Overview of Rickettsial Diseases: History, Transmission, and Impact
Rickettsial
Diseases
Dr.
Sudhanshu Mishra
Assistant
Prof.,
Department of
Community Medicine
Career Institute of Medical Sciences & Hospital
I
n
t
r
oduction
•
Rickettsiae
–
smal
l
,
g
r
a
m
n
e
g
a
ti
v
e
b
acill
i
ada
p
t
e
d
t
o
o
bl
i
g
at
e
intracellular
parasitism.
•
Transmitted
by arthropod
vectors.
–
primarily
parasites
of
arthropods
such
as
lice, fleas,
ticks
and
mites,
in
which they
are
found
in the
alimentary
canal.
–
In
vertebrates,
including humans,
they
infect
the
vascular
endothelium and reticuloendothelial
cells.
•
Th
e
f
a
m
i
l
y
Ric
k
e
t
tsiaecea
e
cur
r
e
n
t
l
y
c
om
pris
es
of
three
genera:
i.
Rickettsia
ii.
Orientia
iii.
Ehrlichia
•
Former members
of the
family
which
have
been
excluded:
i.
Coxiella
burnetii
(causes
Q
fever)
is not
primarily
arthropod
borne
ii.
Rochalimaea
quintana
(causes
trench
fever)
is not
an
obligate
intracellular parasite,
being capable
of
growing
in
cell‐free media,
besides being
different
in
genetic
properties.
History
•
Hippocrates
(460
BC)
–
T
y
phus
mea
nin
g
‘
c
o
n
fused
s
t
a
t
e
of
th
e
i
n
t
e
l
l
e
c
t’
associated
with
fevers.
–
As
‘
f
ebrile,
ex
a
n
them
a
ti
c
illness,
a
ssoci
a
t
ed
with
nervous
system’
described in
L’epidemion
.
•
Thucydides
(430‐425
BC)
–
‘Classical
epidemic typhus’
vs.
Plague
vs.
Measles
vs.
Smallpox.
•
Civil
wars
in
Granada
(in
1492)
–
Six
times
more
people
were
killed
from
febrile
illness termed
Tabardillo
(Spanish
‘red
cloak’)
than
in
battle.
•
Siege‐warfare
(in
1494)
–
French
Imperial
Army’s
siege
of
Naples
•
During
1485‐1551
–
Five
epidemics
‘English
sweat’
occur in
UK.
•
Girolamo
Fracastoro
–
Fracastorius
(in
1546)
–
Differentiated
‘plague’
from
‘typhus’
–
describe
d
i
n
De
c
o
n
t
agio
n
e
t
c
o
n
t
agiosi
s
morbis
(‘On
Contagion
and
Contagious
Diseases).
•
Napoleone’s
Grande
Armee
(in
1812)
–
Reduced
over
42
fold
(from
422000
men
to
10000
men)
during
invasion
of
Russia
–
Majority dying
from
typhus
rather
than
combat.
•
The
Second
World
War
(1942‐1945)
–
Scrub typhus:
18000
cases
and
639
deaths
–
Murine typhus:
787
cases
and
15
deaths
•
Major impact on
Scrub
Typhus
research
–
Imp
r
o
v
eme
n
t
s
i
n
diagno
s
t
ic
s
,
p
r
e
v
e
n
tion,
epidemiology,
clinical
management,
transmission.
‘
’
•
During
outb
r
e
a
k
s
i
n
a
rmies,
shi
p
s
and
prison,
following
measures
were
taken:
–
Burning
of
clothes
–
Changing of
bedding
–
Crude
quarantine
measures
•
These
were
found
to
be
very
effective
in
–
reducing
mortality,
–
p
r
omotin
g
the
unde
r
st
a
nding
of
th
e
epidemic
and
‘contagious’
notion of the
disease.
