1. Paragonimus westermani & Gastrodiscoides hominis
For
MBBS Batch 2016
6th August 2018
By: Dr Puneet Kumar Gupta
Assistant Professor, Microbiology

2. Oriental Lung fluke (flatworm)
Infects lungs of humans after eating an infected raw or undercooked crab or crayfish
Less frequent, but more serious cases when parasite travels to CNS
>30 Species-Infect human & Animals
> Infect humans
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3. P. mexicanus - Central & South America
P. westermani (MC), 
Primarily in Asia including China, Philippines, Japan, Vietnam, South Korea, Taiwan, &Thailand
India (Assam, Bengal, South India)
P. africanus-Africa
P. mexicanus - Central & South America
shellfish consumed raw or prepared only in vinegar, brine, or wine without cooking
Raw crabs or crayfish -used in traditional medicine practices in Korea, Japan, and some parts of Africa
P. kellicotti-Rare- US (Midwest)
ingestion of uncooked crawfish during river raft float trips in Missouri.
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4. Morphology Adult worm: Life span: 6-7 yrs
Egg shaped
Ant end broad>
post end
8-12 X 4-6 X 3-5 mm
(L X B X Thickness)
Ventral Sucker Middle of body
Life span: 6-7 yrs
Habitat: Respiratory tract (Lungs)
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5. Morphology Egg: Golden brown Oval with flattened opercula 80 X 55 µm
Unsegmented ovum surrounded by yolk sac
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6. Life cycle 3 hosts 1 Definitive: 2 Intermediate:
Man & Domestic animals
Usual host Asia: Tiger & lepord
Reservoir: Feline
2 Intermediate:
Fresh water Snail: Melania
Fresh water crayfish or crab
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7. Eggs are excreted unembryonated in the sputum, or alternately they are swallowed and passed with stool  . In the external environment, the eggs become embryonated  , and miracidia hatch and seek the first intermediate host, a snail, and penetrate its soft tissues  . Miracidia go through several developmental stages inside the snail  : sporocysts  , rediae  , with the latter giving rise to many cercariae  , which emerge from the snail. The cercariae invade the second intermediate host, a crustacean such as a crab or crayfish, where they encyst and become metacercariae. This is the infective stage for the mammalian host  . Human infection with P. westermani occurs by eating inadequately cooked or pickled crab or crayfish that harbor metacercariae of the parasite  . The metacercariae excyst in 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 oviposition is 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 harbor P. westermani.
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9. Pathogenicity Mode of infection
Eating raw/improper cooked flesh of infected crayfish/crab
Drunken crab: Strips of raw crab meat soaked in alcohol
Infective stage: Metacercaria (adolescaria inside a cyst)
Portal of Entry: Digestive tract
Site of Localization: Lungs
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10. Disease No symptom with light infection Pulmonary Paragonimiasis:
Acute syndrome with cough, abdominal pain, discomfort & low-grade fever occur 2 to 15 days after infection
Long-term infection may mimic bronchitis, bronchiectasis or tuberculosis
with Chronic cough with recurrent bout of blood-tinged sputum
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11. Disease
Coffee-colored or blood-tinged sputum, often accompanied by chest pain and/or shortness of breath
sputum clumps of eggs
Peripheral eosinophilia- early larval migration stages –intense
CXR: lobar infiltrates, coin lesions, cavities, calcified nodules, hilar enlargement, pleural thickening & effusions
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12. Disease
Ring-shaped opacities of contiguous cavities -bunch of grapes -highly suggestive of pulmonary paragonimiasis
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13. Disease Extrapulmonary paragonimiasis:
CNS disease “grapebunch” findings, temporal & occipital lobes on CT brain
CNS involvement 25% of hospitalized patients
may be associated with Paragonimus-induced meningitis.
symptoms -headaches, seizures, and visual disturbances
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14. Disease Ectopic lesions
Aberrant migration of flukes -any organ, including abdominal viscera, heart & mediastinum
Liver, spleen, intestinal wall, peritoneum, and abdominal LN & skin
Cerebral -highly endemic countries-children
Eosinophilic meningoencephalitis, seizures, or signs of space-occupying lesions
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15. Diagnosis Eggs: Sputum, Stool M/E Destroyed by ZN Stain
Yellowish brown
µm long X µm wide
thick-shelled with an obvious Shouldered operculum
D/d D. latum egg:
Devoid of shoulder
Knoblike protrusion at
other end
(Absent in P. westermani)
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17. Diagnosis Serologic tests Intradermal Test: Epidemiological Help
useful for early infections (prior to maturation of flukes) or for ectopic infections where eggs are not passed in stool
IHA & ELISA
Test negative 3-4 months after successful treatment
Intradermal Test: Epidemiological Help
Immediate hypersensitivity test
Remains + ve long after recovery
Indicate past infection
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18. Diagnosis Complement fixation test Radiology PCR: Research use
Positive in Active infection
Test negative soon after death of worm
Radiology
X ray:
Abnormal Shadow (Nodular/cystic, Infiltrative) in middle or lower lung field
Presence of shadow of tunnels & burrows in lung CT
PCR: Research use
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19. Diagnosis Patient with CNS disease also have pulmonary infections
Trematode larva migrans:
P. skrjabini 
often produces skin nodules, subcutaneous abscesses, or a type of creeping eruption reatment
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20. Treatment DOC: Praziquantel: 5 mg/kg Per oral TDS X 2d Alternative:
Triclabendazole: 10 mg/kg Per oral OD or BD
For cerebral disease: Additional a short course of corticosteroids to reduce inflammatory response around dying flukes
Triclabendazole: CDC
Not in United States (Not approved by FDA)
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21. Prevention & Control Never eat raw freshwater crabs or crayfish
Cook crabs & crayfish for to at least 145°F (~63°C)
Travelers advised to avoid traditional meals containing undercooked freshwater crustaceans
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22. Gastrodiscoides hominis
Caecum: 1st reported in Indian patient suffering from Diarrhoea
India: Assam, Bengal, Bihar, Orissa
Vietnam, Phillippines
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23. Morphology Adult worm: Pyriform shaped Ant end Conical
post end Hemispherical
5-10 X 4-6 mm
Bright pinkish color
Ventral Sucker
Large intestine (Caecum & Ascending Colon of definitive host: Man, pigs, monkey , rodents)
Pig & Monkey: Reservoir
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24. Morphology Egg: Greenish brown ovoid Operculated 150 X 60-70 µm
Immature when laid
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25. Life cycle Egg----Passed in faceces infect water- -Miracidium
Penetrate aquatic gastropod Mollusc
Sporocyst
Rediae
Cercariae
metacercariae in Vegatation & Snail
infect
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26. Disease
Mucous diarrhoea & Oedema of intestinal wall: worm attachment to caecum & ascending colon with help of Large sucker
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27. Diagnosis Eggs D/d F. buski and F. hepatica (130-150 X 60-90 µm)
Gastrodiscoides hominis
 may be slightly larger
( micrometers
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28. Thank you
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29. 3/27/2020