Canine neosporosis: perspectives on pathogenesis and management

“Vertical transmission happens during terminal stages of gestation (transplacental transmission with fetal infection) or postnatally, by the transmission of tachyzoites via milk (transmammary transmission).(3,52) In horizontal transmission, the infection occurs postnatally after ingestion of water containing sporulated…”

“The parasite can be transmitted multiple times from the infected female dog to her offspring, because no preventive treatment is available.(12) Dogs should never have access to bovine placental materials, dead calves, fetal membranes, aborted fetuses, or raw/ undercooked meat, and should be prevented from defecating a…”

“Articular deformation and joint curvature (genu recurvatum) can occur in some puppies,(30) followed by cervical weakness, dysphagia, megaesophagus, and death.(8,25,26) Dogs remain”

“10,85 No breed predisposition or differential sex susceptibility to neosporosis in dogs is known, 33 but age can be a risk factor.”

“caninum in sheep is less clear when compared with cattle.(6) In Norway, Bjerkås et al(7) diagnosed a disease similar to toxoplasmosis, another”

“9 McAllister et al 10 defined the domestic dog ( Canis lupus familiaris ) as the definitive host of N. caninum , and Gondim et al 2 reported the coyote ( C. latrans ) as a wild definitive host of the parasite by confirming the sexual stage of the parasite, and oocysts being shed in feces.”

“and described the disease caused by a protozoan infecting a puppy with clinical signs similar to those reported by Bjerkas et al.(7) Afterwards, this protozoan was recognized”

“caninum can produce necrotic lesions, which are detectable in a few days; it causes cell death by the active multiplication of the tachyzoites, and can induce neuromuscular diseases in dogs and other species by the destruction of a large number of neuronal cells, ie, cranial and spinal nerves, which affect the nerve-i…”

“Direct methods consist in the visualization of oocysts, tissue cysts, or tachyzoites, stained or not, by light microscopy, histopathology, immunohistochemistry, in vitro cell culture and in vivo isolation by gerbil and/or mouse bio assay, fecal flotation of dog feces, and molecular methods, ie, polymerase chain reacti…”

“Neosporosis is a worldwide emergent disease, and is usually associated with reproductive (ie, neonatal mortality in animals, particularly in dogs and cattle) and neurological (ie, neuromuscular degeneration) disorders and presents progressive evolution, being more severe in young animals.(4,5) For cattle, it is consid…”

“Bradyzoites survive at 4 ° C for over 14 days, 13,14,18 and are also resistant to pepsin and trypsin digestion.”

“41 Low levels of horizontal transmission in cattle were also observed by Hietala and Thurmond 47 and Davison et al, 46 but the importance of this route should not be underestimated, mainly due to the maintenance of the parasite in regional herds.”

“…16 Dubey et al 17 Round and oval Bradyzoites and tachyzoites have conoids, numerous micronemes (size 232 × 58 nm), rhoptries (145 nm wide), amylopectin, and nucleus Cyst wall ∼ 0.5–4 μ m thick Dubey et al 14 Speer et al 18 Smooth, irregular, wavy contour in tissue sections, but without protrusions.”

“21 Dog ( C. lupus familiaris ) is considered the definitive nonwild host of the parasite, 10,22 whereas coyote ( C. latrans ), 2 Australian dingo ( C. lupus dingo ), 23 and gray wolf ( C. lupus ) 24 are the definitive wild hosts.”

“41 Low levels of horizontal transmission in cattle were also observed by Hietala and Thurmond 47 and Davison et al, 46 but the importance of this route should not be underestimated, mainly due to the maintenance of the parasite in regional herds.”

“caninum infection in adult animals and herds, and both are also considered complementary techniques in the diagnosis of neosporosis.(96) Western blotting is usually recommended to confirm uncertain results in valuable samples.”

“at the host-cell surface are required to provide enough signals for the invasion of the parasite into the cell cytoplasm.(86) In order to initiate host-cell invasion, tachyzoites reorient themselves perpendicularly to the host cell-surface membrane and enter the cytoplasm by advancing anterior end first, until they ar…”

“In herbivorous creatures, N. caninum is the major cause of abortion in both dairy and beef cattle, 6 but lactogenic transmission can also occur and be important, 49,50 and should be considered and demonstrated in further studies under natural circumstances in calves or dogs.”

“as the causative agent of the disease in dogs, and identified in bovine aborted and mummified fetuses and in calves with neonatal paralysis.(9) McAllister et al(10) defined”

“21 Dog ( C. lupus familiaris ) is considered the definitive nonwild host of the parasite, 10,22 whereas coyote ( C. latrans ), 2 Australian dingo ( C. lupus dingo ), 23 and gray wolf ( C. lupus ) 24 are the definitive wild hosts.”

