Effect of nitazoxanide on cryptosporidiosis in experimentally infected neonatal dairy calves.
Cryptosporidium is a zoonotic protozoan that is most often diagnosed in association with diarrhea in 1- to 3-wk-old dairy calves. There are neither consistently effective nor approved antimicrobial drugs for treatment in animals. The objective of this study was to test nitazoxanide (NTZ) as a treatment for cryptosporidiosis in experimentally infected dairy calves. A randomized, controlled, and blinded trial was performed using Holstein bull calves obtained from a large commercial dairy. All births were attended by study personnel and calves were fed 4 L of heat-treated colostrum within 1 h of birth. Calves were randomly assigned to treatment or placebo group and maintained for a 32-feeding (16 d) study period. Twenty-three calves were enrolled with 3 lost to follow up. Thirteen calves were assigned to the treatment group and 7 calves to the placebo group. All calves were inoculated with 1 x 10(6) viable Cryptosporidium parvum oocysts at feeding 3. Treatment was a commercially available NTZ product and the placebo was the carrier of the same product. Nitazoxanide was administered at 1.5 g twice per day for 5 d. Nitazoxanide or placebo treatment began after feeding 10 and when the fecal score was greater than 1 out of 3. Outcome measurements included twice-daily fecal and health scores and a once-daily oocyst count by an immunofluorescent antibody assay. Data were analyzed by nonparametric and time-to-event methods. Measures of passive transfer of antibodies, initial body weight, and onset of oocyst shedding were not different between treatment and control calves. Eighty-five percent of the NTZ-treated calves stopped shedding oocysts by the end of the observation period whereas only 15% of the placebo group stopped shedding. The median number of feedings with a fecal score equal to 3 was 2 in the NTZ group while it was 6 in the placebo group. Calves receiving NTZ were 0.13 times as likely to have severe and sustained diarrhea than control calves (95% confidence interval, 0.02-0.98). Treating calves with NTZ reduced the duration of oocyst shedding and improved fecal consistency.
Ollivett
T L
TL
Department of Clinical Sciences, Box 20, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
Nydam
D V
DV
Bowman
D D
DD
Zambriski
J A
JA
Bellosa
M L
ML
Linden
T C
TC
Divers
T J
TJ
D000818:Animals; D000831:Animals, Newborn; D000977:Antiparasitic Agents / Q000627:therapeutic use*; D002417:Cattle; D002418:Cattle Diseases / Q000188:drug therapy* / Q000469:parasitology; D003457:Cryptosporidiosis / Q000188:drug therapy / Q000662:veterinary*; D003612:Dairying; D005243:Feces / Q000469:parasitology; D053208:Kaplan-Meier Estimate; D008297:Male; D009574:Nitro Compounds; D033661:Oocysts / Q000502:physiology; D013844:Thiazoles / Q000627:therapeutic use*
D000977:Antiparasitic Agents; D009574:Nitro Compounds; D013844:Thiazoles; C041747:nitazoxanide