THE FLIES THAT CAUSE MYIASIS IN MAN 11 



the soft and hard palate may be pierced, the pharynx may be eaten 

 away to the bone, and even the hyoid bone may be destroyed. 



The second type, known as thim'ni or tamne in North Africa, where 

 it is most abundant, is discussed under Oestrus ovis, its etiological 

 agent. 



AURAL MYIASIS 



Myiasis of the ears is often associated with that of the nose and 

 mouth, with the same etiology. Maggots infesting the accessory 

 sinuses of the nose may easily invade the ear either externally or 

 through the Eustachian tubes. In at least one known case, a maggot, 

 entering the ear through the tubal route, produced an abscess which, 

 with the weakened condition of the patient following the expulsion of 

 the larvae from his nose and sinuses, brought about his death. Some- 

 times, however, aural myiasis may develop independently. In such 

 cases the fly involved is usually a semispecific or accidental myiasis 

 producer, and the invasion is secondary to some pathogenic condition. 

 In one case cited by Onorato (96) , maggots of Phaenicia serieata were 

 taken from an otherwise healthy ear; such an infestation had pre- 

 viously been considered impossible because of the deterrent effect of 

 the eai wax. 



The symptoms of auricular myiasis are pain or discomfort accom- 

 panied by deafness and a ringing in the ear if the maggots are in the 

 external meatus, and a bloody purulent discharge if they have entered 

 the middle ear. Obviously, severe cases of aural myiasis, particularly 

 those in which primary invaders are involved, may, if not treated in 

 time, result in the loss of the organ affected. 



OCULAR MYIASIS 



Myiasis of the eye and surrounding tissue may, like that of the ear, 

 be concomitant with that of the nose and accessory sinuses, and with 

 the same etiology. The destructive action of larvae of Wohlfahrtia 

 magnified, Chrysomya vezziana, CalUtroga mnericana, and sometimes 

 Phaenicia serieata and other species, may consume the entire organ if 

 unchecked. 



Two other types of myiasis may affect the eye. One type is the pain- 

 ful but otherwise usually not serious form of conjunctivitis caused by 

 the first-stage larvae of Oestrus oris or Bhinoestrus purpureus ; the 

 larva is similar in the two species and is discussed under Oestrus oris. 

 In the other, and more serious type, Hypoderma larvae, in the course 

 of their wanderings through the body, enter the surrounding tissue or 

 the eyeball itself and, particularly if 'they lodge in the posterior cham- 

 ber, may bring about the destruction of the organ. This type is dis- 

 cussed more fully under the heading of Hypoderma. 



In medical literature myiasis of the eye is usually called ophthalmo- 

 myiasis, a term proposed by Hope and later expanded by Behr to in- 

 clude three types, as follows : Ophthalmomyiasis externa* in which the 

 orbit is affected but not the eyeball itself; ophthalmomyiasis interna 

 anterior, to indicate invasion of the anterior chamber'; and opthal- 

 momyiasis interna posterior, to indicate invasion of the posterior 

 chamber. 