‘Dissection of
Typhus’
and
Creation
of
Rickettsiology
•
In
1
9
t
h
Ce
n
tur
y
,
il
l
‐d
e
fined
e
n
tity
of
‘typhus’
was
dissected
into
triad
of
–
Typhus,
–
Typhoid
–
Relapsing
fevers
•
Based on
refinement
of clinical
syndromes
–
‘
e
x
a
n
them
a
tic
f
e
v
e
r
s
’
,
‘
abdominal
or
e
n
t
eric
fevers’
and
‘recurrent
fevers’
‘Dissection
of
Typhus’
Exanthematic
Abdominal
or
f
e
v
e
r
s
Enteric
fevers
T
yphoid
T
yphus
Slow
nervous
fever
Putrid
malignant
fevers
R
e
l
a
p
sin
g
f
e
v
er
R
e
c
ur
r
e
n
t
fevers
•
Charles
Nicole (in
1909)
–
Demonstrated
Pediculus corporis
(body
louse)
was
the
vector
of
epidemic
typhus
•
Howard
Taylor
Rickets
(in
1910)
–
Described
rickettsial
organisms
in blood of
typhus
patients
and in
infected
lice
and their
feces
•
Ho
w
a
r
d
T
a
ylor
Ric
k
e
ts
and
S
t
anislaus
v
o
n
Prowazek
–
Die
d
f
r
o
m
typhus
a
cq
ui
r
e
d
duri
n
g
their
r
esea
r
ch
efforts
Rickettsial
Diseases
•
Scrub
typhus
•
Epidemic
typhus
•
Murine
Typhus
•
Indian tick
typhus
•
Brill Zinser
disease
•
Rocky
Mountain
Spotted
Fever
•
Other tick borne
infections
Weil‐Felix
Test
OX
19
OX
2
O
XK*
Scrub
Typhus
0
0
Epidemic
Typhus
++++
+
++
+
0
Murine
Typhus
++++
+
0
Indian
tick
typhus
+
++++
0
Brill
Zinser
disease
++++
+
RMSF
++++
+
0
0
++++
0
Other
tick
borne
infections
+
Weil
&
Felix
(In 1916,) and
*Dr.
A.N. Kingbury
(in
1924)
Scrub
Typhus
•
‘Chigger borne
typhus’,
‘
tsutsugamushi
fever’.
•
A
bacterial
disease.
•
Caused
by
Orientia
tsutsugamushi
•
Spread through trombiculid
(“chigger”)
mites.
•
Rodents
are
usuall
y
i
n
f
e
c
t
ed
,
whil
e
humans
a
r
e
accidental
hosts.
•
First
described
from
Japan
in
1899.
–
where it
was
found to
be
transmitted
by
mites.
•
The
disease
was
called
‘tsutsugamushi’
–
‘tsutsuga’
meaning
dangerous
–
‘mushi’ meaning
insect
or
mite.
•
The
term
“
scrub
”
is
used
because of
the
type
of
vegetation
(terrain
between woods
and
clearings)
that harbours
the
vector.
–
“
tall‐growing coarse
grass
”,
–
forests,
–
gardens,
–
beaches,
–
paddy
fields,
–
bamboo
patches
and
–
oil
palm
or rubber
estates.
Geographical
distribution
•
Scrub
typhus
is
endemic
to
a
part of the
world
known
as
the “
tsutsugamushi
triangle
”
–
extending from
northern
Japan
and
the
F
e
de
r
a
tion
f
ar‐
ea
s
t
ern
to
Russian
nor
t
h
ern
Australia
and
Pakistan.
–
include
s
Bhu
t
a
n
,
Indonesia,
India,
Maldi
v
es,
Myanmar,
Nepal,
Sri
Lanka
and
Thailand.
•
P
r
o
b
abl
y
one
of
t
h
e
mo
s
t
u
n
d
e
r
diagnos
e
d
and
under
r
epor
t
ed
f
e
bril
e
illnesse
s
r
e
quiring
hospitalization
in the
SEAR.
–
estimated
1
billion
people
are at
risk
for
scrub
typhus
and
–
estimated
1
million cases
occur
annually
.
•
The
case‐fatality
rate
in
untreated
cases
varies
from
1– 60%
according
to:
–
area,
strain
of
infectious agent,
and
previous
exposure
to
the
disease;
–
it is
consistently
higher
among
older
people.
Scrub
typhus‐affected countries
of
Asia
Scrub typhus in
India
•
Specific
data
are
not
available.
•
Out
b
r
e
a
k
s
i
n
a
r
eas
lo
ca
t
ed
i
n
the
su
b
‐Himal
a
y
an
belt,
from
Jammu
&
Kashmir
to
Nagaland.
•
Reported from
Rajasthan
and
Vellore.
•
S
crub
ty
p
h
us
is
a
r
e
‐
eme
r
g
in
g
i
n
f
ec
ti
ous
d
iseas
e
in
India.
•
In
India,
the
disease had occurred
among
troops
during
World
War
II
in
Assam
and
West
Bengal,
and
in
the 1965
Indo‐Pak
war.
•
There
was
a
resurgence
of the disease in
1990
in
a
unit
of an
army
deployed
at
the
Pakistan
border
of
India.
•
There
were
reports
of
scrub typhus
outbreaks in
Himachal
Pradesh
,
Sikkim
and
Darjeeling
(West
Bengal)
during
2003‐2004 and
2007.
