Lecture #4.
Medical
helminthology.
Flat worms.
Medical helminthology is the field of medicine
that studies parasitic worms (helminths).
The main classes of human helminths are
Trematodes, Cestodes and Nematodes.
Plan of the lecture:
1. Phylum Flat worms (Plathelminthes). General
characteristics.
2. Trematodes: life-cycles and morphology.
3. Adaptations to parasitism in trematodes.
4. Intestinal flukes. Liver flukes. Lung fluke .
Blood flukes.
5. Cestodes. Life-cycle and morphology.
6. Adaptations to parasitism in cestodes.
7. Cestodes parasitizing humans.
General characteristics of Phylum
Platyhelminthes
1. Multicellular, triploblastic invertebrates
2. Bilaterally symmetrical unsegmented body
3. Dorsoventrally flattened
4. Acoelomates (have no body cavity)
5. Body wall: epithelium and three layers of
muscles – circular, longitudinal, diagonal
6. Four organ systems: digestive, nervous,
excretory and reproductive
7. About 25 000 species
Three main classes of flat worms
•Turbellaria – free-living, covered
with ciliae, have eyes and tactile
organs
•Trematoda – or flukes, all parasitic,
possess two suckers, or “tremae”,
leaf-like in shape.
•Cestoda – tape worms, all
parasitic, possess attachment
organs – suckers, hooks or
bothriiae, ribbon-like body, no
digestive tract
Phylum
Platyhelminthes
(flat worms)
Class
Turbellaria
(free-living, have
ciliae and eyes)
Class
Trematoda
(parasites, have
2 suckers –
“tremae”.Leaflike in shape
Class
Cestoda
(parasites,
ribbon-like body,
no digestive
tract)
Class Turbellaria.
Planaria – a free-living flat worm
Morphology of flat
worms
Flat worms have no coelom, body cavity is filled
with parenchyma
Trematodes have four organ systems
Nervous system consists of ganglia (“brain”) and nerve
cords.
A – D – different flat worms.
E. Planaria (ladder-like type)
Digestive system of flat worms is blind – there is no anus
Excretory system of flat worms is protonephridial
Reproductive system of flat worms is
hermaphrodite. They have sexual
and asexual reproduction.
Ovary
Testes
Oviduct
Cyrrus in a
sac (penis)
Genital
pore
Asexual reproduction is
by fragmentation
Class Trematoda
(flukes)
Size: microscopic to 75 mm
- Covered by a cytoplasmic tegument
- Possess 2 suckers, or tremae
- Nervous system is primitive (ladder-like)
- Digestive system is blind (no anus).
- Excretory system- protonephridiae.
- Reproduction: Most species are
hermaphroditic; schistosomes are an
exception.
Trematodes, or Flukes
Tegument – serves for protection and nutrition
A hypothetical trematode and the digestive tract of Fasciola hepatica
Reproductive system is hermaphrodite (exception:
blood flukes) and very complex
Cyrrus in
bursa
Uterus
Vasa
deferens
Mehlis’
gland
Semimal
reciptacle
Ootype
Laurer’s canal
Ovary
Testes
Vittelaria, or
yolk glands
Male organs:
Cirrus
Testes
Vasa deferens
Seminal
vesicle
Prostate
gland
Ejaculatory
duct
Female organs:
Ovary
Uterus
Mehlis’ gland
Vittelaria, or
yolk glands
Laurer’s canal
Ootype
Seminal
receptacle
Life-cycle of Trematodes was discovered by
Danish biologist J. Steenstrup in 1842
Egg  miracidium  sporocyst  redia
cercaria  metacercarium  adult form (marita)
Johannes Japetus Smith
Steenstrup (1813–1897)
was a Danish biologist. He
discovered the trematodes’
life-cycle
Trematodes have a complex life-cycle.
•Definitive host is some vertebrate, in this
host sexual reproduction occurs and fertilized
eggs are passed to the environment.
•Intermediate host is a snail (mollusk), where
asexual reproduction takes place.
