Ranch-management factors associated with antibody seropositivity for Neospora caninum in consignments of beef calves in Texas, USA

The seroprevalence and risk factors for exposure to Neospora caninum and Neospora hughesi in Ontario broodmares

The seroprevalence and risk factors for exposure to Neospora caninum and Neospora hughesi in broodmares in Ontario were investigated. Sixty of the 219 (27.4%) study broodmares were seropositive for N. caninum and 65/219 (29.7%) for N. hughesi with cut-offs of ≥1:40 and ≥1:160, respectively. Thirty-one of 63 participating farms (49.2%) had at least 1 broodmare seropositive for N. caninum. Thirty-three of the 63 (52.4%) participating farms had at least 1 broodmare positive for N. hughesi. Risk factors for N. caninum included presence of farm dogs (OR = 6.70; 95% CI = 2.14-20.97; p = 0.001), and high stocking density (OR = 2.83; 95% CI = 1.27-6.30; p = 0.011). Presence of livestock, excluding cattle, was associated with reduced risk of exposure (OR = 0.17; 95% CI = 0.06-0.53; p = 0.002). The only risk factor for exposure to N. hughesi was feeding hay on the ground in the paddock (OR = 4.31; 95% CI = 1.65-11.22; p = 0.003). This study demonstrated widespread exposure to Neospora spp. in broodmares in Ontario.

Neospora caninum infection in dairy cattle in Egypt: a serosurvey and associated risk factors

Neospora caninum (N. caninum) is one of the causative agents that causing cattle abortion, and severe economic losses. Due to the scarcity of data on N. caninum infection in Egyptian cattle, the purpose of this study was to estimate the seroprevalence and determine the risk factors for parasite infection. In four governorates in northern Egypt, 540 blood samples from cattle were taken, and tested using a commercial ELISA kit. The overall seroprevalence of N. caninum in examined cattle was 28.89%. A multivariate logistic regression model determined that age (OR = 2.63, P < 0.001), manual milking (OR = 1.39, P = 0.14), abortion history (OR = 2.78, P < 0.0001), repetition of estrus (OR = 2.31, P < 0.0001), and contact with dogs (OR = 2.57, P < 0.0001) were significant risk factors. The findings proved that N. caninum infection was one of the factors contributing to abortion and financial losses in dairy cattle in Egypt. Therefore, the application of sanitary security and control programs is very important in dairy farms.

Seroprevalence and risk factors analysis of Neospora caninum and Toxoplasma gondii in cattle of Beheira, Egypt

Introduction

Neospora caninum and Toxoplasma gondii are closely related obligate intracellular protozoan parasites. They are considered to be the major causes of infectious abortions and congenital abnormalities in livestock worldwide resulting in huge economic losses. Currently, there are no reports on the prevalence of neosporosis or toxoplasmosis in cattle in Beheira, Egypt's most important region for cattle industry.

Methods

The current study investigated the presence of anti-N. caninum and anti-T. gondii antibodies in apparent healthy cattle from eight localities representing the whole area of Beheira. A total of 358 plasma samples were randomly collected from 6 dairy and 10 beef farms and analyzed by commercially available ELISAs. Production type (dairy versus beef), sex (female vs male), age (< 3 years, 3-5, and > 5 years old), breed (mixed vs Holstein vs Colombian Zebu), and location (various locations) were assessed as risk factors for N. caninum and T. gondii infections.

Results and discussion

Of the samples, 88 (24.6%) and 19 (5.3%) were positive for anti-N. caninum and anti-T. gondii antibodies, respectively, and mixed infection was detected in 7. Of the 16 herds, 6 dairy and 7 beef herds were positive for antibodies to N. caninum. Antibodies to T. gondii were detected in 4, and 5 of dairy and beef herds, respectively. Production type (dairy) and, therewith, sex (female), age (aged over 5 years), and location were considered as risk factors for N. caninum infection. No factors statistically associated with T. gondii infection were identified. Overall, this study provided the first serological detection of N. caninum and T. gondii infections in cattle from Beheira, demonstrating the endemicity of both parasites in the main cattle rearing region of Egypt. This study also confirmed earlier reports of N. caninum being more present in dairy cattle than in beef cattle. Routine monitoring of N. caninum and T. gondii infections and the implementation of control strategies are urgently needed.

Apicomplexans in Goat: Prevalence of Neospora caninum, Toxoplasma gondii, Cryptosporidium spp., Eimeria spp. and Risk Factors in Farms from Ecuador

Simple Summary

Neospora caninum, Toxoplasma gondii, Cryptosporidium and Eimeria species are parasites of phylum Apicomplexa, which includes several protozoa affecting animals and humans. In Ecuador, the maintenance of goat health is a matter of utmost importance because it affects the economic welfare of the breeders. N. caninum and T. gondii cause reproductive problems in goats, leading to abortions or weak offspring. Severe diarrhea in kids and delays in growth are due to the Cryptosporidium and Eimeria species. Moreover, T. gondii and Cryptosporidium are zoonotic parasites with serious consequences for human health. The aim of this work was to determine, by serological and parasitological tests, the prevalence of these parasites and the risk factors for goat populations in Southern Ecuador. On some farms, the prevalence of N. caninum and T. gondii reached more than 50%; up to 17% of the kids were positive for Cryptosporidium and 90% of the goats were positive for the Eimeria species. The analysis of risk factors revealed differences according to the parasite species. Considering the zoonotic significance of these results, control and prevention measures are essential and constitute a warning to veterinarians and governmental institutions.

