EHRLICHIA

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EHRLICHIA
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Introduction

• Small gram negative, obligate, intracellular
  parasites
• These are tiny organisms measuring
  0.2-2.4micromtrs. Which have affinity towards WBC
  particularly mononuclear phagocytes

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• Clusters of Ehrlichia multiply in host cell
  vacuoles to form large mulbery shaped aggregates
  called MORULAE
• Ehrlichia inclusions like morulae are visible in
  cytoplasm of infected cell after 5-7 days

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Ehrlichia sps

• Ehrlichia sennetsu
• Ehrlichia caffeensis
• Ehrlichia phagocytophila

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EHRLICHIA SENNETSU

• Endemic in JAPAN and SOUTH EAST ASIA
• It causes GLANDULAR FEVER
• It shows lymphoid hyperplasia and atypical
  lymphocytosis
• No arthropod vector identified
• Human infection is suspected to be caused by
  ingestion of fish carrying infected flukes

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EHRLICHIA PHAGOCYTOPHILA

• Causes human GRANULOCYTIC EHRLICHIOSIS
• Transmitted by IXODES ticks
• Deer, cattle and sheep are suspecte reservoirs
• Leucopenia and thrombocytopenia observed in
  patients

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EHRLICHIA CAFFEENSIS

• Cause human MONOCYTIC EHRLICHIOSIS
• Transmitted by Amblyomma ticks
• Deers and rodents reservoirs
• Leucopenia and
• thrombocytopenia
• increased liver
• enzymes
• Most dangerous can cause multisystem failure and
  fatality

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EHRLICHIOSIS

• Ehrlichiosis is infection of WBC that is
  characterised by mulbery shaped aggregates called
  morulae in infected cells
• These morulae are visiible after 5-7days of
  infection

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Pathophysiology

• It is not completely known
• Like RICKETTSIA sps EHRLICHIA gain access to
  blood via bite from infected tick

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• AMBLYOMMA AMERICANAM(lone star tick)
• E.chaffeensis
• IXODES PERSUKATUS
• DERMACENTOR VARIABILIS
• (dog tick
• wood tick)

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• The major antigen determinants are surface
  membrane protien
• These are complexes consisting of
  
  1)thermolabile
  2)thermostable
• Key protien bands associated are
• E.phagocytophia - 27,29,44 KD bands
• E.caffeensis - 40,44,65 KD bands

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LIFE CYCLE
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Mortality and morbidity

• Great majority of EHRLICHIOSIS are asymptomatic
• Most cases present as mild to moderate acute
  febrile illness
• In immunocompromised persons ehrliosis
• may be severe manifesting as ROCKY MOUNTAIN
  SPOTTED FEVER may be fatal

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• Sex malefemale 41
• Age occurs at all ages but more common in young
  adults
• Clinical manifestations usually begin in 5-14
  days after tick bite

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Clinical features
Rash and pedal edema
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• Patients with Ehrlichiosis usually present with
  
• head ache,
• myalgia,
• fever,
• shaking chills.
• Nausea and vomiting are common
• Abdominal pain is uncommon and is typically mild
• Skin rash due to ehrlichiosis is rare. When
  present as macculopapular rash rather than
  peticheal

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Cont

• Some patients develop heptomegaly
• Lymphadenopathy is observed in lt25
• Splenomegaly is uncommon
• Patients with severe ehrlichiosis develop
  thrombocytopenia and disseminated intravascular
  coaggulation(DIC) which can result in hemorrhage
  into skin

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Distribution

• Ehrlichiosis occurs worldwide and frequensy
  parallels distribution of appropriate tick vector
  for transmission of ehrlichia and mammalian host
• In USA it occurs in states of CALIFORNIA, TEXAS
  and SOUTH EAST NORTHERN REGIONS OF CAENTRY
• World wide it occurs in JAPAN, SOUTH EAST ASIA

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Lab diagnosis

• Diagnosis rests on
• 1)single elevated IgG IFA antibody titre
• 2)demonstration of incr. in acute and
  convalescent IFA ehrlichia titre
• Difficult to culture
• Detection with PCR

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• Blood smear for cytoplasmic inclusions
• CBP for thrombocytopenia and neutropenia
• Atypical lymphocytes in blood
• Serum transaminases are
• mild high
• DIC may be diagnosed with cutaneous bleeding
• Lumbar puncture to rule out meningitis

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Treatment

• Doxycyclin
• Chloramphenicol
• Rifampacin
• fluoroquinolones

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Prevention