H.Navetat, rue du général de Gaulle,03130 Le Donjon,France
A.Richard, Alpharma Silic 411 —91347 Verrières le Buisson cedex, France, email: firstname.lastname@example.org
F.Cantaloube, av du 8 mai 1945, 12200 Villefranche de Rouergue, France
Cryptosporidiosis causes severe diarrhea in new born ruminants.
Decoquinate is a non antibiotic synthetic molecule, active on certain protozoa : coccidia,toxoplasma cryptosporidia, Neospora.
Considering the practical difficulty of treating calves in a suckling herd, the treatment of cows was undertaken over a period of 7 years on more than 10,000 cows. The animals received a medicated feed supplying 1.25 mg decoquinate / kg bodyweight / day for 30 days prior to calving and for 8 days following it, in order to reduce oocyst shedding in cows and thereby contamination of the environment.
Using this treatment over 7 consecutive years on more than a total 10,000 cows prevented the occurrence of cryptosporidiosis in calves. An identical protocol was also successfully tested in ewes.
In veals, decoquinate at the rate of 2.5 mg/ kg/day for 15 days diminished diarrhea and improved growth.
Cryptosporidiosis is a parasitic disease in humans and animals, spread world-wide, due to a protozoa of the genus Cryptosporidium. Infection with Cryptosporidium parvum causes severe diarrhea in ruminant neonates, calves and kids particularly, the infection rate normally at 40 to 50 %, may rise to 100 % at the end of calving and lambing periods when the contamination of the environment is high.
Decoquinate is a non-antibiotic synthetic molecule, active on certain protozoa : coccidia (Mage and al,
2001 ,Jurjanz and all 1997 : calves:0,5 mg/kg BW ; lambs : 1 mg), cryptosporidia, (Naciri et al, 1998 :young goat :2,5 mg/kg BW), toxoplasma,(Buxton and al, 1996 : 2 mg / kg BW), Neospora (Lindsay and al,1997,Journel 2001 : 2mg /kg BW)
Decoquinate has been recently classified in Annexe II of the EU regulation 2377/90 regarding MRL. Its means no MRL are requested for decoquinate, therefore no withdraval period is necessary for bovine and ovine tissues.
Decoquinate is also approved in EU as feed additive- coccidiostat for the prevention of coccidiosis in broilers (20-40 ppm).
Our field trials were based on the efficacy of decoquinate showed by R.Mancassola, A.Richard, M.Naciri in the treatment of experimental cryptosporidiosis in kids which is summed up in the first paragraph.
I - EVALUATION OF DECOQUINATE TO TREAT EXPERIMENTAL
CRYPTOSPORIDIOSIS IN KIDS
The purpose of this trial was to evaluate the effects of decoquinate at 2.5 mg / kg / day for 21 days to prevent an experimental cryptosporidiosis in kids. Twenty 1-day-old male kids (French Alpin), fed initially goat colostrum heated 1h at 56°C and fed twice daily with non-medicated milk replacer, were assigned into 2 groups. Kids of both groups were orally inoculated with 106 Cryptosporidium parvum (D.0 = inoculation day). Group A kids were kept as non-medicated controls and group B kids were orally medicated with 2.5 mg / kg /day of decoquinate (Deccox L, Rhône Poulenc Animal Nutrition) for 21 days from D.-3 to D.17. The studied criteria were body weight gain, oocyst shedding and specific anti-C. parvum immune response. In group A, the inoculation was not followed by mortality; but only by diarrhea and high oocyst shedding. Decoquinate reduced the severity of cryptosporidiosis in group B kids. The treatment prevented episodes of diarrhea and weight gain decrease for the D.0 - D.7 and D.0 - D.14 disease periods but did not allow a better final weight gain. The oocyst shedding was decreased in number and in duration. This parasitic development has induced a specific anti- C. parvum immune response. This drug is well-tolerated by animals and may be recommended in the prevention of ruminant cryptosporidiosis, a disease which has very limited treatment options.
Fig.1 Mean number of the oocysts shed per gram of faeces from D3 to D16.
A : group inoculated with 106 C. Parvum oocysts and not treated.
