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Korean J Parasitol > Volume 17(2):1979 > Article

Original Article
Korean J Parasitol. 1979 Dec;17(2):132-146. English.
Published online Mar 20, 1994.  http://dx.doi.org/10.3347/kjp.1979.17.2.132
Copyright © 1979 by The Korean Society for Parasitology
Lung findings in experimental paragonimiasis
Won-Young Choi,Ok-Ran Lee,Young-Kwan Jin and Je-Geun Chi
Catholic Institute of Parasitic Diseases, Korea.
Department of Pathology, College of Medicine, Seoul National University, Korea.

A pathological study was done to elucidate sequential changes of the lungs in various time intervals following experimental paragonimiasis in 15 dogs and 15 cats. The dogs and cats were fed with 30~50 metacercariae of Paragonimus westermani, and were sacrificed at 15, 20, 30, 45, 60, 90 and 120 days after infection respecively. Autopsies were performed immediately after death. Gross and microscopic examination of the lungs showed following findings:

There were no qualitative difference in pathological findings between dogs and cats.

2. Pathological findings were first noticed at 20 days of infection in thoracic cavity, which consisted of fibrinous plueritis along with superficial hemorrhage. Although no worm was found in the lung parenchyma at this period, juveniles were seen in pleural cavity together with turbid effusion.

3. Paragonimus juveniles were first recognized inside the lung parenchyma by 30 days of infection. This was the period when the lungs showed multiple areas of hemorrhage and probably active penetration by smaller worms. Hemorrhagic bronchopneumonia was quite pronounced from this stage through 45 days of infection.

4. Paragonimus worm cyst was essentially composed of fibrous scar and heavy inflammatory cellular infiltrate. The lining epithelial cells were first became noticed by 2 months of infection. And these epithelial cells were thought to be probably transformed alveolar lining cells rather than bronchiolar epithelial cells. As the infection progress, the cyst wall became more stabilized and often showed squamous metaplasia.

5. Fibrinous pleuritis with pleural effusion was very prominent finding in early periods of infection. Bronchiolitis and focal vascular sclerosis were often seen in experimental paragonimiasis.


Figs. 1-6
Fig. 1. C79-113. Fresh cat lung 8 days after inoculation. The lungs show no abnormal finding.

Fig. 2. C79-114. Fresh dog lung 15 days after inoculation. Scattered puncture wounds (arrows) by the worms are seen on the pleural surface, together with hemorrhage and fibrin exudation.

Fig. 3. C79-114. Fixed dog lung 15 days after inoculation. Pleural surface shows foci of fibrin deposit.

Fig. 4. C79-104. Fixed cat lung 15 days after inoculation. Punctuate hemorrhage with irregular pleural surface is seen.

Fig. 5. C79-136. Fixed cat lung 21 days after inoculation. Puncture marks (arrows) on pleura and foci of subpleural consolidation are seen.

Fig. 6. C79-110. Fixed dog lung 20 days after inoculation. Diffuse fibrinous pleuritis is seen together with nodular consolidations of the puncture wounds(arrows).

Figs. 7-13
Fig. 7. C79-140. Fixed dog lung 30 days after inoculation. A marked fibrinous and focally fibrous pleuritis is seen on the left. Cut sections(right) show patchy gray white consolidations.

Fig. 8. C79-139. Fixed cat lung 30 days after inoculation. Outer surface(A) shows craters plugged with blood (arrow). Cut sections are shown in(B). Other area shows hemorrhagic patches, one of which contain small cavity (arrow) made by the worm (C).

Fig. 9. C79-120. Fixed dog lung 30 days after inoculation. Nodular consolidation and hemorrhagic bronchopneumonia are seen on cut sections.

Fig. 10. C79-105. Fixed dog lung 30 days after inoculation. Patchy fresh hemorrhage is noted.

Fig. 11. C79-120. Fixed dog lung 30 days after inoculation. Multiple subpleural scars (arrows) are seen on cut sections.

Fig. 12. C79-111. Fixed cat lung 45 days after inoculation. Note dense organized fibrinous and fibrous pleuritis with irregular gray white exudates.

Fig. 13. Cut sections of the lungs shown in Fig. 12. Worms(w) are seen in the lung and cavitation is seen around them.

Figs. 14-19
Fig. 14 & 15. C79-141. Fixed dog lung 60 days after inoculation. Irregular nodular protrusions on the pleural surface are seen in Fig. 14. Cut sections (Fig. 15) show well formed worm cysts containing grayish worms. One of the worms is seen in the bronchial lumen(arrow).

Fig. 16. C79-134. Fixed dog lung 90 days after inoculation. Cut sections show many worm cysts that contain 2 worms.

Fig. 17. C79-138. Fixed cat lung 90 days after inoculation. Fairly well circumscribed worm cysts are seen.

Fig. 18 & 19. C79-143. Fixed dog lung 120 days after inoculation. Pleural surface shows fibrous scar, and cut sections(Fig. 19) show two mature worms in a cyst.

Figs. 20-25
Fig. 20. Microscopic picture of early pleural lesion consisting of focal fibrinous exudate mixed with red blood cells. C79-109 (15 days). H&E×360.

Fig. 21. Early puncture mark with surrounding lung edema and focal inflammatory reaction. C79-110(20days). H&E×100

Fig. 22. Puncture mark hemorrhage in the lungs, and fibrin cap on pleural surface. 20 days. H&E×40

Fig. 23 & 25. Patchy pulmonary consolidation showing pools of inflammatory cells in the alveoli. The inflammatory cells consist chiefly of neutrophils and eosinophils(Fig. 25). Also note diffuse pleural exudate. H&E ×100 and ×360.

Fig. 24. A larva is seen penetrating into lung parenchyme. Note a linear track of worm, starting from the pleural surface. Fresh hemorrhage is seen around the track. C79-105 (30 days). H&E×40

Figs. 26-33
Fig. 26~29. Different size of the worms in the lungs, 30 days (Fig. 26), 45 days (Fig. 27&28) and 60 days (Fig. 29) after inoculation. H&E×40.

Fig. 30. Early alveolar cell proliferation around the worm. Large vesicular nuclei with abundant cytoplasm are characteristics of these cells. C79-137 (45 days). H&E×360.

Fig. 31. A focus of infarction is seen, around the worms. The infarction is probably of fibrous vascular occlusion induced by the worm. H&E×40.

Fig. 32 & 33. Paragonimus eggs show often patchy pneumonic consolidation (Fig. 32) or egg granulomas (Fig. 33). Also note vascular sclerosis in the granulomatous lesion. H&E×100.

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