Characteristic
feature
of
an
outbreak
of
scrub
typhus
i
.
th
e
obvious
associ
a
tio
n
w
it
h
c
er
t
ai
n
types
of
terrain;
ii
i.
ii
.
th
e
mar
k
ed
lo
c
ali
z
a
tio
n
of
ma
n
y
c
ases
within
certain
small
foci;
th
e
la
r
g
e
pe
r
c
e
n
t
a
g
e
o
f
susceptibl
e
peopl
e
,
who
may
be
infected
simultaneously
following exposure
over
relatively
short
periods;
iv.
th
e
absence
of
a
hi
s
t
o
r
y
of
bi
t
es
or
a
tt
ack
b
y
arthropods
Seasonal
Occurrence
•
The period of epidemic
is influenced by
the
activities
of
the
infected
mite.
•
It
occurs
more frequently
during the
rainy
season.
–
However,
outbreaks
have
been
reported
during the
cooler
season
in southern
India.
•
Areas
such as
forest
clearings, riverbanks,
and
grassy
regions provide
optimal conditions
for
the
infected
mites
to
thrive.
A
g
e
n
t
•
Orientia
tsutsugamushi
–
a
small
(0.
3
t
o
0.5
b
y
0
.
8
t
o
1.5
μ
m),
g
r
am
ne
g
a
t
i
v
e
bacterium
of
the
family
Rickettsiaceae.
–
differs
from
the other members in its
genetic
make
up
and
in the composition
of
its cell
wall
structure
–
it has
five
major
serotypes.
Reservoir
–
Chi
g
g
er
m
i
t
es
act
as
th
e
prima
r
y
r
ese
r
v
o
i
r
s
f
or
O
.
tsutsugamushi.
V
ec
t
or
•
Chigger
mites
(
Leptotrombidium deliense
and
others)
very small
in
size
(0.2–0.4mm)
–
c
a
n
o
nl
y
be
see
n
t
h
r
oug
h
a
mic
r
o
s
c
op
e
o
r
magni
f
y
ing
glass.
–
inhabi
t
s
harpl
y
dema
r
ca
t
ed
a
r
eas
i
n
t
h
e
soi
l
whe
r
e
the
microecosystem
is
favourable
(
mite
islands
).
–
eithe
r
e
s
t
a
blishe
d
f
o
r
e
s
t
v
e
g
e
t
a
t
io
n
o
r
se
c
onda
r
y
vegetation
after clearance
of
forest
areas.
–
abundant
on
grasses
and herbs
where
bushes
are
scarce.
Mode of
transmission
•
Human
beings
are
infected
when
they trespass
into
mite
islands
and
are
bitten
by
the
mite
larvae
(chiggers).
•
The
mite
feeds
on the serum
of
warm
blooded
animals
only once during
its
cycle
of
development,
•
Adult
mites
do not
feed
on
man
.
•
The
microbes
are
transmitted transovarially
in
mites.
•
Scrub typhus normally
occurs
in
a
range
of
mammals,
small
particularly field
mice
and
rodents.
coexisting
–
Mi
t
e
c
o
e
xi
s
t
p
rimari
l
y
wit
h
r
ode
n
ts
an
d
other
mammals.
Mode of
transmission
Risk
factors for
Human
Infection
•
Scrub typhus
is
essentially
an
occupational disease
among
rural
residents
in the
Asia‐Pacific
region.
•
An
increase
in
the
prevalence
of
scrub typhus has
been
reported from
some Asian
countries,
which
coincides
with
urbanization
of
rural
areas.
Habitats
favourable for
disease
transmission
•
Scrub typhus,
originally
found
in
scrub
jungles,
has
also been
identified
in
a
variety
of other
habitats,
such
as
sandy
beaches,
mountain
deserts
and
equatorial
rain forests.
Incubation
period
•
5–20
days (average
10–12
days)
after
the
initial
bite.
Clinical
signs and
symptoms
•
The chigger
bite
is
painless
•
M
a
y
b
e
noticed
as
a
t
r
a
n
si
e
n
t
l
o
c
a
li
z
ed
i
t
ch
,
of
t
en
found
on
the
groin,
armpits,
genitalia
or
neck.
•
A
papule
develops
at
the
site
of
inoculation.
•
Th
e
p
apule
ulce
r
a
t
es
and
e
v
e
n
tuall
y
heal
s
with
development
of
a
black
eschar
.
•
Sudde
n
shakin
g
c
hills,
hig
h
g
r
ad
e
f
e
v
e
r
,
s
e
v
e
r
e
headache,
photophobia,
myalgia,
apathy,
and
swelling
of
the lymph
nodes
are
also
seen.
•
Approximately
one
week
later,
a
spotted
and
then
maculopapular
rash
appears
first
on the
trunk
and
then on the
extremities
and
blenches within
a
few
days.
