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 20 ml syringe. The administered dose was 50 mg/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:
- 0 for normal feces
- 1 for pasty feces
- 2 for liquid feces
- 3 for liquid feces containing blood
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 pere 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.
- Reduction in incidence and severity 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.
- Reduction in the number of oocysts per gram of feces
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).
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.
References are available on request.
