OVERVIEW
Ehrlichiosis is a febrile illness caused by a tick-borne, genus Ehrlichia, a rickettsia-like pathogenic microorganism. Ehrlichia is an absolute intracellular parasite that forms small cytoplasmic inclusion bodies in lymphocytes and neutrophils. People are infected by tick bites and sometimes by contact with dogs carrying ticks.
Etiology
Ehrlichia is an absolute intracellular parasite that forms small cytoplasmic inclusions in lymphocytes and neutrophils. People are infected by tick bites and sometimes by contact with dogs carrying ticks. In the United States, most cases are found in the Southeast and South Central regions. There are two types of ehrlichia that cause disease in humans in the United States: E. chaffeenis causes human monocytic ehrlichiosis and E. phagocytophilia and its related pathogens cause human granulocytic ehrlichiosis.E. canis is currently thought to cause human monocytic ehrlichiosis.
Symptoms
Symptoms and signs are the same regardless of the species causing the infection.Although asymptomatic infections exist, in most cases the onset of the disease is sudden 12 days after the tick bite, with fever, chills, headache and fatigue.Some patients develop a maculopapular or petechial rash, but E. canis rarely causes a rash, abdominal pain, vomiting, and diarrhea.Hematologic and hepatic abnormalities include leucopenia, thrombocytopenia, and abnormalities of hepatic function, particularly elevated transaminases.
Currently Ehrlich’s disease occurs primarily in the United States, males are more susceptible than females, most people have a history of a tick bite 4 weeks prior to the onset of symptoms, the main clinical features are acute fever, headache, anorexia, myalgia, malignant chills/frigidity, nausea/vomiting, and weight loss, recently there has been a very close antigenic link between E. canis and Ehrlich’s canis isolated from humans.
Examination
1. Hematologic and hepatic abnormalities
These include leukopenia, thrombocytopenia and abnormal liver function, especially elevated transaminases. Serologic tests and PCR can help early diagnosis.
2. Pathogen isolation and identification.
Diagnosis
Diagnosis can be made on the basis of etiology, symptoms and relevant tests.
Differential diagnosis
1. Meningococcal septicemia
The rash of meningococcal septicemia is pink, maculopapular, maculopapular or petechiae in subacute; petechiae are fused or petechiae in fulminant form; meningococcal rash develops rapidly in acute stage, and petechiae are soft to palpation; whereas, rickettsial rash often appears on the 4th day of fever, and becomes petechiae within a few days gradually.
2. Rubella
The rash begins on the face, then spreads to the trunk and limbs and quickly blends; the rash is often scattered. Rubella is also accompanied by swollen lymph nodes behind the ears, and there are no signs of systemic poisoning.
3. murine typhus
The rash is nonpurple, nonconfluent and not widespread; renal and vascular complications are uncommon, specific serologic diagnosis is required, and treatment should not wait until after the differential diagnosis is complete.
4. Epidemic lice-borne maculopapular rash
Typhoid fever causes severe abnormal physiologic and pathologic responses similar to ehrlichiosis, including peripheral circulatory failure, shock, cyanosis, petechial skin necrosis, gangrene of the fingers (toes), azotemia, renal failure, delirium, and coma. The rash of epidemic typhus first appears in the axillae and trunk, then spreads to the extremities, and rarely appears on the palms of the hands, soles of the feet, and face.
5. Scrub typhus
Rickettsial pox, occasional spotted fever will have localized crusting, and epidemiological history often helps to identify.
Treatment
If found after tick bite, do not remove it by yourself, go to the hospital to remove it in time. Ticks burrow their heads into the skin with a hook that gets tighter and tighter, so it is easy to leave the head inside the skin and continue to get infected. It is extremely troublesome to go to the hospital to have the head removed.
Treatment is best started before the diagnosis is established. If the treatment is started early, the patient will respond quickly and well; if the treatment is delayed, serious complications will easily arise, including overlapping viral and fungal infections and death.
1. Systemic therapy
Tetracycline and doxycycline are given orally or intravenously. Chloramphenicol may also be used; treatment should continue for at least 7 days.
Tulipine hydrochloride, deep intramuscular injection, 6 to 9 consecutive days for a course of treatment, repeat treatment to be after 20 to 30 days.
Antihistamines or corticosteroids should be given for signs of systemic toxicity. Tick paralysis or tick-bite fever should be rescued in time. If there is secondary infection on the injured surface, anti-inflammatory treatment should be carried out.
2.Local treatment
Use 2% lidocaine hydrochloride as local closure around the wound, and some people use trypsin 2000u plus saline 100mL wet compresses on the wound, which can accelerate the healing of the wound.