Comparison of a real-time PCR method with serology and blood smear analysis for diagnosis of human anaplasmosis: importance of infection time course for optimal test utilization

Epidemiology of Anaplasma species amongst cattle in Africa from 1970 to 2022: A systematic review and meta-analysis

Tick-borne pathogens of the genus Anaplasma cause anaplasmosis in livestock and humans, impacting health and livelihoods, particularly in Africa. A comprehensive review on the epidemiology of Anaplasma species is important to guide further research and for implementation of control approaches. We reviewed observational studies concerning Anaplasma species amongst cattle in Africa. Peer-reviewed studies published in PubMed, Google Scholar, and Web of Science - from database inception to 2022 - were searched. The quality of individual studies was assessed using the Joanna Briggs Institute Critical Appraisal Tool and the pooled prevalences by diagnostic method were estimated using random-effects models. Heterogeneity across the studies was tested and quantified using the Cochran's Q statistic and the I2 statistic. Potential sources of heterogeneity were investigated by subgroup analysis. A total of 1117 records were retrieved and at the end of the screening, 149 records (155 studies) were eligible for this meta-analysis. The occurrence of Anaplasma species was reported in 31/54 countries in all regions. Seven recognised species (A. marginale, A. centrale, A. phagocytophilum, A. platys, A. capra, A. bovis, A. ovis) and nine uncharacterised genotypes (Anaplasma sp. Hadesa; Anaplasma sp. Saso; Anaplasma sp. Dedessa; Anaplasma sp. Mymensingh; Anaplasma sp. Lambwe-1; Candidatus Anaplasma africae; Anaplasma sp.; Candidatus Anaplasma boleense) were reported in African cattle. Anaplasma marginale was the most frequently reported (n=144/155 studies) and the most prevalent species (serology methods 56.1%, 45.9-66.1; direct detection methods 19.9%, 15.4-24.7), followed by A. centrale (n=26 studies) with a prevalence of 8.0% (95% CI: 4.8-11.9) and A. platys (n=19 studies) with prevalence of 9.7% (95% CI: 5.4-15.2). Anaplasma marginale, A. centrale and A. platys were reported in all Africa's regions, while A. ovis and A. capra were reported only in the northern and central regions. The uncharacterised Anaplasma taxa were mostly detected in the eastern and southern regions. Subgroup analysis showed that significant determinants for A. marginale exposure (serology) were geographical region (p=0.0219), and longitude (p=0.0336), while the technique employed influenced (p<0.0001) prevalence in direct detection approaches. Temperature was the only significant variable (p=0.0269) for A. centrale. These findings show that various Anaplasma species, including those that are zoonotic, circulate in African cattle. There is need for more genetic and genome data, especially for unrecognised species, to facilitate effective identification, improve livestock and minimise the health risk in human populations. Additional epidemiological data including pathogen occurrence, tick vectors and host range, as well as pathogenicity are essential.

Strategies for the Diagnosis of Granulocytic Anaplasmosis in Two Naturally Infected Dogs

This study describes granulocytic anaplasmosis in two dogs naturally infected with Anaplasma phagocytophilum. The 3-year-old dogs (male and female) came from the same household and were referred to the Faculty of Veterinary Medicine in Iasi for blood donation. They were subject to standard routine tests: haematology blood test, blood smear, and serological tests (VETSCAN® FLEX4 and IDEXX SNAP 4Dx Plus). The female dog had no medical problems, while the male dog experienced joint pain. The blood smear was negative for tick-borne pathogens, and the haematology findings indicated thrombocytopenia in both dogs, with the male dog also displaying eosinophilia. The two dogs were mildly positive in the ELISA tests for the detection of Anaplasma spp. antibodies; therefore, the blood samples were tested using the qRT-PCR method for Anaplasma platys and Anaplasma phagocytophilum. The qRT-PCR result was negative for A. platys, but it was positive for A. phagocytophilum. The treatment consisted of the administration of doxycycline for 28 days. In conclusion, the high number of cases with non-specific clinical signs, the different sensitivity and specificity of the immunochromatographic serological tests, as well as the possibility of confusing the morula during the cytological examination, make the molecular test mandatory for precise diagnosis.

Tick-Borne Pathogens Screening Using a Multiplex Real-Time Polymerase Chain Reaction-Based Method

PURPOSE

This study aims to develop and evaluate a cost-effective, user-friendly multiplex quantitative real-time polymerase chain reaction (qPCR) method for detecting multiple tick-borne pathogens associated with human and veterinary diseases.

METHODS

In silico PCR was performed to design and evaluate primer sequences reported for amplifying Rickettsia spp., Borrelia spp., and Ehrlichia spp. Single and multiplex qPCR assays were then standardized to detect individual pathogens and multiple pathogens in a single reaction. Positive controls were generated to determine the dynamic range of the methods. In the validation phase, a total of 800 samples were screened for the presence of tick-borne pathogens.

