NEMATODA, THREAD-WORMS 549 



Ascaris maritima, Leuckart, 1876, has up to this time been found only 

 once — in Greenland. 



Wherever ascarides hosts, including swine and cattle, distribute the ova in 

 the vicinity of human habitations, man, whose habits and customs bring him 

 into close contact with the foci of infection, acquires the ova of the nema- 

 tode. The agricultural population, in particular, by their occupation, and, 

 above all, the children, by playing in the infected earth take up the embryo. 

 Children in cities are much more rarely contaminated. By the slaughter of 

 pigs and cattle at home or in ihe immediate vicinity, the infectious germs are 

 widely distributed about the house and in the garden, which is the ordinary 

 playground of the children. In the first and second years children are much 

 more rarely attacked than in the third year and upward. In later life ascarides 

 are more rarely met with but no age is exempt. Often infection occurs 

 through drinking-water or food, such as fruit, vegetables, and the like. 



The, usual seat of the parasite is the small intestine. A single parasite is 

 rarely found ; usually they collect in numbers. 



The parasites frequently produce no symptoms, and their accidental dis- 

 charge betrays their presence. When the parasites are numerous, they pro- 

 duce more or less decided disturbance. In the milder cases only gastric symp- 

 toms appear : Anorexia, nausea, salivation, irregular bowel action. In children 

 there is frequently a slightly swollen appearance, deeply sunken eyes, itching 

 of the nose, nocturnal grinding of the teeth. Various nervous symptoms, such 

 as convulsions, epileptiform attacks, headache, pain in the back of the neck, 

 etc., may occur, although these are less frequent. Demme saw cases of severe 

 anemia due to the presence of numerous nematodes; Baelz also believes that 

 ascaris may occasionally produce severe anemia. Leichtenstern saw severe 

 anemia, and in another case larval malaria with enlargement of the spleen, 

 improve after expulsion of the ascarides. These, as well as many other obser- 

 vations, do not permit us to regard this nematode as the harmless guest which 

 it is usually assumed to be. The severe nervous symptoms have, for the most 

 part, been looked upon as reflex. The observations of Huber, v. Linstow and 

 others have shown that this nematode contains a poison which may give rise 

 to urticaria and conjunctivitis. It has a sharp odor, manifest even on handling 

 of the parasite. As I have explained elsewhere it is quite possible to look 

 upon the nervous symptoms which accompany infection by nematodes not as 

 reflex but as toxic. 



Decided local disturbances may also appear when numerous ascarides are 

 present. Sometimes, rarely it is true, the worms may form a ball so that the 

 symptoms of intestinal occlusion may arise. Leichtenstern questions this, 

 but from the observations of Hosier, Pelczynski, Stepp, Sperling and others, 

 it may be considered as proven. The view that nematodes may perforate the 

 intact mucous membrane has not yet been positively demonstrated by investi- 

 gation, but if ulcer formation is present it is quite possible that the parasites 

 may perforate the ulcerated surface. 



It is a remarkable fact that at certain times, especially in serious febrile 

 diseases, ascarides leave their usual seat, the small intestine, and begin to wan- 

 der. Either they enter the large intestine, are voided from this independently, 



