EFFECTS OF INTESTINAL MYIASIS 527 



pure hydrochloric acid or turpentine. It is a httle wonder, then, 

 that fly maggots are not destroyed by the 0.2 per cent hydro- 

 chloric acid of the stomach or by the other digestive juices. 



Effects. — The effects of fly larvae in the intestine are extremely 

 variable, depending on the heaviness of the infection, the species 

 of flies, and on individual susceptibility. There are many cases 

 where the presence of the larvae in freshly passed stools is the 

 first indication of their having existed in the intestine, and it is 

 practically certain that the majority of infections are never known 

 or suspected. 



On the other hand more or less serious symptoms may be 

 caused by intestinal m3dasis. The presence of Fannia larvae or 

 of cheese-skippers in the digestive tract often gives rise to tem- 

 porary intestinal disturbances, such as loss of appetite, vomit- 

 ing, general malaise, abdominal pains, diarrhea, constipation and 

 intestinal bleeding. Sometimes headache and vertigo indicate 

 the absorption of toxic substances secreted by the maggots or 

 their entrance to the blood circulation through the wounds. 

 Four cases of death from intestinal myiasis have been recorded, 

 and it is probable that appendicitis may sometimes be caused 

 through injury to the walls of the appendix by fly larvae which 

 start sores leading to ulceration. Those maggots which pass 

 directly through the digestive tract, feeding only on food sub- 

 stances with which they come in contact en route, do little or 

 no harm to the temporary host. Those larvse, however, which 

 attack the living tissues lining the stomach and intestine are the 

 cause of the symptoms named above. Even the maggots of 

 the housefly, Musca domestica, have been known to damage the 

 walls of the digestive tract. In a case which occurred in the 

 Philippines, the walls of the stomach were extensively eaten away 

 by larvae of this common fly, and 20 or 30 maggots were obtained 

 by means of a stomach pump. A liver abscess which was not due 

 to the usual amebic infection accompanied this case, but whether 

 due directly or indirectly to the myiasis can only be conjectured. 



Fly maggots can usually be expelled readily by means of 

 purges and doses of the drugs which are used for intestinal worms 

 (see p. 237). The chief danger from infection, as in other forms 

 of myiasis, lies in the fact that the presence of the maggots is 

 usually not even suspected until much of their damage has been 

 done. Prevention, of course, consists principally in care as to 