RESULTS

Identification in a single qPCR reaction (multiplex) of Ehrlichia spp., and Borrelia spp. with a limit of detection of 10 copies and Rickettsia spp. with 100 copies, a PCR efficiency (E) of 90-100% and a coefficient of correlation (R2) of 0.998-0.996 for all pathogens.

CONCLUSION

The ability to detect three significant pathogens (Ehrlichia spp., Rickettsia spp., and Borrelia spp.) in a single qPCR reaction offers a significant advantage in the field of molecular diagnostics for tick-borne diseases. This advancement has a profound impact on public health as it facilitates the selection of appropriate treatment protocols, thereby reducing complications associated with disease progression. The streamlined approach provided by this method simplifies the diagnostic process and enables timely intervention, ultimately improving patient outcomes and mitigating the potential risks associated with untreated or misdiagnosed tick-borne infections.

Anaplasmosis in Pennsylvania: Clinical Features, Diagnosis, and Outcomes of Patients Diagnosed With Anaplasma phagocytophilum Infection at Hershey Medical Center From 2008 to 2021

Anaplasmosis is an emerging infection in the United States and in particular, Pennsylvania. We highlight the abrupt rise in cases of anaplasmosis in the past decade in the state of Pennsylvania with the hope of increasing clinician awareness. We identified a cohort of 61 patients diagnosed with anaplasmosis at our institution as well as cases reported to the Department of Health. From our review, we identified not only an increase in cases over time but what appears to be an expansion further into central and western Pennsylvania over time.

Using Serum Specimens for Real-Time PCR-Based Diagnosis of Human Granulocytic Anaplasmosis, Canada

Whole blood is the optimal specimen for anaplasmosis diagnosis but might not be available in all cases. We PCR tested serum samples collected in Canada for Anaplasma serology and found 84.8%-95.8% sensitivity and 2.8 average cycle threshold elevation. Serum can be acceptable for detecting Anaplasma spp. when whole blood is unavailable.

Ehrlichiosis and anaplasmosis subcommittee report to the Tick-borne Disease Working Group

Ehrlichioses and anaplasmosis have undergone dramatic increases in incidence, and the geographic ranges of their occurrence and vectors have also expanded. There is marked underreporting of these diseases owing to deficient physician awareness and knowledge of the illnesses as well as limited access to appropriate diagnostic tests. Human monocytic ehrlichiosis and anaplasmosis are life threatening diseases with estimated case fatality rates of 2.7 and 0.3%, respectively. However, knowledge of their full range of signs and symptoms is incomplete, and the incidence of subclinical infections is unknown. Currently available laboratory diagnostic methods are poorly utilized, and with the exception of nucleic acid amplification tests are not useful for diagnosis during the acute stage of illness when timely treatment is needed. The Ehrlichiosis and Anaplasmosis Subcommittee of the Tick-Borne Disease Working Group recommended active clinical surveillance to determine the true incidence, full clinical spectrum, and risk factors for severe illness, as well as standardized surveillance of ticks for these pathogens, and enhanced education of primary medical caregivers and the public regarding these diseases. The subcommittee identified the needs to develop sensitive, specific acute stage diagnostic tests for local clinical laboratories and point-of-care testing, to develop approaches for utilizing electronic medical records, data mining, and artificial intelligence for assisting early diagnosis and treatment, and to develop adjunctive therapies for severe disease.

Epidemiological and Clinicopathological Features of Anaplasma phagocytophilum Infection in Dogs: A Systematic Review

Anaplasma phagocytophilum is a worldwide emerging zoonotic tick-borne pathogen transmitted by Ixodid ticks and naturally maintained in complex and incompletely assessed enzootic cycles. Several studies have demonstrated an extensive genetic variability with variable host tropisms and pathogenicity. However, the relationship between genetic diversity and modified pathogenicity is not yet understood. Because of their proximity to humans, dogs are potential sentinels for the transmission of vector-borne pathogens. Furthermore, the strong molecular similarity between human and canine isolates of A. phagocytophilum in Europe and the USA and the positive association in the distribution of human and canine cases in the USA emphasizes the epidemiological role of dogs. Anaplasma phagocytophilum infects and survives within neutrophils by disregulating neutrophil functions and evading specific immune responses. Moreover, the complex interaction between the bacterium and the infected host immune system contribute to induce inflammatory injuries. Canine granulocytic anaplasmosis is an acute febrile illness characterized by lethargy, inappetence, weight loss and musculoskeletal pain. Hematological and biochemistry profile modifications associated with this disease are unspecific and include thrombocytopenia, anemia, morulae within neutrophils and increased liver enzymes activity. Coinfections with other tick-borne pathogens (TBPs) may occur, especially with Borrelia burgdorferi, complicating the clinical presentation, diagnosis and response to treatment. Although clinical studies have been published in dogs, it remains unclear if several clinical signs and clinicopathological abnormalities can be related to this infection.

