New article: Seasonal recovery of Eimeria oocysts from soil on naturally contaminated pastures

Abstract
Though Eimeria is an important parasite of cattle, research is lacking on how the parasite persist in the pasture soils. In this study, feces samples were collected from three pastures in June and October 2010 and soil samples in April 2011. Coordinates of sampling locations were recorded with Global Positioning System together with information about grass cover, shade, and elevation. All soil samples were collected from the same locations as the fecal samples and used in model evaluating the possible factors influencing the concentration of oocysts in the soil. Feces and soil samples were investigated using a quantitative flotation technique. Eimeria oocysts were found in 95.6% of fecal samples collected in summer and 84.5% of samples in fall. In contrast, the same locations soil samples were positive for Eimeria oocysts in 37.3% (summer) and 44.3% (fall). Despite larger numbers of oocysts in fecal samples shed during summer compared to fall, there was no difference in the concentration of oocysts in soil samples the following spring. The odds of higher numbers of oocysts in soil samples in spring were higher if fecal samples collected in summer were in shade or if containing Eimeria alabamensis during the fall. Factors other than the concentrations of oocysts shed in feces appear to affect whether oocysts persist between grazing seasons.

Full article: 
Lassen B, Lepik T, Järvis T. Seasonal recovery of Eimeria oocysts from soil on naturally contaminated pastures. Parasitol Res. 2014 Mar;113(3):993-9. doi: 10.1007/s00436-013-3731-6. Epub 2013 Dec 12.

New article: Persistence of Eimeria bovis in soil

Abstract
Eimeriosis is a disease that occurs globally and often affects cattle grazing on pastures contaminated with oocysts of the pathogenic species Eimeria bovis, Eimeria zuernii or Eimeria alabamensis, respectively. Nonetheless, little is understood regarding oocyst persistence on the pasture. The study was performed in the temperate climate zone. Soil samples were spiked with 100,000 E. bovis oocysts in July 2010 or with 50,000 oocysts in October 2010, respectively, both either with our without addition of cattle faeces. The soil samples were exposed to natural environmental conditions until April 2011. A subset of the samples was analysed immediately after spiking as positive control. The oocysts were recovered by a flotation method and counted in a reading chamber. On average, 23 % of the oocysts could be recovered from the positive control. The recovery of oocysts dropped to 0.30 % of the original level in the samples prepared in July independent of the addition of faeces, whereas the oocyst count was higher in the samples prepared in October, both without (2.05 %) and with (2.64 %) faecal material. No differences were observed between presence of oocysts or oocyst counts recovered in the presence or absence of faeces. Presence of faeces had a positive influence on oocyst integrity. During the winter season, the number of oocysts in the soil was lowered under the detection limit in most samples. On the other hand, the comparatively short 3-month summer period had a significant influence on the number of persisting oocysts too.

Full article: 
Lassen B, Lepik T, Bangoura B. Persistence of Eimeria bovis in soil. Parasitol Res. 2013 Jul;112(7):2481-6. doi: 10.1007/s00436-013-3413-4. Epub 2013 Apr 7.

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.