Symptoms and Prevention and Treatment Methods of Pig Lung Fluke Disease

1. Pathogen Pig lung fluke disease is caused by the parasitism of Paragonimus ohirai in pig lungs. Paragonimus ohirai is a dark brown, oval-shaped, thick fluke, 8-16 mm long, 4-8 mm wide, and 2.5 mm thick.

Adult worms parasitize in pig lung tissue. After eggs are produced, they are coughed up with sputum, swallowed into the mouth, and discharged from the body with feces. Under suitable conditions, miracidia escape from the eggs, enter the first intermediate host (freshwater snail), and develop into cercariae within it. The cercariae leave the snail body and enter the second intermediate host (sesarmid crabs, etc.), forming metacercariae within them. The final host (pigs, etc.) becomes infected with this disease by swallowing sesarmid crabs, etc., carrying metacercariae.

2. Symptoms Clinically, the main manifestation is coughing.

3. Necropsy The formation of cysts on the lungs is the main symptom of this parasite. The cysts are about 0.6 cm in diameter, with a cyst wall of connective tissue proliferation about 0.1 cm thick, relatively firm. They slightly protrude from the lung surface and appear grayish-blue or brownish-black. Most cysts contain one pair of worms; those with only 1 worm or 3 worms are fewer. The cysts contain a brownish-black, thick, serous fluid. Due to larval migration, liver lesions such as small pinpoint hemorrhages are caused. There are also cases where larvae parasitize the liver, causing hard nodules and liver cirrhosis.

4. Diagnosis A definitive diagnosis can be made by combining clinical symptoms with fecal egg examination.

5. Prevention The main measure is to prevent pigs from eating raw sesarmid crabs and other second intermediate hosts.

6. Treatment Bithionol can be tried, 50 mg per kg body weight per day, divided into 3 oral doses, administered every other day, with 20 days as one treatment course (actually 10 days of medication).