Fig. 112.—Paragonimus westermanni: natural size; to left showing ventral surface; to right showing dorsal surface. (Braun after Katsuruda.) (From Tyson.)
Arce has recently reported cases of paragonomiasis in three Peruvians who had been in contact with Japanese immigrants.
In 1880, Baelz found the ova in the sputum of a case of haemoptysis in a Japanese, as did also Manson in a Chinaman. Manson’s case subsequently died and when autopsied showed in his lungs a fluke which was responsible for the eggs seen by Manson. The fluke itself is a little more than ⅓ of an inch (8 mm.) long and is almost round on transverse section, there being, however, some flattening of the ventral surface. The acetabulum is conspicuous and opens just anterior to the middle of the ventral surface.
The branched testicles are posterior to the laterally placed uterus and the genital pore opens below the acetabulum. The branched ovary is opposite the uterus on the other side.
It is rather flesh-like in appearance and is covered with scale-like spines. The flukes are usually found in tunnels in the lungs, the walls of which are thickened connective tissue. These tunnels result from hypertrophy of the bronchioles. There may be also cysts formed from the breaking down of adjacent tunnel walls. In addition to lung infection with this fluke, brain, liver and intestinal infections may be found.
The life history and mode of infection of man, further than the miracidium stage, has been unknown until recently. If the eggs in the sputum are shaken up with water and the water renewed from time to time a ciliated embryo or miracidium develops after a few weeks and, at this time if one presses on a cover-glass covering some of these more mature ova, the miracidium will break through the operculated extremity of the egg and swim about actively in the surrounding water.
Fig. 113.—Sputum of man containing eggs of the lung fluke, greatly enlarged. (After Manson.)