“The indirect fluorescent antibody test (IFAT), 8 Neospora-agglutination test, 98 and enzyme-linked immunosorbent assay (ELISA) 44,96 are the most used techniques for N. caninum - antibody research.”

“Septa and a secondary tissue cyst wall are absent Bradyzoite ∼ 4.5–8 × 1.2–1.9 μ m Barr et al 16 Speer et al 18 Dubey et al 14 Dubey et al 17 Slender, elongated with a subterminal nucleus, slightly longer than tachyzoites Tachyzoite Tachyzoite ∼ 3–7 × 1–2 μ m Dubey et al 14 Speer et al 18 mission…”

“65 This high seroprevalence has ranged from 1.5% (three of 200) in southern Vietnam 45 and 3.8% (four of 105) in the Philippines 53 to 88% (169 of 192) in Brazil 62 and 88.3% (424 of 480) in Australia.”

“N. caninum antibodies have been detected in the serum samples of immunocompetent 54,125,126 and immunosuppressed humans, 126,127 but no parasite isolation or detectable DNA has been reported.”

“N. caninum antibodies have been detected in the serum samples of immunocompetent 54,125,126 and immunosuppressed humans, 126,127 but no parasite isolation or detectable DNA has been reported.”

“41 Low levels of horizontal transmission in cattle were also observed by Hietala and Thurmond 47 and Davison et al, 46 but the importance of this route should not be underestimated, mainly due to the maintenance of the parasite in regional herds.”

“Once inside, the parasite induces metabolic alterations in the host, which favor its maintenance.(43) Both parasites reorganize the host microtubular cytoskeleton and attract endo plasmic reticulum, mitochondria, lysosomes, multivesicular bodies (temporary storage compartments enriched in sphingolipids and cholesterol…”

“tachyzoite lysate using different adjuvants failed to protect against fetal death.(118)”

“This process releases bradyzoites, which reactivate the infection.(32,83) This is well documented to occur in pregnant animals, causing fetal infection.”

“20,82,84 In definitive hosts, tachyzoites transform in merozoites, ie, macrogametes and microgametes, into the intestinal epithelium, undergo merogony (sexual stage), and form a zygote.”

“On the other hand, Baszler et al 94 and Sanchez et al 95 observed 97% and 85% agreement, respectively, between immunohistochemistry and a well-standardized PCR protocol in formalin-fixed paraffin-embedded brain tissue of bovine fetuses.”

“This is well documented to occur in pregnant animals, causing fetal infection.(20,82,84) In definitive hosts, tachyzoites transform in merozoites, ie, macrogametes and microgametes, into the intestinal epithelium, undergo merogony (sexual stage), and form a zygote.”

“They can actively penetrate membranes of a wide range of nucleated cells, which suggests low host-cell specificity.(18,19) Tachyzoites multiply by endodyogeny,(20) and promote the expansion of the PV up to the cell lysis.”

“caninum infections should not be dismissed.(128) In this way, N.”

“…(six of 104) 29 to 12.9% (21 of 163) 28 in England, 5.5% (19 of 344) to 23.6% (36 of 152) in the Netherlands, 32 7.1% (14 of 198) to 31.3% (15 of 48) in Japan, 31 and 0 to 19.2% in the Czech Republic, according to the use of these dogs (4.7% army, 0 police, 2.6% private, and 19.2% shelter dogs).”

“Western blotting is usually recommended to confirm uncertain results in valuable samples.(99,100) In addition, avidity tests are useful for investigating the route of N.”

“Low levels of horizontal transmission in cattle were also observed by Hietala and Thurmond(47) and Davison et al,(46) but the importance of this route should not be underestimated, mainly due to the maintenance of the parasite in regional herds.(49) Worldwide seroprevalence ranges a lot in beef and dairy cattle and bu…”

“20 Fecal trans-Table 15 Barr et al 16 Dubey et al 17 Round and oval Bradyzoites and tachyzoites have conoids, numerous micronemes (size 232 × 58 nm), rhoptries (145 nm wide), amylopectin, and nucleus Cyst wall ∼ 0.5–4 μ m thick Dubey et al 14 Speer et al 18 Smooth, irregular, wavy contour in tissue…”

“67 This observed scenario corroborates with the comparisons between species predispositions made by Nasir et al, 69 Anastasia et al, 70 and Liu et al, 63 which indicated sheep to be more likely susceptible to N. caninum infection than goats.”

“8 It has been used extensively for diagnosis of the infection in dogs, is considered a gold-standard test, 48 and used in epidemiological studies for domestic and wild animals.”

“caninum (NeoGuardTM) for use in cattle,(121) but with low efficacy (,25%).(109) Also, live vaccines presented higher efficacy, up to 100% in experimental infections,(118,119) producing strong cellular and IFNγ responses correlated with”

“The indirect fluorescent antibody test (IFAT), 8 Neospora-agglutination test, 98 and enzyme-linked immunosorbent assay (ELISA) 44,96 are the most used techniques for N. caninum - antibody research.”

