Efficacy of various anticoccidials against experimental porcine neonatal isosporosis

The efficacies of 20 mg/kg body weight (BW) of toltrazuril (Toltra) 2 days post-infection (dpi), 2 mg/kg BW of diclazuril 2 and 3 dpi and 200 mg/kg BW of sulphadimidine 2, 3 and 4 dpi were compared in a model for piglet isosporosis. Weight gain (first 4 weeks of life) and diarrhoea and oocyst excretion from 4 to 11 dpi were evaluated (10-12 piglets/group). Additionally, animals were killed and examined for pathohistological changes of the small intestines 5, 7, 11 and 14 dpi (n = 3 per group and time point) and lengths of the intestinal villi. Diarrhoea (semi-liquid or liquid faeces) was seen from 5 dpi in all groups except Toltra, and the differences in prevalence and intensity of diarrhoea were statistically significant (p < 0.05) between Toltra and the other groups, which were similar (trial 1). Oocyst excretion was greatly reduced in the Toltra group, which was also statistically significant for the mean and median excretion rates and the percentage of excreting piglets between Toltra and the other groups (p < 0.05). Weight gain was highest in Toltra (p < 0.05). Histopathology revealed mostly villous necrosis and atrophy in the small intestines except the duodenum, which peaked at 7 dpi, in all groups except Toltra. Between 5 and 11 dpi, the Toltra group had significantly longer villi than the other groups. Reduced weight gain and diarrhoea caused by Isospora suis was controlled by a single application of Toltra in the pre-patent period, while neither diclazuril nor sulphadimidine improved the clinical picture of isosporosis.

Autofluorescence microscopy for the detection of nematode eggs and protozoa, in particular Isospora suis, in swine faeces

Parasites from swine faeces were examined for autofluorescence. Oocysts of Eimeria polita, E. scabra and Isospora suis, cysts of Balantidium coli and eggs of Oesophagostomum dentatum, Strongyloides ransomi and Trichuris suis (but not those of Ascaris suum) emitted light after excitation with UV light. I. suis oocyst counts in McMaster chambers utilising autofluorescence were compared to those from conventional bright field microscopy. Similarly, faecal smears containing I. suis were examined using the same techniques. Autofluorescence was superior to bright field microscopy in detecting oocysts after flotation and was highly significantly more sensitive when direct smears were examined.

Toltrazuril treatment of cystoisosporosis in dogs under experimental and field conditions

Coccidia of the genus Cystoisospora cause mild to severe diarrhoea in dogs. The effects of toltrazuril treatment on cystoisosporosis were studied under experimental and field conditions. Twenty-four puppies were experimentally infected each with 4 x 10(4) oocysts of the Cystoisospora ohioensis group. Three groups of six puppies were treated 3 dpi with 10, 20 or 30 mg/kg body weight of toltrazuril suspension (5%); the remaining six puppies served as non-treated controls. Toltrazuril suspension or microgranulate were given once in a dose of 10 or 20 mg/kg body weight, respectively, to naturally infected puppies in conventional dog breeding facilities, depending on the coproscopical evidence of infection. Oocyst excretion and clinical data were recorded. Under experimental conditions, the non-treated puppies excreted oocysts beginning at 6 dpi and suffered from catarrhalic to haemorrhagic diarrhoea. On 12 dpi, four of six non-treated puppies died. Irrespective of the dose, toltrazuril treatment totally suppressed oocyst excretion and no diarrhoea or other signs of disease were observed in the treated groups. Natural Cystoisospora infections were regularly found during the 3rd or 4th week of age in dog breeding facilities although not always associated with diarrhoea. A single oral application of toltrazuril abrogated oocyst shedding and the treated puppies remained generally coproscopically negative during the following 2-4 weeks. Cystoisospora is pathogenic for puppies and can induce severe disease. Natural infections are common in conventional dog breeding facilities. Toltrazuril treatment is suitable for controlling cystoisosporosis under experimental and field conditions. A single oral treatment for puppies in the 3rd or 4th week of age is recommended.

[Sulfonamide and toltrazuril therapy of experimental turkey coccidiosis]

Following experimental infection of caged turkeys with a mixed oocyst suspension of E. meleagrimitis, E. adenoeides and E. gallopavonis, the efficacy of sulfachlorpyrazine, sulfaquinoxaline + pyrimethamine, sulfaquinoxaline + diaveridine, and toltrazuril was investigated based on clinical and parasitological parameters. Infected turkeys developed severe clinical symptoms. Only weak symptoms were observed in those groups which were treated with the sulfa- and sulfa-DHFR-inhibitors. The toltrazuril-treated group remained free of clinical symptoms. At the 8th day after infection, the clinical lesions coincided with the intensity of the gut lesions together with parasitological findings based on microscopical examination of mucosal smears. The same coincidence was observed for parameters such as oocyst excretion and body weight development.

[Use of toltrazuril in pullet breeding flocks raised on floors with anticoccidial-free feed]

In 28 replacement pullet flocks with flock size of 4,000 to 25,000 birds Toltrazuril (experimental preparation, 2.5% solution, approx. 7 mg/kg body weight) was administered for a period of two days in the drinking water for metaphylactic purpose and therapeutic use, respectively. All flocks were reared without anticoccidial feed additives. Exposition to Eimeria spp. was recorded by examination of faecal samples and intestinal scrapings. Clinical flock control was achieved by vets at eight to ten day intervals. Toltrazuril was characterized by short application period, rapid mode of action, significant reduction of oocyst shedding, good compatibility and acceptance thus proving superior to conventional chemotherapy of coccidiosis. The results suggest that, even without administration of anticoccidial feed additives. Toltrazuril is an effective agent for therapeutic use in acute coccidiosis. Under insufficient management and rearing conditions repeated metaphylactic application has to be considered.