•Life-cycle includes: adult (marita)egg
miracidiumsporocystrediacercaria
metacercaria (adolescaria)adult.
Trematodes’ eggs have a lid or a spine
Most of trematodes have eggs with
opperculum
Schistosome’s egg
has a spine
Miracidium (Greek – little boy) comes out of its
shell.
Structure of a miracidium
Miracidium is looking for its intermediate host – a snail
In snail a sporocyst is formed
sporocyst
1: sporocyst
Inside the sporocyst rediae are formed
redia
Inside the redia cercariae are formed
cercaria
Cercariae of schistosomes have a
forked tail
There are three possibilities for cercaria
1. Adolescarium on
the grass blades
Sporocyst redia  cercaria
cercaria
mollusk
One miracidium that
enters a host can
produces (by
parthenogenesis) up
to 1000 cercariae in
the end
2. Metacercarium in the
second intermediate host
3. Direct penetration
into the skin of human
1. Metacercarium becomes adolescarium on a leave
of a water plant
(magnified)
2. Metacercarium in the second intermediate
host (magnified)
Metacercarium of
Paragonimus westermani in
crab
Metacercarium of
Clonorchis sinensis in fish
3. «Swimmer’s itch – result of direct penetration
of Schostosoma’s cercariae.
In the definitive host trematodes’ larvae grow
into marita – adult form
Trematodes parasitizing humans are
divided into
•Intestinal flukes (Fasciolopsis buski)
•Liver flukes (Fasciola hepatica,
Opisthorchis felineus, Clonorchis
sinensis, Dicrocoelium lanceatum)
•Lung flukes (Paragonimus
westermani)
•Blood flukes (Schisosomae mansoni,
japonicum, haematobium)
Intestinal fluke – Fasciolopsis
buski
Fasciolopsis buski – is the biggest of human
Trematodes
Up to 7,5 cm in length
Fasciolopsis’ life
cycle
Definitive hosts
egg
Adolescarium on the grass
cercarium
miracidium
Intermediate host
Fasciolopsiasis
is a parasitic disease that infects pigs and humans in
mainland China, Taiwan, Vietnam, Thailand, Indonesia,
Malaysia, and across the Indian subcontinent.
In is estimated that ten million cases occur annually. Those
especially at risk are people who raise pigs or eat fresh
water plants in the areas listed above.
Means of infection: ingestion of adolescaria encysted on
aquatic plants
Location: small intestine
Clinical symptoms: abdominal pain, diarrhea, edema,
Diagnosis: eggs in stool
Prevention: protection ponds and rivers from infected feces,
do not use water from ponds for watering
Liver flukes
(Fasciola hepatica, Opisthorchis felineus, Clonorchis sinensis,
Dicrocoelium lanceatum)
Liver fluke – Fasciola hepatica, "the common liver
fluke" or "the sheep liver fluke."
3 – 5 cm
Fasciola hepatica: life
cycle
Definitive hosts
egg
Adolescarium on the grass
cercarium
miracidium
Intermediate host
Clonorchis sinensis и Opisthorchis felineus (both
about 1 cm in length)
Clonorchis sinensis
Opisthorchis felineus
Testes are
branchiate
Testes are
compact
History of Opisthorchis felineus discovery
It was first discovered in 1884
in a cat's liver by Sebastiano
Rivolta of Italy. In 1891,
Russian scientist K.N.
Vinogradov found it in a
human, and named the
parasite a "Siberian liver
fluke". In the 1930s,
helminthologist Hans Vogel of
Hamburg published an article
describing the life cycle of
Opisthorchis felineus.
Life cycles of Clonorchis sinensis и Opisthorchis felineus
Definitive hosts
1st intermediate host
2nd intermediate host
Dicrocoelium lanceatum
(about 1 сm in length)
Testes are at the
anterior part of
the body
Dicrocoeliasis
Definitive hosts – herbivorous
mammals and human
1st intermediate host – snail
2nd intermediate host – ant
Means of infection – ingesting
ants
Location – liver
Diagnosis – eggs in feces
Prevention – not to digest
ants (accidentally)
Definitive hosts
Dicrocoelium: life
cycle
2nd intermediate
host
Snail, the 1st intermediate host
produces “very tasty” slime,
and ant adore it. It contains
cercariae. Under the some
influence of the cercariae the
infected ant crawls up the grass
and wait for hours to be eaten
by the definitive host.
