Calf scours are one of the most widespread diseases affecting cattle livestock enterprises in both the beef and dairy industries. Cryptosporidium occurs in approximately 30-50% of diarrheal calves worldwide. Because of its substantial economic impact on farms and given the difficulties around preventing the spread of the zoonotic agents, control of cryptosporidiosis remains a major challenge.
Cryptosporidium is transmitted via the fecal-oral route. The low infectious dose of directly infective oocysts and the prolonged survival in moist environments explain the difficulty of eradication when the parasite is established on a farm.
Trial description
A trial was conducted on a German dairy farm with a confirmed history of cryptosporidiosis induced diarrhea in calves. The farm milks 2,500 animals housed on a partly slatted floor with active ventilation and no additional thermoregulation.
The diarrhea occurrence with a confirmed presence of oocysts was determined at the start of the trial. The diagnosis was made through fecal analysis by rapid on-farm tests based on immunochromatography (Huve-Check®).
60 Holstein Friesian calves (4 - 15 days of age) were included in this blind study. Animals were randomly assigned to two groups, one treated and one untreated. After treatment allocation, animals were kept and maintained individually throughout the trial. Different personnel were used for the clinical and laboratory examinations and the administration of treatments. All farm staff involved in the study were not aware of the treatment allocations.
In the treated group, the animals received an oral dose of Paromomycin 20% oral solution (Parofor® Crypto) using a 20ml syringe. The administered dosage was 50mg/kg/day for seven consecutive days.
The animals allocated to the control group received no treatment. All animals in the experiment were monitored for a period of 21 days. Fecal scoring and the presence of Cryptosporidium oocysts in the feces were measured.
The fecal score was recorded daily from day 0 to day 7. The consistency of individual fecal samples was scored using the following system:
Fecal scores of 2 and above were considered diarrheic.
To assess the presence of oocysts, fecal samples were collected daily for the first seven days, and three times per week for the following two weeks. The samples were analyzed using a modified McMaster method (Bellosa et al., 2011).
Results
The primary efficacy criteria used to assess the protocol of treatment was the incidence of diarrhea associated with cryptosporidiosis up to day 7. The other criteria analyzed indicated the severity of diarrhea and the number of oocysts excreted.
Figure 1. Incidence of diarrhea (%)
For both the incidence (Figure 1) and the severity of the diarrhea (Figure 2), the difference between the treated and untreated group was statistically significant (Wilcoxon MW test) in favour of the Parofor® Crypto group.
Figure 2. Mean severity (sum of scores)
For day 0-7 and over the whole duration of the trial there was a statistically significant reduction in the oocyst count in the treated group compared to the control group (P < 0.001).
Figure 3. Reduction in the number of excreted oocysts per gram of feces over time
Conclusion
Parofor® Crypto administered orally at a dosage of 50 mg paromomycin sulphate/kg body weight for seven days demonstrated safe and efficacious control of cryptosporidiosis.
Bellosa, M.L., Nydam, D.V., Liotta, J.L., Zambriski, J.A., Linden, T.C. and Bowman, D.D. 2011. A comparison of fecal percent dry matter and number of Cryptosporidium parvum oocysts shed to observational fecal consistency scoring in dairy calves. Journal of Parisitology, 97. 349-351.