Human granulocytic anaplasmosis in Kinmen, an offshore island of Taiwan

Background

Human granulocytic anaplasmosis, a tick-borne infection caused by Anaplasma phagocytophilum, has received scant attention, while scrub typhus, a mite-transmitted disease caused by Orientia tsutsugamushi, is the most common rickettsiosis in Taiwan. The clinical presentations of both diseases are characterized by undifferentiated fever, headache and malaise. Moreover, both pathogens have been detected in small mammals that serve as hosts for chiggers and ticks in the wild. The objective of the present study was to investigate whether human granulocytic anaplasmosis occurs in Taiwan.

Methodology/Principal findings

Blood samples from 274 patients suspected of having scrub typhus in Kinmen, an offshore island of Taiwan, in 2011 and 2012 were retrospectively examined by immunofluorescence assays. IgG antibodies reactive with Anaplasma phagocytophilum was found in 31.8% (87/274) of the patients. Paired serology identified 3 patients with human granulocytic anaplasmosis and 8 patients with coinfection with O. tsutsugamushi and A. phagocytophilum. Laboratory tests showed that elevated serum ALT/AST, creatinine, and BUN levels were observed in patients with anaplasmosis and coinfection, but elevated serum CRP levels, thrombocytopenia, and anemia were only observed in coinfected patients. PCR detected A. phagocytophilum 16S rDNA and p44/msp2 in 2 patients. The phylogenetic analysis suggested that the replicons of the 16S rDNA shared high sequence similarity with the reference sequences in the Korea, USA, Japan, and China. The amplicons of p44/msp2 were close to those of the human variants identified in the USA and Japan.

Conclusions

Our findings indicated that A. phagocytophilum infection was prevalent but unrecognized in Taiwan.

Human granulocytic anaplasmosis is a tick-borne rickettsial infection caused by Anaplasma phagocytophilum. Although most cases resolve readily, life-threatening complications can occur without prompt antibiotic treatment. The major difficulty in diagnosing human granulocytic anaplasmosis is due to the nonspecific nature of the symptoms. Given that scrub typhus is the most frequently reported rickettsial disease in Taiwan and shares similar early clinical signs with anaplasmosis, we retrospectively examined blood samples from patients with suspected diagnoses of scrub typhus in 2011 and 2012. While serological evidence of potential past exposure was found in as many as 31.8% (87/274) of the patients, current or recent anaplasmosis was supported by seroconversion in 11 patients, including 8 patients coinfected with scrub typhus. Anaplasma phagocytophilum DNA was detected in acute phase samples, and the amplified fragments were phylogenetically close to those of variants in the Korea, the USA, Japan, and China. Herein, for the first time, we confirmed the presence of human granulocytic anaplasmosis in Taiwan. By reporting coinfections with anaplasmosis and scrub typhus, the study further highlighted the health risk of increasing contact with wild rodents.

Serological survey of canine vector-borne diseases in Saskatchewan, Canada

Whole blood samples were collected from 515 dogs in the practice region surrounding Saskatoon, Saskatchewan, Canada between 2008 and 2010 and evaluated for seroprevalence of vector-borne diseases. Of 515 samples, 12 (2.3%) were positive, with 7 (1.4%) positive for antibodies to Borrelia burgdorferi. These prevalences are higher than those previously reported for this region.

Detection of Dirofilaria immitis antigen and antibodies against Anaplasma phagocytophilum, Borrelia burgdorferi and Ehrlichia canis in dogs from ten provinces of China

Despite the fact vector-borne diseases (VBDs) have been increasingly reported in dogs worldwide, there are only limited reports on VBDs in dogs in China with most being based on molecular detection of active infections. To provide further data on the exposure of dogs in China to VBD agents, we used commercial immunochromatographic assays to test plasma from 637 apparently healthy indoor and breeding colony dogs from 21 veterinary clinics in 10 provinces in China and a commercial dog breeding facility for circulating antigen of Dirofilaria immitis, and for circulating antibodies against Ehrlichia spp., Anaplasma spp., and Borrelia burgdorferi. Overall, we found only low levels of exposure to Ehrlichia spp. (4.7%; 30/637), Anaplasma spp. (1.4%; 9/637), B. burgdorferi (0.9%; 6/637) and D. immitis (0.2%; 1/637) with most of the positive animals coming from the commercial breeding colony (26/103; 25.2%) where ectoparasites were most commonly noted. At least one vector-borne agent was found in dogs from 6 of the 10 provinces investigated. Our results confirm exposure of dogs from around China to a variety of VBDs, even indoor pets seldom observed to harbor ectoparasites.

A serological study of antibodies to Anaplasma phagocytophilum and Borrelia burgdorferi sensu lato in the sera of healthy individuals collected two decades apart

Sera collected from healthy individuals from the general population in the Czech Republic during repeated cross-sectional surveys were analyzed. Samples collected in the same six districts in two time periods, 1978-1989 and 2001, were compared. The study subjects were divided into six age categories between 10 and 59 years. Overall, 434 samples from 1978-1989 and 270 samples from 2001 were screened for Anaplasma phagocytophilum (AP) and Borrelia burgdorferi sensu lato (BB). The anti-AP positivity rates were 13.1% and 11.5% in the first and second period, respectively, and did not differ significantly between the periods (P = 0.559). The anti-BB antibodies were detected in 33.9% and 14.8% of study subjects, respectively. The positivity rates were significantly lower in the second period (P<0.001). No considerable changes were observed in the sex distribution of positive findings between the two periods. The highest positivity rates of anti-AP antibodies were found in the 10-14 year age group: 16.0% in 1978-1989 and 16.7% in 2001. The age distribution of the anti-AP antibody positivity rates did not change substantially (P = 0.872). In 1978-1989, the lowest anti-BB antibody positivity rate (26.7%) was found in the 10-14 year age group, with a gradual increase with age to 41.1% in 50-59 year-olds. In 2001, the positivity rate in the 10-14 year age group was 26.2% and was not significantly different from that in the first period (P = 0.955). However, the positivity rates in the older age groups 15-59 years decreased significantly (P<0.001) and varied between 8.3% and 15.1%.

Serologic responses to peptides of Anaplasma phagocytophilum and Borrelia burgdorferi in dogs infested with wild-caught Ixodes scapularis

Anaplasma phagocytophilum and Borrelia burgdorferi are both transmitted by Ixodes spp. and are associated with clinical illness in some infected dogs. This study evaluated canine antibody responses to the A. phagocytophilum p44 peptides APH-1 and APH-4 as well as the B. burgdorferi C6 peptide before and after doxycycline treatment. A total of eight dogs were infested with wild-caught I. scapularis for 1 week. Blood was collected prior to tick attachment and from Days 3-77 to 218-302 with doxycycline treatment beginning on Day 218. Blood was assayed for A. phagocytophilum DNA by PCR assay. Sera was assessed for antibodies by immunofluorescent antibody (IFA) test and ELISA. Anaplasma phagocytophilum DNA was amplified from blood of all dogs by Day 7. Antibodies to APH-4 were detected in serum as early as 14days after tick exposure and six dogs had APH-4 antibodies detected 3-7 days before antibodies against APH-1. All dogs were seropositive for A. phagocytophilum from Days 218 to 302. Antibodies to B. burgdorferi were detected in 6/8 dogs beginning 21days after I. scapularis infestation. Among the five dogs that remained seropositive at Day 218, C6 antibody levels declined on average 81% within 84days of initiating treatment. The results suggest that the APH-4 peptide may be more useful than APH-1 for detecting antibodies earlier in the course of an A. phagocytophilum infection. After doxycycline administration, C6 antibody levels but not APH-1 or APH-4 antibody levels decreased, suggesting a treatment effect on C6 antibody production.