•
Compli
ca
tion
s
m
a
y
include
pneumonia,
meningoencephalitis and
myocarditis.
Di
agno
s
i
s
•
Indirect
Immunoflorescence Antibody
(IFA)
•
Indirect Immunoperoxidase
test
(IIP)
•
Complement
Fixation
Test
•
Weil‐Felix
Test
•
ELISA
•
PCR
•
Isolation
of the
organism
I
n
v
e
s
ti
g
a
ti
on
m
a
y
r
e
v
eal
ea
rl
y
l
ym
p
h
ope
nia
wit
h
l
a
t
e
l
ym
ph
oc
y
t
os
is.
Albuminuria
is
a
common laboratory
finding.
Differential
Diagnosis
•
Other
rickettssial
diseases
•
Malaria
•
Dengue
•
Chikungunya
•
Leptospirosis
•
Relapsing
fever
•
Typhoid
•
Meningococcal
disease
•
Viral
fevers
Treatment
•
Doxycycline:
the
drug
most
commonly
used.
–
100 mg BD X 7‐15
days
•
A
c
ombin
a
tion
the
r
a
p
y
wit
h
d
o
x
y
c
y
clin
e
and
rifampicin
–
i
n
a
r
eas
whe
r
e
the
r
e
is
poo
r
r
e
spons
e
t
o
d
o
x
y
c
y
cline
alone.
•
Azithromycin
or
chloramphenicol
–
i
s
us
e
f
u
l
f
or
t
r
e
a
t
in
g
i
n
f
ectio
n
i
n
child
r
e
n
o
r
p
r
egna
n
t
women.
Prevention
and
control
Individuals
•
I
n
endemic
a
r
eas
,
w
ear
f
ul
l
‐len
g
t
h
clothin
g
,
soc
k
s
and
shoes.
•
Avoid
walking
barefoot.
•
Apply,
as
necessary,
insect
repellents containing
dibutyl
phthalate,
benzyl
benzoate,
and
diethyltoluamide
(DEET)
,
to
the
skin
and
clothing
to prevent
chigger
bites.
•
Do
not
sit
or
lie
on
bare
ground
or
grass.
Community
•
Rapid
case
identification
by
health‐care
workers
can
help
provide
prompt
treatment.
•
Public
education
on
case
recognition
and
personal
protection
will
help in the
identification
and
prompt
treatment
of
cases.
•
Rodent control
and
improved
living conditions will
help
prevent
spread
of
the
disease.
•
Clear
vegetation
and do
chemical
treatment
of the
soil
to
help
break
the
cycle
of
transmission.
Epidemic
Typhus
•
Louseborne typhus,
Classical
typhus,
Gaol
fever
•
One
of
the
great
scourges
of
mankind, occurring
in
devastating
epidemics during
times
of
war
and
famine.
•
Reported from
all
parts of the
world
but
has
been particularly common in Russia
and
Eastern
Europe.
–
During
1917‐1922,
there
were
some 25
million
cases
in
Russia,
with
about
three
million
deaths.
•
In
recent
times, the main
foci
have
been
Eastern
Europe, Africa,
South
America
and
Asia.
•
In India, the endemic
spot is
Kashmir.
•
Th
e
c
aus
a
ti
v
e
a
g
e
n
t
of
e
pidemic
typhus
is
R.
prowazekii
.
•
Humans
are
the only
natural
vertebrate
hosts.
–
N
a
tu
r
a
l
i
n
f
ectio
n
i
n
fl
y
in
g
squir
r
els
h
a
s
bee
n
r
ep
or
t
ed
from
South‐
eastern
USA.
•
Th
e
human
bod
y
lous
e
,
P
ediculu
s
humanus
corporis
,
is the
vector.
–
The
head
louse
may
also
transmit
the
infection
but not
the
pubic
louse.
in
f
ec
t
ed
b
y
f
eedin
g
on
•
The
lice
become
rickettsiaemic
patients.
•
The
rickettsiae
multiply
in
the
gut
of
the
lice
and
appear
in the
faeces
in 3‐5
days.
•
Lic
e
succumb
t
o
the
i
n
f
ection
within
2
‐4
w
ee
k
s,
remaining
infective
till they
die.
•
They
can transmit
the
infection
after
about a
week of
being
infected.
Transmission
•
Lice
may
be
transferred
from person
to
person.
–
Being sensitive
to temperature
changes
in
the
host,
they
leave
the
febrile
patient
or the cooling
carcass
and
parasitise
other
persons.
•
Lice
defecate
while
feeding.
•
Infection
is
transmitted
when
the
contaminated
louse
faces
is
rubbed
through
the
minute abrasions
caused by
scratching.
