Paragonimus westermani

paragonimiasis is a intracellular food born disease mainly cause by paragonimus westermani (lung fluk) . it is mainly found in middle Asia, central Africa and Latin America. The first intermediate host fresh water snail and second is human.

1. Paragonimuswestermani
Gopiram(Shulav) Syangtan
M.Sc. Medical Microbiology
Institute of Science & Technology(IOST)
TRIBHUVAN UNIVERSITY
E-Mail:[email protected]

2. Paragonimiasis
•Paragonimiasisis a food-borne parasitic infection
•Paragonimiasis, or lung fluke disease, is caused
by infection with a number of species of
trematodesbelonging to the genus Paragonimus.
•The most common are:
P. westermani, P. heterotremus
andP. philippinensisin Asia
(China, the Democratic People’s
Republic of Korea, the Republic
of Korea, the Lao People’s
Democratic Republic, the Philippines, Thailand, Viet Nam and
other east Asian countries); P. africanusand P.
uterobilateralisin western and central Africa; P. caliensis, P.
kellicottiand P. mexicanusin north, central and south America
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3. History
• Most discoveries made between 1874-1918
• Discovered in Brazil in 1850 by Diesing
• First described in Bengal tigers housed in zoos in
Hamburg and Amsterdam in 1877
• CoenraadKerbertnamed the parasite after the manager
of the zoo G.F Westerman
•Sidney Ringer discovered the parasite in a human in a
Portuguese man during an autopsy in 1879
•Rudolf Luekartfound that the parasite found in the
tiger is the same as the parasite that caused hemoptysis
in Formosa and Japan
• 1916-1922 Japanese workers discovered the life cycle
in the snail
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4. Paragonimusspp
•Also known as the Oriental lung fluke ( the lung
distome)pinkish-brown colourand bean shaped
tremadotes.
•More than 30 species of trematodes(flukes) of the
genus Paragonimushave been reported to infect
animals and humans. Among them, more than 10
species are reported to infect humans, the most
common is P. westermani.
•The parasite is endemic in the Far East—Japan, Korea,
Taiwan, China, and South East Asia—Sri Lanka and
India. Cases have been reported from Assam, Bengal,
Tamil Nadu and Kerala.
•P. mexicanusis an important human pathogen in
Central and South America.
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5. Geographical Distribution
Source:-WHO 2015 ‘a’
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6. Epidemiology
•It is estimated that 20 million are infected with
Paragonimuswestermani
• It is endemic in China, Korea, Japan, the
Philippines, and Taiwan
• Japan, Korea, Formosa, China, Manchuria, the
Philippine Islands and India
• Infection is also found in parts of tropical West
Africa, from the Congo and Nigeria, especially
from Southern Cameron
• Rare in the US but it is found in Missouri
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7. •Habitat:-adult worm live in respiratory tract
(lung) of man.
•Definitive Hosts:-Man and Domestic animals
(usually host in Asia are the tiger & leopard)
•Intermediate Host:-
First Host:-A fresh-water snail of the genus Melania
Second Host:-A fresh-water crayfish or a crab
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8. Morphology
Fig:-Morphology of P. westermani
Adult
•The adult worm is hen egg-shaped
•Size:-10 mm long, 5 mm broad and 4 mm thick.
•Adults worms live in the lungs, usually in pairs in
cystic spaces that communicate with bronchi.
•Its anterior end is slightly broader than the
posterior end.
•The ventral sucker in situated near about the
middle of the body.
•Life span of the adult worm is about 6 to 7 years
•The excretory vesicle is large and extends from the
posterior extremity to the anterior region, dividing
the body into two equal halves:-unbranchintestinal
caecaand Caudal region.
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9. Morphology
Egg
•Golden brown in colour
•oval in shape
•flatenedopercula
•80-120 μm by 50-60μm
in size
•Contain an un-segmented
ovum surrounded by yolk
cell
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10. Life cycle of P. westermani
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12. Life cycle of P. westermani
•The eggs are excreted unembryonatedin the sputum, or alternately they are
swallowed and passed with stool.
•In the external environment, the eggs become embryonated, and
miracidiahatch and seek the first intermediate host, a snail, and penetrate
its soft tissues.
•Miracidiago through several developmental stages inside the snail:
sporocysts, rediae, with the latter giving rise to many cercariae, which
emerge from the snail.
•The cercariaeinvade the second intermediate host, a crustacean such as a
crab or crayfish, where they encystand become metacercariae. This is the
infective stage for the mammalian host.
•Human infection withP. westermanioccurs by eating inadequately cooked
or pickled crab or crayfish that harbor metacercariaeof the parasite.
•The metacercariaeexcystin the duodenum, penetrate through the intestinal
wall into the peritoneal cavity, then through the abdominal wall and
diaphragm into the lungs, where they become encapsulated and develop
into adults(7.5 to 12 mm by 4 to 6 mm). The worms can also reach other
organs and tissues, such as the brain and striated muscles, respectively.
However, when this takes place completion of the life cycles is not
achieved, because the eggs laid cannot exit these sites. Time from infection
to ovipositionis 65 to 90 days.
•Infections may persist for 20 years in humans. Animals such as pigs, dogs,
and a variety of feline species can also harborP. westermani.2/6/2019 12G.R.(Shulav)

