Ehrlichiosis Infection

Ehrlichiosis Infection in Dogs, Canine & Humans – Symptoms & Treatment

Ehrlichiosis is an infection of white blood cells transmitted by the bite of a tick and affects not only humans, but also dogs, cattle, sheep, and many others. It is caused by one of several rickettsial organisms of the family Anaplasmataceae, genera Ehrlichia and Anaplasma. These gram-negative and obligate intracellular that can cause multiple serious diseases worldwide, including Rocky Mountain spotted fever and typhus. It was first described in 1990 by Dr. Ehrlich and is most common during spring and summer during these seasons ticks are most active. According to reports, the annual incidence of Ehrlichiosis is 0.7 cases per million.

Ehrlichia bacteria can be carried by the following Primary vectors:

  1. American Brown dog tick for E. Canis
  2. Deer tick — which can also cause Lyme disease
  3. Lone Star tick

Symptoms of Ehrlichiosis are the same as common flu, usually start to mild body aches, fever, chills, headache, and loss of appetite. These clinical manifestations usually appear within one to two weeks of a tick bite. The incubation period of Ehrlichiosis occurs from 7 to 14 days. This is called the incubation period. The incubation period refers to the time of the start of the exposure until the appearance of the signs and symptoms of the disease. If treated immediately with correct medications, ehrlichiosis generally improves within a few days. Ehrlichiosis can also affect the immune system, which may result in opportunistic infections such as candidiasis.

Ehrlichiosis Infection in Dogs, Canine and Humans

As mentioned in the introduction, Dogs and other animals can also be affected by Ehrlichia. It is most commonly caused by the following:

  1. Ehrlichia canis (Canine Moncytotropic Ehrlichiosis)
  2. Most common in Dog infection
  3. Ehrlichia chaffeensis (Canine Granulocytotropic Ehrlichiosis)
  4. Most common in Human infection
  5. Ehrlichia Ewingii
  6. Ehrlichia lewinii
  7. Most common in Dog infection
  8. Anaplasma phagocytophilum
  9. Neorickettsia sennetsu

And transmitted by the following ticks:

  1. Brown dog tick
  2. Usually spreads Ehrlichia canis, Ehrlichia lewinii and others
  3. Rhipicephalus sanguineus
  4. Long Star tick
  5. The Main vector of Ehrlichia Lewinii
  6. Black-legged tick
  7. American dog tick

Ehrlichiosis Infection in Canine

Canine Monocytic Ehrlichiosis (CME)

Is caused by the etiologic agent Ehrlichia canis that infect the monocytes, Primarily transmitted by Rhipicephalus sanguineus, the brown dog tick. Dogs may manifest different clinical symptoms, but thrombocytopenia with bleeding tendencies is the most consistent presenting complaint in dogs in both the acute and chronic stages of the disease.

Acute stage:

  1. Splenomegaly
  2. Lymphadenomegaly
  3. Chronic Stage:
  4. Nonregenerative Anemia
  5. Thrombocytopenia
  6. Leukopenia

Canine Granulocytic Ehrlichiosis (CGE)

Caused by Ehrlichia ewingii that cause damages to Neutrophils and sometimes in eosinophils as well.
Acute signs are:

  1. Fever
  2. Anorexia
  3. Vomiting
  4. Diarrhea.

Severe clinical signs are:

  1. Transient Thrombocytopenia
  2. Transient mild nonregenerative anemia.

Symptoms of Ehrlichiosis has 3 phases:

Acute Phase

Developed in 1 to 3 weeks after the bite of the infected tick and generally lasts for 2 to 4 weeks. The Ehrlichia infect the white blood cells and multiply inside them. WBC found in the lymph nodes, spleen, liver, and bone marrow has become infected. The lymph nodes, liver, and spleen are often enlarged. Platelets are also often destroyed. The following symptoms are often seen in this phase:

  1. Anemia
  2. Fever
  3. Shortness of breath
  4. Pain and stiffness of the joints
  5. Signs of bleeding
  6. Rashes

Sub-Clinical Phase

In the situation that infection has not yet been treated, the Sub-clinical phase is the next stage of the disease. In this period, the Ehrlichia inhabit inside the spleen and can last for months or years. The dog will have the following manifestations:

  1. Intermittent fever
  2. Loss of Appetite

Chronic Phase

The chronic phase is the final phase of the disease, in this situation wherein the infection still does not improve after the Sub-clinical phase. WBC and Platelets often decrease, but lymphocytes may increase and be abnormal in size. Clinical manifestations for this phase are the following:

  1. Lethargy
  2. Anorexia
  3. Swollen lymph nodes
  4. Signs of bleeding like hematuria, pupura, Epistaxis
  5. Glomerulonephritis

Human Monocytic Ehrlichiosis (HME)

Is an infectious disease caused by Ehrlichia (Ehrlichia chaffeensis) and belongs to the group of diseases known as the Human Ehrlichioses. It affects the monocytes, is a type of white blood cells, and play important role in immune function. It occurs in a different part of the United States of America and mostly affects the elders.

Most symptoms are consists of the following:

  1. Fever
  2. Headache
  3. Body and muscle pain
  4. Rashes
  5. In people with compromised immunity, Septic or Toxic shock may develop.

Human Granulocytic Ehrlichiosis

Human granulocytic Ehrlichiosis or most commonly known as Human granulocytic anaplasmosis is an infection caused by an Anaplasma phagocytophilum.

Typically transmitted to humans by the following kinds of ticks:

  1. Ixodes scapularis
  2. Ixodes pacificus
  3. Dermacentor variabilis

It infects the Neutrophils, a type of WBC that has a role in the inflammatory response.

Symptoms are the following:

  1. Sudden, High grade fever
  2. Muscle pain
  3. Chills
  4. Generalized weakness


The following tests are used to diagnose Ehrlichiosis Infection:

Indirect Fluorescent Antibody Assay (IFA). Dogs’ blood sample is examined to detect the presence of antibodies to the disease. It is considered more reliable than Giemsa Smear to detect exposure or infection.

Giemsa Smear. It is used to detect the location of the organism in the dog’s blood.

Polymerase Chain Reaction (PCR). A diagnostic procedure to test the presence of organisms’ DNA in the dogs’ blood. A positive result means an Active infection.

Complete Blood Count (CBC) with Platelet Count. To rule out Anemia, infection, and low platelet count.

Abdominal Xray. It is performed to reveal an enlarged liver or spleen.


Antibiotics are used to treat Ehrlichiosis Infection, Doxycycline or Tetracycline is the drug of choice for it has been proven effective against Ehrlichia and has lesser side effects. It must be taken three times a day or as prescribed by your Physician. The clinical improvement will most experience after 48 hours of taking medications. Antibiotic treatment will last for three weeks up to one month. Reinfection may happen since previous infection does not provide lifetime immunity.


Ehrlichiosis if left untreated may result in the following life-threatening situations:

  1. Lyme Disease
  2. Kidney failure (Glumerulonephritis)
  3. Respiratory failure
  4. Coagulopathy (Impaired clotting ability of the blood)
  5. Seizure
  6. Coma
  7. Death


  1. Decrease exposure to dog ticks
  2.  Apply proper hygiene on your dogs to prevent ticks infestation.
  3.  Apply repellant containing DEET to clothes.
  4.  Wear clother that covers the skin.
  5.  Keep your grass and weeds cut.
  6.  Avoid staying too long under trees or bushes.
  7.  Studies suggest that a tick must be attached to your body for at least 24 hours to cause disease. Early removal will prevent infection.
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