Filariasis

“ In 1894, however, Sir Patrick Manson, arguing with greater precision by analogy from his own discovery of the cause of filariasis and the part played by mosquitoes, suggested that the malarial parasite had a similar intermediate host outside the human body, and that a suctorial insect, which would probably be found to be a particular mosquito, was required for its development. ”

“ Most of the elderly men, by the way, had elephantiasis.
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Because elephantiasis was something I had to meet as I went along, it may be apropos to explain what I have mentioned before: that it is not a disease, but the manifestation of a disease. The disease is filariasis, caused by the filarial worm, a long, threadlike creature that lives in the lymphatic glands. The eggs pass into the lymphatic and blood streams and hatch into microfilariae. The low power of a microscope will show them in a drop of blood, but their sex cannot be distinguished. ”

“ So the fleas upon plague stricken rats, leaving their natural hosts, may and do infest men instead of other rats when men herd where rats abound.
In more torrid or tropical countries insect-borne diseases are more numerous than in our more temperate clime, and there the mosquitoes, bearing a much greater variety of fevers, also transmit organisms of much higher character than "germs." Filariasis is a disease caused by minute thread-worms or filaria, and these also require the mosquito as an intermediate host to complete their development. ”

“ It is a well-known fact that filarial embryos may be present at night in the peripheral blood of persons not showing a single symptom of filariasis and again, in those with marked elephantiasis, varicose groin glands or chyluria there may be an entire and permanent absence of embryos in the blood. When certain mosquitoes bite persons having embryos in the blood they take into their stomachs the sheathed embryos of F. bancrofti. ”

“ Thomas, the other member of this expedition, has succeeded in conveying the disease to the chimpanzee by the bites of infected mosquitoes, thus affording a lower animal to take the place of the human sacrifices made to discover the cause, and also offering a hope for a cure.
A third disease spread by mosquitoes is filariasis, a worm infection of the lymphatics and of the blood. The work of the school in this direction has been to describe a number of new species of filaria found in birds. ”

“ Abscess: In Fiji, by Bahr, they have been found in the substance of various muscles, e.g., quadriceps extensor, latissimus dorsi, serratus magnus, in the popliteal space, groin, axilla, and over the internal condyle of the humerus, and in the upper extremity they are frequently infected with cocci. They not infrequently contain fragments of dead adult filariæ. Their mode of origin is not clear. They form nearly 30 per cent. of cases of filariasis in Fiji. ”

“ Germs and worms love to visit around. The northern-born influenza has swept away thousands in the South Pacific; neglected, its germ may bide its time for a plunge back into the North. Amoebic dysentery is a “tropical disease”—yes, and a few years ago it appeared in Chicago. The distinctly tropical filariasis (often manifested in elephantiasis) has been identified in several cases in an incomplete survey of the Carolinas. Dr. Boyd, investigating in Florida, asserted that our temperate-climate mosquito can carry a tropical strain of malaria. ”

“ The gastro-intestinal infections, typhoid fever, dysentery, diarrhoea, probably serve as a barometer of the sanitary conditions of a city.
But there are many other diseases whose importance from an economic standpoint may not be fully appreciated from mortality tables. Notable among these are venereal diseases, malaria, filariasis, yaws and hookworm diseases. Further it may be noted that many diseases without being the direct cause of death have a distinct bearing on the mortality. ”

“ Bahr notes the influence of adult filariae in producing an increase in connective tissue in glands and considers such glands as less resistant to bacterial infection.
Manson has an idea that some factor may cause the female to give off immature embryos, which being oval, and of considerable width, may block the lymphatics.
It has often been claimed that various cocci were the exciting factors in the lymphangitis associated with filariasis. Recently Dutcher has reported the isolation of an organism resembling B. subtilis as the cause of filarial lymphangitis (Bacillus lymphangiticus) . ”

“ Low examined the night-blood of 600 cases of all kinds in the General Hospital, the Central Almshouse, and elsewhere, and found the filaria-embryos in no less than 76 = 12.66 per cent. He caught and dissected a hundred mosquitoes (Culex fatigans) from the wards and corridors of the General Hospital, and found that no less than 23 of them were infected. If it were not for Culex, and for men's indifference and apathy, filariasis could be kept down all over the island:—
"There is a perfect water supply, and people can get their water fresh from the standpipes at their doors. ”