B : group inoculated and treated with 2,5 mg/kg/day of decoquinate for 21 days
II - FIELD USES OF DECOQUINATE IN BEEF COWS TO PREVENT
CRYPTOSPORIDIOSIS IN CALVES
In the Charolais region, cryptosporidiosis appears in young calves of 5 to 15 days of age, with putrid-odor mucoid diarrhea. The differential diagnosis is based on the presence of ookysts revealed at the lab.
Clinical cryptosporidiosis generally appears in suckling or dairy herds, at the end of the calving period, when the pressure of infection is maximum. Curative treatments in calves are few, difficult to use and often provide poor results. A systematic preventive treatment in suckling calves is also difficult to carry out owing to the constraint of treating them preventively once a day during 7 consecutive days. Moreover, weight gain decreases are often observed.
1) when the quantities of medicated feed were insufficient (feed manufactured by multiples of 1.5 to 2.5 metric tons owing to the size of the mixer), a number of farmers, who could not treat the entire herd and who preferred respecting the protocol in terms of rates, lengths and bodyweights, would not treat another lot of cows most often located in another building. Several times, clinical cases were observed and confirmed by the lab in calves from these non treated cows, whereas calves from the treated cows did not reveal symptoms imputable to cryptosporidiosis.
2) in bigger herds (more than 100 cows) all cows were treated at the same time, choosing the peak calving period. The calves from cows treated during pregnancy (as opposed to end of pregnancy, early beginning of the milking period) regularly showed signs of cryptosporidiosis. Since these observations were made, treatment has been recommended lot by lot according to the periods of calving or, sometimes, decoquinate has been used as a treatment on the totality of cows, but over a longer period of time to make sure to " surround " calving. Of course these field observations would require validation by controlled clinical trials, difficult to implement in suckling herds. However, this prophylactic method, easy to implement, deserves being used.
This treatment was also used succesfully in ewes following the same protocol (30 days before lambing and 10 days after) but at a slightly higher rate (1.5 mg/ kg BW). It is to be noted that our colleagues have made the same observations concerning the failure of treatments which did not surround dropping, and the success of those carried out " around " dropping.
III - Field uses of decoquinate to control clinical cryptosporidiosis in veals
Referring to the experimental work of Redman and Fox in the United States, and to those of INRA in France, our calves started to be treated as from 1995. Here are related our first two cases.
In two farms of 180 to 200 Holstein veals in the Lot and Gers regions, half of the animals aged 21 days, already preventively treated with colistin, showed the following clinical signs, letting suspect salmonellosis : nauseating-odor diarrhea with few blood stains, dehydration, slight hyperthermia and average general weakness.
Animals were orally medicated with a quinolone-based treatment (oxolinic acid or flumequin), a rehydration formulation, and with a gastro-intestinal protective agent which did not improve this clinical picture. On the contrary, high mortality (13 calves in a farm, 4 in the other) occurred after treating over a week. Feces samples revealed the presence of cryptosporidia.
The decoquinate-based treatment at the rate of 2.5 mg/kg/day (i.e. 50 g of the Deccox® 6 premix per kg milk replacer) decreased diarrhea within three days and led to clinical healing within one week. The treatment was several times reiterated successfully, always noting a retrocession of the symptoms and improvement in growth rates in cases when the treatment was continued longer (4 to 5 weeks) but at a rate active on coccidia (0.5 mg/kg BW).
These field observations (non comparative) cannot be considered as demonstrative. And the efficacy results of decoquinate would of course deserve being confirmed by the implementation of more rigorous experimental protocols.
In all cases, not any sign of toxicity was ever noted.
Keywords : Ruminant, Cryptosporidium parvum, treatment, coccidiostat, decoquinate.
Redman, D.R. and Fox, J.E., 1994. The bovine proceedings, 26: 157-159.
Journel C., Chatagnon G., Martin D., Richard A., Tainturier D. (2001) INRA, 7e Rencontres Recherches Ruminants,Paris
Jurjanz.S,Colin-Schoellen.O,Richard.A, (1997) VII th International conference ,Oxford Lindsay D.S., Butler J.M., Blagburn B.L. (1997) Veterinary Parasitology, 68, 35-40
Mage.C,Poiseau.O,Richard.A, (2001) INRA 7e Rencontres Recherches Ruminants , Paris
Mancassola R., Richard A., Naciri M.(1997) Veterinary Parasitology, 69, 31-37