Abstract

Neospora caninum, Toxoplasma gondii, Cryptosporidium and Eimeria cause severe impacts on the productivity of goat herds. The objectives of the present study were to establish the prevalence of these apicomplexans in goat farms from Ecuador; to evaluate a rapid test for Cryptosporidium diagnosis and to identify the risk factors associated with the infections. A questionnaire was designed to obtain information from 24 goat farms from Zapotillo, Garza Real, Cazaderos, Limones and Paletillas parishes in Ecuador. Blood (n = 388) and feces (n = 391) samples were collected. Indirect ELISA and standard parasitological assays were carried out to evaluate the seroprevalence of N. caninum and T. gondii and to detect oocysts of Cryptosporidium and Eimeria. The overall prevalence values of N. caninum and T. gondii were 12.11% and 18.20%, Cryptosporidium spp. and Eimeria spp. oocysts were detected in 10.49% and 89.51% of the total samples. A low correlation value was found between the results obtained by Ziehl-Nielsen and the rapid test. The multinomial logistic regression analysis revealed that vitamin supplementation, age of diarrhea, frequency of deworming, pasture area, presence of artiodactyls, domestic fowl, administration of sulfas, age group, body condition, abortions, type of pastures and the presence of cattle were risk factors according to the parasite species.

Spatial-temporal trends and economic losses associated with bovine abortifacients in central Argentina

The aims of this work are, firstly, to provide the geolocalization of cases of bovine abortion with definitive diagnosis and, secondly, to estimate the economic losses due to the most frequent abortifacients diagnosed agents in cattle in Buenos Aires province, Argentina. The total beef and dairy cattle population at risk of abortion is 8,358,186 and 538,076, respectively. In beef cattle, the overall risk of abortion was estimated at 4.5% for all pregnancies, where 27.9% are due to Campylobacter fetus, Neospora caninum, Leptospira spp., Brucella abortus, and bovine viral diarrhea virus with economic losses of US$ 440 per abortion, being the annual loss to the beef industry of US$ 50,144,101. In dairy cattle, there was an 8.0% risk of suffering abortion, 26.1% produced by the same abortigenic agents. The economic losses were estimated at US$ 1,415 per abortion, which equals a total loss of US$ 17,298,498 for the dairy industry in the region. The results of this study show that infectious causes are highly prevalent in Buenos Aires province, and they caused severe economic impacts in the dairy and beef industries. Furthermore, changes in temporal trends of infectious abortion occurrence were detected, probably related to the inclusion of molecular diagnostic techniques with more sensitivity or different epidemiological or husbandry conditions in the region analyzed.

Neosporosis in sheep: a systematic review and meta-analysis of global seroprevalence and related risk factors

Neosporosis is recognized as the main cause of abortions in cattle worldwide and there is an increasing concern about its role in ovine reproductive losses; however, epidemiological studies regarding neosporosis in sheep are still limited. This meta-analysis aimed to estimate the global pooled seroprevalence and associated risk factors of ovine neosporosis. In the current report, a comprehensive strategy of search and data collection from 7 worldwide databases was performed. A final set of 73 studies (80 datasets) published from 2000 to 2021 were selected based on inclusion criteria, comprising data on 35,740 sheep (corresponding to 37,565 evaluated samples) from 30 countries worldwide. The global pooled seroprevalence of Neospora caninum infection in sheep estimated by the random-effects model was 13% (95% CI, 10-15) and showed high heterogeneity (Q = 5147.15, I² = 98%, p< 0.001). Furthermore, by meta-analyses of subgroups it was demonstrated for the first time that seroprevalence significantly varied between continents (highest in Africa; 20%, 95% CI, 4-44), WHO regions (highest in African Region; 42%, 95% CI, 36-48), countries (highest in Colombia; 79%, 95% CI, 61-92%) and diagnostic methods (highest by IFAT; 17%, 95% CI, 12-23). Meta-regression indicated significant increasing trends in the prevalence of ovine neosporosis with decrease in geographical latitude (coefficient = -0.013; p<0.001), whereas longitude did not influence it (coefficient = -0.001; p=0.365). Regarding associated risk factors, older sheep were more likely to be infected with N. caninum than younger ones (OR 1.42; 95% CI 1.08-1.87), and sheep bred under intensive or semi-intensive systems resulted less susceptible to be seropositive than those bred under extensive system (OR 0.65; 95% CI 0.42-0.99 and OR 0.74; 95% CI 0.62-0.89, respectively). Conversely, no apparent association was found between seroprevalence and other variables, such as sex (OR 1.06; 95% CI 0.9-1.24), the presence of dogs on the farm (OR 1.15; 95% CI 0.63-2.12) or the presence of abortion (OR 1.80; 95% CI 0.87-3.74). In conclusion, the seroprevalence of ovine neosporosis is widely and heterogeneously distributed throughout the world, and it is negatively associated with increasing geographical latitude. In addition, age and extensive production system represent risk factors, which suggest that the horizontal transmission route is relevant for this host species. It is recommended to pay more attention to this disease and emphasize the global need for more indexed studies concerning the seroprevalence and risk factors of ovine neosporosis to better understand the epidemiology of this coccidian infection.