Are other tick-borne infections overlooked in patients investigated for Lyme neuroborreliosis? A large retrospective study from South-eastern Sweden

In Europe, the hard tick Ixodes ricinus is considered the most important vector of human zoonotic diseases. Human pathogenic agents spread by I. ricinus in Sweden include Borrelia burgdorferi sensu lato (s.l.), Anaplasma phagocytophilum, Rickettsia helvetica, the recently described Neoehrlichia mikurensis, Borrelia miyamotoi, tick-borne encephalitis virus (TBEV), and Babesia spp. (Babesia microti, Babesia venatorum and Babesia divergens). Since these pathogens share the same vector, co-infections with more than one tick-borne pathogen may occur and thus complicate the diagnosis and clinical management of the patient due to possibly altered symptomatology. Borrelia burgdorferi s.l., TBEV and B. miyamotoi are well-known to cause infections of the central nervous system (CNS), whereas the abilities of other tick-borne pathogens to invade the CNS are largely unknown. The aim of this study was to investigate the presence and clinical impact of tick-borne pathogens other than B. burgdorferi s.l. in the cerebrospinal fluid (CSF) and serum samples of patients who were under investigation for Lyme neuroborreliosis (LNB) in a tick-endemic region of South-eastern Sweden. CSF and serum samples from 600 patients, recruited from the Regions of Östergötland County, Jönköping County and Kalmar County in South-eastern Sweden and investigated for LNB during the period of 2009-2013, were retrospectively collected for analysis. The samples were analysed by real-time PCR for the presence of nucleic acid from B. burgdorferi s.l., B. miyamotoi, A. phagocytophilum, Rickettsia spp., N. mikurensis, TBEV and Babesia spp. Serological analyses were conducted in CSF and serum samples for all patients regarding B. burgdorferi s.l., and for the patients with CSF mononuclear pleocytosis, analyses of antibodies to B. miyamotoi, A. phagocytophilum, spotted fever group (SFG) rickettsiae, TBEV and B. microti in serum were performed. The medical charts of all the patients with CSF mononuclear pleocytosis and patients with positive PCR findings were reviewed. Of the 600 patients, 55 (9%) presented with CSF mononuclear pleocytosis, 13 (2%) of whom had Borrelia-specific antibodies in the CSF. One patient was PCR-positive for N. mikurensis, and another one was PCR-positive for Borrelia spp. in serum. No pathogens were detected by PCR in the CSF samples. Four patients had serum antibodies to B. miyamotoi, four patients to A. phagocytophilum, five patients to SFG rickettsiae, and six patients to TBEV. One patient, with antibodies to SFG rickettsiae, had both clinical and laboratory signs suggestive of a current infection. Nine patients had serum antibodies to more than one pathogen, although none of these was assessed as a current co-infection. We can conclude from this study that tick-borne co-infections are uncommon in patients who are being investigated for suspected LNB in South-eastern Sweden, an area endemic for borreliosis and TBE.

Severe Anaplasmosis presenting as possible CVA: Case report and 3-year Anaplasma infection diagnosis data is based on PCR testing and serology

Introduction

Anaplasmosis is a tick-borne illness caused by Anaplasma phagocytophilum. A review of CDC reports showed an increase in Anaplasmosis, with 1,193 cases reported in 2009 compared to 5,672 cases reported in 2017, with the majority of cases between May and October. Neurologic manifestations are uncommon.

Case

A 72-year-old male presented in August with acute left-sided weakness. Patient was found to have an acute kidney injury (creatinine 5.3 mg/dL), thrombocytopenia (platelet count 25,000/mL), and rhabdomyolysis (CPK 25,000 units/L). Workup for an acute stroke was negative. Peripheral blood smears showed Anaplasma neutrophil inclusions in >30 % of the buffy coat prep. PCR testing was positive for Anaplasmosis. He was treated with doxycycline for 10 days, with improvement within 48 h. He was discharged home after a 13-day hospital course with no residual neurological deficits.

A review of our medical system between January 1st, 2016 and December 31st, 2018 revealed 20 cases of Anaplasmosis. All cases presented between May and December and had fever of unclear etiology, but only our case presented with stroke-like symptoms. All cases involved people living in heavily wooded areas, with a mean age of 70 years.

