THE FLIES THAT CAUSE MYIASIS IN MAX 125 



characteristic processes, or rudiments of them, may occur dorsally or 

 ventrally. These processes, in some species, act as organs of notation, 

 and are adaptive to life in a semiliquid medium; they were mistaken 

 for gills by earlier authors. The first (prothoracic) segment bears 

 a pair of antennalike processes. The head is very small : the anterior 

 spiracles are rather prominent and ending in a number of digitate 

 processes : the posterior spiracles are more or less elevated and three- 

 lobed. each lobe containing an opening. 



Pathogenesis. — There are on record numerous cases of parasitism 

 of the digestive and urinary tract of man by several species of Fannin. 

 When present in the stomach, the larvae may cause vertigo, nausea. 

 and violent pains; they may be expelled by vomiting. In the intes- 

 tine they may produce abdominal pains, diarrhea, and sometimes 



Figuee 68. — Synthesiomyia nudiseta, posterior spiracles of mature larva. 



hemorrhage resulting from the lesions of the intestinal mucous mem- 

 brane. The patient will sometimes complain of disagreeable epi- 

 gastric feelings of a tremulous nature. The abdomen may be swollen. 

 Loss of sleep and appetite and general weakening may result. Intes- 

 tinal myiasis is diagnosed by the recovery of larvae in stools ; in severe 

 cases a quart or more of larvae may be passed, and the period of expul- 

 sion may extend over several months. 



A number of records of myiasis of the urinary passage and bladder 

 are on hand. Some of these are doubtful, but a sufficiently large 

 number are well authenticated. The usual symptoms consist of 

 difficulty and pain in urination; the number of parasites is generally 

 small, and when they are passed, relief is obtained. In one ease, cited 

 by Mumford (91). a heavily parasitized 1-year-old boy became seri- 

 ously ill. with convulsions ; however, he recovered when the maggots had 

 been passed. 



Infestation may come from food eaten in the raw state, or the eggs 

 may be deposited on or near the anus, where the maggots, after 

 hatching, may make their way into the urinary tract or intestine. 

 Such an infestation may result from the use of unsanitary open 

 privies, from unsanitary care of small children, or from sleeping with 

 the body exposed in warm weather in places where flies are abundant. 



