Anaplasma phagocytophilum DNA, Qualitative Real-Time PCR
Real-time PCR detection of Anaplasma phagocytophilum DNA in whole blood is the most sensitive and specific method for diagnosing human granulocytic anaplasmosis during the acute febrile phase, before antibody seroconversion. Sensitivity is highest within the first week of symptoms and before doxycycline therapy; negative results after this window require serological confirmation.
1
Biomarkers
Blood (whole blood)
Sample
3–5 business days
Turnaround
No
Fasting
What is the Anaplasma PCR test?
The Anaplasma phagocytophilum DNA Qualitative Real-Time PCR Test detects circulating bacterial DNA in whole blood and is the diagnostic method of choice during the acute phase of human granulocytic anaplasmosis. Practitioners order this assay when a patient presents with fever, headache, myalgia, and thrombocytopaenia or leucopaenia following tick exposure in an endemic region, particularly when the clinical picture suggests a tick-borne illness but the specific pathogen is unclear. PCR is time-sensitive: sensitivity is highest within the first week of symptoms, when bacteraemia is present and before doxycycline drives the organism below the detection threshold. Because serological tests remain negative early and morulae are seen in fewer than half of cases, nucleic acid amplification fills the diagnostic gap during the treatment-critical acute window and allows practitioners to confirm anaplasmosis, distinguish it from Lyme disease or other co-infections, and tailor empiric therapy with confidence.
What does the Anaplasma PCR test measure?
Anaplasma phagocytophilum is an obligate intracellular, Gram-negative bacterium transmitted by Ixodes ticks that preferentially infects neutrophils, forming intracytoplasmic morulae visible on blood films during acute infection. The organism disrupts neutrophil apoptosis and oxidative killing, enabling its survival and replication within the phagosome. Bacteraemia peaks during the first week of illness, coinciding with fever and non-specific systemic symptoms, and DNA circulates in whole blood during this acute window before the adaptive immune response clears the organism.
Real-time PCR detection of A. phagocytophilum DNA is the most sensitive and specific method for diagnosing human granulocytic anaplasmosis during the acute febrile phase, before doxycycline therapy and before antibody seroconversion. A positive result confirms active infection and supports immediate treatment; a negative result does not exclude disease if the specimen was collected late (beyond 7–10 days of symptoms) or after antibiotic initiation, and serology is then required for retrospective diagnosis.
Why is the Anaplasma PCR test ordered?
- Acute febrile illness with headache, myalgia, and thrombocytopaenia or leucopaenia in a patient with known or possible tick exposure in an Ixodes-endemic area
- Suspected tick-borne infection during the first week of symptoms, before antibody seroconversion and when serological assays will be negative
- Differentiation of human granulocytic anaplasmosis from Lyme disease, babesiosis, ehrlichiosis, or rickettsial infection in a patient with overlapping clinical features
- Evaluation of severe or atypical presentations — including respiratory distress, altered mentation, or multisystem organ failure — in which rapid aetiological confirmation guides intensive management
- Pre-treatment confirmation in patients for whom doxycycline is contraindicated or requires careful risk–benefit discussion, such as pregnant women or young children
- Investigation of an acute illness in an endemic traveller or outdoor worker when clinical suspicion is moderate to high but morulae are not seen on blood film
- Monitoring of treatment response or persistent symptoms in immunocompromised patients, where delayed clearance may occur
Sample collection and turnaround
Sample type
Blood (whole blood)
Fasting required
No
Collection method
Venipuncture at patient service centre
Turnaround
3–5 business days
Collection notes
Phlebotomy at a Quest patient service centre. Collect whole blood in an EDTA (lavender-top) tube during the acute febrile phase, ideally within the first 5–7 days of symptom onset and before doxycycline or other tetracycline therapy is initiated. If treatment has already begun, collect the specimen as soon as possible; even a single dose may reduce sensitivity. Transport promptly to the laboratory at 2–8°C; avoid prolonged storage at room temperature, which can degrade DNA.
Specimen requirements
Minimum 3 mL whole blood in EDTA anticoagulant. Serum or plasma is not acceptable. Refrigerate during transport; stable refrigerated for up to 48 hours. Freeze at –20°C or below if longer storage is required before testing.
What can affect Anaplasma PCR results?