Diagnostic Investigation of 100 Cases of Abortion in Sheep in Uruguay: 2015–2021

The aim of this work was to identify causes of abortion through laboratory investigations in sheep flocks in Uruguay. One hundred cases of abortion, comprising 58 fetuses, 36 fetuses with their placentas, and 6 placentas were investigated in 2015–2021. Cases were subjected to gross and microscopic pathologic examinations, and microbiological and serological testing for the identification of causes of abortion, including protozoal, bacterial, and viral pathogens. An etiologic diagnosis was determined in 46 (46%) cases, including 33 (33%) cases caused by infectious pathogens, as determined by the detection of a pathogen along with the identification of fetoplacental lesions attributable to the detected pathogen. Twenty-seven cases (27%) were caused by Toxoplasma gondii, 5 (5%) by Campylobacter fetus subspecies fetus, and 1 (1%) by an unidentified species of Campylobacter. Fourteen cases (14%) had inflammatory and/or necrotizing fetoplacental lesions compatible with an infectious etiology. Although the cause for these lesions was not clearly identified, T. gondii was detected in 4 of these cases, opportunistic bacteria (Bacillus licheniformis, Streptococcus sp.) were isolated in 2 cases, and bovine viral diarrhea virus 1 subtype i (BVDV-1i) was detected in another. Campylobacter jejuni was identified in 1 (1%) severely autolyzed, mummified fetus. BVDV-2b was identified incidentally in one fetus with an etiologic diagnosis of toxoplasmosis. Microscopic agglutination test revealed antibodies against ≥1 Leptospira serovars in 15/63 (23.8%) fetuses; however, Leptospira was not identified by a combination of qPCR, culture, fluorescent antibody testing nor immunohistochemistry. Neospora caninum, Chlamydia abortus, Chlamydia pecorum, Coxiella burnetii and border disease virus were not detected in any of the analyzed cases. Death was attributed to dystocia in 13 (13%) fetuses delivered by 8 sheep, mostly from one highly prolific flock. Congenital malformations including inferior prognathism, a focal hepatic cyst, and enterohepatic agenesis were identified in one fetus each, the latter being the only one considered incompatible with postnatal life. Toxoplasmosis, campylobacteriosis and dystocia were the main identified causes of fetal losses. Despite the relatively low overall success rate in establishing an etiologic diagnosis, a systematic laboratory workup in cases of abortion is of value to identify their causes and enables zoonotic pathogens surveillance.

Epidemiological study of neosporosis in Uruguayan dairy herds

Neosporosis is one of the leading causes of abortion in cattle worldwide, posing a great economic burden on cattle producers. The aim of this study was to determine the national seroprevalence and putative risk factors of Neospora caninum (N. caninum) in dairy cattle in Uruguay. A cross-sectional study was carried out. Herds were stratified by size (1-50, 51-250, and >250 cattle) and up to 60 dairy cows per herd were randomly selected. Four thousand two hundred twenty-three serum samples from 102 dairy herds were analyzed by indirect ELISA test, under the manufacturer's recommendations. In addition, the herdsman was surveyed and a population study was carried out. The in degree data, geographical coordinates, and seroprevalence of bovine viral diarrhea, enzootic bovine leukemia and infectious bovine rhinotracheitis were available for each herd. A sampling design was used to estimate population seroprevalence of N. caninum. In order to determine the factors associated with the disease, herds with an intra-herd seroprevalence over 20% were considered as case herds. Seroprevalence of N. caninum was 22.3% (95% CI: 18.7-25.9 %) and 96.0% (95% CI: 92.1-99.8%) at the animal and herd level, respectively. The number of dogs on the dairy farms were associated with infection levels (OR: 1.43, 95% CI: 1.02 to 2.03). It was concluded that N. caninum is endemic in the country, and is spreading over dairy herds. Although this study showed evidence that the number of dogs were associated with high levels of infection, more studies should be conducted, to better understand the epidemiology of the disease and thus develop efficient control measures.