“Jordan and Hunter 88 emphasized that the CD8 + T-cell population participates in a protective mechanism used by the host in infections caused by apicomplexan protozoa.”

“caninum tachyzoites, but is thought to have little or no effect on bradyzoites.(106) In this way, tissue cysts may persist with even ∼2 months of treatment, and treatment of chronic neosporosis by exposing bradyzoites to the immune response should be considered and researched.”

“tions of hygiene are important risk factors that contribute to the infection in these species.(63,71)”

“3,52 In horizontal transmission, the infection occurs postnatally after ingestion of water containing sporulated oocysts, or of infected tissues (raw or undercooked meat, fetal membranes) of intermediate hosts with tissue cysts or contaminated with sporulated oocysts.”

“caninum life cycle are still unknown, mainly concerning the sexual stage of the parasite evolution.(39) More studies are necessary to clarify the entire enteroepithelial cycle and to elucidate the interaction between the dog and the parasite in natural, not experimental, infection.”

“Corroborating this, van Maanen et al 93 observed low agreement between the majority scores of immunohistochemistry and PCR methods (single or nested) in bovine fetal tissues on an interlaboratory comparison in Europe, with false-positive PCR results indicating contamination problems in some…”

“caninum transmission in herds by differing acute and chronic infections.(100,101) Again, performance (sensitivity, specificity, and positive and negative predictive values) can range among laboratories, and costs are directly linked to the performance of the tests.”

“108 120 Studies began with the use of a crude lysate of the parasite to prevent infection of offspring, followed by application in cattle and commercialization of a registered vaccine for N. caninum (NeoGuard™) for use in cattle, 121 but with low efficacy ( , 25%).”

“89 The participation of this immune cell in host protection is well known to the T. gondii infection, but recently Correia et al 90 observed that the production of IFN γ is also a predominant host-protective mechanism conferred by CD8 + T cells in the course of neosporosis, as observed in…”

“Adult dogs shed fewer oocysts than puppies following primary exposure, and puppies may also develop reexcretion after new challenge.(36) Some important factors to be considered when reporting N.”

“6 N. caninum antibodies have been detected in dogs from North, Central, and South America, Europe, South Africa, Asia, and Oceania.”

“6% (21 of 89) in the Philippines.(53) In sheep, it has ranged from 0.”

“109 Also, live vaccines presented higher efficacy, up to 100% in experimental infections, 118,119 producing strong cellular and IFN γ responses correlated with protection against fetopathy, but immunization with whole-tachyzoite lysate using different adjuvants failed to protect against fetal death.”

“2% (353 of 596) in São Paulo, Brazil(71) and 63% (214 of 339) in the north of Jordan.(67) This observed scenario corroborates with the comparisons between species predispositions made by Nasir et al,(69) Anastasia et al,(70) and Liu et al,(63) which indicated sheep to be more likely susceptible to N.”

“Septa and a secondary tissue cyst wall are absent Bradyzoite ∼ 4.5–8 × 1.2–1.9 μ m Barr et al 16 Speer et al 18 Dubey et al 14 Dubey et al 17 Slender, elongated with a subterminal nucleus, slightly longer than tachyzoites Tachyzoite Tachyzoite ∼ 3–7 × 1–2 μ m Dubey et al 14 Speer et al 18 mission…”

“caninum is that the immune response itself is potentially pathogenic to the fetus.(108) Vaccine research has been under way for a long time, and most approaches have focused on inactivated whole vaccines (killed tachyzoites), the use of subunit native (tachyzoite-extract vaccine formulated with a soy lecithin/β-glucan…”

“N. caninum antibodies have been detected in the serum samples of immunocompetent 54,125,126 and immunosuppressed humans, 126,127 but no parasite isolation or detectable DNA has been reported.”

“Treatment is most effective in early stages, before muscular contracture has occurred.(103) For cutaneous neosporosis, it seems to be more effective.”

“Tachyzoites can be found free in organic fluids and in a parasitophorous vacuole (PV) placed at the cytoplasm of the host cell, but are particularly vulnerable to the harmful effects of extracellular maintenance and rapidly lose their capacity for invasion.(4) They can actively penetrate membranes of a wide range of n…”

“…producing N. caninum IgG antibodies but no clinical signs, and infectious canine herpesvirus was not recovered from these dogs, whereas Staska et al 116 detected parasite-specific CD4 + T lymphocytes and IFN γ response in experimentally infected cattle, which supports further investigations of…”

“Though a possibly good candidate in preventing vertical transmission in cattle, an important draw-back of this vaccine may be that the irradiated tachyzoites may not persist in the host for as long as a live vaccine, 123 requiring booster immunizations.”

