Introduction Small gram negative, obligate,

intracellular parasitesThese are tiny organisms measuring

0.2-2.4micromtrs. 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 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 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