Neospora caninum infection in dairy farms with history of abortion in West of Iran

Neospora caninum is a major cause of abortion and economic losses among dairy farms in Iran and other countries. The main goal of current investigation was to evaluate the presence of antibodies against N. caninum and associated risk factors in dairy herds with history of abortion in Hamedan province of West Iran. A total numbers of 476 and 185 blood samples of pregnant cattle and farm dogs from 10 dairy farms with history of abortion were randomly collected. Bulk milk sample was taken from each farm. All samples were subjected for detection of IgG antibody against N. caninum using ELISA technique. Of all examined animals, 24.8% of cattle and 8.65% of dogs were seropositive to N. caninum. The seroprevalence had significant differences with abortion, stillbirth, metritis, breed, close contact to dogs, wild carnivores, rodents, poultry, and pregnancy using artificial insemination method. There were no significant differences among seroprevalence and different age groups, number and stage of gestation, and herd population. In all investigated farms, bulk milk examination was positive. In examined dogs, there was significant difference between seroprevalence and sex. It was concluded that N. caninum infection may be responsible for abortion and economic losses in dairy farms of the region. This was also the first comprehensive report on associated risk factors to N. caninum infection in dairy farms in the region.

Meta-analysis of the prevalence and risk factors associated with bovine neosporosis

Neospora caninum is one of the main infectious agents that cause reproductive disorders in cattle. However, knowledge about the prevalence and causal factors of bovine neosporosis is needed in order to establish control measures. The purpose of this study was to estimate the pooled prevalence and determine the risk factors of bovine neosporosis using meta-analytic methods. Searches for data on N. caninum seroprevalence and potential risk factors were conducted in the PubMed, LILACS, and SciElo databases. The random effects model was used for the meta-analysis of the included studies. The pooled prevalence of N. caninum in cattle was 24% (95% confidence interval (CI), 19-29) in North and Central America, 24% (95% CI, 20-28) in South America, 18% (95% CI, 14-21) in Asia, 15% (95% CI, 12-18) in Europe, 13% (95% CI, 11-16) in Africa, and 8% (95% CI, 4-14) in Oceania. A significant correlation was found between N. caninum infection and abortion in cows (odds ratio (OR) = 2.66, 95% CI, 1.97-3.59). The following risk factors were signicantly associated with N. caninum seroprevalence: presence of dogs on the farm (OR = 2.84; 95% CI, 1.40-5.80) and the type of cattle production system, with dairy cattle being more susceptible to bovine neosporosis (OR = 1.60; 95% CI, 1.16-2.19) than beef cattle. The adoption of measures to prevent the dissemination of N. caninum in cattle herds is suggested, aiming to reduce the economic losses incurred to the dairy and beef industry.

Antibodies to Neospora caninum in sheep from slaughterhouses in the state of São Paulo, Brazil

Neosporosis is an emergent disease responsible for considerable economic impact due to reproductive losses. Its zoonotic potential remains unknown. This study involved a survey of antibodies to Neospora caninum in slaughtered sheep and their association with epidemiological variables. Serum samples from 596 sheep from the states of São Paulo and Rio Grande do Sul, Brazil, were collected in two slaughterhouses located in São Paulo and evaluated by indirect fluorescence antibody test (IFAT), using cut-off titers of 25. Among these samples, 353/596 (59.23%; 95%CI 55.23-63.10) were positive and 263/353 (74.50%; 95%CI 69.71-78.77%) were from Rio Grande do Sul. Statistical associations were determined in the univariate analysis between the serological results and sex, breed and municipality of origin. Sheep that came from extensive breeding system showed higher chance (OR=2.09) of presenting antibodies to N. caninum in relation to those from semi-intensive system. Higher chance was also observed for the different studied breeds, except Bergamácia, in relation to Hampshire Down. The results revealed the presence of infection by N. caninum in sheep from slaughterhouses.

Frequency of Neospora caninum infections in beef cow-calf operations under extensive management

The aim of this study was to evaluate the frequencies of Neospora caninum horizontal and vertical transmissions in beef cow-calf operations under three different extensive management systems: group A: 0.75 head per hectare pasturing on natural grass; group B: 1.1 head per hectare on natural grass and improved cultured pastures; and group C: 2 head per hectare on natural grass, improved cultured pasture and whole corn silage. Serum samples from 72 multiparous cows assigned to each beef cow-calf operations were obtained every 3 months during 2 years. A group of 30 replacement heifers from each group were tested similarly since they were 10-21 months old. Twenty four, 20 and 34 calves from groups A, B and C respectively, were bled before colostrum intake and again 6 months later. The samples were analyzed by indirect fluorescence antibody test (IFAT) for detection of total IgG against N. caninum at a serological titre ≥ 200 for multiparous cows and replacement heifers, and a serological titre ≥ 25 for calves. Serum samples from seropositive cows were assessed by ELISA to evaluate the avidity of their specific antibodies. There were no differences in the proportion of seropositive cows from groups A, B and C at the beginning of the trial (p>0.05). Interestingly, the lowest serological titres in seropositive cows from all groups were observed during the first trimester (p<0.05). Although seropositive cows had medium to high avidity antibodies, suggesting chronic infection; seroconversion associated with low antibody avidity was found in 2, 3 and 3 seropositive cows from groups A, B and C. All replacement heifers remained seronegative. No abortions were recorded but 2, 1, and 2 calves from groups A, B and C were seropositive before colostrum intake, respectively. Seropositive calves born from cows having intermediate or high avidity remained with the same serostatus at 6 months of age. Even under varying extensive management conditions, both N. caninum horizontal and vertical transmission methods do occur in beef cow-calf operations.