–
Occasionally,
infection
may
also
be
transmitted
by
aerosols
of dried
louse
faces through
inhalation
or
through
the
conjunctiva.
•
Incubation
period:
–
5
‐
15
days
Clinical
Presentation
•
The disease
starts
with
fever
and
chills.
•
A
characteristic
rash
appears
–
on the
fourth
or fifth
day,
–
s
t
artin
g
o
n
th
e
t
run
k
an
d
s
p
r
eadin
g
o
v
e
r
th
e
limb
s
but
sparing
the
face,
palms
and
soles.
•
T
o
w
a
r
ds
the
se
c
on
d
w
eek,
th
e
p
a
tie
n
t
be
c
omes
stuporous
and
delirious.
–
The
nam
e
typhus
c
om
es
f
r
o
m
th
e
cloudy
stat
e
of
consciousness
in the
disease.
•
The
case
fatality may
reach
40%
and
increases
with
age.
•
In
some who
recover
from
the
disease,
the
rickettsiae may
remain
latent
in
the
lymphoid tissues
or
organs
for
years.
•
Such
latent
infection
may,
at
times, be
reactivated
leading
to
recrudescent
typhus or
Brill Zinsser
disease
.
Endemic
Typhus
•
‘Murine
typhus’
•
A
milder disease than epidemic
typhus.
•
In India, endemic typhus has been
reported from
Pune,
Lucknow,
Mysore,
Kolkata,
Golkunda, Karnal,
R
ewari
and
Kashmir.
•
Endemic
typhus
is caused
by
R. typhi
–
i
t
is
m
a
i
n
t
a
i
n
ed
in
n
a
tu
r
e
as
a
m
il
d
i
n
f
ecti
o
n
of
rats.
•
I
t
is
t
r
a
ns
m
i
tt
e
d
b
y
t
he
r
a
t
flea
,
X
enop
s
y
l
la
cheopis
.
–
The
rickettsia
multiplies
in
the
gut of the
flea
and
is
shed
in
its
faeces.
–
Th
e
f
le
a
i
s
u
n
a
f
f
ec
t
e
d
but
r
e
mains
i
n
f
ectious
f
o
r
the
rest
of
its
natural
span of
life.
•
Humans
acquire
the
disease
usually through
the
bite
of
infected
fleas
–
whe
n
thei
r
sali
v
a
o
r
f
a
eces
i
s
rubbe
d
i
n
or
t
h
r
ough
aerosols
of
dried
faeces.
•
Ingestion
of
food
recently
contaminated
with
infected
rat
urine or
flea
faeces may
also
cause
infection.
•
Human
infection
is
a dead
end.
–
Man
to
man
transmission
does not
occur.
Clinical
presentation
•
Endemic
typhus
resembles
many
other illnesses and very
few
patients
are
provisionally diagnosed
correctly.
•
Headache and
fever
(in
12%
of
cases)
•
Rash
develops
in 54% of
patients.
•
Nausea,
vomiting,
diarrhoea and abdominal
pain
suggest
gastrointestinal
diseases while
cough
and abnormal
chest
radiograph
suggests pneumonia
or
bronchitis.
•
Severe
illness including seizures,
coma, renal
insufficiency and
respiratory failure are
seen
in
approximately
10%
of
cases,
only 1% of
cases
are
fatal
.
Spotted
Fever
Group
•
They
are
all
transmitted
by
ticks,
except
R.
akari
,
which is
mite
borne.
•
Rickettsiae
of
this
group
possess
a
common
soluble
antigen
and
multiply in
the nucleus
as
well
as in
the cytoplasm
of
host
cells.
•
Many
species
have
been
recognized
in
this
group.
•
The
rickettsiae
are transmitted
transovarially
in
ticks,
which
therefore
act as both
vectors
and
reservoirs.
•
The
infection
may
be
transmitted to
vertebrate
hosts
by
any
of the
larval
stages
or
by
adult
ticks.
•
Tic
k
s
a
r
e
not
harme
d
b
y
th
e
ric
k
e
t
tsia
e
an
d
r
emain
infected
for
life.
•
The
rickettsiae
are
shed in
tick
faeces
but
transmission
to
human
beings is
primarily
by
bite
,
as
the
rickettsiae
also
invade
the
salivary
glands
of
the
ticks.
•
All
rickettsiae
of this
group
pass
through
natural
cycles
in
domestic
and wild
animals
or
birds.
Tick
Typhus
(Indian Tick
Typhus)
•
Tick
typhus, in
several
parts of
Europe,
Africa
and
Asia
is caused by
R.
conori
,
strains
of
which
isolated
from
the
Mediterranean region,
Kenya,
South
Africa
and India
are
indistinguishable.
