The penetration of the skin by the larvæ also in man causes reddening and burning at the affected points, and this is followed in a few days by transitory swelling in the subcutaneous connective tissue. Skin affections can also be set up by such Ancylostoma (and Strongyloides) larvæ as do not gain access to the blood or lymphatic vessels or gut; such larvæ apparently wander further in the connective tissue, and, as Looss has in his own person observed, gain access to the cutis at different points, thus causing progressive swellings (accompanied by intense itching), which cease when the worm again penetrates into the deep tissues. Skin affections such as “ground-itch” or “pani-ghao” occurring in the tropics and only attacking the feet, or other affections (e.g., sump bunches) are now well recognized as being due to the invasion of Ancylostoma larvæ.
Other names for these skin affections are water-sore, sore feet of coolies, maza-morra, bunches, botches, quaddeln, krätze, ampoules, gourmes, taons, pitirr. Whether oral or dermal infection is the more important one further observation must decide.
The duration of life of Ancylostoma duodenale, which is a specific parasite of man and has not been observed in other mammals, amounts to about five years, as strayed larvæ according to Looss wander for this extent of time in the body.
Cultivation of Larvæ.—(1) Mix the fæces (free from drugs such as salines or thymol) with animal charcoal, adding water if necessary till a consistence of porridge is obtained. If the stools are very fluid, allow to sediment first and pour off the fluid. The best charcoal is that made from bones, and should not have an acid reaction. Charcoal is necessary in order to prevent fermentation, which kills the larvæ. Spread in layers 2 to 3 mm. thick in Petri dishes. Incubate at room temperature. To extract the larvæ from the culture allow the surface thoroughly to dry, then pour on water; the larvæ wander out and are poured off and subsequently further purified by sedimentation or filtering through blotting paper, the larvæ passing through.
(2) A funnel is plugged with cotton wool, then filled with washed sand to within a centimetre or two of the rim. Stand this in a jar of water so that the level of the water is slightly below that of the sand. On the surface of the wet sand now place layers of blotting paper, and spread the fæces, diluted if necessary, on this in layers of a few millimetres thick (vide p. 474).
Detection of Eggs.—Vide p. 473.
Dermal Infection of Dogs.—Infection with larvæ of A. caninum. In two hours most of the larvæ are free in the cutis and in four hours in the subcutaneous tissue. By scraping a few days later the mucosa of the trachea large numbers of larvæ are found there.
Ancylostoma ceylanicum, Looss, 1911.
Fig. 332.—Ancylostoma ceylanicum: head end, two teeth on each side, the inner almost concealed by the outer. × c. 200. (After Looss.)
At the anterior edge of mouth capsule one large tooth; below or behind this towards the middle line a very small tooth, the tip only of which is seen. Male 5 mm. average. Lobes of bursa almost as long as broad, strongly projecting towards the ventral side. Rays short and relatively thick. Female 7 mm.
Habitat.—Intestine civet cat (Viverricula malacensis), Ceylon, and man in Bengal according to Clayton-Lane.
Other species are: A. caninum (Ercolani), in cat and dog, Europe and Africa; A. malayanum (Alessandrini), 1905, in the Malay bear (Helaretos malayanus); A. pluridentatum (Alessandrini), 1905, in Felis mitis, Brazil.
Ancylostoma braziliense, Gomez de Faria, 1910.
In cats (and dog), Brazil. Female 8·5 mm., male 7·5 mm. long. Eggs 65 µ by 32 µ. Leiper considers it to be identical with A. ceylanicum.
Group. Bunostomeæ, Railliet and Henry, 1909.
Bursa with median double, postero- and postero-external arising from a common trunk, posterior bifurcated, each limb bidigitate (fig. 336). Vulva in middle of body or a little in front. Uteri divergent.
Contains the following genera: (1) Bunostomum (= Monodontus); (2) Necator; (3) Bathmostomum; (4) Gaigeria.
Genus. Necator, Stiles, 1903.
Mouth capsule small, narrowed anteriorly (ventrally) by chitinous plates, as in Uncinaria. On each side of the base of the dorsal cone a lateral chitinous plate or lancet with smooth edge (not serrated), ventral lancets as in Ancylostoma. No ridges on outside of ventral wall. Aperture of dorsal œsophageal gland on tip of a cone projecting freely into the buccal capsule. Bursa closed. Posterior ray cleft to its root.
Necator americanus, Stiles, 1902.
Syn.: N. africanus, Harrison, 1910.
Fig. 334.—Necator americanus. Showing cutting plates and the projecting dorsal ridge, and deep in the cavity the edges of the ventral lancets. × c. 475. (After Looss.)