Neospora caninum exposure in overlapping populations of coyotes (Canis latrans) and feral swine (Sus scrofa)

Limited information exists on Neospora caninum transmission dynamics in wildlife. This coccidian parasite, whose presence can lead to substantial economic losses in cattle operations, requires a canid definitive host for reproduction. We examined exposure in a definitive host, coyotes (Canis latrans), and in overlapping populations of feral swine (Sus scrofa) to determine if spatial proximity between a definitive and incidental host influences the likelihood of parasite exposure. Eighteen percent of coyotes (95% confidence interval [CI] = 14.2-21.8) and 15.8% of feral swine (95% CI = 12.5-19.2) had been exposed to N. caninum, and this is the first report of exposure in US feral swine populations. Analyses suggest that the parasite is present throughout the environment and that exposure is not temporally or spatially linked to antibody-positive coyotes. Antibody-positive feral swine were found in an area where the only definitive host is domestic dogs (Canis familiaris), indicating that wild canids are not required to maintain the parasite in the environment.

Control options for Neospora caninum--is there anything new or are we going backwards?

Recent work has highlighted and enumerated the economic annual losses due to Neospora caninum abortions worldwide, which should provide strong motivation for the control of bovine neosporosis. However, with the recent withdrawal from sale of the only commercially available vaccine, control options for N. caninum have become more restricted. While researchers continue to work on developing alternative efficacious vaccines, what are the control options presently available for the cattle industries? At the practical level, recommendations for 'Test-and-cull', or 'not breeding from seropositive dams' stand diametrically opposed to alternative options put forward that suggest a primary producer is better advised to keep those cows in the herd that are already seropositive, i.e., assumed to be chronically infected, and indeed those that have already aborted once. Treatment with a coccidiostat has been recommended as the only economically viable option, yet no such treatment has gained official, regulatory approval. Dogs are central to the life cycle of N. caninum and have repeatedly been associated with infection and abortions in cattle by epidemiological studies. Knowledge and understanding of that pivotal role should be able to be put to use in control programmes. The present review canvasses the relevant literature for evidence for control options for N. caninum (some of them proven, many not) and assesses them in the light of the authors' knowledge and experience with control of N. caninum.

Vaccines against neosporosis: what can we learn from the past studies?

Neospora caninum is an intracellular apicomplexan parasite, which is a leading cause of abortion in cattle; thus neosporosis represents an important veterinary health problem and is of high economic significance. The parasite can infect cattle via trans-placental transmission from an infected cow to its fetus (vertical transmission), or through the oral route via ingestion of food or water contaminated with oocysts that were previously shed with the feces of a canid definitive host (horizontal transmission). Although vaccination was considered a rational strategy to prevent bovine neosporosis, the only commercialized vaccine (Neoguard®) produced ambiguous results with relatively low efficacy, and was recently removed from the market. Therefore, there is a need to develop an efficient vaccine capable of preventing both, the horizontal transmission through infected food or water to a naïve animal as well as the vertical transmission from infected but clinically asymptomatic dams to the fetus. Different vaccine strategies have been investigated, including the use of live attenuated vaccines, killed parasite lysates, total antigens or antigen fractions from killed parasites, and subunit vaccines. The vast majority of experimental studies were performed in mice, and to a certain extent in gerbils, but there is also a large number of investigations that were conducted in cattle and sheep. However, it is difficult to directly compare these studies due to the high variability of the parameters employed. In this review, we will summarize the recent advances made in vaccine development against N. caninum in cattle and in mice and highlight the most important factors, which are likely to influence the degree of protection mediated by vaccination.

Neospora caninum and Wildlife

Bovine neosporosis caused by Neospora caninum is among the main causes of abortion in cattle nowadays. At present there is no effective treatment or vaccine. Serological evidence in domestic, wild, and zoo animals indicates that many species have been exposed to this parasite. However, many aspects of the life cycle of N. caninum are unknown and the role of wildlife in the life cycle of N. caninum is still not completely elucidated. In North America, there are data consistent with a sylvatic cycle involving white tailed-deer and canids and in Australia a plausible sylvatic cycle could be occurring between wild dogs and their macropod preys. In Europe, a similar sylvatic cycle has not been established but is very likely. The present review is a comprehensive and up to date summary of the current knowledge on the sylvatic cycle of N. caninum, species affected and their geographical distribution. These findings could have important implications in both sylvatic and domestic cycles since infected wildlife may influence the prevalence of infection in cattle farms in the same areas. Wildlife will need to be taken into account in the control measures to reduce the economical losses associated with this important disease in cattle farms.

