New insight into how bovine Eimeria oocysts may survive freezing

Bovine Eimeria parasites survives and thrives well in the Northern hemisphere. But how do they handle sub-zero temperatures during winter months and does it matter if the oocysts of the parasite are sporulated into an infective stage or not?

A new laboratory study of these questions has just been released. It appears that bovine Eimeria species are able to handle sub-zero temperature and even sporulate from a frozen unsporulated stage once thawed. The results indicate there may be differences between Eimeria species to tolerate the changes in temperature.

For experimental purposes the study demonstrated that freezing in an oxidizing sporulation medium (2% K2Cr2O7) significantly reduced the number of oocysts tolerating sub-zero temperatures. Some previous studies that investigated oocysts sub-zero tolerance to temperatures used  an oxidixing sporulation medium as the freezing medium.
 
The study also demonstrated a significant breakdown by microbial activity in fecal samples left at room temperature compared to a sterile solution over a duration of one month. These results indicate that microbial predators of the parasite oocyst may play a significant role in the parasites persistence.  

Link to article (Open Access)
Lassen B, Seppä-Lassila L, 2014. RECOVERY AND SPORULATION OF BOVINE EIMERIA OOCYSTS AFTER EXPOSURE TO SUB-ZERO TEMPERATURE. Vet Med Zoot. T. 66 (88), 35-39.