Introduction Small gram negative, obligate, intracellular parasites These are tiny organisms…
-
Upload
miles-norman -
Category
Documents
-
view
217 -
download
0
description
Transcript of Introduction Small gram negative, obligate, intracellular parasites These are tiny organisms…
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