Improvised temporary laboratory for study of encephalitis at Chincoteaguc Wildlife Refuge. The isolated refuge 

 area was ideal for the virus transmission study because of the presence of wild ponies, a large bird population, 

 and the known occurrence of the virus in the area. (Photo by Patuxent Wildlife Research Center.) 



raccoons have been shown to be carriers 

 in other areas, but no other hosts have been 

 detected in studies at Patuxent. 



Continued observations were made at the 

 Bear River Migratory Bird Refuge, Utah, 

 on the relationship of botulism outbreaks 

 and populations of bottom-dwelling macro- 

 invertebrates. The first sick and dead birds 

 w^re observed in mid-July, following a 

 gradual decline in numbers of tendipedid 

 larvae. A peak in bird losses was reached 

 at the end of August and another peak during 



the latter part of September following 

 localized die-offs of aquatic invertebrates. 

 In the course of an attempt to induce ex- 

 perimentally a small-scale botulism out- 

 break by the use of insecticide on the in- 

 vertebrates assumed to produce the toxins, 

 the potentially useful observation was made 

 that malathion inhibits the growth of 

 Clostridium botulinum type C in the test 

 tube. Further controlled studies are anti- 

 cipated to determine the concentration of 

 malathion required to inhibit bacterial 

 growth in naturally occurring media. 



22 