“ Both the chyluria and the presence of filariae in the blood are curiously intermittent; it may happen that not a single filaria is to be seen during the daytime, while they swarm in the blood at night, and it has been ingeniously shown by Dr S. Mackenzie that they may be made to disappear if the patient sits up all night, reappearing while he sleeps through the day. ”

“ On all the island there was nothing like a latrine; like the followers of Moses, these primitives dug holes in the sand and carefully covered “that which they had done”—this as a precaution against some witch’s charm. Sand, however, is far too porous to hold down the enterprising larvae, especially when the hole is only a surface scratch. We devoted much time to examining blood for filariasis, which was conspicuous for its absence. Our spleen examinations revealed no malaria, either on Rennell or its little neighboring sister, Bellona, although both were definitely in the malaria belt. ”

“ Pathologically, the march of disease was beginning to show. Yaws, which seemed to have been brought by civilization, was making heavy inroads. Tuberculosis was working its way into handsome youths, who lacked the European’s immunity. Filariasis was a vexing puzzle, because it seemed impossible to control the mosquitoes that carried it. Intestinal parasites were fortunately few; the people lived near the beaches, and tidewater is Nature’s handy sewage system.
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In my notebook I jotted down “interesting items”:—
Gilbertese stick-throwers.... ”

“ In view of the need for pathologic material in undergraduate and graduate education, the Committee on Pathology of the National Research Council urges that all who have suitable anatomic specimens forward them to the Curator of the Army Medical Museum * * * for correlation and distribution to other central agencies and to teaching institutions. Material from the following is particularly wanted: the malarial diseases, bacillary dysentery, endamebiasis, filariasis, the trypanosomiases, the relapsing levers, the leishmaniases, the rickettsial diseases, yellow fever, cholera, plague, and yaws. ”

“ Manson, who writes the article on filaria, reports the case of a negro who had been affected with Filaria loa, and in whose blood he afterwards found the Filaria diurna, and raises the question whether the Filaria loa may not turn out to be the female parental form of the Filaria diurna.
I am afraid we must confess that we are as yet very ignorant of many points connected with the life history of the Filaria loa. With the adult female parasite we have a limited acquaintance, but till now we are ignorant of the appearance of the male worm. ”

“ You will see that it has the appearance of a typical case of elephantiasis of both legs, and in a tropical country would have been accepted as a case of filarial elephantiasis, and the fact that no filaria were found in the blood would have been cited as a proof that it was caused by F. bancrofti, and that the obstruction had shut off the embryos from the blood-stream. But this case occurred in a country where the possibility of filarial infection was definitely excluded, and the obstruction was found to be due to a fibrosis of the lower part of the thoracic duct. ”

“ Filarial periodicity.—A singular feature in the life of the microfilaria is what is known as "filarial periodicity."
If under normal conditions of health and habit the blood be examined during the day, the parasite is rarely seen, or, if it be seen, only one or two specimens at most are encountered in a slide. It will be found, however, that as evening approaches, commencing about five or six o'clock, the microfilariæ begin to enter the peripheral circulation in gradually increasing numbers. The swarm goes on increasing until about midnight, at which time it is no unusual thing to find ”

“ 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. ”

“ 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 ”

“ 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. ”

“ 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. ”

“ 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. ”

“ Prout stated: "I propose, then, for the sake of argument, to assume that elephantiasis is not due to filaria, to criticise as impartially as possible the various suggestions put forward, to examine the possible mechanism of its production, and to see whether, if possible, there is not another explanation which would account for the production of this and other so-called filarial diseases." In the adverse criticism of a theory, one expects at least an equally good explanation to be put forward ”

“ It may be that it is not until the gravid female arrives at some organ or tissue that she deposits her young in such a position that they can get access to the circulation, and that the wanderings for which these worms are so remarkable are an effort to attain this situation. It would be well for those who have the opportunity to look for the parasite at autopsies, especially in the serous cavities. Quite recently Penel stated that he had found mf. loa in the saliva and urine of a patient who presented this larval filaria in the peripheral circulation. ”

“ 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 transference of the Filaria bancrofti, whose presence in the human body in the adult stage is associated with various diseases of the lymphatics, the most pronounced of which is the terrible elephantiasis, is due to more than one species of gnat or mosquito. It is true that no one has ever seen the actual transference of the Filaria from the biting organs of the Culex, Anopheles, Panoplites, or Stegomyia into the human body, but the circumstantial evidence is so strong that on it any jury would convict. ”