The incidence of Borrelia burgdorferi, Anaplasma phagocytophilum and Babesia microti coinfections among foresters and farmers in eastern Poland

BACKGROUND & OBJECTIVES

Lyme borreliosis is the most common tick-borne disease in Europe and the USA. However, a great variety of pathogens are transmitted by ticks, which results in mixed infections, with Lyme borreliosis. The aim of the present study was to show the incidence of Borrelia burgdorferi, Anaplasma phagocytophilum, and Babesia microti coinfections among the population of foresters and farmers, as these people, due to their profession, are particularly exposed to tick contact.

METHODS

The study was carried out in eastern Poland (the northern part of the Lublin Province) in 2013. The study was performed in a group of 93 individuals occupationally exposed to tick bites (foresters and farmers), whose blood serum showed the presence of IgG anti-B. burgdorferi antibodies. Blood serum in this group were evaluated for IgG anti-A. phagocytophilum and IgG anti-B. microti antibodies by means of IFA IgG indirect immunofluorescence tests. Information related to age, sex, number of tick bite episodes, presence of various symptoms related to the tick bites, and antibiotic therapy applied as treatment for diagnosed Lyme borreliosis were obtained from the subjects through a structured questionnaire. The results were analyzed in Statistica v. 7.1 statistical analysis software.

RESULTS

The presence of IgG antibodies against the analyzed pathogens revealed B. burgdorferi and A. phagocytophilum coinfection in 26 (28%) of the examined subjects and B. burgdorferi and B. microti coinfection in one person (1.1%). No coinfection with all the three pathogens was observed in any individual. The co-occurrence of headache plus bone, joint and muscle pain was noted significantly more often among individuals diagnosed with B. burgdorferi and A. phagocytophilum coinfection.

INTERPRETATION & CONCLUSION

Foresters and farmers are exposed to B. burgdorferi and A. phagocytophilum coinfection in the study area. Therefore, it is probable that these pathogens may severely interfere with the clinical course of Lyme borreliosis.

Human Exposure to Anaplasma phagocytophilum in Two Cities of Northwestern Morocco

Anaplasma phagocytophilum is an emerging tick-borne zoonosis with extensive increased interest. Epidemiological data are available in several regions of the USA, Europe and Asia in contrast to other parts of the world such as North Africa. Blood samples of 261 healthy individuals divided in two groups i.e., dog handlers and blood donors were analysed. Indirect immunofluorescent assay using a commercial kit was performed to detect specific A. phagocytophilum IgG. Two dilutions were used to assess the prevalence of seroreactive samples. Demographic variables were assessed as potential risk factors using exact logistic regression. Seropositivity rates reached 37% and 27% in dog handlers and 36% and 22% in blood donors. No statistically significant differences were found in the prevalence rates between the two groups. Analysis of risk factors such as gender, age groups, outdoor activities, self-reported previous exposure to ticks, or contact with domestic animals (dogs, cats, ruminants and horses) did not shown any significant difference. A. phagocytophilum exposure was common in both high-risk population and blood donors in Morocco.

The Prostaglandin E2-EP3 Receptor Axis Regulates Anaplasma phagocytophilum-Mediated NLRC4 Inflammasome Activation

Rickettsial agents are sensed by pattern recognition receptors but lack pathogen-associated molecular patterns commonly observed in facultative intracellular bacteria. Due to these molecular features, the order Rickettsiales can be used to uncover broader principles of bacterial immunity. Here, we used the bacterium Anaplasma phagocytophilum, the agent of human granulocytic anaplasmosis, to reveal a novel microbial surveillance system. Mechanistically, we discovered that upon A. phagocytophilum infection, cytosolic phospholipase A2 cleaves arachidonic acid from phospholipids, which is converted to the eicosanoid prostaglandin E2 (PGE2) via cyclooxygenase 2 (COX2) and the membrane associated prostaglandin E synthase-1 (mPGES-1). PGE2-EP3 receptor signaling leads to activation of the NLRC4 inflammasome and secretion of interleukin (IL)-1β and IL-18. Importantly, the receptor-interacting serine/threonine-protein kinase 2 (RIPK2) was identified as a major regulator of the immune response against A. phagocytophilum. Accordingly, mice lacking COX2 were more susceptible to A. phagocytophilum, had a defect in IL-18 secretion and exhibited splenomegaly and damage to the splenic architecture. Remarkably, Salmonella-induced NLRC4 inflammasome activation was not affected by either chemical inhibition or genetic ablation of genes associated with PGE2 biosynthesis and signaling. This divergence in immune circuitry was due to reduced levels of the PGE2-EP3 receptor during Salmonella infection when compared to A. phagocytophilum. Collectively, we reveal the existence of a functionally distinct NLRC4 inflammasome illustrated by the rickettsial agent A. phagocytophilum.

Recent study on canine vector-borne zoonoses in southern Slovakia - serologic survey

Over the last decade a significant spread of Canine Vector Borne Diseases has been recorded in Central Europe. The aim of the study described here, was to collect current data on the occurrence and distribution of three major canine vector-borne pathogens in the veterinary clinical practice by a newly-developed commercial ELISA test for the detection of Dirofilaria immitis antigen as well as specific circulating antibodies to Anaplasma phagocytophilum and Borrelia burgdorferi sensu lato. Circulating D. immitis antigen was detected in five of 180 investigated sera samples. Two of D. immitis seropositive dogs revealed also microfilariae of D. repens in the blood and three of them were negative for the presence of microfilariae in the Knott's test. From the practical point of view, the finding of D. immitis occult infections might influence existing knowledge about distribution of this species among dogs in Central European countries. In 11.7% of the tested dogs the presence of specific antibodies against A. phagocytophilum was confirmed. Antibodies against B. burgdorferi s.l. were detected in 2.8% of tested sera samples. Coinfection with A. phagocytophilum and B. burgdorferi s.l. was observed in two dogs from Košice district in south-eastern Slovakia. Our data point toward the presence of Canine Vector Borne Diseases in the studied area. Therefore, veterinarians should include these diseases in their differential diagnosis and higher awareness should be focused also on prophylactic measures to prevent the pathogens transmission by arthropod vectors.

Evidence of Anaplasma phagocytophilum and Borrelia burgdorferi infection in cats after exposure to wild-caught adult Ixodes scapularis

Cats are infected by Anaplasma phagocytophilum and Borrelia burgdorferi when exposed to infected Ixodes scapularis (black-legged ticks). The purpose of our study was to allow wild-caught I. scapularis to feed on healthy research cats (n = 4) and temporally evaluate for A. phagocytophilum DNA in blood by a polymerase chain reaction (PCR) assay as well as for antibody responses to the B. burgdorferi C6 peptide, to the A. phagocytophilum P44 peptide, and to a novel A. phagocytophilum peptide (P44-4). Prior to I. scapularis infestation, all cats were negative for antibodies against both organisms based on a kit optimized for dog serum, and negative for A. phagocytophilum DNA in blood using a conventional PCR assay. Using the pre-infestation samples, an enzyme-linked immunosorbent assay for detecting antibodies against the P44-4 peptide was optimized. Cats were infested with wild-caught I. scapularis for 7 days. Genomic DNA of A. phagocytophilum was amplified from the blood before antibodies were detected in all 4 cats. Antibodies against the C6 peptide, P44 peptide, and P44-4 peptide were detected in the sera of all 4 cats. Antibodies against P44-4 were detected prior to those against P44 in 3 out of 4 cats. The results suggest that a PCR assay should be considered in acutely ill cats with suspected anaplasmosis that are seronegative.

