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EHRLICHIA
Introduction
Small gram negative, obligate, intracellular
parasites
These are tiny organisms measuring 0.22.4micromtrs. Which have affinity towards
WBC particularly mononuclear phagocytes
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
Ehrlichia sps
 Ehrlichia sennetsu
 Ehrlichia caffeensis
 Ehrlichia phagocytophila
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
EHRLICHIA PHAGOCYTOPHILA
 Causes human GRANULOCYTIC
EHRLICHIOSIS
 Transmitted by IXODES ticks
 Deer, cattle and sheep are suspecte reservoirs
 Leucopenia and thrombocytopenia observed
in patients
EHRLICHIA CAFFEENSIS
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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
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
Pathophysiology
 It is not completely known
 Like RICKETTSIA sps EHRLICHIA gain access
to blood via bite from infected tick
 AMBLYOMMA AMERICANAM(lone star tick)
E.chaffeensis
 IXODES PERSUKATUS
 DERMACENTOR VARIABILIS
(dog tick
wood tick)
 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
LIFE CYCLE
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
 Sex:
male:female = 4:1
 Age: occurs at all ages but more common in
young adults
 Clinical manifestations usually begin in 5-14
days after tick bite
Clinical features
Rash and pedal edema
 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
Cont…
 Some patients develop heptomegaly
 Lymphadenopathy is observed in <25%
 Splenomegaly is uncommon
 Patients with severe ehrlichiosis develop
thrombocytopenia and disseminated
intravascular coaggulation(DIC) which can
result in hemorrhage into skin
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
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
 Blood smear for cytoplasmic
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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
Treatment
 Doxycyclin
 Chloramphenicol
 Rifampacin
 fluoroquinolones
Prevention