PALESTRA20a RAIB 57

BOVINE NEOSPOROSIS AND COCCIDIOSIS

Milton M. McAllister

University of Illinois, College of Veterinary Medicine, Department of Pathobiology E-mail: [email protected]

Coccidiosis level of contamination of the environment and the rate of exposure of naive young stock to the parasites. After Bovine coccidiosis was recently reviewed by being passed in feces, coccidial oocysts typically take DAUGSCHIES & NAJDROWSKI (2005). There are many 2 - 4 days to “sporulate” and become infectious, so species of Eimeria that infect cattle, but most cases of frequent cleaning of calf pens is an important technique clinical coccidiosis are caused by E. bovis and E. zurnii. to help limit the rate of exposure. Individual calf Diarrhea caused by E. alabamensis has been reported hutches, when cleaned and moved between calves, in Sweden and Germany (SVENSSON et al., 1994; VON are superior to group pens. Sunlight and dessication SAMSON-HIMMELSTJERNA et al., 2006). Other species of are the best disinfectants for protozoal oocysts, while Eimeria seldom cause diarrhea, and mixed infections chemical disinfection is difficult. In dairy cattle, are common. All bovine Eimeria have a fecal-oral indoor pens that receive little sunlight, moist bedding transmission cycle, with cattle as the sole hosts. Almost with infrequent changes, and crowding all increase all cattle shed Eimeria oocysts at one time or another, the build-up and survival of oocysts. most without clinical signs of disease. Nevertheless, In beef cattle, clinical coccidiosis may occur shortly coccidiosis is a common and important cause of after calves are stressed by weaning. Certain pastures diarrhea, reduced weight gain, and mortality in calves. may be associated with coccidiosis, possibly because The occurrence of diarrhea depends upon the they are shaded and moist (favoring long survival of interaction of many factors, including: the species of oocysts), were recently fertilized with fresh manure, coccidia; the density of Eimeria oocysts in the or because of disadvantageous pasture rotation environment and the related rate of exposure of naive practices. Hay or other feeds should not be spread on calves to oocysts; environmental temperature, the ground, which increases fecal-oral transmission, humidity, and sunlight, which affect the development but should be placed in elevated feeders. If practical, and survival of oocysts; and stressors such as weaning, locations that feeds are provided may be moved poor nutrition, or severe weather extremes (DAUGSCHIES frequently to avoid excessive concentration of feces & NAJDROWSKI, 2005). and to move cattle away from oocysts before they have Clinical coccidiosis most frequently affects calves sporulated. between 3 weeks and 6 months of age, or soon after In studies with toltrazuril, which is available in weaning. The onset of diarrhea may slightly precede Europe, a single administration to calves as they are fecal shedding of oocysts, but many diarrheic calves placed on pasture may result in less diarrhea and will be shedding large numbers of oocysts. Although increased weight gains, compared to untreated control Eimeria oocysts are smaller than helminth ova, they calves (EPE et al., 2005). Diclazuril is related to are nevertheless easy to observe in routine fecal floats toltrazuril and is used similarly. Many studies have when they are shed in large numbers. Counts of less shown benefits of prophylactic decoquinate or than 5,000 oocysts per gram of feces may not be amprolium, although these drugs are provided in clinically significant, while counts well above 100,000 feed or water for days or weeks. Coccidiosis is a per gram may occur in disease outbreaks. Diarrheic common problem in beef calves entering feedlots, feces may contain mucous, red blood, and shreds of unless prophylactic coccidiostats are used such as sloughed mucosa, and calves exhibit tenesmus. Milder monensin, lasolocid, or decoquinate; monensin and cases may exhibit only soft stools, rough hair coats, lasolocid have the added advantage of increasing and poor growth. feed efficiency. Amprolium, sulfa drugs, and Cattle of all ages shed Eimeria, but calves with tetracycline may be used to treat animals that already primary infections shed the greatest number. Massive have diarrhea. infections can create massive contamination of a premises, thus leading to a vicious cycle of Neosporosis overwhelming exposure, severe infections, and further environmental contamination. Fecal contamination Neospora caninum is a common infection in cattle is of course a simple fact of life in all cattle operations, (see Diagram). Owners of infected herds may not but certain management techniques may reduce the notice any problem. Usually, most congenitally