Discussion

The typical presentation of Anaplasmosis is a nonspecific febrile illness with leukopenia and thrombocytopenia. Although headache is common, stroke-like symptoms are a rare but known complication. Elderly and immunocompromised patients living in heavily wooded areas are at higher risk for Anaplasmosis. Delayed diagnosis was common (55 % of case review) and associated with worse prognosis.

Tick-borne zoonoses and commonly used diagnostic methods in human and veterinary medicine

Around the world, human health and animal health are closely linked in terms of the One Health concept by ticks acting as vectors for zoonotic pathogens. Animals do not only maintain tick cycles but can either be clinically affected by the same tick-borne pathogens as humans and/or play a role as reservoirs or sentinel pathogen hosts. However, the relevance of different tick-borne diseases (TBDs) may vary in human vs. veterinary medicine, which is consequently reflected by the availability of human vs. veterinary diagnostic tests. Yet, as TBDs gain importance in both fields and rare zoonotic pathogens, such as Babesia spp., are increasingly identified as causes of human disease, a One Health approach regarding development of new diagnostic tools may lead to synergistic benefits. This review gives an overview on zoonotic protozoan, bacterial and viral tick-borne pathogens worldwide, discusses commonly used diagnostic techniques for TBDs, and compares commercial availability of diagnostic tests for humans vs. domestic animals, using Germany as an example, with the aim of highlighting existing gaps and opportunities for collaboration in a One Health framework.

Use of Routine Complete Blood Count Results to Rule Out Anaplasmosis Without the Need for Specific Diagnostic Testing

BACKGROUND

Anaplasmosis presents with fever, headache, and laboratory abnormalities including leukopenia and thrombocytopenia. Polymerase chain reaction (PCR) is the preferred diagnostic but is overutilized. We determined if routine laboratory tests could exclude anaplasmosis, improving PCR utilization.

METHODS

Anaplasma PCR results from a 3-year period, with associated complete blood count (CBC) and liver function test results, were retrospectively reviewed. PCR rejection criteria, based on white blood cell (WBC) and platelet (PLT) counts, were developed and prospectively applied in a mock stewardship program. If rejection criteria were met, a committee mock-refused PCR unless the patient was clinically unstable or immunocompromised.

RESULTS

WBC and PLT counts were the most actionable routine tests for excluding anaplasmosis. Retrospective review demonstrated that rejection criteria of WBC ≥11 000 cells/µL or PLT ≥300 000 cells/µL would have led to PCR refusal in 428 of 1685 true-negative cases (25%) and 3 of 66 true-positive cases (5%) involving clinically unstable or immunocompromised patients. In the prospective phase, 155 of 663 PCR requests (23%) met rejection criteria and were reviewed by committee, which endorsed refusal in 110 of 155 cases (71%) and approval in 45 (29%), based on clinical criteria. PCR was negative in all 45 committee-approved cases. Only 1 of 110 mock-refused requests yielded a positive PCR result; this patient was already receiving doxycycline at the time of testing.

CONCLUSIONS

A CBC-based stewardship algorithm would reduce unnecessary Anaplasma PCR testing, without missing active cases. Although the prospectively evaluated screening approach involved medical record review, this was unnecessary to prevent errors and could be replaced by a rejection comment specifying clinical situations that might warrant overriding the algorithm.

Surge in Anaplasmosis Cases in Maine, USA, 2013-2017

Incidence of human granulocytic anaplasmosis is rising in Maine, USA. This increase may be explained in part by adoption of tick panels as a frequent diagnostic test in persons with febrile illness and in part by range expansion of Ixodes scapularis ticks and zoonotic amplification of Anaplasma phagocytophilum.

Spatio-Temporal Dynamics of Tick-Borne Diseases in North-Central Wisconsin from 2000-2016

Lyme disease is a well-recognized public health problem in the USA, however, other tick-borne diseases also have major public health impacts. Yet, limited research has evaluated changes in the spatial and temporal patterns of non-Lyme tick-borne diseases within endemic regions. Using laboratory data from a large healthcare system in north-central Wisconsin from 2000-2016, we applied a Kulldorf's scan statistic to analyze spatial, temporal and seasonal clusters of laboratory-positive cases of human granulocytic anaplasmosis (HGA), babesiosis, and ehrlichiosis at the county level. Older males were identified as the subpopulation at greatest risk for non-Lyme tick-borne diseases and we observed a statistically significant spatial and temporal clustering of cases (p < 0.05). HGA risk shifted from west to east over time (2000-2016) with a relative risk (RR) ranging from 3.30 to 11.85, whereas babesiosis risk shifted from south to north and west over time (2004-2016) with an RR ranging from 4.33 to 4.81. Our study highlights the occurrence of non-Lyme tick-borne diseases, and identifies at-risk subpopulations and shifting spatial and temporal heterogeneities in disease risk. Our findings can be used by healthcare providers and public health practitioners to increase public awareness and improve case detection.

