388 Microbes and You 



in stockyards, slaughterhouses, or dairies are particularly prone to 

 infection with Coxiella burnetii. Coxiellae were named for Herald 

 R. Cox who first described the organism in guinea pigs inoculated 

 with infected ticks collected in Montana. F. M. Burnet discovered 

 the microbes in Australia. 



Several species of ticks have been found to harbor coxiellae, but 

 the exact mode of transmission to man is not clear. There is even 

 some evidence that persons who drink raw milk might contract 

 "Q" fever, and man-to-man transmission by way of the respiratory 

 tract has been suggested by others. Coxiellae are capable of pass- 

 ing through bacterial filters which hold back other microorganisms 

 classified as rickettsiae. 



HEARTWATER DISEASE 

 The third sfenus listed under the family Rickettsiaceae is 



o 



Cowdria, and the species name is ruminantium. They are small, 

 pleomorphic, spherical or rod-shaped organisms found intracellu- 

 larly in infected ticks. Once the ruminants are infected with these 

 microbes, fluids accumulate in the sac around the heart (pericardial 

 sac) of the animals, and the mortality rate is high. Cowdria 

 differs morphologically from rickettsiae in being spherical and 

 elliptical. 



TRENCH FEVER 



This was apparently a new disease first recognized during 

 World War I. There is still enough remaining to be learned about 

 the etiological organisms causing trench fever to warrant their 

 being placed in an appendix to the regular classification schemes 

 until such time as they can be properly classified. The organisms 

 are slightly larger than those found in typhus fever, and they have 

 been designated Rickettsia quintana. 



These rickettsiae resist a moist temperature of 60° C. for thirty 

 minutes and dry heat at 80° C. for twenty minutes. Drving in 

 sunlight for at least four months has not inactivated them. Lice 

 allowed to feed on trench fever patients have been found harboring 

 the microorganisms, and the habitat appears to be the lining of the 