Biológico, São Paulo, v.69, n.2, p.57-61, jul./dez., 2007 58 20a RAIB

infected calves are clinically healthy and are refuse to listen to more moderate advice, 2) in some indistinguishable from uninfected herdmates, except circumstances a guard dog may actually reduce the by serology. Nevertheless, not all congenitally infected risk of infections spread by other canids, and 3) there calves fare well. Neosporosis is one of the most are other practical control methods. I have studied 3 common causes of bovine abortion, and is also a cause severe abortion outbreaks, involving a dairy with of congenital neurological defects (weak or “dummy” 1,200 cows, a dairy with 60 cows, and a beef herd with calves) including poor suckle reflex, poor balance, 200 cows. Each of these herds suffered a point source improper positioning of rear fetlocks (knuckling,” a exposure, each herd was feeding a mixed ration to the proprioceptive deficit), inability to stand, and seizures. pregnant cows, and each farm had dogs with access A few studies have also investigated the possible to feed piles. Stored feedstuffs should be protected so association of N. caninum serologic status with that dogs and other canids cannot defecate in them subclinical production losses, but the conclusions (which they commonly will do). Small farms may be have varied between no subclinical effect or modest able to keep feedstuffs within silos, grain bins, and reductions in average milk production or rate of gain enclosed sheds. However, modern large dairies con- (BARLING et al., 2000; THURMOND & HIETALA, 1997; sume too much feed to keep it all within containers. WALDNER et al., 2004; HOAR et al., 2007). Feedstuffs are frequently kept in large open piles. Endemic transmission is common within These feedstuffs are attractive to dogs and wild canids chronically infected herds. Epidemic transmission such as North American coyotes (Canis latrans). Dogs has been reported in numerous articles that show and coyotes consume silage, hunt rodents, and sleep outbreaks of abortion, premature births, and and defecate in hay. If a dog is actively shedding N. neurologically impaired calves. Transplacental caninum in its feces, then contamination of any feedstuff transmission may occur from a cow that first becomes can cause rapid, widespread dissemination of the infected during pregnancy as a result of ingesting parasite to a large number of cattle that consume the oocysts shed in the feces of infected canids (“exogenous mixed ration. This is to be avoided. Large dairies can transplacental transmission”) (GONDIM et al., 2004), or erect a dog-proof fence around the area where feedstuffs transplacental transmission may occur from a are stored. A gate can be designed to open congenitally infected dam to her own offspring automatically when machinery approaches, or some (“endogenous transplacental transmission”) farmers may prefer to leave the gate open during the (ANDERSON et al., 1997; BJÖRKMAN et al., 1996; SCHARES et day when human activity is high and visits by feral or al., 1998). Well-studied abortion epidemics were wild canids are less likely. Infections acquired from caused by exogenous transmission, while in contrast grazing may be unavoidable, but these infections may the majority of congenital infections in endemically occur sporadically in individuals rather than infecting infected herds result from endogenous transmission. a large number of cows at once. On a national or international level, endemic Steps can also be taken to reduce the risk of abortions account for more losses than do abortion transmitting N. caninum from cattle to dogs, thereby epidemics, and this may be why many articles state inhibiting dogs from shedding oocysts. Carcasses of that endogenous transplacental transmission is more cattle may harbor this parasite in muscle and nervous important than is transmission by canids (PABÓN et al, tissue, regardless of the reason that the animal has 2007). However, in all instances endemic transmission died. Therefore, dead stock or offal should be disposed must have been preceded at some point in the past by of in a manner that keeps dogs from eating the carcass. ingestion of oocysts. Without periodic transmission Burying carcasses, using a rendering service for from canids the parasite would gradually disappear removal, or placing fences or electric fences around from any endemically-infected herd. Consistent with carcasses until they have decomposed, will prevent this, epidemiologic studies from many different dogs from eating dead stock. Dogs may also become countries have associated the prevalence of infected by consuming cattle placentas (DIJKSTRA et al., neosporosis in cattle with the presence and number of 2001), which will not always be possible to prevent. dogs or other canids (BARTELS et al., 1999; BARLING et al., Keep in mind that the goal is to reduce the risk of 2000; DIJKSTRA et al., 2002; MAINAR-JAIME et al., 1999; transmission, but complete elimination of this risk is OTRANTO et al., 2003; OULD-AMROUCHE et al., 1999; PARÉ not possible even when no dogs are on the farm; for et al., 1998; RINALDI et al., 2005; SANCHEZ et al., 2003; example, feral and wild canids may defecate in SAWADA et al., 1998). pastures, or a feedstuff may be purchased that is Fortunately, practical steps can be taken to reduce already contaminated. the risk of widespread transmission of N. caninum It is usually advisable to cull cows that have an from dogs to cattle. I do not recommend removing all abortion, regardless what caused the abortion. In dogs from farms for several reasons: 1) many farmers some herds with endemic neosporosis, cows that would reject such a recommendation and might then abort once may abort again (PABÓN et al, 2007).