1st intermediate
host
All the liver flukes may
produce hyperplastic changes in the epithelium of bile
ducts and fibrosis around them. Massive invasion of any of
them leads to portal cirrhosis, with all its associated
manifestations. Cancer of liver is more common in these
patients. Symptoms of liver trematodoses are: jaundice,
ascitis, abdominal pain and numerous other symptoms and
signs.
Clonorchis in the dilated bile duct
Uterus with eggs
Cirrhosis of
the liver
Signs of cirrhosis
Gynaecomastia, jaundiced skin, ascitis,
“caput medusae” and liver palms
Diagnosis of all invasion with liver flukes is based on eggs
found in the patients’ feces
Misdiagnosis
(spurious infection)
Eggs of Fasciola or Dicrocoelium may appear in the patient’s stool
after consumption of the liver of a herbivorous animals infected
with these trematodes.
Re-examination of feces after some days (without eating liver)
must be done
Fasciola can infect humans when plants are
watering with water containing cercariae
To eat liver of an infected animal is not dangerous! But
the stool examination can demonstrate spurious eggs!
Lung fluke – Paragonimus
westermani
The lung fluke
(Paragonimus westermani)
Paragonimus westermani is most prominent in Asia and South
America. It was discovered from two Bengal tigers that died in zoos
in Europe in 1878. Several years’ later, infections in humans were
found in Formosa.
Paragonimus westermani: life cycle
Paragonimiasis: means of infection
Reservoir hosts of Paragonumus spp. include numerous
species of carnivores including felids, canids, viverrids,
mustelids, some rodents and pigs.
Humans only become infected after eating raw fresh
water crabs that have been encysted with the
metacerciaria.
Southeast Asia is predominately more infected because
of lifestyles.
Raw seafood is popular in these countries. Raw crabs
are marinated or pickled in vinegar or wine to coagulate
the crustacean muscle. This process of cooking does
not kill the metacercariae, consequently infecting the
host. About 22 million people are infected.
Paragonimus westermani in the lungs
(paragonomiasis)
The symptoms are localized in the pulmonary system, which include
a bad cough, bronchitis, and blood in sputum (hemoptysis).
If the worm becomes disseminated and gets into the spinal chord, it
can cause paralysis; capsules in the heart can cause death.
Eggs of paragonimus can be found in feces or
sputum of the patient
To make diagnosis sputum or feces of the
patient are examined. Time from infection to
oviposition (laying eggs) is 65 to 90 days.
Infections may persist for 20 years in humans.
Radiological methods can be used to X-ray the
chest cavity and look for worms.
This method is easily misdiagnosed, because
pulmonary infections look like tuberculosis or
pneumonia. A lung biopsy can also be used to
diagnose this parasite.
Serodiagnosis can also be used for diagnosis.
Prevention – to cook fresh-water crabs properly.
Blood flukes
Blood flukes were found even in Egyptian
mummies
Ancient Egyptians believed that the
advent of manhood was signaled by
the appearance of blood in the urine,
analogous to the advent of
womanhood, signaled by
menstruation. The hematuria, in fact,
represented a Schistosoma
hematobium infection.
History
The eggs of these parasites were first seen by Theodor
Maximilian Bilharz, a German pathologist working in Egypt
in 1851 who found the eggs of Schistosoma haematobium
during the of a course post mortum.
In 1858 Weinland proposed the name Schistosoma
(Greek: 'split body') after the male worms morphology.
A genus of trematodes, Schistosoma spp., commonly
known as blood-flukes and bilharzia, cause the most
significant infection of humans by flatworms
(schistosomiasis) and are considered by the World Health
Organization as second in importance only to malaria, with
hundreds of millions infected worldwide.
