New article: Systemic acute phase proteins response in calves experimentally infected with Eimeria zuernii

Abstract
Acute phase proteins (APPs) have been demonstrated to be useful in evaluating general health stress and diseases in cattle. Serum amyloid A (SAA) and haptoglobin (Hp) are APPs that are produced during inflammation, and likely play a role in host immunological defence against Eimeria infection and the associated intestinal tissue damage. We investigated the involvement of SAA and HP in an experimental study, including three groups of calves: a control group (group 0, n=11), and two groups infected with either 150,000 or 250,000 Eimeria zuernii oocysts (group 1 (n=11) and group 2 (n=12), respectively). The calves were monitored for 28 days and data was collected on oocyst excretion, faecal score, animal weight, and SAA and Hp serum concentrations. Generalized linear mixed models showed that the clinical symptoms, indicated by an increase in the number of oocysts in the faeces and severe diarrhoea, manifested at patency for group 1 and 2. Serum Hp and SAA levels also increased during this period. Hp appeared to be a more sensitive marker than SAA, and differences between groups 1 and 2 were observed only for Hp. Linear regression models showed a negative association between weight gain and Hp concentrations, calculated as the area under the curve (AUC) during the overall experimental period and the patency period. A similar result was seen for SAA only during the patency period. This result supports the assumption that reduced weight gain due to E. zuernii infection is an immunologically driven process that involves an increase in APPs. A random intercept regression model of oocyst shedding groups showed that calves shedding 1-500 oocysts had reduced concentrations of Hp, indicating that a different immunological reaction occurs during mild shedding of E. zuernii oocysts than during more intensive shedding. A similar model was used to examine associations between faecal scores and Hp concentrations for each group. Group 2 calves with haemorrhagic diarrhoea displayed higher Hp levels than calves in that group with lower faecal scores, which may be in response to an increased demand for Hp in the repair process as a result of haemolysis. APPs seem to play an important role in determining the course of E. zuernii infection in calves, which may enhance our understanding of the immunological reaction and development of this disease.

Full article: 
Lassen B, Bangoura B, Lepik T, Orro T. Systemic acute phase proteins response in calves experimentally infected with Eimeria zuernii. Vet Parasitol. 2015 Sep 15;212(3-4):140-6. doi: 10.1016/j.vetpar.2015.06.024. Epub 2015 Jul 8.

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 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.

Cost of Eimeria infections and benefits of control in Estonian dairy herds

It is recognized that coccidia, especially Eimeria, is the cause of weight loss and mortalities in calves world wide.

In Estonia few efforts are made to control the infection and the situation has basically been unchanged for decades (Lassen et al. 2009).



Image: Calves infected with Eimeria bovis; left untreated and to the right treated. Source: Daniel et al. Better herd health. Implants decrease severity of disease response in cattle. Highlights of Agricultural Research. 2000; Vol 47, No. 3. 

Without proper tools and data, it is difficult to convince farmers and veterinary practitioners that a situation that has persisted as long as the memory can be changed to the benefit of animals and the farmers production.

Scientifically it is a challenge to create a holistic picture of a problem due to the long study period needed to monitor the animal and the many factors to control. For this reason the cost of coccidia infections and the benefits of control remains an estimate.

One of the most recognized estimates is by Fitzgerald (1980) who estimated that Eimeria at the time on a global scale cost 723 US$/year in lost earnings, or as a rule of thumb: 1 US$/calf/year. Adjusting the value to inflation this would amount to around 1,600 US$/year today. However, this estimate was based on current understanding of weight losses of calves infected with pathogenic Eimeria, mortalities, and assumptions on treatments with related costs. Doing so it only calculated calf-associated expenses, and not the long term effects or considering the management choices and herd dynamics throughout the life of the cattle.

In the summary presented here are based on the results from the article by Lassen and Østergaard (2012) where we present the outcome of simulating the effects of Eimeria on a herd of 100 animals over 10 years. The model (SimHerd v4) is a dynamic model that takes changes into account on weekly basis, has been designed using experimental data and an extensive understanding of management dynamics. In addition prices and expenses are part of the simulation so that also a balanced financial outcome of changes can be estimated.

Our experiment included a raised mortality in the scenario containing an endemic infection of Eimeria in the herd and a slower weight gain of the animals. As a result of slower weight gains a delay in reaching a weight suitable for the first insemination of cattle was adjusted in the model setup.

Results showed that mortality of calves had little impact on the production as a whole while slower weight gains showed to be an expensive additional expense in extra food requirements to fatten the cows. The delay in the first insemination had the largest impact and caused losses due to delay in entering the production.

Compared to a hypothetical parasite free herd, the best estimate of Estonian conditions made an annual 8% negative balance of the balanced income of the farmer.

In addition the study tried to estimate the benefits of prevention and control.

Timely supportive treatment and isolation of infected animals showing symptoms of coccidiosis increases the calves chances of survival dramatically. This was included in the model scenarios. Treating preventally with anti-coccidials would lower the infection pressure in the herd, but not remove the parasite. It was thus estimated that prevention would be equal to a lower infection pressure with less impact on weights and mortalities. Good hygiene measures may achieve similar effects.

Cost-benefit of treating with anti-coccidial drugs was very small if only considering the value of a calf. This may also be why this option is not favoured. However, when considering the effects over time and for the herd, the economic benefits was substantial.  


READ MORE IN THE ARTICLE:
Lassen, B., Østergaard, S. Estimation of the economical effects of Eimeria infections in Estoniandairy herds using a stochastic model. Preventive Veterinary Medicine 106 (2012) 258–265.