[Seroprevalence of Anaplasma phagocytophilum in patients with suspected Lyme borreliosis]

Human granulocytic anaplasmosis (HGA) is an emerging tick-borne zoonotic disease caused by an obligate intracellular bacterium, Anaplasma phagocytophilum. In Europe, A. phagocytophilum is transmitted by Ixodes ricinus ticks. After Lyme borreliosis and European tick-borne encephalitis, HGA is the third most common tick-borne infection in the USA and Europe. The clinical symptoms of anaplasmosis are non-specific and include malaise, fever, headache, myalgia, and arthralgia. In more severe cases, the gastrointestinal or respiratory tract may be affected. However, most infections are asymptomatic. The aim of our study was to determine the seroprevalence of A. phagocytophilum in patients with suspected Lyme borreliosis. A total of 314 sera from patients with suspected Lyme borreliosis were screened for IgG and IgM antibodies against A. phagocytophilum. The immunoblot assay was used to detect the antibodies. Anti-A. phagocytophilum antibodies were detected in 34 patients, i.e. in 10.82%. IgM antibodies were positive in 19 cases and IgG antibodies in 10 cases. Positivity to both IgM and IgG antibodies was revealed in five patients. Antibodies against Borrelia burgdorferi sensu lato were detected in 181 patients (57.64%). Co-seroprevalence of Borrelia burgdorferi s. l. and A. phagocytophilum was found in 26 patients (8.3%). Positivity for anti-A. phagocytophilum antibodies was most often seen in samples from the age group 60-69 years. Our results show that A. phagocytophilum infection is not uncommon in the Czech Republic and should be considered in patients with a history of a tick bite.

Seroprevalence of Anaplasma phagocytophilum in well maintained horses from northern Tunisia

The aim of the present study was to determine the seroprevalence of Anaplasma phagocytophilum in 343 well maintained horses belonging to 11 horse stables located in northern Tunisia with indirect immunofluorescence test. Overall, 16.3% (56/343) of tested animals were positive. Anti-A. phagocytophilum antibodies were present in horses located in all studied governorates except the governorate of Ben Arous. Nine horse stables out of 11 contained positive animals, the seroprevalence of each one varied from nought to 50%. Seroprevalence varied according to gender, breed and type of activity, contrary to age. Seroprevalence was higher in females than males (21.4 and 9.5% respectively). Similarly, seropositive animals belonging to the English thoroughbred breed was significantly higher (30.2%) than other breeds. According to the utilization of horses, the highest positivity rate (21.1%) was observed in brood mares. Our results demonstrate that A. phagocytophilum infection is widespread in well maintained horses from northern Tunisia, so equine granulocytic anaplasmosis should be suspected by veterinarians in front of suggestive clinical signs like fever, ataxia and reluctance to move.

[Asymptomatic human infection from contact with dogs: a case of human ehrlichiosis]

INTRODUCTION

Living with dogs leads one to consider the necessity of identifying canine infections found in the people with whom the dogs live.

OBJECTIVE

Dogs which were clinically and serologically positive with the infections Ehirlichia canis, Anaplasma phagocytophilum, Borrelia burgdorferi, and Dirofilaria Immitis were sought. People with the same infections were also identified.

MATERIAL AND METHODS

From a population of 80 dogs identified in the villages of San Bartolo Coyotepec and San Agustín Etla (suburbs peripheral to the city of Oaxaca, Mexico), 27 dogs were selected for study, all of which had adenomegaly, hepatomegaly, splenomegaly, and fevers of at least 43° C. Using enzyme immunoassay in this population of dogs and their closest human contacts, antibodies for Ehirlichia canis, Anaplasma phagocytophilum, Borrelia burgdorferi, and the antigen for Dirofilaria immitis were sought. Positive results in humans were confirmed by polymerase chain reaction (PCR).

RESULTS

Ten dogs with the clinical signs mentioned above tested positive for antibodies to Ehrlichia canis; two cases tested positive for Anaplasma phagocytophilum; one case tested positive for Dirofilaria Immitis. From human contact, one person tested positive for Ehirlichia canis; this case was confirmed by DNA amplification by means of PCR.

CONCLUSION

It is necessary to identify the population of sick dogs in order to reduce related infections in people.

Molecular characterization of Msp2/P44 of Anaplasma phagocytophilum isolated from infected patients and Haemaphysalis longicornis in Laizhou Bay, Shandong Province, China

Molecular characterization of the MSP2/P44 protein of Anaplasma phagocytophilum may determine not only if the bacterium is capable of invading hosts but also whether it generates antigenic variation for the purpose of escaping the host immune response, resulting in various pathologic injuries and serious clinical outcomes. Chinese anaplasmosis patients usually present with serious manifestations, and the fatality rate is as high as 26.5%. In this study, we amplified, cloned and sequenced the msp2/p44 genes of three Chinese A. phagocytophilum isolates from Laizhou Bay, Shandong Province, where human granulocytic anaplasmosis (HGA) patients present severe clinical manifestations, and analyzed their genetic characterization and structural features. We also compared them with the HZ and Webster A. phagocytophilum strains. The sequences for both strains are available in GenBank. Analyses indicated that Chinese A. phagocytophilum isolates were significantly different from the HZ and Webster strains in terms of nucleotide sequences, amino acid sequences and protein secondary and tertiary structures. Moreover, the number of immunologic B-cell epitopes (19) of the MSP2 protein of the Chinese isolates was higher than that of the A. phagocytophilum strains HZ (16) and Webster (9). This genetic diversity of the MSP2/P44 protein of Chinese A. phagocytophilum isolates might be relevant and might have serious clinical outcomes. This observation could provide a clue to further understand the pathogenesis of Chinese A. phagocytophilum.

[Human granulocytic anaplasmosis and its concurrence with other tick-borne infections in the Republic of Altai]

Human granulocytic anaplasmosis (HGA) cases occur everywhere in the Republic of Altai. Anaplasma phagocytophilum is transmitted to humans by at least three genera of ticks: Ixodes, Dermacentor, and Haemaphysalis. The risk of the infection is higher in the northern part of the republic. Most patients with HGA show serologic evidence of coinfection with North Asian tick typhus and other tick-borne diseases. The high probability of HGA concurrent with other tick-borne infections requires an integrated approach to preventing these diseases in the Republic of Altai.

Seroprevalence of tick-borne infections in military working dogs in the Republic of Korea

In this study we endeavored to determine the seroprevalence of tick-borne infections in the military working dog (MWD) population in the Republic of Korea (ROK). Our sample population consisted of 182 serum samples from MWDs for 3 different years (1996, 2002, and 2007). In addition, 63 whole blood samples from 2007 were available for polymerase chain reaction (PCR). Serum samples were evaluated by a commercially available enzyme-linked immunosorbent assay (ELISA) and immunofluorescence assay (IFA) for Ehrlichia canis and Anaplasma phagocytophilum, and by ELISA only for Borrelia burgdorferi. PCR amplification of DNA was performed to screen for Ehrlichia canis, E. chaffeensis, E. ewingii, Anaplasma phagocytophilum, A. platys, Borrelia burgdorferi, and Rickettsia rickettsii, as well as Babesia and Theileria species using previously published primers and probes. A total of 56 (30.8%) MWDs were positive by at least one serologic test. Seroprevalences for Anaplasma and Ehrlichia were 4.4% and 0.6% based on the ELISA, and 24.7% and 22.5% based on the IFA, respectively. ELISA testing for Borrelia yielded 2 (1.1%) positive results. In parallel testing using both the ELISA and IFA tests, the percentages of dogs with one or more positive results were 34.1%, 25.9%, and 28.4%, for 1996, 2002, and 2007, respectively. There was no significant differences in seroprevalence based on location, year, breed, or sex of the MWD. There was poor agreement between IFA and ELISA test results. No MWD sample had a positive PCR result. MWDs stationed in Korea had serologic evidence of exposure to several tick-borne pathogens, but PCR testing did not identify any active infections.