Schistosomes – the blood flukes
Sexes are separate (dioecious)
Numerous testes (7)
Cercaria with forked tail
Eggs with spine
she
he
Schistosomae haematobium, mansoni, japonicum
eggs
There are many species of Schistosomes.Three of
them have the most medical importance
Schistosoma haematobium
(urogenital)
Bulinus, Planorbis spp.
Africa, Middle
East
Schistosoma japonicum
(Japanese)
Oncomelania spp.
China, South-East
Asia
Schistosoma mansoni
(intestinal)
Biomphalaria spp.
Africa, Middle
East, South
America
Blood-flukes, schistosomes or bilharzia
The adult worms inhabit the mesenteric veins (S.mansoni,
S.japonicum), or the veins of the vesical and pelvic plexuses
(S.haematobium).
The life cycle is common to all species with a sexual generation in
vascular system of the definitive host and an asexual generation
in the intermediate hosts (snails).
1) Embrionated eggs are discharged in faeces and urine; in water
miracidia hatch from the egg and penetrate the intermediate hosts.
2) After penetration in the snail the miracidium develops into
sporocysts and, in about 4 weeks, thousand of cercariae are
produced.
3) The infection of the definitive host occurs by penetration of the
skin.
Schistosoma:
life cycle
Typical places of schistosome invasion
Clinical symptoms of schistosomiasis
Summary: The most important trematodes parasitizing human
Trematodes eggs
70-100 mkm in
length, small
lateral spine
About 30 mkm in length
114-175 mkm, lateral or
terminal spine
60 – 100 mkm in length
Up 150 mkm in length
Паразитология. Простейшие, паразиты
человека.»
Тема лекции: «
Тема лекции:
«»
Хрущова Ольга Николаевна
Кафедра биологии ПФ
РНИМУ им. Н.И. Пирогова
Москва, 2015
Cestodes - parasites of humans
Three main classes of flat worms
•Turbellaria – free-living, covered
with ciliae, have eyes and tactile
organs
•Trematoda – or flukes, all parasitic,
possess two suckers, or “tremae”,
leaf-like in shape.
•Cestoda – tape worms, all
parasitic, possess attachment
organs – suckers, hooks or
bothriiae, ribbon-like body, no
digestive tract
Cestoda is a class of parasitic flatworms,
commonly called tapeworms, that live in the
digestive tract of vertebrates as adults and in the
bodies of various animals as juveniles.
• They have no mouth or digestive system.
Nutrients from the host digestive system are
absorbed directly through the outer cuticle.
• The head (scolex) is usually modified with hooks
and/or suckers which fasten to the host gut wall.
• The body is divided into sections called
proglottids. The mature proglottids, gravid with
eggs, detatch and are voided with the host faeces.
• They have three organ systems: excretory,
nervous and reproductive.
Morphology of Cestodes
The body (strobila) of a tape worm is ribbon-like in shape
Scolex (head)
Neck (here new
proglottids are
formed)
Juvenile (immature)
proglottids
Gravid proglottids
can
Mature
(hermaphrodite)
proglottids
The number of proglottids may vary from three –
four to thousands
The length of a tape worm may vary from 3 mm to 10 - 15 m
All the Cestodes dwell the lumen of the small intestine
The bode wall - tegument
Microvillus
Mitochondria
Vacuoles
Nucleolus
Nucleus
Mitochondria
Circular and
longitudinal muscles
Body wall of a tape worm resembles the epithelium of
the small intestine
Tegument serves for protection and nutrition of the parasite
1 mkm
Excretory system - protonephridial
Flame cells
Lateral excretory
trunk
Transverse
canal
Opens distally on
the last segment
Nervous system – ladder-type
Series of ganglia in
scolex from which
nerve trunks arise
Lateral nerve trunks
Transverse commisures
Reproductive system – hermaphrodite
Order Cyclophyllidea
Order Pseudophyllidea
1 — opening of vagina; 2— male genital pore; 3 — sac of cirrus; 4 — internal seminal vesicle; 5 —
external seminal vesicle; 6— vas deferens; 7— vagina; 8 – seminal receptacle; 9— Mehlis’ gland;
10— ducts of testes; 11 — testes; 12— yolk glands; 13—ootype; 14— ovary; 15— uterus; 16—
opening of uterus
Mature (hermaphrodite) proglottid with male and
female organs
Cestodes’ life cycle
Adult stage in the small intestine of a
definitive host
Egg in the
environment
Young tape worm
2nd larva
2nd larva
oncosphere
1st larva – hexacanth larva,
oncosphere
Larval forms of cestodes
a
b
c
The first generation
larva (hexacanth larva,
oncosphere) or
coracidium
d
2nd generation larvae:
a – pleurocercoid, b – cysticercoid, c – cysticercus,
d – hydatid cyst
Cestodes can parasitize human at an adult stage, or a
larval stage, or both
Adult Tapeworms: Diphyllodothrium latum and Taenia
saginata.