Doxycycline rapidly suppresses A. phagocytophilum replication and clears bacteraemia within 24–48 hours, dropping DNA levels below the detection threshold; collect the specimen before treatment or as early as possible if therapy has already begun.
Sensitivity is highest in the first 5–7 days of illness, when bacteraemia peaks; DNA levels fall as the adaptive immune response clears the organism, and specimens collected beyond 10 days may be negative despite true infection.
Whole blood (EDTA anticoagulated) is the required specimen; serum or plasma is unsuitable because the organism resides intracellularly. Delays in transport or storage at elevated temperature can degrade DNA and reduce sensitivity.
In mild or early infection bacteraemia may be below the PCR limit of detection, and in immunocompromised hosts atypical kinetics can produce false-negative results; serial sampling or paired serology adds diagnostic yield.
Ixodes ticks can transmit multiple pathogens simultaneously (Borrelia, Babesia, Powassan virus), and co-infection may alter the clinical course or PCR kinetics; testing for other agents should be considered when clinical features are mixed or severe.
What do Anaplasma PCR results mean?
Elevated
Not applicable — result is qualitative (Detected/Not Detected).
Normal
Not Detected: No A. phagocytophilum DNA was amplified in the specimen. This result supports the absence of active anaplasmosis if collected during the appropriate acute window (first week of symptoms, before antibiotic therapy). A negative PCR does not exclude the diagnosis if the specimen was collected late, after doxycycline initiation, or in a patient with low-level bacteraemia; convalescent serology (IgG titre rise) is required for retrospective confirmation when clinical suspicion remains high. Detected: A. phagocytophilum DNA was amplified, confirming active infection with human granulocytic anaplasmosis. Immediate doxycycline therapy is indicated, and supportive management should be escalated as required. A positive PCR in a patient already on doxycycline suggests either very early treatment (before clearance) or, rarely, doxycycline resistance or non-compliance. Practitioners should correlate the result with clinical severity, haematological parameters (thrombocytopaenia, leucopaenia, elevated transaminases), blood-film morulae if present, and epidemiological context, and consider testing for co-infections when the clinical picture is complex or response to therapy is suboptimal.
Reduced
Not applicable — result is qualitative (Detected/Not Detected).
Note: PCR is the gold standard during the acute phase but is time- and specimen-dependent. Sensitivity falls sharply after the first week and after antibiotic initiation, so negative results in late-presenting or treated patients require serological follow-up. The assay is qualitative and does not quantify bacterial load or predict severity. Because Ixodes ticks transmit multiple pathogens, clinicians should maintain a broad differential and test for Borrelia, Babesia, and other agents when co-infection is suspected. Regional epidemiology matters — anaplasmosis is endemic in the upper Midwest and Northeast United States, parts of northern Europe, and scattered foci elsewhere, and travel or outdoor exposure history refines pre-test probability.
Frequently asked questions
Human granulocytic anaplasmosis is an acute tick-borne infection caused by the intracellular bacterium Anaplasma phagocytophilum, transmitted by Ixodes scapularis and Ixodes pacificus ticks in North America and Ixodes ricinus in Europe. It presents with fever, headache, myalgia, and often thrombocytopaenia and leucopaenia.
How to access the Anaplasma PCR test
The Anaplasma PCR reference page is free and open to all practitioners. Create a free practitioner account to see pricing, save tests to your list, and generate requisition forms. Verification takes 1–2 business days.
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Published: October 7, 2026
Last reviewed: October 7, 2026
- Dumler JS, et al. Diagnosis and management of tickborne rickettsial diseases: Rocky Mountain spotted fever and other spotted fever group rickettsioses, ehrlichioses, and anaplasmosis — United States. MMWR Recomm Rep. (2016)
- Bakken JS, Dumler JS. Human granulocytic anaplasmosis. Infect Dis Clin North Am. (2015)
- Wormser GP, et al. The clinical assessment, treatment, and prevention of Lyme disease, human granulocytic anaplasmosis, and babesiosis: clinical practice guidelines by the Infectious Diseases Society of America. Clin Infect Dis. (2006)
- Ismail N, McBride JW. Tick-borne emerging infections: ehrlichiosis and anaplasmosis. Clin Lab Med. (2017)
This content is for licensed healthcare practitioners only and does not constitute medical advice. Clinical decisions should be based on the full clinical picture and not on any single test result.