HOW IS A DIAGNOSIS MADE? 



A presumptive diagnosis is often made based on a combination of the paralysis observed 

 in sick birds, and the absence of obvious gross lesions of disease in internal organs and 

 tissues of sick or dead birds. However, this initial diagnosis must be confirmed by the 

 mouse-protection test to separate avian botulism from other types of poisoning. 



In this test, blood is collected from a sick or freshly dead bird and the serum fraction is 

 injected into two groups of laboratory mice. One of the groups was previously given an- 

 titoxin. If botulinum toxin is present in the blood, unprotected mice will become sick or die, 

 while the group receiving antitoxin will survive. 



WHAT CAUSES AVIAN BOTULISM EPIDEMICS? 



Environmental Conditions 



Avian botulism is most likely to occur in the presence of high air temperatures, fluc- 

 tuating water levels, and a suitable medium for bacterial growth, such as vertebrate and 

 invertebrate carcasses near bird concentrations. The botulism bacteria are widely 

 distributed in organic soils. They persist, in nature, in a spore form that is resistant to 

 adverse environmental conditions such as drying and low air temperatures. Development of 

 these spores requires complete absence of oxygen, temperatures ranging from 60 to' 97 F, a 

 source of animal protein, and a pH ranging from 5.7 to 8.0. 



LO 



