INFECTIONS OF THE NASAL AND AURAL CAVITIES 385 



The larval form of Linguatula rhinaria is a rare parasite of the nasal cavities; 

 it is not infrequent, however, in the nostrils of dogs. 



Various fly larvae are far more common, and the "screw- worm," 

 the larva of the Chrysomyia macellaria, is common in certain parts of 

 tropical America, and may by its burrowing effects cause fatal results. 



The larvae of Sarcophaga have in particular been found in the nasal cavities of 

 children. Myriapods, while of very little importance elsewhere, have been reported 

 more than 30 times from the nasal fossae. 



In a study of the bacteriology of otitis media, in 277 cases, Libman 

 and Celler found streptococci present alone in 81%, Streptococcus 

 mucosus in 10% and the Pneumococcus in 8%; Staphylococcus, B. pyo- 

 cyaneus and B. proteus have also been found. Mixed infections are 

 common. 



Streptococci are the organisms which most often cause sinus thrombosis and brain 

 abscess. The influenza bacillus has been reported as a cause of acute otitis media. 



Nonvirulent diphtheroid bacilli are not infrequently obtained in cultures from 

 ear discharges. 



Other organisms which have been isolated from middle-ear or mastoid discharges 

 are B-. coli, M. catarr kalis, M. tetragenus and Friedlander's bacillus. 



B. typhosus may be found in middle-ear discharges of persons who have had an 

 attack of typhoid fever. 



The middle ear is normally free of bacteria, but in affections of the 

 throat, as with streptococci, pneumococci, and diphtheria bacilli, 

 these organisms may infect it by way of the Eustachian tube. 



The moulds are of greater importance in affections of the external auditory canal 

 than the bacteria. The cerumen seems to make a good culture medium so that 

 various species of Aspergillus, Mucor, etc., develop and close the canal. These 

 infections are often introduced by the patient's finger. Various mites and fly larvae 

 have been reported from the ear. 



The "screw worm," the larva of Chrysomyia macellaria, is the most common 

 cause of aural myiasis in tropical America. The fly deposits its eggs about aural 

 and nasal cavities of those with offensive discharges. The larvae develop and 

 cause intense pain and giddiness. Larvae of Sarcophaga, Calliphora and Anthomyia 

 have also been reported from the external auditory meatus. The tympanic mem- 

 brane may be perforated. 