Severe anaplasmosis represents a treatable cause of secondary hemophagocytic lymphohistiocytosis: Two cases and review of literature

Anaplasmosis is an emerging infection in the United States and remains under-recognized in many areas including Pennsylvania. Presenting signs and symptoms are often nonspecific, but fulminant infection can occur in vulnerable populations. We present two cases of severe anaplasmosis that progressed to secondary hemophagocytic lymphohistiocytosis (HLH). This severe immune dysregulation syndrome has an extremely high mortality, but anaplasmosis represents one of the few treatable underlying etiologies. It is imperative for physicians to recognize this complication and start empiric doxycycline, as early treatment improves mortality. We also present a case of anaplasmosis-induced HLH successfully treated with a combination of doxycycline, steroids, and anakinra (an IL-1 receptor antagonist), highlighting that this primarily immune-mediated complication is amenable to treatment with both antibiotics and immune suppression.

Performance Analysis of Anaplasma Antibody Competitive ELISA Using the ROC Curve for Screening of Anaplasmosis in Camel Populations in Egypt

Anaplasmosis is a tick-born and potential zoonotic disease caused by Anaplasma (A.) phagocytophilum, A. ovis, A. platys and A. capra. Anaplasma marginale affecting bovines and camels causing significant economic losses. Camels as an integral part of the socio-economic lifestyle of nomads in semi-arid to arid ecosystems are prone to suffer from subclinical Anaplasma infections. This study aimed to determine the performance and adaptation of commercial competitive Anaplasma ELISA (cELISA) as a tool for screening the seroprevalence of anaplasmosis whitin the camel populations in Egypt. This study was based on the serological investigation of 437 camel sera collected between 2015 and 2016 during a Q fever prevalence study in Egypt using commercially available cELISA for the detection of antibodies specific for Anaplasma in bovine serum. The receiver operating characteristic (ROC) curve, an analysis method for optimizing cutoff values in cELISAs, was used to estimate the sensitivity and specificity using 76 true as serological positive (n = 7) and negative (n = 60) for Anaplasma antibodies. ROC curve analysis was done for 7 true positive and 60 true negative bovine samples and 7 true positive and 29 true negative camel samples serum. Real time PCR and/or conventional PCR was applied to confirm Anaplasma spp. specific-DNA in camel serum as an indication of a true positive and true negative for ROC analysis. Chi square analysis was performed to estimate the association between risk factors and anaplasmosis in camels. The cutoff value was determined as 0.42 (p value ≤ 0.001). Data simulation with randomly generated values revealed a cutoff value of 0.417 (p ≤ 0.001) with resulting 58.1% Se and 97.8% Sp. Seven true positive and 29 true negative camel serum samples was confirmed by PCR. Using the estimated cut off, the seroprevalence in the Nile Valley and Delta and the Eastern Desert domain was 47.4% and 46.4%, respectively. The potential risk factors as domains and origin of animals were less significantly associated with the prevalence of anaplasmosis (domains: χ(2) = 41.8, p value ≤ 0.001 and origin: χ(2) = 42.56, p value ≤ 0.001). Raising awareness especially for veterinarians and animal owners will significantly contribute to the best understanding of anaplasmosis in camels in Egypt. Alternative (in silico) validation techniques and preliminary prevalence studies are mandatory towards the control of neglected anaplasmosis in the camel population.

Simultaneous differential detection of canine blood parasites: Multiplex high-resolution melting analysis (mHRM)

Recently, the incidence of canine infection by the tick-borne parasites Babesia spp., Hepatozoon canis, Ehrlichia canis and Anaplasma platys has been increasing globally. We have developed a multiplex high-resolution melting analysis (mHRM) technique to reduce the time demands and costs associated with detecting haemoparasites in canine blood, while increasing the degree of reliability of this method of analysis. We have designed primers that are specific for protozoans (B. vogeli and H. canis) and Rickettsia-like bacteria (E. canis and A. platys) based on the 18S or 16S rDNA sequences, respectively. Two primer pairs (Protz18S-C and Bact16S-A) were found to be suitable for detecting these agents since their melting temperatures (T_m) exhibited discernible differences among the four haemoparasites, A. platys, B. vogeli, E. canis and H. canis (83.10 °C, 82.41 °C, 80.37 °C and 78.56 °C, respectively). The sequences acquired from these PCR products were >94 % identical to those of A. platys, B. vogeli, E. canis and H. canis in GenBank. The limit of detection (LOD) for B. vogeli, E. canis and A. platys was 10³ copies/μl, while the LOD for H. canis was 10⁴ copies/μl. Of the 68 dogs tested, 28 (41 %) were infected with these agents. The most commonly occurring infection involved E. canis, followed by B. vogeli, A. platys and H. canis, with infection percentages of 26 %, 13 %, 7 % and 6 %, respectively. These results demonstrate that mHRM can serve as a rapid, economical and reliable tool for the detection of parasitic diseases in canine blood for diagnosis and epidemiology.