Biológico, São Paulo, v.69, n.2, p.57-61, jul./dez., 2007 20a RAIB 59

In herds with long-term, persistently elevated, culling decisions. Second, there is no ideal serological endemic abortions attributable to neosporosis, then cut-off to reliably distinguish between infected and selective culling of heifers in infected lines may be uninfected cattle. Third, reinfection of the herd is considered (LARSON et al., 2004). For example, possible, thereby negating efforts to eradicate the seropositive heifers may be sold or fed for slaughter, parasite. Fourth, as the seroprevalence rate in a herd while seronegative replacement heifers may be decreases, the susceptibility of the herd to a retained for breeding. Or seropositive dairy cows neosporosis abortion outbreak may actually increase, may be inseminated with semen from a beef breed, because chronically infected cows may be immune to thus ensuring that replacement heifers come only exogenous transplacental transmission, while naive from seronegative dams. Embryos may be transferred cows are more likely to abort if they should ingest from particularly valuable seropositive cows to Neospora oocysts during pregnancy (MCALLISTER et seronegative surrogates, thus breaking the cycle of al., 2000). Who wants to eradicate neosporosis from endogenous transplacental transmission and their herd, and then have an abortion epidemic? helping the next generation to be free of this parasite Therefore, in my opinion any attempt to reduce the (BAILLARGEON et al., 2001). These strategies speed the prevalence of endogenous neosporosis in a herd by decline of N. caninum seroprevalence in a herd, which selective culling must also include management may reduce endemic abortions in herds in which practices to reduce the risk of exogenous this is a problem. Not all infected herds have abortion transmission by canids. problems, so I do not recommend going to the trouble A commercial vaccine for bovine neosporosis and expense of culling seropositive animals in herds has been sold in the U.S. for about 9 years. There is that do not have a reproductive problem associated still a great need for well-designed and adequately with N. caninum serologic status. There are several funded studies to test the effect of this vaccine on additional important considerations when endogenous and exogenous transplacental considering a selective culling program to control transmission and abortion. These studies need to bovine neosporosis. First, Neospora serologic status be published whether the results are positive or is only one of many important factors when making negative.

