Case of Filaria loa

by Douglas Argyll Robertson

He considered that the worm was a dracunculus (dragonneau) similar to those removed from other parts of the body in negroes, only finer and shorter.

The next case recorded is one by M. Mongin, a surgeon at St. Domingo, in the ‘Journal de Médecine’ for 1770, occurring in a negress who had for twenty-four hours complained of severe pain in the eye with scarcely any inflammation.

At first glance he saw a worm, which appeared to him to wriggle over the globe, but on trying to seize it with forceps he found it to be between the conjunctiva and sclerotic.

To remove it he incised the conjunctiva, and it emerged through the opening. It was one and a half inches long, and the thickness of a violin string, and of an ashy colour. It was larger at one end than at the other, and very pointed at the two extremities. 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. The first case in which he discovered the filaria was that of a negress in whom, after several examinations, he noticed a ridge of the conjunctiva resembling a varicose vein, which induced him to make minute openings over it to empty it. On pricking the elevated conjunctiva with the point of a lancet he was surprised to observe the projection disappear. The patient at the same time stated that she felt something move in her eye, and that the movement was deep-seated. He suspected that this could be nothing else than a roving worm (ver ambulant), which sometimes appeared under the conjunctiva, sometimes dived into the posterior parts of the eye. From inquiry he found that a worm in the eye was common enough among natives of that land, and that it was called a “loa,” and he consequently applied the term filaria loa to the affection. He saw the worm on many occasions in the eye of the negress, but whenever he touched the spot where it was it retreated to the posterior parts of the orbit. On that voyage he saw several negroes with this affection, for which he employed various collyria without effect.

In 1777 he made another voyage to the coast of Angola. Having many negroes on board the ship he renewed his researches, and found several individuals affected with the disease. As no benefit had been derived from the applications he had previously used he proposed to extract the worm through a small opening in the conjunctiva. To effect this it was necessary to fix the worm, to which end he employed dissecting forceps, without, however, being able to seize it.

On another occasion he employed a ligature needle of medium size, with which he pierced the conjunctiva by the side of the worm, and passed it between the worm and the sclerotic, making it emerge at the opposite side. By this manœuvre he was able to raise the fold of conjunctiva along with the worm on the concavity of the needle. This fold he divided, and drew out the worm without mutilation. The operation required to be done very quickly, otherwise the worm escaped and disappeared, sometimes for a very long time. Of five negroes upon whom he thus operated he was only able to remove the worm twice. The worms were about fifteen lines in length, and a little less thick than a violin string. He did not think the worms were a species of dracunculus, for they were quite white, firmer, and less long in proportion. He never saw the worm make an opening for itself. In the seven voyages he had made to the Angola coast he had never seen a negro affected with dracunculus. Other surgeons who had sailed on these coasts assured him they also had seen no cases, which made him conclude that the negroes of that country are not subject to dracunculus. The cases on which he operated were healed in twenty-four hours.

We next find M. Clot at a meeting of the Académie Royale des Sciences in December, 1832, referring to the case of a negress, who suffered from a dracunculus under the conjunctiva of the eye. It appeared now and then gliding between the conjunctiva and sclerotic, lifting up the conjunctiva. This case appears to be one that was seen by Dr. Roulin at Monpox in America.

Another case is mentioned by Dr. Sigaud in his work on the ‘Climate and Diseases of Brazil.’ He states he was witness in 1833 of the extraction, by M. dos Santos, of a filaria situated in the orbit on the surface of the sclerotic of a negress.

In 1838 Dr. Guyon made an interesting communication to the French Academy of Sciences, in which he narrated the case of a young negress affected with two filariæ, one in the right and the other in the left eye, but occasionally both appeared in the same eye; the passage of the worm from the one eye to the other occurring with great rapidity through the cellular tissue under the skin at the root of the nose. The filariæ were in different eyes when the operator (Dr. Blot of Martinique) extracted the filaria from the left. Some hours after, when he returned to extract the other worm, he found that it had passed to the left eye, from which he extracted it by a fresh incision.