OF WASHINGTON, VOLUME XVII, 1915 63 



Is it not possible that the presence of insects in considerable 

 numbers in food products may result in the formation of toxins, 

 or at least increase greatly the natural tendency of the products 

 to develop toxins? It is even conceivable that the work of some 

 insect in the food product might result in the destruction, or 

 reduction, of important vitamines. These speculations may be 

 going rather far afield but one recent contribution to our knowl- 

 edge seems to indicate the probability of a new class of maladies 

 caused by insect secretions. Messrs. Seyderhelm, 1 working in 

 Germany, have apparently proven that infectious aenemia of the 

 horse, a widespread and mysterious malady, is caused by toxins 

 secreted by the larvae of the species of Gastrophilus. They made 

 injections of extracts made from the larvae of two species of the 

 genus and reproduced conditions in experimental animals which 

 appear to be identical with those of infectious aenemia. The toxin 

 obtained, which they call oestrin, was found in experiments to be 

 specific for the horse and non-pathogenic for other animals. It 

 was even found that the toxin from Gastrophilus hemorrhoidalis 

 is much more active than that obtained from Gastrophilus egui. 

 The probability of the existence of a definite toxin was proven by 

 numerous tests with chemicals and cultural methods which did 

 not reveal any of the indications of plant or animal organisms 

 which might be the cause of the reactions following the injec- 

 tions. These investigators went so far as apparently to cause 

 the disease in susceptible animals through the agency of blood 

 extracted from animals in which the disease had been induced 

 solely by the injection of the toxin derived from the larva?. 



This phase of the discussion will be ended with a mere refer- 

 ence to the popular belief that the larvae of Chrysomyia are respon- 

 sible, probably through the formation of toxins, for the disease 

 known as limberneck of fowls, and to Doctor Saunders' investi- 

 gations in St. Louis which show various symptoms simulating 

 those of poliomyelitis occuring in animals into the diet of which 

 fly larvae of various kinds have been introduced. 2 Whatever the 

 outcome the work along this line which is now under way will 

 add greatly to our knowledge. 



We propose at this point to make a survey of some of the 

 important diversities which present themselves in the nature 

 and manner of disease transmission by insects. These include 

 pathogenic organisms of widely different groups and striking 

 diversity in the habits and systematic position of the insect 

 vectors. 



1 Seyderhelm, K. R., and R. Seyderhelm. Arch. Exp. Pathol. u. 

 Pharmak., XXVI, 1914, 149. 



2 Saunders, E. \V. Journal St. Louis Medical Association, IX, No. 

 12, 385-389. 