Biológico, São Paulo, v.69, n.2, p.57-61, jul./dez., 2007 60 20a RAIB

REFERENCES HOAR, B.R.; MCQUARRY, A.C.; HIETALA, S.K. Prevalence of Neospora caninum and persistent infection with bovine ANDERSON, M.L.; REYNOLDS, J.P.; ROWE, J.D.; SVERLOW, K.W.; viral diarrhea virus in dairy-breed steers in a feedlot. PACKHAM, A.E.; BARR, B.C.; CONRAD, P.A. Evidence of JAVMA, v.230, p.1038-1043, 2007. vertical transmission of Neospora sp. infection in LARSON , R.L.; HARDIN, D.K.; PIERCE, V.L. Economic dairy cattle. Journal of the American Veterinary Medical considerations for diagnostic and control options for Association, v.210, p.1169-1172, 1997. Neospora caninum-induced abortions in endemically BAILLARGEON, P.; FECTEAU, G.; PARÉ, J.; LAMOTHE, P.; SAUVÉ, R. infected herds of beef cattle. Journal of the American Evaluation of the embryo transfer procedure proposed Veterinary Medical Association, v.224, p.1597-1604, 2004. by the International Embryo Transfer Society as a MAINAR-JAIME, R.C.; THURMOND, M.C.; BERZAL-HERRANZ, B.; method of controlling vertical transmission of HIETALA, S.K. Seroprevalence of Neospora caninum and Neospora caninum in cattle. Journal of the American abortion in dairy cows in northern Spain. Veterinary Veterinary Medical Association, v.218, p.1803-1806, 2001. Record, v.145, p.72-75, 1999. BARLING, K.S.; SHERMAN, M.; PETERSON, M.J.; THOMPSON, J.A.; MCALLISTER, M.M.; BJÖRKMAN, C.; ANDERSON-SPRECHER, R.; MCNEILL, J.W.; CRAIG, T.M.; GARRY ADAMS, L. Spatial ROGERS, D.G. Evidence of point-source exposure to associations among density of cattle, abundance of Neospora caninum and protective immunity in a herd wild canids, and seroprevalence to Neospora caninum of beef cows. Journal of the American Veterinary Medical in a population of beef calves. Journal of the American Association, v.217, p.881-887, 2000. Veterinary Medical Association, v.217, p.1361-1365, 2000. OTRANTO, D.; LLAZARI, A.; TESTINI, G.; TRAVERSA, D.; REGALBONO, BARLING, K.S.; MCNEILL, J.W.; THOMPSON, J.A.; PASCHAL, J.C., A.F.; BADAN , M.; CAPELLI, G. Seroprevalence and MCCOLLUM , T.; C RAIG, T.M.; GARRY A DAMS, L. Association associated risk factors of neosporosis in beef and of serologic status for Neospora caninum with dairy cattle in Italy. Revista de Medicina Veterinaria y postweaning weight gain and carcass measurements Parasitologia, v.118, p.7-18, 2003. in beef calves. Journal of the American Veterinary Medical OULD-AMROUCHE, A.; KLEIN, F.; OSDOIT, C.; MOHAMMED, H.O.; Association, v.217, p.1356-1360, 2000. TOURATIER, A.; SANAA, M.; MIALOT, J.P. Estimation of BARTELS, C.J.; WOUDA, W.; SCHUKKEN, Y.H. Risk factors for Neospora caninum seroprevalence in dairy cattle from Neospora caninum-associated abortion storms in dairy Normandy, France. Veterinary Research, v.30, p.531- herds in The Netherlands (1995 to 1997). Theriogenology, 538, 1999. v.52, p.247-257, 1999. PABÓN, M.; LÓPEZ-GATIUS, F.; ALMERÍA, S. Chronic Neospora BJÖRKMAN, C.; J OHANSSON, O.; STENLUND, S.; H OLMDAHL, O.J.M.; caninum infection and repeat abortion in dairy cows: UGGLA, A. Neospora species infection in a herd of dairy A 3-year study. Revista de Medicina Veterinaria y cattle Journal of the American Veterinary Medical Parasitologia, v.147, p.40-46, 2007. Association, v.208, p.1441-1444, 1996. PARÉ, J.; FECTEAU, G.; FORTIN, M.; MARSOLAIS, G. DAUGSCHIES, A. & NAJDROWSKI, M. Eimeriosis in cattle: current Seroepidemiologic study of Neospora caninum in dairy understanding. Journal of