Adult worms are found in the small intestine; these
infections are usually well tolerated or asymptomatic, but
may cause abdominal distress, dyspepsia, anorexia (or
increased appetite), nausea, localized pain, and diarrhea.
Larval Tapeworms: Echinococcus granulosus and
Alveococcus multilocularis.
Larvae locate in extraintestinal tissues and produce
systemic infections with clinical effects related to the size,
number, and location of cysts.
Adult and larval stages parasites: Taenia soleum and
Hymenolepis nana.
Aristotle wrote about the cysticercus stage of tape
worms, but there is no evidence that he
understood the relation between larval and
adult stages of parasites.
(Gottlieb Heinrich Friedrich
Küchenmeister 1821- 1890) was the
man who discovered cestodes’ life
history. He transmitted the infection
to a man who was condemned
murderer by secretly contaminating
his food with cysticerci that
Küchenmeister recovered from meat
at a local restaurant.
5 days later at autopsy, the small
intestine of the prisoner contained
immature adults of a tape worm
Adaptations to parasitism in Cestodes
1. Flattened body
2. Attachment organs
3. Absence of digestive system
4. Tegument for protection and digestion
5. Complicated hermaphrodite reproductive
system.
6. Ability to reproduce at larval stages.
There are two main orders in class Cestoda
Оrder Pseudophyllidea
Оrder Cyclophyllidea
Attachment organs – two grooves
(bothriae)
Attachment organs – 4 suckers and
hooks
Genital pore at the centre of the
segment
Genital pore at the side of the segment
Uterus open tubular type
Egg oval in shape with operculum
1st larva – coracidium (with ciliae)
2nd larvae – procercoid and
pleurocercoid)
Two intermediate hosts
Examples: Diphyllobothrium latum,
Spirometra spp.
Uterus branching and closed type
Egg with double layered shell
1st larva - oncosphere
2nd larvae – cisticercus, cysticercoid,
hydatid cyst
One intermedite host or none
Examples: Echinococcus granulosus ,
Alveococcus multilocularis, Taenia
soleum, Taeniarrhynchus saginatum,
Hymenolepis nana
Order Pseudophyllidea. Broad fish tapeworm
(Diphyllobothrium latum)
Up to18 m
long
Scolex and neck of Diphyllobothrium latum
Proglottids of Diphyllobothrium latum. Open
type of uterus
Hermaphrodite and gravid segments of fish
tapeworm
Life cycle of fish tapeworm (Diphyllobothrium latum)
Pleurocercoid in
fresh water fish
Definitive hosts
– fish-eating
mammals
Procercoid
in cyclop
coracidium
egg
D. latum. Egg is about 70 mkm in length and has an
operculum.
Egg, coracidium, procercoid inside cyclop,
pleurocercoid
Procercoid in Cyclops and pleurocercoid in fish
Invasive form for human – pleurocercoids in fish
Diphyllobothriasis can be asymotomatic, but in
some patients В12-deficiency anemia develops:
The parasite absorbs
vitamin from the
intestine of the host
Diagnosis is made by finding broad fish
tapeworm’s eggs in patients feces;
Prevention:
cook fish properly
About 70 mkm in length
Sparganosis. Parasite Spirometra spp.
