00:01
Echinococcus, parasites.
00:04
The Echinococcus come from
the genus of Cestoda class,
so they are helminthic
like or worm-like.
00:11
In fact,
they have a segmented body
and appear more like
a ribbon in nature.
00:16
Echinococcosis is classified as either
cystic echinococcosis which is more common
or alveolar echinococcosis.
00:24
Cystic echinococcosis
or hydatid disease
is caused by infection with the larval
stage of echinococcus granulosus.
00:32
Most infections
are asymptomatic.
00:34
It is common in sheep-raising areas
of the Mediterranean, Middle East,
Australia, New Zealand,
South Africa and South America.
00:42
It is also found in both side of
Canada, Alaska and California.
00:46
Dogs are the definitive hosts,
having adult tapeworms in
their gastrointestinal tract.
00:51
The intermediate hosts are
herbivores, for example,
sheep, horses and deer,
as well as humans.
00:57
The tapeworm can cause the
development of slowly enlarging,
and potentially
harmful cystic lesions
in the liver,
lungs and other organs.
01:05
Alveolar echinococcosis
is caused by infection with the larval
stage of Echinococcus multilocularis.
01:12
It is less common than
cystic echinococcosis
but it is a much more
serious infection
because the cysts are
locally aggressive,
causing destruction
of surrounding tissue,
and possibly leading to
liver failure and death.
01:25
Adult E. multilocularis worms
are present in foxes,
coyotes, and dogs
which are all definitive hosts.
01:33
The intermediate hosts
are small rodents
which harbor the hydatid larvae.
01:37
Infected dogs are the primary link
to the occasional human infection.
01:41
This disease occurs
mainly in Central Europe,
Alaska, Canada, and Siberia.
01:47
In the United States,
it is found in the Upper Midwest.
01:50
Other hydatid diseases are rare
and cause cyst production
primarily in the liver.
01:56
Two causative species are E.
Vogelii and E. Oliganthus.
02:00
Both that which are found in
Central and South America.
02:03
This slide shows the life cycle of
echinococcus granulosus sensu lato
or in the broad sense,
since it includes
several genotypes.
02:11
The adult echinococcus granulosus
measures 2 to 7mm in length
and resides in the small intestine of
the definitive host, which is the dog.
02:20
The pregnant or
gravid proglottids
release eggs that are
passed in the feces
and which are
immediately infectious.
02:27
After ingestion by a
suitable, intermediate host,
eggs hatch in the small intestine
and release six-hooked oncospheres
that penetrate the intestinal wall and
migrate through the circulatory system
into various organs,
especially the liver and lungs.
02:42
In these organs, oncosphere develops
into a thick walled hydatid cyst
that enlarges gradually,
producing protoscolices
and daughter cysts that
filled the cyst interior.
02:53
The definitive host
becomes infected
by injecting the cyst containing organs
of the infected intermediate host.
03:00
After ingestion, the protoscolices
evaginate, attach the intestinal mucosa
and develop into adult
stages in 32 to 80 days.
03:09
Humans are aberrant
intermediate hosts
and become infected
by ingesting eggs.
03:14
Oncosphere are release
in the intestine
and hydatid cysts develop
in the variety of organs.
03:20
If the cysts rupture,
deliberated protoscolices
may create secondary cysts in
other sites within the body.
03:27
Known as "secondary
echinococcosis."
This slide shows the life cycle
of Echinococcus multilocularis
which causes alveolar
echinococcosis.
03:35
The adult parasite measures
1.2 to 4.5mm in length
and lives in the small intestine
of the definitive host.
03:43
Gravid proglottids release eggs
that are passed in the feces
and they are
immediately infectious.
03:48
After ingestion by a
suitable intermediate host,
eggs hatch in the small intestine
and release a six-hooked oncosphere
that penetrates
the intestinal wall
and migrates through the circulatory
system into various organs
primarily the liver as seen at E.
Multilocularis.
04:04
The oncosphere develops into a
multi-chambered thin-walled cyst
that proliferates by
successive outward budding
which reflects it's locally
aggressive character.
04:13
Numerous protoscolices
develop within the cyst.
