From the Guidelines
You should consult your healthcare provider for PCR testing, which is more sensitive and specific for detecting Anaplasma phagocytophilum, rather than relying solely on a blood smear to rule out anaplasmosis. If anaplasmosis is suspected based on symptoms (fever, headache, muscle pain, and fatigue) and potential tick exposure, your doctor may start treatment with doxycycline (typically 100mg twice daily for 10-14 days) while awaiting test results 1. Blood smears can sometimes show characteristic morulae (bacterial clusters) in white blood cells, but these are only visible in about 20-80% of cases and usually only early in the infection 1. PCR testing of blood is more reliable, especially during the first week of illness. Complete blood count (CBC) may show decreased white blood cells, platelets, and elevated liver enzymes, which can support the diagnosis. Early treatment is important as anaplasmosis can become severe if left untreated, particularly in older adults or those with compromised immune systems 1.
Some key points to consider:
- Anaplasmosis is a self-limiting illness in most cases, but severe or life-threatening manifestations can occur 1.
- The disease can resemble other conditions, such as toxic shock syndrome or hemophagocytic syndromes, making diagnosis challenging 1.
- Predictors of a more severe course of anaplasmosis include advanced patient age, immunosuppression, and comorbid medical conditions 1.
- Delay in diagnosis and treatment can lead to a more severe course of the disease 1.
It is essential to consult a healthcare provider for proper diagnosis and treatment, as they can assess the individual's symptoms, medical history, and potential tick exposure to determine the best course of action 1.
From the Research
Diagnosis of Anaplasmosis
To determine if a blood smear is necessary to rule out anaplasmosis, it's essential to understand the diagnosis and presentation of the disease.
- Anaplasmosis, also known as human granulocytic anaplasmosis (HGA), is a tick-borne illness caused by the bacteria Anaplasma phagocytophilum 2.
- The disease can present with nonspecific symptoms such as fever, headache, and myalgia, making diagnosis challenging 2, 3.
- Laboratory findings may include reductions in total leukocyte and platelet concentrations, as well as increases in serum hepatic transaminase concentrations and inflammatory markers 2.
Role of Blood Smear in Diagnosis
- A blood smear can be useful in diagnosing anaplasmosis, particularly in the acute phase of the illness 2, 4.
- Characteristic clusters of bacteria (morulae) can be observed in the cytoplasm of peripheral blood granulocytes in 20% to 80% of infected patients during the acute phase 2.
- However, the absence of morulae on a blood smear does not rule out anaplasmosis, and other diagnostic tests such as polymerase chain reaction (PCR) or serology may be necessary to confirm the diagnosis 2, 5, 3.
Diagnostic Approach
- The clinical diagnosis of anaplasmosis may be confirmed retrospectively by specific laboratory tests, including positive PCR, identification of A. phagocytophilum in culture of acute-phase blood, or the detection of specific antibodies to A. phagocytophilum in convalescent serum 2.
- PCR is considered the confirmatory test of choice for anaplasmosis 3.
- A blood smear analysis can be a useful initial step in the diagnostic workup, especially in patients with a history of tick exposure or symptoms suggestive of anaplasmosis 6.