The example of accidental parasitism
Humans are the accidental hosts in the life cycle, while dogs, cats, and other
mammals are definitive hosts, copepods are first intermediate hosts, and
various amphibians and reptiles are second intermediate hosts.
Once a human becomes
infected, the plerocercoid
larvae migrate to a
subcutaneous location,
where they typically
develop into a painful
nodule.
Sparganosis of brain, eye, pleura
In some countries the
flesh of frogs and fish
are used as food and
poultries
Order Cyclophyllidae
•Taenia soleum
•Taeniarhynhus saginatus
•Hymenolepis nana
•Echinococcus granulosus
•Echinococcus multilocularis
Mature (hermaphrodite)
segment
Gravid segments: uterus
filled with eggs
1 - ootype; 2 ovaries; 3 – yolk
gland; 4 - vagina; 5
- uterus; 6 – testes;
7 – vas deferens; 8
- ejaculatory duct ;
9 – genital pore
Taeniarhynchus saginatus=Taenia saginata
Taenia saginata– beef tapeworm
Life cycle of beef tapeworm
Intermediate host - cattle
Oncosphere
Eggs on grass
Definitive host human
Cesticerci in
muscles
Taenia saginata lives
alone up to 20 years
Morphology of beef tapeworm
Scolex: 4
suckers
Sucker
Neck
2 lobes of ovary in
hermaphrodite
segment
17 – 35 lateral
branches of uterus at
each side in gravid
segment
Diagnosis is based on the morphology of
proglottids
2 lobes of ovary in
hermaphrodite segment
Eggs of different
Taenia are very alike
Gravid segments pass out
with feces, 6 – 8
segments a day and up to
175 000 eggs in each.
30 – 45 mkm in diameter
They can move.
Invasive form for human – cysticerci in beef
Cysticerci in beef. It may be also meat
of a deer, yak or buffalo.
Prevention of taeniasis
•Meat inspection at
slaughterhouses
•Proper cooking;
•Protection of
grazing land from
human feces
•Revealing and
treatment of infected
people
Taenia soleum, pork tapeworm – the causative agent of
taeniaesis and cysticercisis
Pig – intermediate
host
Human –
definitive and
intermediate
host
Taenia soleum morphology
Rostellum
with hooks
4 suckers
3 lobes of ovary in the
hermaphrodite segment
!
Scolex with hooks – “armed
tapeworm”
!
In gravid segment 7 – 12 lateral branches in uterus
Taenia soleum causes taeniasis and cysticercosis
Cysticerci in pork cause of taeniasis
Cysticerci
develop in
pig muscle
tissue
Eggs – cause of
cysticercosis
Pig or human acquire parasites
by eating food and water
contaminated with eggs or by
autoinvasion
Gravid proglottids with eggs
pass out into the
environments via feces
Treatment in case of Taenia soleum
must be conducted with care
If mature segments get into
the stomach due to
antiperistalsis cysticercosis
may develop
Cysticercosis – parasitizing of larval stage of Taenia
soleum
Pork with cysticerci
Cysticercosis of brain and eye
Cysticerci in heart muscle
World distribution of cysticercosis
Prevention of taeniasis and cysticercosis
•Pork inspection at
slaughterhouses
•Proper cooking;
•Protection the
grazing land from
human feces
•Revealing infected
people and pigs;
treatment
Dwarf tapeworm - Hymenolepis nana
2 – 4 cm in length, 100 – 300 segments
Morphology and larval stages of Hymenolepis nana
1- scolex, 2 – egg, 3 – proglottids, 4 – oncosphere, 5 – cysticercoid larva in the
villus of small intestine
Life-cycle may be with intermediate hosts or be
completed in human intestine
Cysticercoids in grain beetles
H. nana can pass all the stages of life-cycle in human
(autoinfection)
Cysticercoid of dwarf tapeworm in human
intestine
Cysticercoid larva
Diagnosis of heminolepidosis is made by finding eggs
in stool
Prevention:
•Control in schools, kindergartens
•Proper personal hygiene and proper disposal
of the feces
•Treatment of infected people and close
household contact
Children have heminolepiasis 3 – 4 times
more often than adults.
