesia bigemina infected blood used as vaccines for immunization trials in Valle del Cauca, were preserved with 4 Molar Dimethyl-Sulfoxide (4M DMSO) and stored in liquid nitrogen (-196 degrees C). The effectivity of the vaccines was determined in 87 healthy calves utilizing serial 10-fold dilutions. The effects of dose, inoculation routes, time and temperature were determined. The minimum infective dose for A. marginale was 10(-3) (2 x 10(6)) when 2 ml of vaccine were given intravenously (i.v.). The same dose when given subcutaneously (s.c.) was not infective. The 10(-2) dilution (2 x 10(7)) was infective when given through both routes, however, the incubation periods were statistically different. The average incubation period using 2 ml s.c. was 30 days, but when the dose was increased to 5 ml and given s.c. the average incubation period decreased to 22 days. The minimum infective doses for b. bigemina and B. argentina were 10(-1) dilutions (4 x 10(-7)) and 10(-2) (4 x 16(6)) respectively, when 2 ml of vaccines were injected i.v.. Infectivity was also recorded when Babesia spp. vaccines were injected s.c. at dosages of 5 ml of dilution 10(-1) (1 x 10(-8)).

Anaplasma↗
PubMed1980

Comparison of three methods of immunization against bovine anaplasmosis: an examination of postvaccinal effects.

Normandy calves ranging in age from 7 to 11 months were immunized against bovine anaplasmosis, using a diluted virulent Anaplasma marginale stabilate of Colombian origin, diluted bovine blood containing an apparently mild strain of A marginale isolated in Colombia, or an attenuated A marginale vaccine of ovine origin from the United States. Calves given the stabilate generally showed a moderate degree of parasitemia and reduction in packed cell volume (PCV). Calves given the apparently mild Colombian isolate of A marginale developed a moderate parasitemia, a reduction in PCV, and in some instances, required treatment to moderate the premunization procedure. Calves given the attenuated vaccine showed minimal evidence of parasitemia and PCV reduction. Most of the immunized calves became seropositive in the complement-fixation test for anaplasmosis and all calves sampled showed evidence of a cell-mediated response, using the leukocyte migration-inhibition test.

Anaplasma↗
PubMed1994

Molecular epidemiology of bovine anaplasmosis.

Bovine anaplasmosis presents a worldwide distribution. However, specific models for studying the epidemiology of the disease are not available. Epidemiological modeling encounters some difficulties due to a lack of culturing techniques for Anaplasma marginale, the causative agent, as well as for the lack of typing techniques to characterize strains. The chronic carrier state and the population dynamics of mechanical and biological vectors also create difficulties. In addition, conventional serology and blood smear diagnostic techniques fail to detect all chronic carriers. Fortunately the needs for the accurate typing of isolates and for detecting chronic carriers made it possible to encourage the development of new tools based on molecular epidemiology principles. A. marginale isolates can now be typed by using panels of monoclonal antibodies, and the genes coding for some major surface proteins can be expressed or analyzed by looking at the nucleotide arrangement level. In the same manner, the latest techniques for detecting A. marginale chronic infections use DNA and RNA probes, and PCR-based methods to detect A. marginale DNA from bovine blood samples with extremely low rickettsaemias. Currently all these new epidemiological tools are being incorporated to experimental models to analyze their applicability for epidemiological studies in the near future.

Anaplasma↗
PubMed1994

Bovine anaplasmosis and babesiosis in the Lesser Antilles: risk assessment of an unstable epidemiologic situation.

A seroepidemiological survey on tick-borne diseases of ruminants was carried out on 11 islands of the Lesser Antilles from Grenada to St Martin. A total of 1,795 cattle were randomly sampled and sera tested for antibodies to anaplasmosis (Anaplasma marginale) and babesiosis (Babesia bovis and B bigemina) using a dot-ELISA test. Except for anaplasmosis, which was virtually absent from Guadeloupe, the seroprevalence of the 3 tick-borne diseases ranged from 18 to 71%. The epidemiologic situation was considered to be unstable in all of the study sites. The risk of clinical outbreaks was high in all the islands except for B bigemina in Montserrat and St Lucia and B bovis in St Lucia. The practical consequences in terms of tick eradication, tick control, and vaccination are discussed.

Age Factors↗
PubMed1978

Eperythrozoon ovis. I. Serological diagnosis of infection by the indirect immunoflurescent antibody test.

The indirect immunofluorescent antibody test (IFAT) was evaluated for the detection of Eperythrozoon ovis infection in sheep. The test first became positive, on the average, 10 days following exposure to E. ovis and remained positive for 24 months, the longest period checked. Reciprocal titres in the first three days after becoming positive in the IFAT were between 4 and 80, but rose to 640 within 9 weeks; in general titres were between 4 and 640, exceptionally titres of 1280 were obtained. Negative sera produced no fluorescence at serum dilutions of 1:4. Paired serum samples collected before and after experimental infection demonstrated the specificity of the test. Further support for the specificity and reliability of the IFAT was provided by lack of cross-reactivity between E. ovis antigen and antisera to Anaplasma ovis and Theileria ovis, the two common blood parasites of sheep and goats in Nigeria, and the results of a longitudinal survey in a flock of sheep on the research farm where E. ovis was first detected.

Anaplasma↗