veterinary medicine. Series B, herds. Journal of the American Veterinary Medical v.52, p.417-427, 2005. Association, v.213, p.1595-1598, 1998. DIJKSTRA, T.; BARKEMA, H.W.; EYSKER, M.; HESSELINK, J.W.; RINALDI L, FUSCO G.; FORTIN, M.; MARSOLAIS, G. Neospora WOUDA, W. Natural transmission routes of Neospora caninum in pastured cattle: determination of caninum between farm dogs and cattle. Revista de climatic, environmental, farm management and Medicina Veterinaria y Parasitologia, v.105, p.99-104, individual animal risk factors using remote sensing 2002. and geographical information systems. Revista de DIJKSTRA, T.; EYSKER, M.; SCHARES, G.; CONRATHS, F.J.; WOUDA, Medicina Veterinaria y Parasitologia, v.128, p.219-230, W.; BARKEMA, H.W. Dogs shed Neospora caninum oocysts 2005. after ingestion of naturally infected bovine placenta SANCHEZ, G.F.; MORALES, S.E.; MARTINEZ, M.J.; TRIGO, J.F. but not after ingestion of colostrum spiked with Determination and correlation of anti-Neospora Neospora caninum tachyzoites. International Journal for caninum antibodies in dogs and cattle from Mexico. Parasitology, v.31, p.747-752, 2001. Canadian Journal of Veterinary Research, v.67, p.142-145, EPE, C.; VON S AMSON-HIMMELSTJERNA, G.; W IRTHERLE, N.; VON DER 2003. HEYDEN, V.; WELZ, C.; RADELOFF, I.; BEENING, J.; CARR, D.; SAWADA, M.; PARK, C.H.; KONDO, H.; MORITA, T.; SHIMADA, A.; HELLMANN, K.; SCHNIEDER, T.; KRIEGER, K. Efficacy of YAMANE, I.; UMEMURA, T. Serological survey of antibody toltrazuril as a metaphylactic and therapeutic treatment to Neospora caninum in Japanese dogs. Journal of of coccidiosis in first-year grazing calves. Parasitology Veterinary Medical Science, v.60, p.853-854, 1998. Research, v.97, supplement 1, S127-S133, 2005. SCHARES, G.; P ETERS, M.; W URM, R.; BÄRWALD, A.; CONRATHS, F.J. FAYER, R.; SANTIN, M.; XIAO, L. Cryptosporidium bovis n. sp. The efficiency of vertical transmission of Neospora (Apicomplexa: Cryptosporidiidae) in cattle (Bos caninum in dairy cattle analysed by serological taurus). Journal of Parasitology, v.91, p.624-629, 2005. techniques. Revista de Medicina Veterinaria y Parasitologia, GONDIM, L.F.P.; M CALLISTER, M.M.; A NDERSON-SPRECHER, R.C.; v.80, p.87-98, 1998. BJÖRKMAN, C.; LOCK, T.F.; FIRKINS, L.D.; GAO, L.; FISCHER, SVENSSON, C.; UGGLA, A.; PEHRSON, B. Eimeria alabamensis W.R. Transplacental transmission and abortion in infection as a cause of diarrhoea in calves at pasture. cows administered Neospora caninum oocysts. Journal Revista de Medicina Veterinaria y Parasitologia, v.53, p. of Parasitology, v.90, p.1394-1400, 2004. 33-43, 1994.

Biológico, São Paulo, v.69, n.2, p.57-61, jul./dez., 2007 20a RAIB 61

THURMOND, M.C. & HIETALA, S.K. Effect of Neospora caninum and epidemiological characteristics of Eimeria infection on milk production in first- lactation dairy infections in first-year grazing cattle. Revista de Me- cows. Journal of the American Veterinary Medical dicina Veterinaria y Parasitologia, v.136, p.215-221, 2006. Association, v.210, p.672-674, 1997. WALDNER, C.; WILDMAN, B.K.; HILL, B.W.; FENTON, R.K.; VON SAMSON-HIMMELSTJERNA, G.; EPE, C.; WIRTHERLE, N.; VON PITTMAN, T.J. Determination of the seroprevalence of DER HEYDEN, V.; WELZ, C.; RADELOFF, I.; BEENING, J.; CARR, Neospora caninum in feedlot steers in Alberta. Canadian D.; HELLMANN, K.; SCHNIEDER, T.; KRIEGER, K. Clinical Journal of Veterinary, v.45, p.218-224, 2004.

Biológico, São Paulo, v.69, n.2, p.57-61, jul./dez., 2007