Anaplasma phagocytophilum dihydrolipoamide dehydrogenase 1 affects host-derived immunopathology during microbial colonization

Anaplasma phagocytophilum is a tick-borne rickettsial pathogen that provokes an acute inflammatory response during mammalian infection. The illness caused by A. phagocytophilum, human granulocytic anaplasmosis, occurs irrespective of pathogen load and results instead from host-derived immunopathology. Thus, characterizing A. phagocytophilum genes that affect the inflammatory process is critical for understanding disease etiology. By using an A. phagocytophilum Himar1 transposon mutant library, we showed that a single transposon insertion into the A. phagocytophilum dihydrolipoamide dehydrogenase 1 gene (lpda1 [APH_0065]) affects inflammation during infection. A. phagocytophilum lacking lpda1 revealed enlargement of the spleen, increased splenic extramedullary hematopoiesis, and altered clinicopathological abnormalities during mammalian colonization. Furthermore, LPDA1-derived immunopathology was independent of neutrophil infection and correlated with enhanced reactive oxygen species from NADPH oxidase and nuclear factor (NF)-κB signaling in macrophages. Taken together, these findings suggest the presence of different signaling pathways in neutrophils and macrophages during A. phagocytophilum invasion and highlight the importance of LPDA1 as an immunopathological molecule.

Evaluation of an indirect enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies against Anaplasma phagocytophilum in sheep

An indirect enzyme-linked immunosorbent assay (ELISA) for detection of antibodies against Anaplasma phagocytophilum in ovine serum samples was evaluated. The assay used purified A. phagocytophilum grown in tick cell cultures as antigen. Serum samples were diluted 1 in 200 and binding was detected with anti-sheep IgG conjugated to horseradish peroxidase. All tests were carried out in the presence of positive and negative control samples. Optical density (OD) values obtained for each test sample at 490 nm were used to calculate percentage positivity (PP) of each sample based on the ratio of the OD of the test sample that of the positive reference sample. Known negative samples (n=69) obtained from uninfected sheep bred and maintained in a tick-free environment and subsequently shown to be susceptible to A. phagocytophilum were used to establish the cut-off point between negative and positive samples and to establish the specificity of the test. Serum samples obtained from 92 animals 14-21 days after infection were used to establish the sensitivity of the test. Using a cut-off point of 20PP (mean+2 standard deviations of the PP of 69 control samples) the test was shown to have a sensitivity of 84.8% and a specificity of 95.7%. Lowering the cut-off point to 15PP increased the sensitivity to 94.6%, but reduced the specificity to 92.8%.

Prevalence of antibodies against Borrelia burgdorferi sensu lato and Anaplasma phagocytophilum and their clinical relevance in dogs in Munich, Germany

Although prevalences of antibodies against Borrelia (B.) burgdorferi sensu lato (sl) and Anaplasma (A.) phagocytophilum have been reported to be high in the German dog population, the importance of the diseases caused by both agents is still not well characterized in a field situation.The aim of this study was (1) to determine the prevalence of antibodies to B. burgdorferi sl and A. phagocytophilum in dogs in Munich, Germany, and (2) to assess the clinical presentation and laboratory values of antibody-positive dogs and compare them to a negative control group. In total, 448 randomly selected dogs were screened for antibodies to B. burgdorferi sl and A. phagocytophilum with the SNAP 4Dx assay (IDEXX, Laboratories, Inc., USA). Dogs carrying antibodies against B. burgdorferi sl and/or A. phagocytophilum were classified as "positive"(n=100), the following 100 negative dogs served as control group. In both groups, physical examination and laboratory parameters were compared. 22 (4.9%) dogs had antibodies to B. burgdorferi sl, 78 (19.4%) to A. phagocytophilum, nine (2.0%) to both agents. Bernese Mountain Dogs had significantly more often antibodies against B. burgdorferi sl. Negative dogs were more often diagnosed as "healthy" compared to A. phagocytophilum antibody-positives that showed more often elevated body temperature and poor general condition; beyond that, there were no differences in clinical and laboratory abnormalities between both groups. Although dogs tested negative were more often considered healthy, there were no differences in parameters considered "specific" for both infections between dogs with and without antibodies. Hence, tests detecting antibodies against both agents are not able to detect animals with the clinical disease.

Determining the repertoire of immunodominant proteins via whole-genome amplification of intracellular pathogens

Culturing many obligate intracellular bacteria is difficult or impossible. However, these organisms have numerous adaptations allowing for infection persistence and immune system evasion, making them some of the most interesting to study. Recent advancements in genome sequencing, pyrosequencing and Phi29 amplification, have allowed for examination of whole-genome sequences of intracellular bacteria without culture. We have applied both techniques to the model obligate intracellular pathogen Anaplasma marginale and the human pathogen Anaplasma phagocytophilum, in order to examine the ability of phi29 amplification to determine the sequence of genes allowing for immune system evasion and long-term persistence in the host. When compared to traditional pyrosequencing, phi29-mediated genome amplification had similar genome coverage, with no additional gaps in coverage. Additionally, all msp2 functional pseudogenes from two strains of A. marginale were detected and extracted from the phi29-amplified genomes, highlighting its utility in determining the full complement of genes involved in immune evasion.

Seroprevalence and bacteremia [corrected] of Anaplasma phagocytophilum in cats from Bavaria and Lower Saxony (Germany)

Anaplasma (A.) phagocytophilum is a tick-transmitted obligate intracellular bacterium and has been identified in a wide range of mammalian species, causing febrile disease in some. Few reports show that it can also cause granulocytic anaplasmosis in cats. As data on the occurrence of A. phagocytophilum in cats from Germany is limited, a total of 326 serum and 306 EDTA-blood samples from cats from Germany were screened by direct (Giemsa-stained blood/buffy coat smears, real-time PCR) and indirect (IFAT) methods. Of 274 Giemsa-stained blood smears which could be evaluated none was positive for morulae, but one blood sample (< or =0.1%; 1/306) was positive for A. < or = phagocytophilum-DNA in PCR. Antibodies (cutoff > or = 1:64) were detected in 53 out of 326 samples (16.2%). Altogether, the results show a high seroprevalence rate of anti-A. phagocytophilum antibodies in cats in Germany while the low detection rate of this bacterial agent by direct methods is similar to those of other studies on A. phagocytophilum infections in cats.

Adaptive immunity to Anaplasma pathogens and immune dysregulation: implications for bacterial persistence

Anaplasma marginale is an obligate intraerythrocytic bacterium that infects ruminants, and notably causes severe economic losses in cattle worldwide. Anaplasma phagocytophilum infects neutrophils and causes disease in many mammals, including ruminants, dogs, cats, horses, and humans. Both bacteria cause persistent infection - infected cattle never clear A. marginale and A. phagocytophilum can also cause persistent infection in ruminants and other animals for several years. This review describes correlates of the protective immune response to these two pathogens as well as subversion and dysregulation of the immune response following infection that likely contribute to long-term persistence. I also compare the immune dysfunction observed with intraerythrocytic A. marginale to that observed in other models of chronic infection resulting in high antigen loads, including malaria, a disease caused by another intraerythrocytic pathogen.

[Serology of Lyme borreliosis and human granulocytic ehrlichiosis in 2005-2010]

The subject of this study is serological screening of blood and CSF (cerebrospinal fluid) samples for the presence of borrelial and ehrlichial antibodies. A total of 165 patients suspected to be at risk of Lyme disease were tested. Indirect immunofluorescence and enzyme immunoassay were used as diagnostic methods. Ehrlichial antibodies were detected in 36 (21.8%) patients. Borrelial antibodies were found in 70 samples (42.4%). The widening range of tick-borne diseases brings about the need for more data on these zoonoses.

