Paragonimus Westermani ( Lung Fluke )
species of lung flukes may infect humans, but this particular one is
frequently involved. The adult lung fluke is a tiny, short and plump,
reddish-brown flatworm that lives in the lungs of humans. Here they deposit
their eggs where they are coughed up, and then either spit out or swallowed.
If they are swallowed, they go through the intestines and pass out with the
stool. When the eggs reach fresh water, they develop and enter a snail.
Their life cycle continues as they pass from the snail to a crab.
When humans eat crayfish, freshwater crabs, or snails that are not cooked
enough or eaten raw, the cyst form of these parasites enters the small
intestines. The majority of the lung flukes continue their migration through
the diaphragm and reach maturity in the lungs 5 to 6 weeks later. Some
organisms stay in the intestines or wander to other areas of the body such
as the liver, pancreas, kidney, skeletal muscle, under the skin, or into the
central nervous system.
Lung flukes prefer to infect humans or wild carnivores, especially
felines, but they will find rats, dogs, and pigs acceptable. Eating
undercooked pork or leaving fresh crab juice on the kitchen surfaces can
transmit this parasite to humans. Children living in areas where the lung
fluke is endemic may be infected while playing with crabs. This parasite is
most often found in Far Eastern nations such as Korea, China, Japan, Taiwan,
the Philippines, and Indonesia, but it has recently been found in India,
Africa, and Latin America.
The lung fluke can perforate and weaken the lungs and even cause oxygen
starvation of the entire blood system. Once the lungs are weakened, it is
easy to attract other illnesses, such as repeated flu and fungi infections.
In a severe infection, a person can develop chronic pneumonia. Other
symptoms include the occasionally mild cough and a peculiar bloodstained,
brown, rusty sputum on awakening, along with an note-resolving lung abscess.
This set of symptoms looks like tuberculosis. If the adult lung fluke enters
the intestines, there can be symptoms of pain and bloody diarrhea, and on
occasion produce abdominal masses. After lung flukes enter the brain, they
can cause seizures similar to epilepsy or other central nervous system
A diagnosis of lung flukes depends on these findings: signs similar to
tuberculosis on x-ray; about half of the people with brain lesions will show
calcification on x-ray of the skull; elevated eosinophils on blood test;
detection of circulating antibodies; sputum or feces contains eggs. Eggs may
not be seen in the sputum during the first 3 months of obvious infection.
Repeated stool or sputum examinations will eventually produce the eggs in
most infected people.
To prevent and control this organism there needs to be the proper
disposal of feces and sputum; control snails; cook crabs and crayfish well
before eating or handling them. Lightly salted, pickled, or wine immersion
practices seldom kill this fluke. The disease responds well to the drugs
bithionol or praziquantel.