Paragonimus westermani

Egg of lung worm

The lungworm ( Paragonimus westermani ) is a trematode that befalls as a parasite, and cancerous human -eating mammals. He calls forth human lung Paragonimiasis. It is estimated that about three million people are affected by this disease worldwide.

Dissemination

Paragonimus westermani is found in China, Taiwan, Laos, Korea, Japan, Thailand, the Philippines, Malaysia, Indonesia, India, Sri Lanka and the countries of the former Soviet Union. Other species are known from Asia, Africa and Latin America. Since 2008, cases of Paragonimiasis in patients diagnosed who have consumed raw crayfish in the state of Missouri in the United States.

Features

The adult parasites are fleshy, brown, and bean-shaped flukes. Its length is 8-16 mm, its width 4-8 mm and thickness 2-6 mm. They are hermaphrodites and live in cysts of the lung, rare in other organs such as the brain. Behind the ventral sucker is the genital pore.

Life cycle

Reservoir

The adult lung flukes living in lung cysts to cats, dogs and many other carnivores and produce their eggs, which come with the sputum or swallowed with the chair to the outside of a cough. Achieved an egg fresh water, it develops in three weeks to a miracidium. After hatching, this penetrates a snail.

First intermediate host: snail

Most aquatic snails are affected as the first intermediate host, especially from the families Thiaridae, Pachychilidae, Pleuroceridae and Hydrobiidae. In several stages, called redia, the development continues in the screw until the then resulting cercariae leave the snail and infect freshwater crabs or crayfish.

Second intermediate host: freshwater crab and cancer

In the muscles and other organs of the shellfish the pathogens encapsulate as metacercariae.

Definitive host: eater of raw shellfish

Humans or other appropriate final hosts who eat raw shellfish, suffer an invasion by the parasites that hold metacercariae as the ability to move through the wall of the duodenum in the abdominal cavity or liver. From here they pass through the diaphragm and into the lungs and form a capsule in which they mature to adult lung flukes. After 8 to 10 weeks, oviposition starts. 10 to 20 years can survive the adult flukes, but mostly they die from just a few years.

Harmful effect

Lung Paragonimiasis manifests as first acute illness with fever, chills, night sweats, diarrhea, abdominal and chest pain, cough and shortness of breath. After a few weeks, the symptoms regress spontaneously. After months or even years, the chronic phase of the disease begins. Periodic cough up small amounts of blood in a tough, gelatinous sputum is considered characteristic. Fever and other general symptoms are common.

In ectopic settlements ( other organs ) leads to abscesses in the abdomen and chest cavity and if lesions of the brain epilepsy, encephalitis, meningitis, blindness and paralysis.

Prevention

On the consumption of raw or insufficiently cooked crabs or crayfish should be avoided. Marinating and salting definitely provide no reliable prevention dar.