Seroprevalence of Borrelia burgdorferi, Anaplasma phagocytophilum, Ehrlichia canis, and Dirofilaria immitis among dogs in Canada

The seropositivity of dogs to Borrelia burgdorferi, Anaplasma phagocytophilum, and Ehrlichia canis antibodies, and Dirofilaria immitis antigen was assessed in Canada. Borrelia burgdorferi had the highest seroprevalence, while that of Dirofilaria immitis has not changed significantly in the past 20 y. The risk for these vector-borne infectious agents in Canadian dogs is low but widespread with foci of higher prevalence.

Antigen diversity in the parasitic bacterium Anaplasma phagocytophilum arises from selectively-represented, spatially clustered functional pseudogenes

Anaplasma phagocytophilum is a tick-transmitted bacterial pathogen of humans and other animals, and is an obligate intracellular parasite. Throughout the course of infection, hosts acquire temporary resistance to granulocytic anaplasmosis as they develop immunity specific for the major antigen, major surface protein 2 (Msp2). However, the bacterium then utilizes a novel recombination mechanism shuffling functional pseudogenes sequentially into an expression cassette with conserved 5' and 3' ends, bypassing host immunity. Approximately 100 pseudogenes are present in the only fully sequenced human-origin HZ genome, representing the possibility for almost unlimited antigenic diversity. In the present study, we identified a select group of 20% of the A. phagocytophilum HZ msp2 pseudogenes that have matched preferentially to human, canine, and equine expression cassettes. Pseudogenes cluster predominantly in one spatial run limited to a single genomic island in less than 50% of the genome but phylogenetically related pseudogenes are neither necessarily located in close proximity on the genome nor share similar percent identity with expression cassettes. Pseudogenes near the expression cassette (and the origin) are more likely to be expressed than those farther away. Taken together, these findings suggest that there may be natural selection pressure to retain pseudogenes in one cluster near the putative origin of replication, even though global recombination shuffles pseudogenes around the genome, separating pseudogenes that share genetic origins as well as those with similar identities.

Seroprevalence of human granulocytotropic anaplasmosis in central and southeastern China

Human granulocytic anaplasmosis (HGA) is an emerging tick-borne infectious disease. To determine the prevalence of HGA in central and southeastern China, a total of 323 human sera were collected from individuals at high risk for exposure to ticks and animals. The IgG antibody against the etiologic agent of HGA, Anaplasma phagocytophilum was detected with indirect immunofluorescence assay. The results showed that 20% of the tested individuals (64/323) were positive to A. phagocytophilum and that the incidence was higher in male (22%) than female (16%). We concluded that A. phagocytophilum infection was prevalent in central and southeastern China.

Variant-specific and diminishing immune responses towards the highly variable MSP2(P44) outer membrane protein of Anaplasma phagocytophilum during persistent infection in lambs

Anaplasma phagocytophilum is the causative agent of tick-borne fever in small ruminants and has been identified as the zoonotic agent of human granulocytic anaplasmosis. The Norwegian strains of the rickettsia are naturally persistent in lambs and represent a suitable experimental system for analyzing the mechanisms of persistence. Variation of the outer membrane protein MSP2(P44) by recombination of variable pseudogene segments into an expression site is believed to play a key role in persistence of the organism. The goal of the present study was to analyze the dynamics of the immune response towards A. phagocytophilum and MSP2(P44) during persistent infection of lambs. Responses to the hypervariable region of MSP2(P44) were detected shortly after appearance of the respective variants in cyclic rickettsemic peaks, consistent with a process of antigenic variation. In addition, there was a diminishing antibody response to MSP2(P44) and to other A. phagocytophilum antigens overall with time of infection, that was not associated with clearance of the infection.

Short report: serologic evidence of human ehrlichiosis in Peru

A serosurvey for human ehrlichiosis caused by Ehrlichia chaffeensis and Anaplasma phagocytophilum was performed in different regions of Peru by using indirect immunofluorescence assays (IFAs). Regions included an urban community in a shantytown in Lima (Pampas) and three rural communities located on the northern coast of Peru (Cura Mori), in the southern Peruvian Andes (Cochapata), and in the Peruvian jungle region (Santo Tomas). An overall E. chaffeensis seroprevalence of 13% (21 of 160) was found by IFA. Seroprevalences in females and males was 15% (16 of 106) and 9% (5 of 53), respectively. Seroprevalences in Cura Mori, Cochapata, Pampas, and Santo Tomas were 25% (10 of 40), 23% (9 of 40), 3% (1 of 40), and 3% (1 of 40), respectively. Seroprevalences in Cura Mori and Cochapata were significantly higher than in Santo Tomas or Pampas (P < 0.01). No sera were reactive to A. phagocytophilum. These findings suggest that human infection with E. chaffeensis occurs in Peru. Further studies are needed to characterize Ehrlichia species in Peru, their vectors and their clinical significance.

Occurrence of IgG antibodies to Anaplasma phagocytophilum in humans suspected of Lyme borreliosis in eastern Slovakia

Human granulocytic anaplasmosis (HGA) and Lyme borreliosis (LB) are tick-borne and emerging infectious diseases caused by the Anaplasma phagocytophilum and Borrelia burgdorferi species. In Europe, including Slovakia, the principal vector of both pathogens is the common tick - Ixodes ricinus, in which double infections with these pathogens have been reported. The aim of our study was evidence of IgG antibodies against A. phagocytophilum in blood sera of humans with suspects LB from several Clinics of University Hospitals, and the evaluation of the possibility of B. burgdorferi and A. phagocytophilum co-infection in examined patients. The serological method ELISA was used to detect IgM and IgG antibodies against B. burgdorferi. Anti-A. phagocytophilum IgG antibodies were analyzed by the A. phagocytophilum Indirect Immunofluorescence Antibody (IFA) IgG test. A total of 214 human samples (91 men, 123 women) were obtained from patients living in Kosice town and in villages around Kosice (Eastern Slovakia). IgG antibodies against A. phagocytophilum were detected in 15 cases (6 men, 9 women), which represented 7.0 % positivity. Two cases of the co-infection B. burgdorferi with A. phagocytophilum, which equals 0.93 % of the total number, were found.

Anaplasma phagocytophilum transmitted through blood transfusion--Minnesota, 2007

Anaplasma phagocytophilum, a gram-negative, obligate intracellular bacterium of neutrophils, causes human anaplasmosis, a tickborne rickettsial disease formerly known as human granulocytic ehrlichiosis. In November 2007, the Minnesota Department of Health was contacted about A. phagocytophilum infection in a hospitalized Minnesota resident who had recently undergone multiple blood transfusions. Subsequent investigation indicated the infection likely was acquired through a transfusion of red blood cells. This report describes the patient's clinical history and the epidemiologic and laboratory investigations. Although a previous case of transfusion-transmitted anaplasmosis was reported, this is the first published report in which transfusion transmission of A. phagocytophilum was confirmed by testing of the recipient and a donor. Although polymerase chain reaction (PCR) assays provided reliable evidence of transmission in this case, no cost-effective method for screening blood donors for A. phagocytophilum exists. Screening donors for a recent history of tick bite is not likely to be sensitive or specific because such exposures are common and often not recalled by persons with anaplasmosis. Physicians should consider the possibility of anaplasmosis in patients who develop posttransfusion acute thrombocytopenia, especially if accompanied by fever, and should report suspected transfusion-associated cases to health authorities.