•
Tick
typhus
was
first
observed in India in
the
foothills
of
the
Himalayas.
•
Subseque
n
tl
y
,
t
h
e
diseas
e
w
as
r
e
por
t
ed
f
r
o
m
ma
n
y
parts of the
country
Na
r
sap
a
tnam
,
R
a
t
lam
,
Secunde
r
abad,
B
an
g
alo
r
e
,
J
hansi
,
Darjeelin
g
,
Pune
and
–
Allahabad,
T
r
ichinapal
l
y
,
Lucknow.
•
The
tick
sp.
Rhipicephalus sanguineus
is
the
most
important vector
and
is
generally found infesting
dogs
all
over.
•
Some
species of
Haemaphysalis
and
Hyalomma
ticks
may
also
transmit
the
infection.
Rickettsial diseases are caused by small, intracellular parasites primarily transmitted by arthropod vectors. This overview covers the history of these diseases, their transmission, the genera involved, and key historical events such as their impact during wars. Understanding rickettsial diseases is crucial for effective prevention, diagnosis, and management.
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Rickettsial Diseases Dr. Sudhanshu Mishra Assistant Prof., Department of Community Medicine Career Institute of Medical Sciences & Hospital
Introduction Rickettsiae small, intracellular parasitism. gram negative bacilli adapted to obligate Transmitted by arthropod vectors. primarily parasites of arthropods such as lice, fleas, ticks and mites, in which they are found in the alimentary canal. In vertebrates, including humans, they infect the vascular endothelium and reticuloendothelialcells.
The family Rickettsiaeceae currently comprises of three genera: i. ii. iii. Ehrlichia Rickettsia Orientia Former members of the family which have been excluded: i. Coxiella burnetii (causes Q fever) is not primarily arthropod borne ii. Rochalimaea quintana (causes trench obligate intracellular parasite, being capable of growing in cell free media, besides properties. fever) is not an being different in genetic
History Hippocrates (460 BC) Typhus meaning confused state of the intellect associated with fevers. As febrile, exanthematic illness, associated with nervous system described in L epidemion. Thucydides (430 425 BC) Classical epidemic typhus vs. Plague vs. Measles vs. Smallpox.
Civil wars in Granada (in 1492) Six times more people were killed from febrile illness termed Tabardillo (Spanish red cloak ) than in battle. Siege warfare (in 1494) French Imperial Army s siege of Naples During 1485 1551 Five epidemics English sweat occur in UK.
Girolamo Fracastoro Fracastorius (in 1546) Differentiated plague from typhus described in De contagion et contagiosis morbis ( On Contagion and Contagious Diseases). Napoleone s Grande Armee (in 1812) Reduced over 42 fold (from 422000 men to 10000 men) during invasion of Russia Majority dying from typhus rather than combat.
The Second World War (19421945) Scrub typhus: 18000 cases and 639 deaths Murine typhus: 787 cases and 15 deaths Major impact on Scrub Typhus research Improvements in epidemiology, clinical management, transmission. diagnostics, prevention,
During outbreaks in armies, ships and prison, following measures were taken: Burning of clothes Changing of bedding Crude quarantine measures These were found to be very effective in reducing mortality, promoting the understanding of the epidemic and contagious notion of the disease.
Dissection of Typhus and Creation of Rickettsiology In 19thCentury, ill defined entity of typhus was dissected into triad of Typhus, Typhoid Relapsing fevers Based on refinement of clinical syndromes exanthematic fevers , fevers and recurrent fevers abdominal or enteric
Dissection of Typhus Exanthematic fevers Abdominal or Enteric fevers Typhoid Typhus Putrid malignant fevers Slow nervous fever Relapsing fever Recurrent fevers
Charles Nicole (in 1909) Demonstrated Pediculus corporis (body louse) was the vector of epidemic typhus Howard Taylor Rickets (in 1910) Described rickettsial organisms in blood of typhus patients and in infected lice and their feces Howard Taylor Rickets and Stanislaus von Prowazek Died from typhus acquired during their research efforts
Rickettsial Diseases Scrub typhus Epidemic typhus Murine Typhus Indian tick typhus Brill Zinser disease Rocky Mountain Spotted Fever Other tick borne infections
WeilFelix Test OX19 OX2 OXK* Scrub Typhus 0 0 ++ + Epidemic Typhus ++++ + 0 0 Murine Typhus ++++ + Indian tick typhus + ++++ 0 Brill Zinser disease ++++ + 0 RMSF ++++ + 0 Other tick borne infections + ++++ 0 Weil & Felix (In 1916,) and *Dr. A.N. Kingbury (in 1924)
Scrub Typhus Chigger borne typhus , tsutsugamushi fever . A bacterial disease. Caused by Orientia tsutsugamushi Spread through trombiculid ( chigger ) mites. Rodents are usually infected, while humans are accidental hosts.
