Clinical presentation and syndromes
The diseases manifest acutely, with the rapid development of a febrile reaction. The clinical picture consists of several leading syndromes that require careful differential diagnosis with rickettsioses and certain viral infections.
The main manifestations include:
- Intoxication syndrome. Patients complain of pronounced chills, severe fatigue, intense headache, and muscle pain (myalgia).
- Dyspeptic disorders. Against the background of intoxication, anorexia (loss of appetite) often occurs, which may be accompanied by nausea and vomiting.
The most important dermatological and differential diagnostic sign is the complete absence of a primary affect at the site of pathogen entry in all forms of the disease. Skin rashes (exanthema) are erythematous or petechial in nature, but do not occur in all patients. For example, in Sennetsu fever, a rash appears rarely, whereas in granulocytic anaplasmosis and monocytic ehrlichiosis, exanthema is recorded in 10–30% of cases.
Time parameters and forms of infection
From the moment of infection to the appearance of the first clinical signs (incubation period), an average of 7 to 14 days pass. The further development and duration of the febrile period directly depend on the specific clinical form of the disease.
There are three main forms with different fever durations:
- Granulocytic anaplasmosis — fever usually persists for 7–10 days.
- Sennetsu fever — the duration of the febrile period is no more than two weeks.
- Monocytic ehrlichiosis — characterized by the longest course, in which fever can last up to 3 weeks.
Microbiological diagnostics
Making a definitive diagnosis is impossible without the use of specific laboratory methods, since the clinical picture lacks absolute specificity. In modern practice, an integrated approach is used.
- Serological methods. The main task is the study of paired sera (taken from patients in the acute period and from convalescents during recovery). Immunofluorescence assays (IFA, indirect IFA) or enzyme-linked immunosorbent assay (ELISA) using a specific antigen are used.
- Molecular genetic methods. Polymerase chain reaction (PCR) makes it possible to detect the pathogen's DNA in the test material.
- Microscopy. Smears are stained according to the Romanowsky–Giemsa method. The laboratory doctor looks for specific structures — morulae (dense clusters of ehrlichiae). Depending on the form of infection, these inclusions are localized inside the cytoplasm of monocytes or neutrophils.
Management and Prevention
The basis of treatment for ehrlichiosis and anaplasmosis is timely etiotropic therapy. The drugs of choice are tetracycline antibiotics, primarily doxycycline. In case of intolerance or contraindications, chloramphenicol is used as a reserve drug (which is much less common).
Prevention approaches:
- Specific prevention. Vaccination for humans has not yet been developed.
- Emergency prophylaxis. Consists of the preventive administration of doxycycline immediately after a confirmed tick bite.
- Non-specific prevention. Includes standard tick control measures: the use of repellents, wearing protective clothing, and regular inspections when visiting natural zones endemic for tick-borne infections.
Briefly: answers to topical questions
Which specific species of microorganisms cause monocytic ehrlichiosis and granulocytic anaplasmosis?
- Monocytic ehrlichiosis is caused by Ehrlichia chaffeensis and Ehrlichia muris.
- Granulocytic anaplasmosis is caused by Anaplasma phagocytophilum.
What types of ticks are specific vectors of ehrlichiosis and anaplasmosis pathogens?
The specific vectors of the pathogens of monocytic ehrlichiosis and granulocytic anaplasmosis are various species of ixodid ticks living in endemic areas.
- Ticks of Eurasia (I. ricinus, I. persulcatus) are a natural reservoir and vector of both monocytic ehrlichiosis and granulocytic anaplasmosis.
- Ticks of the USA (A. americanum, I. scapularis) act as vectors of granulocytic anaplasmosis, while the first species also actively transmits monocytic ehrlichiosis.
What changes in general and biochemical blood tests are characteristic of the acute period of ehrlichioses?
| Investigation | Characteristic changes |
|---|---|
| Complete blood count | Leukopenia (60%), thrombocytopenia (68%), band neutrophil shift, lymphopenia, monocytopenia, accelerated ESR |
| Biochemical analysis | Moderate increase in transaminases and alkaline phosphatase |
To easily remember the target cells: Monocytic ehrlichiosis affects Monocytes (M-M), and Granulocytic anaplasmosis is localized in Granulocytes (G-G, neutrophils).
Class and exam questions
Can a primary skin affect be found in a patient with ehrlichiosis?
No, the absence of a primary affect (changes at the site of pathogen entry) is a key feature distinguishing this group of diseases from certain other vector-borne infections.
What are morulae and where to look for them?
Morulae are characteristic clusters of pathogens (ehrlichiae) that are found in the cytoplasm of monocytes or neutrophils upon microscopy of a Romanowsky–Giemsa stained smear.
Which form of infection lasts the longest?
The longest course is characteristic of monocytic ehrlichiosis, in which the febrile period can last up to 3 weeks.
Is there a vaccine for anaplasmosis?
No, specific prevention (vaccination) for humans is currently not developed, so protection is based on preventing tick bites.
What else to study on this topic
- Features of differential diagnosis with borreliosis and leptospirosis
- Mechanism of morulae formation inside phagocytosing cells
- Regimens of emergency antibiotic prophylaxis after a tick bite
- Interpretation of paired sera test results in IFA and ELISA
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