Ankylostomiasis : its cause, treatment, and prevention.

Date:
[1903]
Catalogue details

Licence: In copyright

Credit: Ankylostomiasis : its cause, treatment, and prevention. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

    3/36
    ANKYLOSTOMIASIS. ITS CAUSE, TREATMENT AND PREVENTION. INTRODUCTORY. E disease known as ankylostomiasis, or “ miners’ anaemia,” is produced by a nematode worm, Ariky- lostomum duodenale* (Dochmius duodenalis or Strongylus duodenalis), (Plate I.) infesting the small intestine, to the mucous membrane of which it attaches itself by a series of hooks (four to six in number, according to the reports of different observers) situated round the mouth of the para- site. The adult male worm is about ^ to ^ of an inch (6 to 8 millimetres) in length, the female being somewhat longer (about 12 mm., or J in.) and thicker. The sexual organs of the male are situated at the posterior extremity, and are surrounded by a characteristic bursaf; whilst those of the female are placed a little to the rear of the middle of the body. The female lays a large number of microscopically- small highly - transparent, elongated eggs, about 0'028 mm. (¥^ in.) wide and 0044 mm. (^^ in.) long, which pass away in the faeces. On issuing from the body the eggs are usually in an advanced state of segmentation (division of the contents into cells), and contain two to eight or more cells; so that, given favour- able conditions for development, they quickly hatch out into larvae (intermediate stage of growth). The essential conditions for this development are a very moist, pasty medium, a temperature exceeding 20 degs. Cent. (68 degs. Fahr.), the most favourable being 25 to 30 degrees Cent. (78 to 86 degrees Fahr.), and absence of daylight. The larvae on issuing from the ova are very active, so long as the medium remains moist, but after a short time develop a thickened integument or capsule, and thus attain their final stage of existence outside the human body. According to Giles, the embryo develops to a sexually * The name is not strictly correct, since the worm does not inhabit the duodenum. t Purse-like enlargement. | complete rhabdite form (full-grown worm) in polluted j soil and at a sufficiently high temperature ; but this j observation does not appear to have been confirmed by other workers, and Dr. Tenholt, of Bochum, states emphatically that the larvae remain asexual and in- capable of reproduction until they gain access to the small intestine. Although Looss states that the larvae are able to pass into the skin and produce a temporary skin eruption, it seems very doubtful whether they could gain access to the intestines in this way ; and, indeed, the attempts made by other workers to imitate his experiments have resulted in failure, so that the mouth appears to be the sole means by which the infection can be transmitted. Owing to carelessness, or perhaps also the absence of proper accommodation, the miners deposit their faeces in the underground workings, where the faecal matter becomes incorporated with sludge. This, in the course of the ordinary operations of mining, gets on to the men’s hands, and, as these are rarely washed previous to meals underground, the eggs and larvae enter the mouth with the food. While the eggs and young larvae are susceptible to the action of the acid gastric juice, and are thus destroyed in the stomach the thicker integument of the capsuled larvae is not dissolved until brought into contact with the alkaline juice of the smaller intestine, and the latter form of larva alone therefore seems to be capable of transmitting the disease and attaining complete development into the adult male or female worm, on reaching its natural habitat. It is worthy of note that, the presence of oxygen being essential for the development of the ova, it is impossible for the complete cycle of reproduction to proceed within the intestine. With regard to the question whether the worm can be carried by any other host than man, it was believed at