First described from Japan in 1899. where it was found to be transmitted by mites. The disease was called tsutsugamushi tsutsuga meaning dangerous mushi meaning insect or mite.
The term scrub is used because of the type of vegetation (terrain between woods and clearings) that harbours the vector. tall growing coarse grass , forests, gardens, beaches, paddy fields, bamboo patches and oil palm or rubber estates.
Geographical distribution Scrub typhus is endemic to a part of the world known as the tsutsugamushi triangle extending from northernJapan and the Federation to Australia and Pakistan. includes Bhutan, Indonesia, Myanmar, Nepal, Sri Lanka and Thailand. far eastern Russian northern India, Maldives,
Probably one of the most underdiagnosed and underreported febrile hospitalization in the SEAR. estimated 1 billion people are at risk for scrub typhus and estimated 1 million cases occur annually. illnesses requiring The case fatality rate in untreated cases variesfrom 1 60% according to: area, strain of infectious agent, and previous exposure to the disease; it is consistently higher among older people.
Scrub typhus in India Specific data are not available. Outbreaks in areas located in the sub Himalayan belt, from Jammu & Kashmir to Nagaland. Reported from Rajasthan and Vellore. Scrub typhus is a re emerging infectious disease in India.
In India, the disease had occurred among troops during World War II in Assam and West Bengal, and in the 1965 Indo Pak war. There was a resurgence of the disease in 1990 in a unit of an army deployed at the Pakistan border of India. There were reports of scrub typhus outbreaks in Himachal Pradesh, Sikkim and Bengal) during 2003 2004 and 2007. Darjeeling (West
Characteristic feature of an outbreak of scrub typhus i. the obvious association with certain types of terrain; the marked localization of many cases within certain small foci; ii. iii. the large percentage of susceptible people, who may be infected simultaneously following exposure over relatively short periods; iv. the absence of a history of bites or attack by arthropods
Seasonal Occurrence The period of epidemic is influenced by the activities of the infected mite. It occurs more frequently during the rainy season. However, outbreaks have been reported during the cooler season in southernIndia. Areas such as forest clearings, riverbanks, and grassy regions provide optimal conditions for the infected mites to thrive.
Agent Orientia tsutsugamushi a small (0.3 to 0.5 by 0.8 to 1.5 m), gram negative bacterium of the family Rickettsiaceae. differs from the other members in its genetic make up and in the composition of its cell wall structure it has five major serotypes. Reservoir Chigger mites act as the primary reservoirs for O. tsutsugamushi.
Vector Chigger mites (Leptotrombidium deliense and others) very small in size (0.2 0.4mm) can only be seen through a microscope or magnifying glass. inhabit sharply demarcated areas in the soil where the microecosystem is favourable (mite islands). either established forest vegetation after clearance of forest areas. abundant on grasses and herbs where bushes are scarce. vegetation or secondary
Mode of transmission Human beings are infected when they trespass into mite islands and are bitten by the mite larvae (chiggers). The mite feeds on the serum of warm blooded animals only once during its cycle of development, Adult mites do not feed on man. The microbes are transmitted transovarially in mites. Scrub typhus normally occurs in a range of mammals, particularly field mice and rodents. coexisting Mite coexist primarily with rodents and other mammals. small
Risk factors for Human Infection Scrub typhus is essentially an occupational disease among rural residents in the Asia Pacific region. An increase in the prevalence of scrub typhus has been reported from some Asian countries, which coincides with urbanization of rural areas.
Habitats favourable for disease transmission Scrub typhus, originally found in scrub jungles, has also been identified in a variety of other habitats, such as sandy beaches, equatorial rain forests. mountain deserts and Incubation period 5 20 days (average 10 12 days) after the initial bite.
Clinical signs and symptoms The chigger bite is painless May be noticed as a transient localized itch, often found on the groin, armpits, genitalia or neck. A papule develops at the site of inoculation. The papule ulcerates and eventually heals with development of a black eschar.
Sudden shaking chills, high grade fever, severe headache, photophobia, swelling of the lymph nodes are also seen. Approximately one week later, a spotted and then maculopapular rash appears first on the trunk and then on the extremities and blenches within a few days. Complications may meningoencephalitis and myocarditis. myalgia, apathy, and include pneumonia,
Diagnosis Indirect Immunoflorescence Antibody (IFA) Indirect Immunoperoxidase test (IIP) Complement Fixation Test Weil Felix Test ELISA PCR Isolation of the organism Investigation Albuminuria is a common laboratory finding. may reveal early lymphopenia with late lymphocytosis.
