62 PROCEEDINGS ENTOMOLOGICAL SOCIETY 



Undoubtedly a great deal more will be learned about different 

 forms of direct attack of insects against man, but it is safe to say 

 that our knowledge of that subject is much more nearly com- 

 plete than on the subject of transmission of disease organisms. 

 We shall mention, however, that the most interesting case of a 

 malady due to direct attack is tick paralysis which is just com- 

 ing to be known. The attachment of a tick causes progressive 

 paralysis ascending from the lower extremities until all parts of 

 the body are involved. A peculiarity is that the motor but not 

 the sensory nerves are involved. The disease evidently occurs 

 in Africa, and Australia as well as in North America. That it 

 is not uncommon is shown by the fact that 13 cases have occurred 

 in the practice of a single physician in Oregon. 1 No virus has 

 been found and the experiments of Hadwen and Nuttall show 

 that it is not infectious. The malady appears to be unique but 

 may be found to be the first representative of a special class of 

 injuries caused by insects. We are aware that Hadwen and 

 Nuttall 2 lean toward the theory of a specific causative organism 

 and this is supported by what appears to be a definite incubation 

 period in the tick. Our reasons for leaning toward the theory 

 of nerve shock are the non-infectiousness of the disorder and the 

 relation of the location of the puncture to the symptoms. At 

 any rate it suggests that we are probably still ignorant of many 

 reactions between man and insects in which the health of the 

 former is involved. 



Omitting tick paralysis for the present we may summarize the 

 more important conditions involved in disease transmission as 

 follows : 



1. Blood sucking. 



2. Domesticity. 



3. Contact with reservoir and accidental contact with man. 



4. Accidental contact with pathogenic organisms, and acci- 

 dental contact with man. 



5. Feeding upon and breeding in body discharges. 



6. Functioning as necessary intermediate hosts for nematode or 

 cestode parasites. 



It is possible that several new groups of diseases in which 

 insects are concerned will be found to exist. In the investigation 

 of beri beri and similar diseases in recent years much has been 

 learned about the effects on the system of the presence of toxins 

 of various kinds, and by the absence of certain so-called vitamines. 



1 Temple, I. U. Medical Sentinel, XV, 507; see also Parasitology, VII, 

 No. 1, 96. 



2 Nuttall, G. H. Parasitology, VI, 299-301; see also Hawden, Para- 

 sitology, VI, 283. 