[Cross-reaction evaluation of PCR-Anaplasma platys positive dogs tested to Anaplasma phagocytophilum antibodies by commercial ELISA]

Anaplasma platys, agent of canine cyclic thrombocytopenia parasites exclusively dogs platelets. Its probable vector is the tick Rhipicephalus sanguineus. Among the existent diagnostic methods, the most used include: morulae identification in blood smears; antibody detection by indirect immunofluorescence; or DNA amplification by polymerase chain reaction (PCR). Recently a new commercial ELISA (IDEXX®), capable of detecting A. phagocytophilum antibodies, has been developed. According to the manufacturer it appears to have a serological cross reaction with A. platys which may be used to help in the diagnosis of this agent. The aim of this study was to test serum samples from 16 PCR-positive dogs to A. platys with an ELISA that detects antibodies to A. phagocytophilum, Borrelia burgdorferi and Ehrlichia canis, and antigens of Dirofilaria immitis in order to verify the occurrence of cross reaction between A. platys and A. phagocytophilum. All animals tested negative for A. phagocytophilum, B. burgdorferi, and D. immitis. One animal tested positive for E. canis. Although it's known that A. phagocytophilum presents serological cross reaction with A. platys, the tested animals were negative, once antibodies against A. platys were not detected probably because of the acute phase of the disease.

Seroprevalence of Anaplasma phagocytophilum in domestic and wild animals from central Italy

From January 2004 to July 2007, 2455 sera were collected from domestic and wild animals living in central Italy and tested by indirect immunofluorescence assay to detect antibodies against Anaplasma phagocytophilum. Considering sera with 1:40 antibody titers as positive, 336 (13.68%) animals scored positive. The percentages of seropositivity were: 46.26% (31/67) in fallow deer, 46.15% (24/52) in red deer, 16.89% (134/793) in horses, 16.78% (23/137) in cattle, 12.74% (13/102) in sheep, 8.76% (108/1232) in dogs, 4.16% (3/72) in goats. These data confirm the presence of A. phagocytophilum in wild ruminants and domestic animals, including pets, in central Italy.

Mitogenic component in polar lipid-enriched Anaplasma phagocytophilum membranes

Human granulocytic anaplasmosis is an emerging tick-borne disease caused by Anaplasma phagocytophilum. A. phagocytophilum cells activate Toll-like receptor 2 signaling and possess mitogenic activity, and A. phagocytophilum infection in vivo activates NKT cells unrelated to major surface protein 2 (Msp2) hypervariable region expression. Thus, we hypothesized that lipoprotein or glycolipid components of A. phagocytophilum membranes could be important triggers of the innate immune response and immunopathology. A. phagocytophilum membranes depleted of Msp2 and protein antigens enhanced the proliferation of naïve mouse splenocytes beyond that of untreated membranes. Protein-depleted and polar lipid-enriched membranes from low-passage A. phagocytophilum cultures enhanced naïve splenocyte lymphoproliferation to a much greater degree than did these fractions from high-passage cultures of bacterial membranes (1.8- to 3.7-fold for protein-depleted fractions and 4.8- to > or =17.7-fold for polar lipid-enriched fractions). These results support the hypothesis that components that are enriched among polar lipids in the A. phagocytophilum membrane stimulate innate immune cell proliferation, possibly activating NKT cells that link innate and adaptive immunity, and immunopathology.

Gray foxes (Urocyon cinereoargenteus) as a potential reservoir of a Bartonella clarridgeiae-like bacterium and domestic dogs as part of a sentinel system for surveillance of zoonotic arthropod-borne pathogens in northern California

Two species of Bartonella, a novel Bartonella clarridgeiae-like bacterium and B. vinsonii subsp. berkhoffii, were isolated from rural dogs and gray foxes in northern California. A novel B. clarridgeiae-like species was isolated from 3 (1.7%) of 182 dogs and 22 (42%) of 53 gray foxes, while B. vinsonii subsp. berkhoffii was isolated from 1 dog (0.5%) and 5 gray foxes (9.4%). PCR and DNA sequence analyses of the citrate synthase (gltA) gene and the 16S-23S intergenic spacer region suggested that strains infecting dogs and gray foxes were identical. Fifty-four dogs (29%) and 48 gray foxes (89%) had reciprocal titers of antibodies against Bartonella spp. of > or =64. The high prevalence of bacteremia and seroreactivity to Bartonella spp. in gray foxes suggests that they may act as a reservoir species for the B. clarridgeiae-like species in this region. Domestic dogs were also tested for other arthropod-borne infectious agents. Fifty-one dogs (28%) were positive for Dirofilaria immitis antigen, seventy-four (40%) were seroreactive to Anaplasma phagocytophilum, and five (2.7%) were seropositive for Yersinia pestis. Fourteen dogs (7.6%) were PCR positive for A. phagocytophilum. Polytomous logistic regression models were used to assess the association of Bartonella antibody titer categories with potential risk factors and the presence of other vector-borne agents in domestic dogs. Older dogs were more likely to be seroreactive to Bartonella spp. There was no association between the exposure of dogs to Bartonella and the exposure of dogs to A. phagocytophilum in this study.

[Clinical and serological evidence of canine rickettsiosis in Chile]

Rickettsial infections in pets have not been documented in Chile. Some of those infections have relevant zoonotic potential.

OBJECTIVES

To report two serologically confirmed cases of canine rickettsiosis. To determine seroprevalence to Rickettsia sp in a group of dogs.

METHODS

IgG antibodies anti-R. conorii and anti-A. phagocitophilum by IFI in two dogs with clinical rickettsiosis. IgG antibodies anti-R. conorii in a group of 77 dogs.

RESULTS

CLINICAL CASES

a dog presented with fever, myalgias and melena, another dog with bleeding and neurological involvement. Seroprevalence: 35% of the dogs had antibodies against Rickettsia.

DISCUSSION

This is the first evidence of canine rickettsiosis in Chile, both clinical and serological. Co-infection with two tickborne agents: Rickettsia and Anaplasma, is documented. Molecular studies are needed to confirm the rickettsial species present in Chile. The zoonotic role of these infections must be also studied.

Antibodies to whole-cell or recombinant antigens of Borrelia burgdorferi, Anaplasma phagocytophilum, and Babesia microti in white-footed mice

Serum samples were obtained from white-footed mice (Peromyscus leucopus) in tick-infested areas of Connecticut during the period 2001 through 2003 and analyzed for antibodies to Borrelia burgdorferi, Anaplasma phagocytophilum, and Babesia microti. Emphasis was placed on the evaluations of highly specific recombinant VlsE or protein (p) 44 antigens of B. burgdorferi and A. phagocytophilum, respectively, in a newly developed enzyme-linked immunosorbent assay (ELISA) as well as testing sera with whole-cell antigens by conventional ELISA or indirect fluorescent antibody staining methods. Of the 414 mouse sera analyzed, 310 (75%) had antibodies to whole-cell B. burgdorferi, whereas 157 (38%) were positive to the VlsE antigen. The latter nearly equaled the overall antibody prevalence rate (37%) computed when sera were tested separately with the p44 antigen. Mice were exposed to these pathogens and B. microti (antibody prevalence = 25%) in extreme northern Connecticut as well as the southern coastal areas of the state, thus indicating further geographic expansion of these infections. Fifty-three (13%) sera from widely separated sites had antibodies to all three pathogens. With expression and immunological recognition of VlsE and p44 antigens in P. leucopus, separate incorporation of these fusion proteins in an ELISA was very helpful in confirming past or current infections and in identifying specific foci for B. burgdorferi and A. phagocytophilum.