Differential Diagnosis Other rickettssialdiseases Malaria Dengue Chikungunya Leptospirosis Relapsing fever Typhoid Meningococcal disease Viral fevers
Treatment Doxycycline: the drug most commonly used. 100 mg BD X 7 15days A combination therapy rifampicin in areas where there is poor response to doxycycline alone. Azithromycin or chloramphenicol is useful for treating infection in children or pregnant women. with doxycycline and
Prevention and control Individuals In endemic areas, wear full length clothing, socks and shoes. Avoid walking barefoot. Apply, as necessary, insect repellents containing dibutyl phthalate, benzyl benzoate, (DEET), to the skin and clothing to prevent chigger bites. Do not sit or lie on bare ground or grass. and diethyltoluamide
Community Rapid case identification by health care workers can help provide prompt treatment. Public education on case recognition and personal protection will help in the identification and prompt treatment of cases. Rodent control and improved living conditions will help prevent spread of the disease. Clear vegetation and do chemical treatment of the soil to help break the cycle of transmission.
EpidemicTyphus Louseborne typhus, Classical typhus, Gaol fever One of the great scourges of mankind, occurring in devastating epidemics during times of famine. war and
Reported from all parts of the world but has been particularly common in Russia and Eastern Europe. During 1917 1922, there were some 25 million cases in Russia, with about three million deaths. In recent times, the main foci have been Eastern Europe, Africa, South America and Asia. In India, the endemic spot is Kashmir.
The causative agent of epidemic typhus is R. prowazekii. Humans are the only natural vertebrate hosts. Natural infection in flying squirrels has been reported from South easternUSA. The corporis, is the vector. The head louse may also transmit the infection but not the pubic louse. human body louse, Pediculus humanus
The rickettsiaemicpatients. lice become infected by feeding on The rickettsiae multiply in the gut of the lice and appear in the faeces in 3 5 days. Lice succumb to the infection within 2 4 weeks, remaining infective till they die. They can transmit the infection after about a week of being infected.
Transmission Lice may be transferred from person to person. Being sensitive to temperature changes in the host, they leave the febrile patient parasitise other persons. or the cooling carcass and Lice defecate while feeding. Infection is transmitted when the contaminated louse faces is rubbed through the minute abrasions caused by scratching. Occasionally, infection may also be transmitted by aerosols of dried louse faces through inhalation or through the conjunctiva.
Incubationperiod: 5 15 days
Clinical Presentation The disease starts with fever and chills. A characteristic rash appears on the fourth or fifthday, starting on the trunk and spreading over the limbs but sparing the face, palms and soles. Towards the second week, the patient becomes stuporous and delirious. The name typhus comes from the cloudy state of consciousness in thedisease. The case fatality may reach 40% and increases with age.
In some who recover from the disease, rickettsiae may remain latent in the lymphoid tissues or organs for years. the Such latent infection may, at times, be reactivated leading to recrudescent typhus or Brill disease. Zinsser
Endemic Typhus Murine typhus A milder disease than epidemic typhus. In India, endemic typhus has been reported from Pune, Lucknow, Mysore, Kolkata, Golkunda, Karnal, R ewari and Kashmir.
Endemic typhus is caused by R. typhi it is maintained in nature as a mild infection of rats. It is transmitted by the rat flea, Xenopsylla cheopis. The rickettsia multiplies in the gut of the flea and is shed in its faeces. The flea is unaffected but remains infectious for the rest of its natural span of life.
Humans acquire the disease usually through the bite of infected fleas when their saliva or faeces is rubbed in or through aerosols of dried faeces. Ingestion infected rat urine or flea faeces may also cause infection. of food recently contaminated with Human infection is a dead end. Man to man transmission does notoccur.
Clinical presentation Endemic typhus resembles many other illnesses and very few patients are provisionally diagnosed correctly. Headache and fever (in 12% of cases) Rash develops in 54% of patients. Nausea, vomiting, diarrhoea and abdominal pain suggest gastrointestinal diseases while cough and abnormal chest radiograph suggests pneumonia or bronchitis. Severe illness including seizures, coma, renal insufficiency and respiratory failure are seen in approximately 10% of cases, only 1% of cases arefatal.
Spotted Fever Group They are all transmitted by ticks, except R. akari, which is mite borne. Rickettsiae of this group possess a common soluble antigen and multiply in the nucleus as well as in the cytoplasm of hostcells. Many species have been recognized in this group. Organism R. rickettsi R. siberica R. conori Disease Rocky mountain spottedfever Siberian tick typhus Indian, Mediterranean, Kenyan and South African tick typhus Queensland tick typhus Oriental spottedfever R. australis R. japonica
