The Anchylostomum is a red, cylindrical worm, with the anterior extremity tapering and recurved. The head end, somewhat enlarged, encloses a capacious oral capsule armed with strong hook-like teeth. The caudal extremity of the female ends in a conical point, and the genital aperture is situated behind the middle of the body. The caudal extremity of the male ends in a trilobate pouch, within which projects the bispiculate penis. The female is from five lines to three-fourths of an inch long; the male is about half the size. The eggs are oval and measure 0.05 mm. long.
The worm inhabits the small intestine, especially the duodenum and jejunum, clinging tenaciously to the lining membrane by means of the armed mouth. It penetrates the mucous membrane to the submucous coat, from which it sucks the blood that forms its food. In the position of its attachment it gives rise to little ecchymoses. It often occurs in large numbers, even to hundreds and thousands. The eggs are laid in the intestine and are discharged with the evacuations. Externally, in water, the embryo undergoes development within the egg, and then escapes to lead for some time an independent existence. Subsequently, it is most probable that the worm obtains access to the human stomach by drinking standing water, and completes its development in the intestine.
The Anchylostomum proves to be a prolific source of wasting diseases in tropical countries, and is pernicious to an extent proportioned to the numbers infesting the intestine. By depriving the body of blood it produces a greater or less degree of anæmia. The affection begins very insidiously, and the general nutrition of the body may not be visibly disturbed until a late period. In moderate cases the disease is indicated by general paleness of the skin and mucous membranes, fatigue on slight exertion, and a tendency to palpitations and quickened pulse. In more severe cases there is constantly increasing debility, with increase of paleness, indisposition to exertion, excessive sleepiness, and feeling of coldness. Dyspeptic symptoms sometimes appear, and loss of appetite may alternate with ravenous hunger. Accompanying this there is often a disposition to eat innutritious articles, as coal, clay, wool, etc. Feeling of weight and oppression in the epigastrium and abdominal pains are frequent. In the advance of the affection shortness of breath appears, increased on exertion to violent dyspnoea. Emaciation becomes obvious in the later stage of the disease. In the worst cases the symptoms increase in severity, the patient becomes dropsical, is attacked with profuse diarrhoea and vomiting, and finally dies.
The severity of the affection is proportioned to the number of parasites present and the quantity of blood they consume and cause to be lost. Bad cases may end fatally in a few weeks, but generally the disease lasts for months, and where the patient is provided with abundance of good food it may continue for years.
The prognosis of the disease is rather unfavorable; if, however, the nature of the affection is ascertained before it has greatly exhausted the patient, and the parasites can be expelled, the result should be favorable.
We have thus far obtained but little information as to the best treatment for Anchylostomum. Calomel and turpentine have been recommended, and, as these are most powerful vermicides, we have reason to believe they would prove most effectual remedies.
In regard to the prophylaxis for Anchylostomum—and we may add in general for all parasites which gain entrance to man through drinking-water—all stagnant or standing waters should be filtered, so as to remove any source of infection, whether by eggs or free embryos of parasites or of larval forms existing within minute aquatic animals which serve as intermediate hosts to parasites. Standing waters, such as those of puddles, ditches, marshes, and ponds, more or less swarm with minute animals, all of which may be entirely removed by filtration. Even the water of cisterns and wells, if supplied from the free surface of the country, may not be free from minute animals, and especially eggs, and therefore requires filtration to be safe. Only spring and freely-running water of rivers and creeks and of lakes is commonly free from microscopic animals and their eggs, and therefore devoid of all danger in these respects.
STRONGYLUS LONGEVAGINATUS; S. bronchialis.—This nematode has been only once satisfactorily observed. Many occurred in the lungs of a boy in Germany, but the real cause of his death was not stated. The female worm is about an inch long, the male about five-eighths of an inch.
Certain worms previously discovered in the bronchial glands of a case of phthisis, and described under the name of Hamularia lymphatica, are regarded by Cobbold as the same with the former; but the descriptions of the two render this improbable. Treutler's drawing of Hamularia, as copied by Leuckart, looks like an Ascaris upside down.
EUSTRONGYLUS GIGAS; Strongylus gigas; Palisade-worm; Kidney-worm.—This worm, recorded in the catalogue of human parasites, is doubtful as such. Pertaining to the same family as Anchylostomum, as the common name indicates its usual habitation is the kidney. It is the largest of the nematodes, and is a long, cylindrical red worm, slightly tapering, and blunt at the ends. The mouth is enclosed by six rounded labial papillæ. The caudal extremity of the male ends in an inverted cup-like pouch, from which the penal spiculum protrudes. The female commonly ranges from one to three feet in length and from a fourth to nearly half an inch in thickness. The male ranges from six inches to a foot in length and from one to three lines in thickness.