Evaluation of a Novel Multiplex High-Definition PCR Assay for Detection of Tick-Borne Pathogens in Whole-Blood Specimens

The prevalence of tick-borne infections has been steadily increasing in both number and geographic distribution in the United States and abroad. This increase, in conjunction with the continued recognition of novel pathogens transmitted by ticks, has made accurate diagnosis of these infections challenging. Mainstay serologic tests are insensitive during the acute phase of infection and are often cross-reactive with similar pathogenic and nonpathogenic organisms. Further, they are unable to reliably differentiate active versus past infection which can lead to misdiagnosis and incorrect understanding of the epidemiology and incidence of specific tick-borne pathogens. We evaluated a novel multiplexed high-definition PCR (HDPCR) Tickborne Panel (TBP) assay (ChromaCode, Carlsbad, CA) for the detection of nine tick-borne pathogens or groups associated with human illness. The HDPCR technology enables multiplex identification of multiple targets in a single fluorometric channel based on fluorescent signal modulation using a limiting probe design. A collection of 530 whole-blood specimens collected from patients being evaluated for tick-borne infections, in addition to a panel of 93 simulated specimens, were used to challenge the HDPCR TBP. The results were compared to a clinically validated traditional multiplexed PCR test with additional sequence analysis and clinical history collected to aid in resolving discrepancies. Among clinical specimens the TBP demonstrated 100% sensitivity for the identification of Anaplasma phagocytophilum, Borrelia miyamotoi, Borrelia mayonii, and Rickettsia rickettsii The sensitivity for identification of B. burgdorferi was 44.4% compared to a composite gold standard. Among simulated specimens containing single or multiple targets present at 10³ to 10⁵ copies/PCR, the sensitivity of TBP was 100% for all targets, with a combined specificity of 99.5%. Of note, an increased rate of false-positive results was observed among simulated specimens that contained multiple targets. Based on these data, we find the HDPCR TBP to be a useful adjunct for the diagnosis of tick-borne infections in patients with suspected tick-borne illness.

Clinical Presentation and Outcomes of Children With Human Granulocytic Anaplasmosis

BACKGROUND

Adults with the tick-borne disease human granulocytic anaplasmosis (HGA) have a spectrum of acute febrile illnesses that, if untreated, might be severe. Clinical presentation and outcomes of children with HGA have been poorly described.

METHODS

A retrospective analysis was conducted to determine the frequency, presentation, and outcomes of pediatric patients with HGA between 1994 and 2015 in a region of Wisconsin in which HGA is highly endemic. Patients with related International Classification of Diseases Ninth and Tenth Revision (ICD-9 and ICD-10, respectively) codes or positive HGA laboratory test results were evaluated and classified as having had confirmed, probable, or suspected HGA on the basis of the Centers for Disease Control and Prevention (CDC) case definition. The Fisher's exact and Wilcoxon rank-sum tests were used in statistical comparisons.

RESULTS

Of 187 children identified with possible HGA, 17 (9%) had confirmed, 75 (40%) had probable, and 91 (49%) had suspected infections. The number of cases rose sharply in 2010 and has remained between 16 and 36 cases per year since that time. A minority of children with confirmed or probable infections had elevated liver transaminase levels (33%), leukopenia (24%), thrombocytopenia (17%), or anemia (8%); 6 (7%) of these children required hospitalization. Children with evidence of concurrent HGA and Lyme disease (27% of confirmed or probable cases) had a higher risk of hospitalization (odds ratio, 6.55 [95% confidence interval, 1.11-38.78]). None of these children had life-threatening disease or died.

CONCLUSIONS

Evidence suggests that the frequency of HGA in children is increasing. Although most children had mild disease, doxycycline remains the treatment of choice, because outcome data for children without treatment remains limited.