Differential innate immune cell activation and proinflammatory response in Anaplasma phagocytophilum infection

Human granulocytic anaplasmosis (HGA) is caused by the obligate intracellular bacterium Anaplasma phagocytophilum. The critical role of gamma interferon (IFN-gamma) for induction of severe inflammatory histopathology, even in the absence of a significant bacterial load, was previously demonstrated in a murine model of HGA. We hypothesized that NK, NKT, and possibly CD8(+) cytotoxic T cells participate in the development of histopathologic lesions with A. phagocytophilum infection. Mice were mock infected or infected with low- or high-passage A. phagocytophilum and assayed for hepatic histopathology and splenocyte immunophenotype during the first 21 days after infection. Compared to high-passage A. phagocytophilum-infected mice, low-passage A. phagocytophilum-infected mice had more severe hepatic lesions and increased apoptosis. The hepatic histopathology severity in low-passage A. phagocytophilum-infected mice peaked on day 2 at the time of peak plasma IFN-gamma levels and gradually decreased through day 21. Low-passage A. phagocytophilum-infected mice also showed significantly increased levels of lymphocyte NK1.1/FasL expression on days 4 to 7 corresponding to early, severe hepatic inflammation, whereas the levels of NKT cells were substantially lower on day 4, suggesting that there was NKT cell involvement. This result supports the concept that NK1.1(+) cells, including NK and NKT cells, are major components in the early pathogenesis of A. phagocytophilum infection.

Msp2 variation inAnaplasma phagocytophilum in vivodoes not stimulate T cell immune responses or interferon-γ production

Msp2 is Anaplasma phagocytophilum's immunodominant protein. Antigenic variability with msp2 gene conversion may drive differential immunopathology with infection by bacteria of different in vitro passage intervals. We examined msp2 transcript variation and its relationship to histopathology, T-cell and antibody responses in mice infected with differentially passaged A. phagocytophilum. Hepatic inflammation peaked on day 2-4 with low passage bacteria and on day 4-7 with high passage bacteria infection. Nineteen msp2 variant transcripts were identified. The low and high passage inocula shared four, but differed in one and two msp2 transcript variants, respectively. After infection, three and two msp2 variants were only identified in low or high passage infected mice. However, per mouse, msp2 variant profiles were unique with no evident expression program. In low and high passage bacteria-infected mice, splenocytes proliferated to whole A. phagocytophilum at day 7-10, diminishing thereafter. Weak mitogenic responses to whole bacteria were detected in mock and infected mice at d0 and sporadically thereafter. Essentially no lymphoproliferation or IFN-gamma production resulted from stimulation by six Msp2 hypervariable region proteins, although antibodies were detected to all, including cross-reactions. Differential A. phagocytophilum Msp2 expression is unrelated to T-cell response and unlikely to induce the cellular immunopathology underlying disease manifestations.

Evidence of tick-borne organisms in mule deer (Odocoileus hemionus) from the western United States

Free-ranging mule deer (MD; Odocoileus hemionus) from Arizona and California were tested for evidence of infection with several tick-borne pathogens, including species of Ehrlichia, Anaplasma, Babesia, and Borrelia. Of 125 mule deer tested from Arizona, 29 (23%) and 11 (9%) had antibodies reactive to E. chaffeensis and A. phagocytophilum by indirect immunofluorescent antibody testing, respectively; none of the six MD tested from California were seropositive. Using a commercial competitive ELISA kit, antibodies reactive to Anaplasma spp. were detected in 19 (15%) MD from Arizona and four of six (67%) MD from California. Polymerase chain reaction (PCR) testing for tick-borne pathogens was conducted on blood samples from 29 MD from Arizona and 11 MD from California. Twenty-two of 29 (75.9%) MD from Arizona had PCR evidence of infection with at least one tick-borne pathogen. We detected an Anaplasma sp. in 19 of 29 (65.5%) MD and a Babesia sp. in 10 of 29 (34%) MD. Sequencing of these amplicons indicated that the Anaplasma sp. was the same that had previously been detected in MD from California and the Babesia sp. was similar to one previously detected in a reindeer (Rangifer tarandus tarandus) from California. All of the California MD had evidence of infection with a tick-borne pathogen. Two different species of Anaplasma spp. were detected in MD from California, eight of of 11 MD were infected with an Anaplasma sp., and three of 11 MD were infected with A. ovis. This is the first report of a mule deer naturally infected with A. ovis. Ten of 11 MD from California were infected with a Babesia-like organism previously associated with human disease, and a single MD was PCR positive for Borrelia coriaceae, which has been associated with epizootic bovine abortion. Together, these data suggest that MD in northern Arizona and eastern California are exposed to several pathogens of human and veterinary importance.

Characterization of Anaplasma phagocytophilum major surface protein 5 and the extent of its cross-reactivity with A. marginale

Major surface protein 5 (Msp5) of Anaplasma marginale is highly conserved in the genus Anaplasma and the antigen used in a commercially available competitive enzyme-linked immunosorbent assay (cELISA) for serologic identification of cattle with anaplasmosis. This study analyzes the degrees of conservation of Msp5 among various isolates of Anaplasma phagocytophilum and the extent of serologic cross-reactivity between recombinant Msp5 (rMsp5) of Anaplasma marginale and A. phagocytophilum. The msp5 genes from various isolates of A. phagocytophilum were sequenced and compared. rMsp5 proteins of A. phagocytophilum and A. marginale were used separately in an indirect ELISA to detect cross-reactivity in serum samples from humans and dogs infected with A. phagocytophilum and cattle infected with A. marginale. Serum samples were also tested with a commercially available competitive ELISA that uses monoclonal antibody ANAF16C1. There were 100% sequence identities in the msp5 genes among all of the A. phagocytophilum isolates from the United States and a horse isolate from Sweden. Sheep isolates from Norway and dog isolates from Sweden were 99% identical to one another but differed in 17 base pairs from the United States isolates and the horse isolate. Serologic cross-reactivity was identified when serum samples from cattle infected with A. marginale were reacted with rMsp5 of A. phagocytophilum and when serum samples from humans and dogs infected with A. phagocytophilum were reacted with rMsp5 of A. marginale in an indirect-ELISA format. Serum samples from dogs or humans infected with A. phagocytophilum did not cross-react with rMsp5 of A. marginale when tested with the commercially available cELISA. These results suggest that rMsp5 of A. phagocytophilum is highly conserved among United States and European isolates and that serologic distinction between A. phagocytophilum and A. marginale infections cannot be accomplished if rMsp5 from either organism is used in an indirect ELISA.

Prevalence of Anaplasma phagocytophilum in Ixodes ricinus ticks determined by polymerase chain reaction with two pairs of primers detecting 16S rRNA and ankA genes

A total of 684 Ixodes ricinus ticks (321 nymphs, 184 males, and 179 females) were collected by flagging lower vegetation in 6 forest districts located on the territory of Lublin province (eastern Poland). Ticks were examined by polymerase chain reaction (PCR) method for the presence of Anaplasma phagocytophilum DNA with two pairs of primers: EHR521/EHR747 for detecting 16S rRNA gene, and LA6/LA1 for detecting ankA gene. To study the relationship between infection in ticks and people occupationally exposed to tick bite, blood serum samples of 261 forestry workers employed in the same forest districts were examined by immunofluorescence method for the presence of specific antibodies against A. phagocytophilum. A total of 70 ticks out of 684 examined (10.2%) showed the presence of A. phagocytophilum 16S rRNA gene. The prevalence of infection was significantly dependent on tick's stage (chi-square=49.2, p<0.00001) and geographical locality (chi-square=34.4, p<0.00001). The percentage of I. ricinus females infected with A. phagocytophilum (24.6%) was significantly greater compared to males (6.5%) and nymphs (4.4%) (p<0.00001). Only 19 ticks out of 684 examined (2.8%) showed the presence of A. phagocytophilum ankA gene, significantly less compared to 16S rRNA gene (p<0.00001). The prevalence of infection demonstrated by the presence of ankA gene was also significantly dependent on tick's stage (chi-square=23.6, p<0.00001) but not on locality (chi-square=9.8, p=0.082). A significant correlation was found between the presence of A. phagocytophilum 16S rRNA gene in I. ricinus female ticks from the particular forest districts and the serologic response to A. phagocytophilum of forestry workers employed in the same districts (p<0.05). No significant correlation was found between the presence of A. phagocytophilum ankA gene in I. ricinus ticks and serologic response of exposed workers. In conclusion, detection of A. phagocytophilum infection in ticks by PCR with the use of EHR521/EHR747 primers detecting 16S rRNA gene is significantly more sensitive compared to LA6/LA1 primers detecting ankA gene.