Male 8 mm. long, female 10 mm. The head is strongly bent dorsalwards so that almost by this character alone it can be distinguished from Ancylostoma duodenale. The buccal capsule is markedly small—in the male, 0·093 by 0·084 mm., in the female 0·11 by 0·097 mm. There are no teeth anteriorly on the ventral side of the capsule, but instead there are two cutting chitinous plates, the anterior portions of which are prominent and angular, and meet in the middle line in front. Posteriorly on each side the plate projects less, while between the anterior and posterior parts there is a deep angle. The inner (posterior) ventral lancets which also occur in A. duodenale are large, and project far into the lumen, the tips of these, of the lateral lancets, and of the dorsal cone almost meeting in the centre of the lumen. As already stated in the definition of the genus Necator, there are also lateral lancets which start from the base of the dorsal cone. This dorsal ridge, or rather in this case cone, is a striking object in the mouth, and projects right out into the cavity, and on its summit opens the dorsal œsophageal gland.
Fig. 335.—Necator americanus: lateral view, showing the dorsal ridge perforated by the duct of the dorsal œsophageal gland, the lateral lancet and ventral lancet and the nerve papillæ. × c. 475. (After Looss.)
The bursa is about as long as broad, but has the lateral lobes strikingly lengthened, giving a trilobed appearance (fig. 336), but as in Ancylostoma duodenale it is closed on the ventral side. The distribution of the rays is best understood from the figure. The genital aperture lies on a marked conical protuberance; the cement gland is bilobed in transverse section. In the female the opening of the vulva is in front of the middle line, in A. duodenale it is behind.
The spicules, 0·92 mm. long are hooked at the extremity.
Fig. 336.—Necator americanus: bursa of male. The rays from right (top) to left are: (1) posterior, (2) postero-external, (3) and (4) median doubled, i.e., postero-median and antero-median, (5) antero-external, (6) anterior (cleft), and above it on left a pre-bursal ray. × c. 120. (After Looss.)
Eggs more pointed at the poles than those of A. duodenale, 64 µ to 72 µ by 36 µ, so that it may not be possible to distinguish single eggs owing to individual variations, yet on comparing a number they can be distinguished.
Geographical Distribution.—Brazil, Porto Rico, Cuba, Central Africa, East Africa, Victoria Nyanza, Gold Coast, Uganda, North-Western Rhodesia, Ceylon, Mysore. For other localities where A. duodenale is also found see p. 450.
Habitat.—In small intestine of man and gorilla (Troglodytes gorilla).
Necator exilidens, Cummins, 1912.
Syn.: N. africanus, Looss, 1911.
Male 7 mm., female 9 mm. long. The edges of the cutting plates are rounded, not angular, and do not meet in the middle line. Inner (posterior) ventral lancets very small. Lateral lobes of bursa broader than long. Rays thick and plump.
Habitat.—In the chimpanzee (Anthropopithecus troglodytes).
Ancylostomiasis.
Morbid Anatomy.—Organs pale and bloodless. Abdominal organs sodden, and there is fluid in the serous cavities. Lungs: œdema. Kidneys: fatty changes, especially large pale kidney. Liver and heart also show fatty changes—there is much hæmosiderin in the liver cells. Blood: early stages, a leucocytosis 20,000 upwards, and eosinophilia 50 per cent. Later, anæmia (hydræmia). The number of worms found varies from ten to 1,000. They are rare in the duodenum, but occur as far as 6 ft. from the pylorus.
Group. Syngameæ, Railliet and Henry, 1909.
Bursa with anterior and median ray cleft; antero-external, close to median; postero-external, arising separately from posterior; posterior bifurcate to base, each branch bifurcate or trifurcate. Vulva in the anterior fourth of body. Uteri divergent.
Genus. Syngamus, von Siebold, 1836.
Head thickened, not tapering; broad mouth with gaping buccal capsule.
Male and female often in permanent copulâ.
Parasitic in respiratory passages of birds and mammals.
Habitat.—S. trachealis in poultry; S. bronchialis in goose; S. laryngeus in cattle; S. vasicola in goats, etc.
Syngamus kingi, Leiper, 1913.
Buccal capsules of male and female on same level. In S. trachealis and S. laryngeus, that of male in front of that of female. In S. dispar, that of male behind that of female. Œsophagus of male one-sixth, that of female one-ninth of total length. Mouth capsule in male and female terminal; it is dorsal in S. trachealis and in mammalian species. Tail of female bluntly pointed. Ovary reaches to anus. Excretory pore opposite the middle of the bulb of œsophagus. In S. trachealis it is opposite the œsophageal valves.
Habitat.—Found in sputum of patient by King in St. Lucia. Normal host probably a carnivore.