50 MISC. PUBLICATION 6 31, U. S. DEPT. OF AGRICULTURE 



beria. Gold Coast, Nigeria, Cameroun, Anglo-Egyptian Sudan, Eritrea, Italian 

 Somaliland, Socotra, East Africa, Belgian Congo, Angola, Uganda, Kenya, Tan- 

 ganyika, Nyasaland, Southern Rhodesia, Natal, South Africa, Seychelles Islands, 

 Mauritius, Admirantes Islands, Cargados Islands, Rodriguez Island. Australian 

 Region : Introduced into New South Wales and Hawaii. Almost world-wide ; 

 apparently absent from the Oriental and much of the Australian Regions, and 

 from the cooler parts of the world ; rare in England and Denmark. 



Biology and Pathogenesis. — Larvae are deposited on carrion, ex- 

 crement, tainted meats, and other suitable breeding media. The dura- 

 tion of the immature stages varies considerably according to climate 

 and locality. The larvae are usually scavengers, although they may 

 become facultative parasites either in wounds or in the digestive tracts 

 of mammals. 



Occasionally the maggots of this fly invade wounds or diseased 

 body openings, and pass from diseased to healthy tissue. The larvae 

 are voracious, and upon invasion may produce deep and serious 

 lesions. Onorato (96) records two cases of wound myiasis in Tripoli- 

 tania, in one of which the larvae had entered healthy tissue and caused 

 considerable pain. In a third case, in a middle-aged woman, entrance 

 had been made through a carcinoma of the uterus, thereby further 

 damaging that organ and causing abdominal pains, bloody discharges, 

 and difficulties of urination ; 132 larvae were removed, some of which 

 were detected only through the use of the cystoscope. Kingscot[t]e 

 (69, p. 63) reports a secondary infestation by this species of a lesion in 

 a mink made by Wohlfahrtia vigil, from which 75 larvae were taken. 

 In Mauritius this species is said to be responsible for a distinct, though 

 small, percentage of the cases of wound myiasis in cattle. 



There is considerable evidence to show that at least most of the 

 authentic cases of gastrointestinal infestation involving Sareophaga 

 are due to this species. Larvae are presumably ingested with contam- 

 inated food. A detailed account of three cases — a mother and two 

 children — with repeated attacks occurring over a period of 6 years, is 

 given by Haseman (56). Contamination probably came from cold 

 foods that had been left exposed to the air during the summer months. 

 The reported symptoms consisted, first, of the sensation of rolling 

 movements in the region of the base of the stomach or transverse colon, 

 probably a result of movements of masses of the larvae; this was 

 followed by griping pains in the abdomen, some fever, sometimes 

 nausea, and, in the case of the mother, much nervousness and at times 

 spasms. Severe attacks were followed by the passings of the maggots 

 in all stages of development and in quantities sometimes amounting 

 to a cupful. 



Other cases have been reported by various authors. Recently Bryan 

 (21), in reporting a case of 2 years' duration, suggested that the mag- 

 gots might be reproducing within the digestive tract by paedogenesis. 



According to Townsend (153, pt. VI, p. 7 If) this is the only species 

 of Sareophaga known to be capable of completing its development in 

 the human intestine. Keilin (65) suggests that it feeds on partially 

 digested and decomposed food in the intestine rather than being truly 

 parasitic. However, Bryan's examination of the colon wall of his 

 patient by means of a sigmoidoscope showed the entire surface covered 

 with ulcers, and an autopsy on a dog suffering from parasitism by this 

 fly showed the intestinal wall considerably damaged. The parasite 

 therefore seems capable of causing considerable injury. 



