Ehrlichisis overview and Definition

       It is the tick borne disease caused by the bacterium Ehlrichia.The vector for this bacterium is the tick which are called as Ixodes scapularis and Ixodes pacificus.The Incubation period is 5-14 days.


It can occur at any age.But common age group is 40yrs.Men are mostly affected than women.It is more common among the northwest population.

Epidemiological Data should be collected.Questionnaire such as recent travel to endemic areas,occupational exposure with ticks,expose to the wooden materials should be considered.


It is acquired through tick bite and the bacterium is transmitted to the spleen and bone marrow.It gets multiplicated in the cytoplasmic vacuoles of the polymorphonuclear cells.It affects the progenitors of the myeloid and monocytic cells and invades the neutrophils.It leads to the deactivation of the neutrophils and release of cytokines leads to degranulation of the neutrophils.Intrrleukin 10 ,Interleukin 12 and IFN gamma plays an important role in the immune response.This cytokine released mechanism is manifested as the himan granulocytic ehlrichiosis.Pancytopenia(decrease in neutrophil count),liver damage and even shock may occur.

Clinical signs & symptoms

Signs and symptoms often begins within 1-2 weeks depending upon the immune system of an individual.

Early Illness-

Early signs and symptoms (days 1-5) are usually mild or moderate and may include:

  • Fever, chills
  • Severe headache
  • Muscle aches
  • Nausea, vomiting, diarrhea, loss of appetite

Late Illness-

Rarely, if treatment is delayed or if there are other medical conditions present, ehlrichiosis can cause severe illness. Prompt treatment can reduce your risk of developing severe illness.

 Signs and symptoms of severe (late stage) illness can include:

  • Respiratory failure
  • Bleeding problems
  • Organ failure
  • Death
  • Urine is dark or yellow due to the presence of bilirubin.

     Risk factors for severe illness:

  • Delayed treatment
  • Age: being older puts you at risk
  • Weakened immune system: People with weakened immune systems (such as those receiving some cancer treatments, individuals with advanced HIV infection, prior organ transplants, or people taking some medications) are at risk for severe illness

Differential Diagnosis

  • Examination of your white blood cells under a microscope.:The bacteria can often be seen inside these white blood cells.Changes in the mononuclear cells is also seen.leucocytopenia can be visualized in response to the bacterial infection.
  • Peripheral Blood Smear:It shows leucopenia(reduction in the number of white blood cells) and thrombocytopenia(reduction in the number of platelets).Presence of intracytoplasmic inclusion bodies is the rapid method in diagnosing the human granulocytic ehlrichiosis.
  • Polymerase chain reaction (PCR): This is a newer method to detect the multiplication of the bacteria and it is used to amplify the bacterial DNA.
  • Antibody test. This often does not become positive until many days or a few weeks after the infection. It is usually not helpful while you are first sick.
  • Immunohistochemical staining Test:It is used in bone marrow,lymph node and spleen.Immunostaining of bone marrow shows the Ehlrichiosis the infection caused by the bacterium ehlrichia.
  • Indirect Immunofluorescent antibody test:This test detects the antibodies such as IgM developed in response to the ehlrichiosis.This test shows negative in 1 st week of illness.Hence subsequent serum sample should be collected in further weeks for the detection of antibodies.
  • Liver function test:Elevation od aspartate transaminase,elevated lactate dehydrogenase and C Reactive protein is seen.



  • Avoid  wooded and bushy areas with high grass and leaf litter
  • Wear light-colored long pants and long-sleeved shirts, and enclosed shoes. Tuck your pants into your socks while out hiking.
  • Use tick repellents such as DEET(N diethyl meta tolumide) or permethrin on exposed skin and clothing.
  • Do a full-body check for ticks after coming in from the outdoors.
  • Bathe or shower within a couple of hours after coming indoors, so you can wash off and more easily find and remove any ticks.
  • Examine gear and pets for ticks.
  • Tumble clothes in a dryer on high heat to kill any remaining ticks.

If you do find a tick attached to your skin, remove it within 24 hours. Follow these steps:

  • Use a pair of tweezers to grasp the tick directly by the head or mouth parts. Don't grab the tick by its body.
  • Remove the tick by pulling it out firmly and directly outward without twisting or turning.
  • Place the tick in alcohol to kill it.
  • Clean the bite wound with a disinfectant.