Douglas Argyll Robertson

“ We are still at a loss to account for the entrance of the worm into the body. There are, I think, two different channels by which it might possibly find access. First, by the passage of the embryo filariæ directly through the conjunctiva, being brought in contact with the eye in water used for washing the face or bathing the eye. This I think an unlikely means of entrance, as in my patient special pains were taken to avoid such a possibility, and yet she became affected with the disease, and the power of the worm to penetrate skin or mucous membrane has never been demonstrated. ”

“ Twisted round the worm, and apparently attached to it near its centre, was a much finer, less firm, transparent filamentous body, which I at first thought might possibly prove to be a second young filaria, or even the male filaria, but which on further careful microscopical examination appears to be the alimentary canal of the worm protruded through an opening in its musculo-cutaneous wall, caused by the forcible grasping of the parasite with the forceps. ”

“ There would be a discharge of the embryos into the water, and if less care were taken about the purity of the water-supply, and supposing there to be no adverse climatic influences, the worm would become common. This little story about guinea-worms shows how these and similar parasites pass from one man to another; and it shows how slight differences of habit, absence of intermediate host, and so on, govern the distribution of a parasite like Filaria loa. ”

“ Two or three years ago I had an opportunity of examining the blood of a number of negroes from Old Calabar in a missionary establishment and elsewhere, and I made the interesting discovery that in 50 per cent. the blood contained the embryos of a species of filaria—Filaria perstans—which were quite different in their zoological characters from the filaria of the blood, with which every one must now be familiar. ”

“ I now grasped with a pair of toothed fixing forceps a good fold of conjunctiva over the centre of the wriggling worm, taking care to include in the fold all structures superficial to the sclerotic. I next made with a pair of scissors an incision through the conjunctiva a little nearer the cornea, in such a manner as to lift up a small flap of conjunctiva, and after a little careful separation of the tissues found one extremity of the worm, which I seized with a pair of iris forceps. On now relaxing the fixing forceps the parasite came away readily. ”

“ The young guinea-worm lives in water, and probably for this reason the mature worm descends to the feet or ankles, the parts of the human body in tropical countries most often within reach of water. Having procured in this way a supply of embryos, I tried to repeat the experiment described by the Russian naturalist, Fedschenko, on the metamorphosis of the embryos of the guinea-worm in its intermediate host. I obtained some fresh-water cyclops and placed them in water with the embryos. ”

“ With respect to the nature of the protrusions from the body of the parasite under the microscope, one of them is certainly the alimentary canal; the other is probably the testis ruptured in two. One must be careful in coming to a conclusion about these and similar connective-tissue parasites. There are four or five whose young inhabit the human blood; and there are others whose young appear to have a different history. Especially in West Africa do we find such parasites. There is the guinea-worm, said, however, not to be found in Old Calabar; it certainly is found in the neighbourhood ”

“ As regards her general appearance, the female Filaria loa resembles the male parasite, only she is considerably larger and her tail is straight, tapers to a diameter of about 0·1 mm., and is then abruptly truncated. The mouth, the head, the stout muscular ring just posterior to the mouth, the stout longitudinal muscular bands, and the bosses on the integument resemble exactly those of the male worm. In consequence of the mutilation of the specimen it is impossible to say where the vagina opens, or where the anus is placed. ”

“ The worm after removal was, on the suggestion of Dr. Muir, Pathologist to the Infirmary, placed in a mixture of equal parts of glycerine and methylated spirits, but the cork of the bottle in which the mixture was put had retained some of the blue colouring matter (methyl violet) of a solution previously in the bottle, and thus the preservative mixture became faintly blue-tinted. The parasite absorbed the colouring matter slightly, but the filamentous body projecting from it absorbed it more freely, becoming markedly blue-tinted. ”

“ Manson’s view as to the mode of development of the worm be substantiated, then naturally the area of the disease must necessarily be limited to the regions in which the intermediate insect host is to be found.
The fully grown worm may, judging by some of the cases recorded, infest the human subject for a good many years, and may yet not give rise to any very serious symptoms. It possesses very considerable locomotive powers. ”

“ It is capable of wandering at will from one eye to the other, to disappear into the deeper parts of the orbit, to wander under the skin of the eyelids, and even to make excursions in the temporal region. These seem to be the limits of its excursions. No doubt the Rev. Dr. Nassau (the missionary at the Gaboon) had sometimes sensations of a filaria under the skin of the fingers as well as under the skin of the eyelid, but it is doubtful if this was a true case of Filaria loa, and even then if the worm had made its way from the fingers to the eyelid. ”

“ She has resided at Old Calabar on the West Coast of Africa at intervals, for nearly eight years altogether. She twice had to return home on account of debility following severe intermittent fever. During her last visit to Old Calabar, which extended to about eighteen months, she suffered almost the whole time from chronic dysentery followed by severe remittent fever, which necessitated her return to this country last January in a very weak state of health. ”

“ He did not notice that the worm was influenced in its visits by the external temperature.
In addition to these cases among members of the Old Calabar Mission, I may refer to the experience of Dr. Thompstone, who was for eighteen months stationed at Opobo, on the delta of the Niger, and who is in this country at present. He informs me that while he was at Opobo he saw two cases of Filaria loa. In the one negro the parasite was situated in the lower eyelid at the inner canthus close to the lachrymal sac—the swelling in that region giving the appearance of dacryocystitis. ”

“ Filaria loa: male.—Body filiform, cylindrical, measuring from 25 mm. to 30 mm. in length, by 0·30 mm. in breadth, of uniform thickness, except where it tapers at the head and tail. The cephalic end tapers somewhat abruptly to the simple mouth, which is destitute of papillæ and armature. There is no distinctly marked [6] neck, but there is a sort of shoulder about 0·15 mm. behind the mouth, where a number of strong muscular longitudinal bands originate to pass down the body. In one of the specimens the extreme head end is retracted and abruptly truncated, measuring at the free end 0·1 mm. ”

“ The larger bosses are found towards the middle of the parasite; at the head and tail they are considerably smaller, and in these situations they are more sparingly distributed. The larger measure at the base 0·12 mm., and rise about 0·004 mm. above the general surface. The extreme ends of the parasite are not provided with bosses, the first met with being about 1·5 mm. ”

“ Examination of the circulatory system shows absolutely nothing abnormal, no dilatation of the ventricles, no arterial, valvular, or [19] venous bruits. The respiratory murmurs and the percussion note of the lungs are normal. The liver is not, and the spleen is, just appreciably enlarged. ”

“ At the same time it must be borne in mind that there are few regions of the body in which the skin is so thin as in the eyelids, whereby the presence of a small filamentous body can easily be discerned. The [21] parasite might readily move about under the coarser cutis of other parts and yet escape detection.
The sensitiveness of the parasite to cold appears to be fully established by the experience of my patient and Mrs. H⸺, and it is possible that a prolonged residence in a cool climate may eventually prove fatal to the worm, as seems to have occurred in the case of the Rev. ”

“ He was inclined to view it as a worm of the blood (ver sanguin) , as it did not appear to him possible for it otherwise to get into that position without giving rise to pain and inflammation at the part.
We have next several cases that were carefully observed and recorded by M. Guyot, a French surgeon, [2] who had made many voyages to the Angola coast of West Africa. ”