13. Pathogenesis
•Mode of Infections:-Eating raw, undercooked or
pickled crustaceans such as crab or crayfish
• Spitting, a habit in asiancountries
• Cultures that eat raw crustaceans
• Drunken Crab in China
• Raw Crab or Crayfish and alcohol in The
Philippines
• GyeMuchimin Korea
• Sushi crab, amaebiand odoriin Japan
•Infecting Agent :-Metacercariaor adolescariain
side a cyst
•Portal of Entry:-Digestive tract/mouth
•Site of localization:-lungs
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14. Pathology
•When humans ingest raw infected crustaceans,
larval flukes develop in the small intestine,
penetrate the intestinal wall into the peritoneal
cavity30 minutes to 48 hours after excysting.
They then migrate into the abdominal wall or
liver, where they undergo further development.
Approximately 1 week later, adult flukes reenter
from the abdominal cavity and penetrate the
diaphragm to reach the pleural space and lungs.
Flukes mature, a fibrous cyst wall develops
around them, and then egg deposition starts 5-6
weeks after infection.
• The symptoms of the early stages of this disease
appear to be few with some people being
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15. pathology
•The worms finally get into the lung parenchyma
and induce acute exudativepneumonitisand
haemorrhage.
•They gradually mature and are encysted, thereby
producing zones of active inflammation with
exudateand of collagenousfibrous tissue. The
worms are found usually in pairs.
•When grown up, these worms are often found
inside the bronchial lumen lined with bronchial
epithelia of squamousmetaplasticcharacter. The
cysts consist of the parasite and of dense
collagenousconnective tissue including various
inflammatory cells and eosinophils.
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16. Pathology
•Once the parasite is in the lung or another organ, the worm
stimulates an inflammatory response that eventually coats
tissue.
•If worms enter the CSF of the spinal cord, it can result in
partial or total paralysis.
•There have also been fatal cases of Paragonimiasisby
infection of the heart.
•Cerebral cases result in cerebral cysticercosis(condition in
which fluid-filled cysts surrounding the worm are present).
•The adult worm , as it move around , cause lesions (worm cyst
and burrows) by mechanical damage.
•The eggs excites a foreign body granulomatousreaction which
may soften to form cavities, the wall of which is compose of
fibrous granulomatissue (epitheloidcell, lymphocyte,plasma
cell, eosinophils, gaintscell and fibroblast.)
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17. Clinical Manifestation
1.Pulmonary paragonimiasis
Chronic cough, Haemoptysis,
pulmonary tuberculosis
(stimulating a case of bronchiectasis),
chest pain with dyspnoeaand fever;
pleural effusion and pneumothoraxare possible complications.
2. Extrapulmonaryparagonimiasis
most frequent locations include the diarrhoea,
abdominal cavity and subcutaneous tissues
and, most frequently, the brain: cerebral
paragonimiasisis a severe condition that may
be associated with headache, visual impairment and epileptic
seizures.
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18. LABORATORY DIAGNOSIS
Sample specimen:-sputum, stool, gastric,
aspired pleural fluid
washing or Tissue material
Diagnosis Technique
1.Parasitological Technique
2.Immunological Technique
3.Molecular Technique
4.Imaging Technology
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19. Parasitological Technique
•Microscopic Examinations
1. Sputum examination:
(1) Alkali digestive method (10%NaOH)
(2) Direct sputum smear
2. Stool examination:
(1) Alkali digestion
(2) Water sedimentation method
(3) Direct fecal smear
3. Biopsy Materials by Staining:-Gimsastains
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22. Immunological Test
•Non-specific Test:-
1.Intradermalskin test
2.complement fixation test
•Specific Test
1.IHA
2.ELISA
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23. Molecular Technique
•PCR technique
Conventional PCR
Real Time PCR
DNA Hybridization
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24. Imaging Technology
1.Chest X-Ray :-nodular,cysticand infiltrative in
the middle and lower lungs similar to TB,
Bronchiectasis
2.CT-scan of Chest:-pulmonary lesions
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25. Treatment
•Praziquantel-Oral,
1.causes severe spasms and
paralysis of the worms' muscles
2. Not for pregnant women
Stomach pains, dizziness,
fever, nausea, vomiting, headache
3. Better tolerated than Bithionel
•Bithionol
Diarrhea, use is limited due to side effects
•Triclabendazole
Can cure cases other drugs failed
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26. CONTROL & PREVENTION
• Fully cook shellfish
• Heat water to 55o C for 5 minutes
• Freeze Fish
• -20 C for 7 days
• -35 C for 15 hours
• Make spitting illegal
• Use Moluskicideto control snail population
•Maintain the hygiene and sanitation
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