Helminths > Trematodes > Paragonimus

Paragonimus （ lung fluke)

50 species of lung flukes in total, only 7-8 of them live in human body. Paragonimus westermani is the most common lung fluke found in human body Paragonimiasis

Paragonimus westermani

1. Adult • Reddish-brown, 0.8~1.2mm long, like half a peanut • The Oral sucker is as large as the ventral sucker • The uterus and ovary lie side by side, two testes lie side by side.

2. Egg

• Ovoid, golden yellow

• Having an larger operculum

• Containing an

embryonic cell and many yolk cells

Life cycle

Adult

metacercaria

cercaria

egg miracidium

Migration of adolescent The adolescents are divided into 4 groups

Life cycle egg

miracidium

sporocyst

redia

snail adult

adolescent

Man,cat,dog

metacercaria Crab or crayfish

cercaria

First intermediate host

miracidium→sporocyst→redia→cercaria

Second intermediate host

Crab in stream

Metacercaria

Metacercaria

Adolescent

Important points Where the adults live? How are the eggs be passed ? Intermediate host: Infective host: The migration routine:

Pathogenesis

1.

Suppurative stage Adults cause abscess,in the center of which there is some pus.

2. Cystic stage The pus break into bronchi, and is passed by bronchi, the abscess becomes empty, looks like a cyst. 3. Fibrous-scar stage Fibrosis of the abscess takes place, and the abscess become a scar.

Symptoms

Pulmonary type: cough,chest pain,sputum with blood,low fever, night sweeting, etc Subcutaneous type: migratory nodi in subcutis, subcutaneous abscess Cerebral type: headache, epilepsy, vomiting,hemiplegia, mental disorder,et al Subcutaneous type: diarrhea,abdominal pain,dysentery with blood and mucosa in feces,hepatomegaly and hepatic pain,etc.

Pulmonary type

Pulmonary type

Cerebral type

Diagnosis

Epidemiology

1. Distribution Widely distributed in Asia,Africa and South America 23 provinces in China Seriously prevalent in Henan province

2. Factors for epidemic Sources of infection Reservoir host Contamination of water with feces Intermediate hosts existence Ingestion of raw crabs or crayfish Drink unboiled river water

Treatment and prevention

Treat the patients Praziquantel and bithion (bitin) Avoid eating raw crabs and crayfish Not drink unboiled river water in endemic area Eliminate and manage the reservoir host in endemic area

The end