What is the global economic impact of Neospora caninum in cattle - the billion dollar question

Neospora caninum is regarded as one of the most important infectious causes of abortions in cattle worldwide, yet the global economic impact of the infection has not been established. A systematic review of the economic impact of N. caninum infections/abortions was conducted, searching PubMed with the terms 'cattle' and 'Neospora'. This yielded 769 publications and the abstracts were screened for economically relevant information (e.g. abortion prevalence and risk, serological prevalence). Further analysis was restricted to countries with at least five relevant publications. In total, 99 studies (12.9%) from 10 countries contained data from the beef industry (25 papers (25.3%)) and 72 papers (72.8%) from the dairy industry (with the remaining two papers (2.0%) describing general abortion statistics). The total annual cost of N. caninum infections/abortions was estimated to range from a median US $1.1 million in the New Zealand beef industry to an estimated median total of US $546.3 million impact per annum in the US dairy population. The estimate for the total median N. caninum-related losses exceeded US $1.298 billion per annum, ranging as high as US $2.380 billion. Nearly two-thirds of the losses were incurred by the dairy industry (US $842.9 million). Annual losses on individual dairy farms were estimated to reach a median of US $1,600.00, while on beef farms these costs amounted to just US $150.00. Pregnant cows and heifers were estimated to incur, on average, a loss due to N. caninum of less than US $20.00 for dairy and less than US $5.00 for beef. These loss estimates, however, rose to ∼US $110.00 and US $40.00, respectively, for N. caninum-infected pregnant dairy and beef cows. This estimate of global losses due to N. caninum, with the identification of clear target markets (countries, as well as cattle industries), should provide an incentive to develop treatment options and/or vaccines.

Seroprevalence and risk factors associated with infection by Neospora caninum of dairy cattle in the state of Alagoas, Brazil

The objective of this study was to investigate the prevalence of anti-Neospora caninum antibodies in cattle from milk producing farms of the microregion of Batalha, state of Alagoas, Brazil, as well as to identify the risk factors associated with the infection. Blood samples were collected from 1,004 cattle of 17 farms for the serological investigation regarding the presence of anti-N. caninum antibodies by the Indirect Immunofluorescence Reaction Technique (IMRT). From the total amount of samples analyzed, 77/1,004 (7.67%) were positive and 927/1,004 (92.33%) were negative. The logistical regression identified that cattle from farms without consortium breeding have an infection risk 6.33 (p<0.001; C.I. 2.89-13.10) times higher than cattle from farms with that type of breeding. Cattle from farms where the aborted fetuses are not adequately buried have an infection risk 3.04 (p<0.001; C.I. 1.64-5.63) times higher than cattle from farms with adequate destination of these fetuses. Infection by N. caninum occurs in cattle of the investigated region. The factors identified in our study can be used as risk indicators, so that control measures could be implemented to avoid infection by N. caninum in the herds of this region.

A review of the infection, genetics, and evolution of Neospora caninum: from the past to the present

This paper is a review of current knowledge on Neospora caninum in the context of other apicomplexan parasites and with an emphasis on: life cycle, disease, epidemiology, immunity, control and treatment, evolution, genomes, and biological databases and web resources. N. caninum is an obligate, intracellular, coccidian, protozoan parasite of the phylum Apicomplexa. Infection can cause the clinical disease neosporosis, which most notably is associated with abortion in cattle. These abortions are a major root cause of economic loss to both the dairy and beef industries worldwide. N. caninum has been detected in every country in which a study has been specifically conducted to detect this parasite in cattle. The major mode of transmission in cattle is transplacental (or vertical) transmission and several elements of the N. caninum life cycle are yet to be studied in detail. The outcome of an infection is inextricably linked to the precise timing of the infection coupled with the status of the immune system of the dam and foetus. There is no community consensus as to whether it is the dam's pro-inflammatory cytotoxic response to tachyzoites that kills the foetus or the tachyzoites themselves. From economic analysis the most cost-effective approach to control neosporosis is a vaccine. The perfect vaccine would protect against both infection and the clinical disease, and this implies a vaccine is needed that can induce a non-foetopathic cell mediated immunity response. Researchers are beginning to capitalise on the vast potential of -omics data (e.g. genomes, transcriptomes, and proteomes) to further our understanding of pathogens but especially to identify vaccine and drug targets. The recent publication of a genome for N. caninum offers vast opportunities in these areas.

Study of the risk factors associated with Neospora caninum seroprevalence in Algerian cattle populations

Bovine abortions due to Neospora caninum infection were reported worldwide. The situation in Algeria was unknown. For the evaluation of the prevalence of N. caninum and its associated risk factors, 799 cattle belonging to 87 farms of the north and northeast of Algeria were analyzed. The cattle were divided into imported cattle, local cattle and improved cattle corresponding to breeding between imported and local cattle. Sera were examined for the presence of N. caninum antibodies by indirect fluorescence antibody test. The overall seroprevalence for the 87 farms was 52.87% (41.28-62.71%). The overall animal seroprevalence was 19.64% (16.82-22.45%). The seroprevalence of N. caninum in local cattle (34.28%) was significantly higher (p<0.05) than in modern (16.04%) and improved (18.64%) cattle. The risk factors analysis indicated that cattle population, geographical location, dog presence, season, global farm hygiene or the presence of abortion were significantly associated with seroprevalence.

