MYIASIS 



!27 



Mode of infection. 



The larvai of flies of the genus Fannia inhabit excrement and 

 decaying- vegetable products, and the females are attracted to 

 such substances in order to lay their eggs. These facts render 

 several modes of infection possible. 



The eggs or young larvai may be ingested with decaying fruit, 

 vegetables, or other food eaten in a raw state, or the flies, which 

 often deposit their eggs in the old-style privies, may deposit their 

 eggs in or near the anus of persons using them (see Nicholson, 

 1910). In the same way babies left exposed in an uncleanly 

 condition may become infected. The larvae on hatching make 

 their way into the rectum, and perhaps penetrate into the 

 intestine. 



Symptoms. 



In some cases symptoms are marked as in the case described 

 by Jenyns (1839) • 



" The patient in the case in question, to which reference has frequently Ijeen made 

 in papers on the subject of myiasis, was an elderly clergyman living near Cambridge, 

 whose symptoms prior to the appearance of the larvae were ' general weakness, loss 

 of appetite, and a disagreeable sensation about the epigastrium, which he described as 

 a tremulous motion.' These symptoms commenced in the spring of 1836, and it was 

 not till the summer and autumn of that year that the larvoe were observed in the 

 motions. They then passed off in very large quantities on different occasions, the 

 discharge continuing at intervals for several months. According to the patient's own 

 statement, the chamber-vessel was sometimes half-full of these animals ; at other times 

 they were mixed with the stools. He thinks that altogether the quantity evacuated 

 must have amounted to several quarts. The larvae were nearly all of equal size, and, 

 when first passed, quite alive, moving with great activity." 



Austen (19 12), who quotes this case, considers from the 

 description given that the larvae were those of F. scalaris. 



Cattle (1906)^ reports the case of a man, who had not been 

 feeling well and complained of abdominal discomfort, who passed 

 these larvai for some months, and McCampbell and Cooper (1909) 

 in America record a case in which a woman with gastric trouble 

 passed larvae in large quantities at intervals for seven years. 



^ Cattle considered the larva; to be 'bots,' but Austen (1912, p. 12), from a 

 consideration of his figure, thinks that they were the larvte of F. scalaris. 



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