Filaria loa 4'3 



swellings in a series of four cases. Apparently Ziemann (1905) 

 has been able to demonstrate the embryos in the swellings, as he 

 explains the difficulties attendant upon the demonstration. He 

 seems to think, however, that these swellings are due to 

 F. Persians, which in his opinion is the embryonic F. loa, while 

 F. diurna does not differ from F. Bancrofti. He is in accord 

 with previous authors in holding that F. loa remains mostly hid- 

 den in its wanderings, but causes inflammation in the subdermal 

 connective tissue. Wurtz et Clerc (1905) found in their case 

 of infection with F. loa that a tumefaction was produced on the 

 right cheek when the parasite was wandering about in the region 

 of the eye. They also added the important observation that a 

 pronounced intense eosinophilia was associated with the presence 

 of F. loa in the system. It should be noted that the general 

 symptoms of this case point unmistakably to the presence of a 

 number of parasites and the extreme character of the eosinophilia 

 noted was perhaps due to the multiple infection. 



The view that in some way Calabar swellings are related etio- 

 logically to the parasitism of F. loa rests thus on strong pre- 

 sumptive evidence, and it is timely to consider the theories which 

 have been offered to explain the pathological conditions noted. 

 It is clear, without further discussion, that the mere presence of 

 the parasite as of a foreign body of equal size would not be 

 sufficient to evoke the swellings. It is equally evident that the 

 constant limitation of the worm to the connective tissue, espe- 

 cially in the subdermal region, would throw out of consideration 

 the introduction even occasionally of foreign matter of any sort 

 and limit the problem clearly to the parasite itself and its own 

 activities and products, working upon the normal tissues with 

 which it comes in contact. 



The earliest suggestion made was that of Robertson that to 

 the migrations of the Loa are due these swellings which are asso- 

 ciates with its presence. Careful study of the data recorded in 

 connection with the various cases seems to show, however, that 

 mere movement can not be the exciting cause. Note first that 

 the swellings are local and infrequent ; now mere migrations, if 

 effective, ought to produce linear tumefactions conforming to 



313 



