CHAPTER XX 



Louse Borne Diseases ^ 

 W. Dwight Pierce 



The parasitic lice belong to two closely related orders, the Anoplura 

 or Siphunculata, commonly called sucking lice or vermin, and the Mal- 

 lophaga, called biting lice, differing principally by the formation of the 

 mouth parts. The sucking lice are parasitic principally on mammals, 

 and the biting lice on birds, but some of the latter also attack mammals. 

 They are more or less definitely limited according to their species to 

 definite species or genera of animal hosts. All cause great annoyance and 

 worry and probably by their attack frequently cause death of the host, 

 especially young hosts. 



We are especially concerned with the sucking lice in this lecture, 

 but will include a few notes on the biting lice. Some of the most serious 

 diseases of man, especially when congested in crowded populations or in 

 armies, are caused or carried by lice. Probably many fatalities among 

 wild animals and birds are due to inoculable diseases carried by lice, which 

 have never been investigated. 



I. DIRECT EFFECT OF LOUSE ATTACK 



The attack of lice on the body is in itself exceedingly annoying and 

 leads to a great deal of itching and scratching. The attack by the 

 various species of lice is differentiated by terms applicable to each. The 

 attack by the body louse, Pediculus corporis DeGeer, or as it is known 

 by Nuttall (1917), Pediculus humanus var. corporis, is known as pedic- 

 ulosis CORPORIS. The attack by the head louse, Pediculus humanus 

 Linnaeus, commonly known as capitis DeGeer is called pediculosis 

 CAPITIS. Attack by the pubic louse, Phthirus pubis Linnaeus, is known 



as PHTHIRIASIS. 



1. Types of Pediculosis Corporis 



Nuttall (1917) has described a considerable number of recorded t3'pes 



of dermatitis caused by louse attack. 



^A lecture on this subject was delivered June 3, 1918, and distributed in mimeo- 

 graphed form, but on accoimt of the great change in the subject since then, the present 

 lecture is practically rewritten. 



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