“5% for beef cattle.(65) This high seroprevalence has ranged from 1.”

“Though a possibly good candidate in preventing vertical transmission in cattle, an important drawback of this vaccine may be that the irradiated tachyzoites may not persist in the host for as long as a live vaccine,(123) requiring booster immunizations.(122) In addition, in silica approaches open a new point of view f…”

“Articular deformation and joint curvature (genu recurvatum) can occur in some puppies,(30) followed by cervical weakness, dysphagia, megaesophagus, and death.(8,25,26) Dogs remain”

“Articular deformation and joint curvature (genu recurvatum) can occur in some puppies, 30 followed by cervical weakness, dysphagia, megaesophagus, and death.”

“In addition, the synergistic action of sulfonamides and pyrimethamine enhances the anti protozoal effects.(104,105) Clindamycin affects the multiplication of N.”

“They can actively penetrate membranes of a wide range of nucleated cells, which suggests low host-cell specificity.(18,19) Tachyzoites multiply by endodyogeny,(20) and promote the expansion of the PV up to the cell lysis.”

“59 In South America, seroprevalence in dairy cattle has ranged from 10.62% (66 of 121) in Brazil 56 to 20.3% in Argentina.”

“108 120 Studies began with the use of a crude lysate of the parasite to prevent infection of offspring, followed by application in cattle and commercialization of a registered vaccine for N. caninum (NeoGuard™) for use in cattle, 121 but with low efficacy ( , 25%).”

“67 This observed scenario corroborates with the comparisons between species predispositions made by Nasir et al, 69 Anastasia et al, 70 and Liu et al, 63 which indicated sheep to be more likely susceptible to N. caninum infection than goats.”

“Direct methods consist in the visualization of oocysts, tissue cysts, or tachyzoites, stained or not, by light microscopy, histopathology, immunohistochemistry, in vitro cell culture and in vivo isolation by gerbil and/or mouse bio assay, fecal flotation of dog feces, and molecular methods, ie, polymerase chain reacti…”

“59 In South America, seroprevalence in dairy cattle has ranged from 10.62% (66 of 121) in Brazil 56 to 20.3% in Argentina.”

“%) and specificities (93%–100%, except the VMRD cELISA test, with 65%), but almost perfect agreement among all tests (80%–90%), as observed by Campero et al 57 comparing IFAT and immunoblotting (considered relative standards of comparison), and p38 ELISA (97%), which resulted in 97.8% sensitivity…”

“59 In South America, seroprevalence in dairy cattle has ranged from 10.62% (66 of 121) in Brazil 56 to 20.3% in Argentina.”

“the parasite can stay in the environment where the definitive host sheds the oocysts in their feces.(37) Wouda et al(32) suggested that once dogs and cattle live in”

“On the other hand, Baszler et al 94 and Sanchez et al 95 observed 97% and 85% agreement, respectively, between immunohistochemistry and a well-standardized PCR protocol in formalin-fixed paraffin-embedded brain tissue of bovine fetuses.”

“129 Also, gene prediction opens wide the way for vaccine candidates by bioinformatic programs.”

“27,51 The frequency ranges from 5.8% (six of 104) 29 to 12.9% (21 of 163) 28 in England, 5.5% (19 of 344) to 23.6% (36 of 152) in the Netherlands, 32 7.1% (14 of 198) to 31.3% (15 of 48) in Japan, 31 and 0 to 19.2% in the Czech Republic, according to the use of these dogs (4.7% army, 0 police, 2.6%…”

“caninum transmission in herds by differing acute and chronic infections.(100,101) Again, performance (sensitivity, specificity, and positive and negative predictive values) can range among laboratories, and costs are directly linked to the performance of the tests.”

“in the jejunum and ileum), myocarditis, and nonpurulent encephalitis may occur in young puppies.(40)”

“In addition, in silica approaches open a new point of view for vaccine-candidate prediction and should be exploited; precise protein targets are paramount, and arguably the most important factor determining the success or failure of this approach.(124) The same happens with drugs to prevent transplacental transmission…”

“On the other hand, Waldner et al 102 observed good agreement (76”

“Necrotizing cerebellitis and hepatitis were also observed.(38) Epidemiological history and clinical findings can help the diagnosis of suspected neosporosis, as well as the control and prevention of the disease.”

“…caninum, Sarcocystis species, Toxoplasma gondii, Isospora species, Cryptosporidium parvum, Giardia, Echinococcus granulosus, Echinococcus multilocularis, Taenia hydatigena, Taenia ovis and Trichinella species (LeJeune & Hancock 2001, Macpherson 2005, Silva & Machado 2016, van Bree et al. 2018).”

“While this disease has a considerable impact on reproduction in cattle, in adult and older dogs appears to be asymptomatic (Silva and Machado, 2016; Kul et al., 2015; Lindsay et al., 1999a).”