Pro-inflammatory immune responses are associated with clinical signs and symptoms of human anaplasmosis

Human anaplasmosis (HA) is an emerging tick-borne disease that may present as a mild flu-like illness or a life threatening, sepsis-like condition. Although disease severity is hypothesized to relate to immunopathology and immune dysfunction in humans, studies to directly measure immune responses in infected humans have been very limited. We quantified cytokines in 80 confirmed HA patients using a multiplex chemiluminescence immunoassay system and compared similarly measured responses in 1000 control subjects. Pro-inflammatory cytokines were significantly elevated in HA patients (all seven p<0.0001). Interferon gamma (IFN-γ) concentrations were particularly high, with average concentrations 7.8 times higher in the HA patients than the controls. A subset of cytokines consisting of IL-1β, IL-8, IL-6, TNF-α, and IL-10 was also coordinately high and significantly associated with severity of thrombocytopenia in HA patients. Patients with infections in the very acute stage (≤ 4 days ill) tended to have the highest IFN-γ, IL-12p70, and IL-2 levels. Higher concentrations of IL-13 and IL-5 were associated with diarrhea and vomiting. Our findings support a pathophysiological role for a pro-inflammatory response in HA, especially with regard to the modulation of hematopoiesis and subsequent hematopoietic complications.

Comparison of three nucleic acid-based tests for detecting <i>Anaplasma marginale</i> and <i>Anaplasma centrale</i> in cattle

Several nucleic acid-based assays have been developed for detecting Anaplasma marginale and Anaplasma centrale in vectors and hosts, making the choice of method to use in endemic areas difficult. We evaluated the ability of the reverse line blot (RLB) hybridisation assay, two nested polymerase chain reaction (nPCR) assays and a duplex real-time quantitative polymerase chain reaction (qPCR) assay to detect A. marginale and A. centrale infections in cattle (n = 66) in South Africa. The lowest detection limits for A. marginale plasmid DNA were 2500 copies by the RLB assay, 250 copies by the nPCR and qPCR assays and 2500, 250 and 25 copies of A. centrale plasmid DNA by the RLB, nPCR and qPCR assays respectively. The qPCR assay detected more A. marginale- and A. centrale-positive samples than the other assays, either as single or mixed infections. Although the results of the qPCR and nPCR tests were in agreement for the majority (38) of A. marginale-positive samples, 13 samples tested negative for A. marginale using nPCR but positive using qPCR. To explain this discrepancy, the target sequence region of the nPCR assay was evaluated by cloning and sequencing the msp1β gene from selected field samples. The results indicated sequence variation in the internal forward primer (AM100) area amongst the South African A. marginale msp1β sequences, resulting in false negatives. We propose the use of the duplex qPCR assay in future studies as it is more sensitive and offers the benefits of quantification and multiplex detection of both Anaplasma spp.

Evaluation of different nested PCRs for detection of Anaplasma phagocytophilum in ruminants and ticks

BACKGROUND

Anaplasma phagocytophilum is a causative agent of granulocytic anaplasmosis in mammals, which has a broad geographical distribution and a high degree of clinical diversity. Currently, numerous PCR assays have been developed and used for the detection of A. phagocytophilum in various specimens. However, their performance varies. The aim of this study was to evaluate the performance of five nested PCR assays by detection of 363 ruminant and tick samples, and to select the most appropriate methods for the sensitive detection of A. phagocytophilum in environmental or clinical samples.

RESULTS

Positive PCR results for A. phagocytophilum were obtained in 75 (20.7%), 42 (11.6%) and 19 (5.2%) specimens with primer sets EC (EC9/EC12a and SSAP2f/SSAP2r), EE (EE1/EE2 and EE3/EE4) and ge (ge3a/ge10r, ge9f/ge2), respectively. The amplification of template DNA with the primer set MSP (MAP4AP5/MSP4AP3, msp4f/msp4r) could not be obtained in both ruminants and ticks, and a low specificity of the EL primers [EL(569)F/EL(1193)R, EL(569)F/EL(1142)R] in tick samples was observed. Our results revealed that the nested PCR with primer set EC complementary to the 16S rRNA gene was the most sensitive assay for detection of A. phagocytophilum in ruminant and tick specimens. A. phagocytophilum was detected in 47 (35.1%) sheep, 12 (10.4%) cattle, and 17 (14.9%) ticks. Two A. phagocytophilum genotypes were identified, that varied between sheep and cattle in sample collection sites.

CONCLUSIONS

This report provides more valuable information for the diagnosis and management of granulocytic anaplasmosis in China.

Human granulocytic anaplasmosis

Human granulocytic anaplasmosis, a deer tick-transmitted rickettsial infection caused by Anaplasma phagocytophilum, is a common cause of undifferentiated fever in the northeast and upper Midwest United States. Patients are often initially diagnosed with a mild viral infection, and illness readily resolves in most cases. However, as many as 3% develop life-threatening complications and nearly 1% die from the infection. Although coinfections with Borrelia burgdorferi and Babesia microti occur, there is little evidence to suggest synergism of disease or a role for A phagocytophilum in chronic illness. No vaccine is available.