Seroprevalence and risk factors associated with neosporosis in sheep and dogs from farms

This study aimed to establish the seroprevalence and risk factors associated with neosporosis in sheep and dogs from rural properties. 1497 blood samples were collected from sheep and 42 from dogs that cohabited with sheep from 16 farms located in the central region of São Paulo State, Brazil. For the detection of N. caninum antibodies it was performed the indirect fluorescent antibody test (IFAT ≥ 25). For the epidemiological study it was applied a questionnaire for the owners or responsible from the sheep and dogs regarding informations related to neosporosis. The seroprevalence obtained out of the 1497 sheep sera tested was 8.0% (CI95%=6.7-9.2%) and out of the 42 dogs 4.8% (CI95%=0-7.2%). Variables statistically related to seropositivity for N. caninum in sheep were: dams well as water supply (P=0.0004; OR=2.15), presence of other domestic canids (P=0.0013; OR=2.38) and presence of reproductive problems (P=0.0031; OR=1.75).

Epidemiology and control of neosporosis and Neospora caninum

Neospora caninum is a protozoan parasite of animals. Until 1988, it was misidentified as Toxoplasma gondii. Since its first recognition in dogs in 1984 and the description of the new genus and species Neospora caninum in 1988, neosporosis has emerged as a serious disease of cattle and dogs worldwide. Abortions and neonatal mortality are a major problem in livestock operations, and neosporosis is a major cause of abortion in cattle. Although antibodies to N. caninum have been reported, the parasite has not been detected in human tissues. Thus, the zoonotic potential is uncertain. This review is focused mainly on the epidemiology and control of neosporosis in cattle, but worldwide seroprevalences of N. caninum in animals and humans are tabulated. The role of wildlife in the life cycle of N. caninum and strategies for the control of neosporosis in cattle are discussed.

If control of Neospora caninum infection is technically feasible does it make economic sense?

Recent work on Neospora caninum, a protozoan parasite that causes abortions in dairy cattle has focused on a number of different control options. Modelling has suggested the most effective options for control but the present paper argues that the most effective option might not necessarily be optimal from an economic point of view. Decision trees, using published quantitative data, were constructed to choose between four different control strategies. The costs of these interventions, such as 'test and cull', therapeutic treatment with a pharmaceutical, vaccination or "doing nothing" were compared, and modelled, in the first instance, on the New Zealand and Australian dairy situation. It is argued however, that the relative costs in other countries might be similar and that only the availability of a registered vaccine will change the decision tree outcomes, as does the within-herd prevalence of N. caninum infection. To "do nothing" emerged as the optimal economic choice for N. caninum infections/abortions up to a within-herd prevalence of 18%, when viewed over a 1-year horizon, or 21% when costs were calculated over a 5 years horizon. For a higher (>or=21%) within-herd prevalence of N. caninum infection vaccination provided the best (i.e. most economic) strategy. Despite being the most efficacious solutions, 'test and cull' or therapeutic treatment never provided a viable economic alternative to vaccination or "doing nothing". Decision tree analysis thus provided clear outcomes in terms of economically optimal strategies. The same approach is likely to be applicable to other countries and the beef industry, with only minor changes expected in the relationships of decisions versus within-herd prevalence of N. caninum infection.

Humoral immune reaction of newborn calves congenitally infected with Neospora caninum and experimentally treated with toltrazuril

Neospora caninum is widely recognized as one of the most important infectious organisms causing abortion and stillbirth in cattle. This parasite causes severe economical losses worldwide. Infection is mostly passed vertically from mother to calf during pregnancy. Under certain circumstances, an infection can lead to abortion, but in most cases it results in a chronically infected calf, which itself will represent the next endogenously infectious generation. So far, no reliable therapeutic or metaphylactic tool has been developed. One possibility to control the problem may consist of treating newborn calves that became vertically infected by a persistently infected mother. This may allow parasite-free offspring. The aim of the present study was to address the questions: (1) can serology be used to assess efficiency of treatment in toltrazuril-medicated animals? and (2) is a strategic prevention measure possible by means of producing N. caninum-free calves from positive cows? Calves from Neospora-seropositive cows and heifers were randomly split into two different medication groups: 36 calves were medicated with toltrazuril and 36 calves obtained a placebo. Medication (20 mg toltrazuril per kg bw) was administered three times, every second day, within the 7 days post natum. Three months after medication, there was no difference in antibody reactivity between the two groups. At later time points (4-6 months), however, significant differences were found, as explained by a strong humoral immunity after chemotherapeutical affection of parasites, while the placebo-treated animals only responded weakly to the persistent infection. In summary, we concluded that (1) serology was not an entirely appropriate tool to answer our initial question and (2) toltrazuril has the potential to eliminate N. caninum in newborn calves. As a consequence, we plan to follow up toltrazuril-medicated calves clinically and serologically over a longer period and investigate if they give birth to Neospora-free calves.