Epidemiological, clinical and laboratory characteristics of patients with human granulocytic anaplasmosis in Slovenia

Human granulocytic anaplasmosis (HGA) has been recently recognized as an emerging tick-borne disease. Several reports indicate the presence of infection with Anaplasma phagocytophilum in Europe. Between January 1996 and December 2004, 24 adult patients with proven HGA were identified in a prospective study conducted at the Department of Infectious Diseases, University Medical Center Ljubljana, Slovenia, on the etiology of febrile illnesses occurring within 30 days after a tick bite. The diagnosis of acute HGA was established from seroconversion in 18 (75%) patients or at least a four-fold increase in antibody titers to A. phagocytophilum antigens in six (25%) patients and molecular identification of ehrlichial organisms in 15 (62.5%) patients. Clinical characteristics and laboratory findings were similar to those reported from the other European countries. All the patients had an acute febrile illness with headache, malaise, myalgia and/or arthralgia. Leukopenia was found in 16 (66.7%) patients, thrombocytopenia in 20 (83.3%), abnormal liver function test results in 23 (95.8%), elevated erythrocyte sedimentation rates in 18 (75%), and elevated concentration of C-reactive protein in 23 (95.8%). The disease course was relatively mild; none of the patients died and no long-term sequelae were found during a follow-up of one year even though only 15 (62.5%) were treated with doxycycline. At the examination one year after the first visit, 16/24 (66.7%) patients tested seropositive (> or =1 : 256) for A. phagocytophilum antibody, and two years after the first visit positive titers were still present in 10/18 (55.6%) patients.

Seroprevalence of human granulocytic anaplasmosis in Berlin/Brandenburg, Germany: an 8-year survey

This study investigated the seroprevalence of antibodies against Anaplasma phagocytophilum in Berlin/Brandenburg, north-eastern Germany. During 1994-2001, 422 sera from patients with proven tick-exposure (specimens with antibodies against Borrelia burgdorferi) were compared with 249 control sera. Using indirect fluorescent antibody testing, significantly more positive samples were detected among Borrelia antibody-positive specimens (4.5%, 95% CI 2.5-6.5%) than among controls (1.2%, 95% CI 0.5-1.9%; p < 0.05). While six (2.2%, 95% CI 1.3-3.1%) samples were positive among Borrelia antibody-positive sera between 1994 and 1997, 13 (8.7%, 95% CI 6.9-10.5%) were positive between 1998 and 2001 (p < 0.01), indicating an uneven annual seroprevalence.

New Findings on Anaplasmosis Caused by Infection withAnaplasma phagocytophilum

Ixodes ricinus (I. ricinus) is one of the vectors of Anaplasma phagocytophilum (A. phagocytophilum) in Europe, in which rates of infection range from 1.9% to 34%. In 1998, human granulocytic ehrlichiosis-like (HGE-like) Ehrlichia DNA was detected in Italy, by PCR technique in one I. ricinus nymph out of 55 ticks that were examined. In 1996, 6.3% of 310 human sera in high-risk subjects from Italy were found positive for antibodies to Ehrlichia phagocytophila (E. phagocytophila). In the same year, the authors reported the first case of equine granulocytic ehrlichiosis. In 1997, only 2 out of 563 equine blood samples examined were found positive for antibodies to E. phagocytophila in the Latium region. In 1998, serological positivity was not observed in 14 symptomatic race horses. In 2002, a symptomatic horse living in Rome was found positive for Ehrlichia equi (E. equi) antibodies, as confirmed by PCR. E. equi was also demonstrated in horses by detection of specific antibodies from two asymptomatic ponies. We tested 128 sera from sheep in different flocks, and antibodies to E. phagocytophila were detected in 17 sera (13.3%) of these sheep. From 2000 to 2004, 147 dog sera were tested for antibodies against A. phagocytophilum, and 7 of these sera were positive (4.8%). These data confirm the presence of the infection in human, domestic animals, and pets in Italy. Studies are under way to correlate the distributions of the disease and tick vector, I. ricinus.

Evaluation of white-tailed deer (Odocoileus virginianus) as natural sentinels for Anaplasma phagocytophilum

Anaplasma phagocytophilum, the causative agent of human granulocytotropic anaplasmosis, can infect white-tailed deer (WTD; Odocoileus virginianus), and this species is a crucial host for adult Ixodes scapularis, the primary vector of A. phagocytophilum. The goal of this study was to determine the geographic distribution of A. phagocytophilum among WTD across a 19 state region and to evaluate the utility of WTD as natural sentinels. Serologic testing using the indirect fluorescent antibody (IFA) assay was conducted on WTD serum samples and molecular and xenodiagnostic tests were performed to confirm serologic results. The surveillance system was assessed through examination of vital attributes including WTD age and gender associations with serologic status, sample size adequacy for accurate infection status classification, and presence of the vector, I. scapularis. Six hundred thirty-three of 2,666 (24%) WTD in 17 states tested positive for antibodies (>or=128) when tested by IFA assay. Testing for p44 and/or 16S rRNA gene targets identified 73 (16%) PCR positive WTD among 458 animals tested, all of which originated from seropositive populations. Attempts to culture A. phagocytophilum from WTD were unsuccessful; however, xenodiagnostic mice inoculated with blood from 3 WTD became infected. Seroprevalence did not differ by deer age or gender; however, WTD<or=0.75 years old had a higher prevalence of PCR positivity. Using seroprevalence data, a sample size of 6-9 animals per population was projected to be adequate for identifying seropositive populations. The presence of I. scapularis was significantly associated with A. phagocytophilum antibodies in WTD. Collectively, the results of this study demonstrate that WTD would be suitable natural sentinels for this emerging zoonotic pathogen.

Serosurveillance forAnaplasma phagocytophilumAntibodies in White-Tailed Deer (Odocoileus virginianus) in Iowa, USA

Cases of human granulocytic anaplasmosis have increased in number and are being identified in new geographic areas since its discovery in 1994. White-tailed deer (WTD) become infected with the causative agent, Anaplasma phagocytophilum, and serve as natural sentinels for this organism. In order to determine if A. phagocytophilum is present in the state of Iowa, sera collected from 628 WTD in 2004 from 13 sites and from 282 WTD in 1999 from a single, common site were tested by enzyme-linked immunosorbent assay and Western immunoblotting. A seroprevalence of 9.1% was found among the 2004 samples, and there was no change in seropositivity rates from 1999 to 2004 at the single, common site. As A. phagocytophilum is another tick-borne human pathogen to be identified in the state of Iowa, this study has important implications for health care providers.

Innate immune response to Anaplasma phagocytophilum contributes to hepatic injury

In mice, Anaplasma phagocytophilum control is independent of phagocyte oxidase (phox), inducible NO synthase (NOS2), tumor necrosis factor (TNF), and MyD88 Toll-like receptor signaling. We show that despite evasion of these host responses, phox, NOS2, TNF, and MyD88 are activated and contribute to inflammation and hepatic injury more than A. phagocytophilum itself.