In adults self-healing take place in 85% of
cases, in children – more than 50%.
Echinococcus granulosus (dog tape worm)
Echinococcus granulosus
5 mm
1 – scolex possesses 4 suckers and
proboscis with hooks; 2 — young
segment; 3 — hermaphrodite segment;
4 – gravid segment; 5; 6 – wall of the
cyst; 7—11 daughter cysts at different
stages of development; 12—15 —
external daughter cysts
Hydatid cysts develop in the intermediate host
Echinococcus granulosus life cycle
Adult worm in
the intestine of
dogs and other
canins
Ovum in the
environment
Definitive host
Intermediate hosts
Hydatid cysts in
organs grow for
years
Structure of a hydatid cyst
Fibrous capsule
(produced by host)
Fibrous capsule
(produced by parasite)
Germinal
layer
Daughter
cysts
protoscolexes
Hydatid cyst from sheep peritoneum
And from sheep lung
In human liver
In the lungs
Hydatid cysts in the brain and columna vertebralis
Echinicoccus multilocularis (Alveococcus
multilocularis)
A multi-locular
tomato fruit.
E. multilocularis produces many
small cysts (also referred to as
locules) that spread throughout the
internal organs of the infected animal
or human
Alveococcus multilocularis: life cycle
Definitive hosts
Gravid segment
Intermediate hosts
Cross section through the larval stage. Multiple
cavities with daughter scoleces
Larval form of Alveococcus in human liver
The disease represents a serious public threat in China,
Siberia, and central Europe. The parasite affects the liver by
inducing a hepatic disorder similar to liver cancer, therefore
becoming extremely dangerous and difficult to diagnose. If
the infection metastasizes, it may spread to any other organ
and could be lethal if not treated. The most common
treatment is to surgically remove the parasite.
Human liver affected be Alveococcus
How to make diagnosis of echinococcosis and
alveococcosis
These are larval tapeworms - they parasitize
human at larval stages, so there are
NO EGGS IN HUMAN FECES!!!
For diagnosis are used:
•Radiology tests (X-ray, ultrasound, CT, MRT)
•Serologic tests (specific antibodies against
parasite)
Prevention and control of larval tapeworms
•Avoiding exposure organs of
infected animals to dogs.
•Control infection in dogs.
•Proper hygiene standards for
people who work with dogs or with
wild canins.
•Proper hygiene standards for
people who work with fur of foxes
and other wild canins.
•Information of hunters.
Cestodes parasitizing human
Tape worm
Means of
infection
Location in
Human
Laboratory diagnosis
Tenia
saginata
Larva in beef
Small intestine
Gravid segment with 17 – 35
lateral branches of uterus
Tenia solium
Larva in pork
Small intestine
Gravid segment with 7 – 12
lateral branches of uterus
T. solium
cysticercosis
Fecal - oral
Brain, eye
X-ray, CT, MRT, serological
tests
D. latum
Larva in fish
Small intestine
Eggs, segments
E.
granulosus
Fecal - oral
Liver and other
organs
X-ray, CT, MRT, serological
tests
H. nana
Fecal - oral,
autoinvasion
Small intestine
Eggs, segments
A.
multilocularis
Fecal - oral
Liver and other
organs
X-ray, CT, MRT, serological
tests
Example of accidental parasitism: Dipylidium caninum,
also called the flea tapeworm,
double-pore tapeworm, or cucumber
Adult worm tapeworm
in intestine
Eggs o
People are recommended not to eat while playing with
a dog. A flee can jump and stick to butter (for
example) and then get into the intestines of human
Спасибо за внимание!