04:16
The definitive host becomes infected
by ingesting the cyst containing organs
of the infected
intermediate host.
04:22
After ingestion, the protoscolices
evagenates attach to the intestinal mucosa
and develop into adult
stages in 32 to 80 days.
04:31
Humans are aberrant
intermediate hosts
and become infected
by ingesting eggs.
04:36
Oncospheres are release
in the intestine
and cysts develop
within the liver.
04:41
Metastasis or dissemination
to other organs,
for example lungs,
brain, heart or bone
may occur if the protoscolices
are released from cysts.
04:50
This sometimes is call
"secondary echinococcosis."
This next slide shows the case
of a 40-year-old Syrian man
with a 9 cm echinococcosis cyst due to E.
Granulosus
which was discovered incidentally
during a chest CT examination.
05:05
The CT examination was
essentially diagnostic
because it showed multiple
septae within the cyst
and the patient was
promen endemic region.
05:13
Suralgae was negative which is not
unusual to see if the cyst is not leaked or ruptured
which would expose
echinococcus antigen
the the immune system
and create a response.
05:23
The patient underwent
a left hepatectomy
with the cyst removed intact.
05:27
The surgical specimen
shows a multiloculated cyst
filled with many daughter cysts and
having a typically thick fibrous wall.
05:35
The microscopic photograph
shows many protoscolices
which account for the hydatid
sand appears in the fluid
which maybe seen on imagining.
05:44
The clinical disease caused by
Echinococcus is cystic echinococcosis,
and it is ingested or
transmitted by ingestion of eggs
in food contaminated
with the eggs
or food contaminated with
dog or I suppose human feces.
06:02
The key is that the definitive
host has to ingest the eggs.
06:07
Over then the period
of months to years,
the eggs might mature into
their next step of larvae
and create around them a cyst.
06:17
And this is not just any cyst,
this is a large cyst
with a very thin wall
filled with clear fluid
and it rarely or in fact almost
never has any septa within it.
06:29
So it's a single compartment,
large, fluid filled cyst.
06:33
Occasionally, a daughter cyst
will bought off from the side
and this even increases the
size of this overall cyst.
06:41
Three forths,
of the cysts occur in the liver
and when so,
they present with abdominal pain,
certainly tenderness to palpation
over the right upper quadrant.
06:50
The patient indeed may have a reactive
hepatomegaly, liver size enlarging
and they may even have what
feels like a very firm mass
along with that there may be some
liver dysfunction causing jaundice
and certainly there may be a
low grade persistent fever.
07:09
In the lungs,
the remainder of the cases almost
one will have sort of
non-specific respiratory symptoms
so, a dry intermittent cough,
a feeling of shortness of breath
although rarely is there true
failure of the
respiratory status.
07:25
Patients may have referred
chest pain as well.
07:28
Importantly, either of this
locations whether it's in the liver
the lungs or even in any
place else in the body,
has a huge potential for anaphylactic
shock should those cysts rupture
and in fact that is sometimes
a clinical presentation
when due to some other trauma,
for example, a car accident and
abdominal injury, the cyst rupture,
delivers all of a sudden
this huge flood of
hypereosinophilic,
anaphylactic type allergen
and the body reacts
in a heartbeat causing
complete and total hyper
IgE based reaction.
08:06
So, the treatment for
this then is albendazole.
08:09
Again, a medication used primarily to
treat helminthic or worm based disease.
08:15
Why not surgically
remove this you ask?
Because the risk of surgical -
surgically induced
rupture of these
is just as severe as should
that occur traumatically.
08:25
Sometimes if there is an
actual, physical impediment,
so, hepatomegaly or blockage
of the common bile duct
or blockage of the
main set of bronchus,
then surgery may be attempted
but it is done in an incredibly
careful and methodical fashion
to remove the entire cyst
together, with surrounding tissue
and to avoid any, any risk,
any even small risk of rupturing these.
08:50
So echinacoccus are very potentially
dangerous if you come across them,
perhaps the key things to remember here
are sheep herders are high risk for those
and they may present
non-specifically
and don’t, don’t, don’t,
don’t, rupture those things.
09:07
This ends the lesson.