Development of a TaqMan Array Card for Acute-Febrile-Illness Outbreak Investigation and Surveillance of Emerging Pathogens, Including Ebola Virus

Acute febrile illness (AFI) is associated with substantial morbidity and mortality worldwide, yet an etiologic agent is often not identified. Convalescent-phase serology is impractical, blood culture is slow, and many pathogens are fastidious or impossible to cultivate. We developed a real-time PCR-based TaqMan array card (TAC) that can test six to eight samples within 2.5 h from sample to results and can simultaneously detect 26 AFI-associated organisms, including 15 viruses (chikungunya, Crimean-Congo hemorrhagic fever [CCHF] virus, dengue, Ebola virus, Bundibugyo virus, Sudan virus, hantaviruses [Hantaan and Seoul], hepatitis E, Marburg, Nipah virus, o'nyong-nyong virus, Rift Valley fever virus, West Nile virus, and yellow fever virus), 8 bacteria (Bartonella spp., Brucella spp., Coxiella burnetii, Leptospira spp., Rickettsia spp., Salmonella enterica and Salmonella enterica serovar Typhi, and Yersinia pestis), and 3 protozoa (Leishmania spp., Plasmodium spp., and Trypanosoma brucei). Two extrinsic controls (phocine herpesvirus 1 and bacteriophage MS2) were included to ensure extraction and amplification efficiency. Analytical validation was performed on spiked specimens for linearity, intra-assay precision, interassay precision, limit of detection, and specificity. The performance of the card on clinical specimens was evaluated with 1,050 blood samples by comparison to the individual real-time PCR assays, and the TAC exhibited an overall 88% (278/315; 95% confidence interval [CI], 84% to 92%) sensitivity and a 99% (5,261/5,326, 98% to 99%) specificity. This TaqMan array card can be used in field settings as a rapid screen for outbreak investigation or for the surveillance of pathogens, including Ebola virus.

Canine ehrlichiosis: prevalence and epidemiology in northeast Brazil

Ehrlichiosis is a zoonotic disease that is caused by bacteria of the genus Ehrlichia. The aims of this study were to detect the presence of Ehrlichia spp. in the blood of dogs in Ituberá, Bahia, and to compare the sensitivities and specificities of blood smear, serological, and molecular examinations. Furthermore, this study identified factors associated with exposure to the agent in dogs in this locality. Blood samples were collected from 379 dogs and submitted for indirect immunofluorescent assay and polymerase chain reaction testing for the detection of Ehrlichia spp. antibodies and DNA, respectively. Additionally, a peripheral blood smear was obtained from the ear tip for parasite identification. Of the 379 animals, 12.4%, 32.7%, and 25.6% were identified as positive on the blood smear, serological, and molecular tests, respectively. The dogs positive in one of the three techniques were considered exposed (46.9%). Younger dogs and rural habitat were protective factors and presence of ticks and contact with other dogs were the risk factors associated with exposure to the agent. It was concluded that dogs of Ituberá have high positivity for Ehrlichia spp. and that the diagnostic methods used for detection are complementary.

High Prevalence of Anaplasma spp. in Small Ruminants in Morocco

The prevalence of infection by Anaplasma spp. (including Anaplasma phagocytophilum) was determined using blood smear microscopy and PCR through screening of small ruminant blood samples collected from seven regions of Morocco. Co-infections of Anaplasma spp., Babesia spp, Theileria spp. and Mycoplasma spp. were investigated and risk factors for Anaplasma spp. infection assessed. A total of 422 small ruminant blood samples were randomly collected from 70 flocks. Individual animal (breed, age, tick burden and previous treatment) and flock data (GPS coordinate of farm, size of flock and livestock production system) were collected. Upon examination of blood smears, 375 blood samples (88.9%) were found to contain Anaplasma-like erythrocytic inclusion bodies. Upon screening with a large spectrum PCR targeting the Anaplasma 16S rRNA region, 303 (71%) samples were found to be positive. All 303 samples screened with the A. phagocytophilum-specific PCR, which targets the msp2 region, were found to be negative. Differences in prevalence were found to be statistically significant with regard to region, altitude, flock size, livestock production system, grazing system, presence of clinical cases and application of tick and tick-borne diseases prophylactic measures. Kappa analysis revealed a poor concordance between microscopy and PCR (k = 0.14). Agreement with PCR is improved by considering microscopy and packed cell volume (PCV) in parallel. The prevalence of double infections was found to be 1.7, 2.5 and 24% for Anaplasma-Babesia, Anaplasma-Mycoplasma and Anaplasma-Theileria, respectively. Co-infection with three or more haemoparasites was found in 1.6% of animals examined. In conclusion, we demonstrate the high burden of anaplasmosis in small ruminants in Morocco and the high prevalence of co-infections of tick-borne diseases. There is an urgent need to improve the control of this neglected group of diseases.