Risk factors associated with Neospora caninum abortion in Ontario Holstein dairy herds

The objective of this epidemiological study was to identify risk factors for Neospora caninum-related abortions in Ontario Holstein dairy herds. A total of 88 herds, consisting of 5080 cattle, and utilizing Dairy Herd Improvement (DHI) services, were divided into three groups. Case (n = 30) and first control (n = 31) herds were selected from 1998 and 1999 fetal abortion submissions to the Animal Health Laboratory, University of Guelph, that were histopathologically positive or negative, respectively, for N. caninum. A second control group (n = 27) was selected from multiple sources of herds sampled within the previous 4 years that had a low seroprevalence (<7%) to N. caninum. Between May and December 1999, all available cows on all farms, in parity one or greater, were blood sampled. The sera were then analyzed for antibody to N. caninum using a kinetic ELISA. A survey administered at the time of sampling recorded information on housing, animal species present, manure management, reproduction, biosecurity practices, wildlife observations, peri-parturient cow management, herd disease history and nutrition. Production and other herd parameters were obtained from DHI records. Logistic regression indicated that the following parameters were positively associated with a N. caninum abortion in a herd: the N. caninum herd seroprevalence (OR = 1.1), the total number of dogs on a farm (OR = 2.8), the frequency that dogs were observed defecating in mangers (OR = 2.8), the number of horses on a farm (OR = 3.1), the observed annual rate of retained fetal membranes (OR = 1.2) and the observed annual rate of cows returning to estrus after pregnancy confirmation (OR = 1.2). Factors negatively associated were the frequency of stray cats and wild canids observed on a farm (OR = 0.4 and OR = 0.7, respectively) and the housing of heifers on loafing packs (a housing pen divided into feed manger, scrape alley and bedded pack areas, OR = 0.1).

Potential risk factors for bovine Neospora caninum infection in Germany are not under the control of the farmers

In the German state of Rhineland-Palatinate, herds were identified that were likely to have a Neospora caninum sero-prevalence > or = 10% by using a bulk milk ELISA. Individual herd data were obtained by a questionnaire. Univariate logistic regression showed that bulk milk positive farms had a significantly higher chance to report an increased abortion rate than negative farms (P(Wald)<0.1). The chance to have a bulk milk positive herd increased with the minimum number of years a farm had reported an increased abortion rate (P(Wald)<0.1). Questionnaire data, population and dog density as well as climatic data specific for the farm localization were used to identify potential risk factors for a herd to have acquired N. caninum infections. Within an optimized multiple logistic regression model 'Number of farm dogs', 'Herd size', and factors related to the municipality the farm was localized, i.e. 'Mean temperature in July', and 'Dog density' were significant risk factors (P(Wald)<0.1). The present study underlines the role farm dogs have in the epidemiology of neosporosis. In addition, it suggests that the risk a herd has to acquire N. caninum infections is also associated with factors related to the farm location, i.e. factors that are largely out of the control of farmers.

Prevalence of Neospora caninum antibodies and factors associated with their presence in dairy cattle of the north of Paraná state, Brazil

To determine the prevalence of Neospora caninum antibodies and associated factors, blood sera from 623 female dairy cattle from 23 farms in the north of the state of Paraná, Brazil, were analyzed by means of the indirect immunofluorescent-antibody test (IFAT > or = 25). Serum samples from 134 dogs living on the same farms also were tested for N. caninum antibodies (IFAT > or = 50), and the presence of dogs was associated with the prevalence of N. caninum antibodies in cattle. The overall seroprevalence in cattle was 14.3%, mainly in animals over 24 months of age. Seroprevalence in Holsteins (15.1% of 558) was greater than in mixed-breed cattle (7.7% of 65). Age (> or =24 months) of cattle, feeding silage and/or concentrate produced on the farm were associated; antibodies were found in 21.6% of dogs; and the presence of dogs was associated with the prevalence of N. caninum antibodies in cattle.

Parelaphostrongylus tenuis and other parasitic diseases of the ruminant nervous system

There are many parasites that affect the ruminant central nervous system. Clinical signs can vary dramatically based on the location and mobility of the parasite. Clinical disease can occur due to the physical presence of the parasite and the resulting host immune response or the toxin produced by the parasite. Differentiating the cause of disease is particularly important because prognosis,treatment, and subsequent control measures vary dramatically depending on the disease process. This article focuses on the pathogenesis,treatment, and control of some of the more common parasitic diseases of the ruminant central nervous system.

Regional distribution of bovine Neospora caninum infection in the German state of Rhineland-Palatinate modelled by Logistic regression

To obtain a rapid overview over the distribution of bovine Neospora caninum-infections in the German state of Rhineland-Palatinate, an ELISA to determine specific bovine antibodies against a p38 surface antigen of N. caninum tachyzoites was modified to examine bulk milk samples from cattle herds. Experimental bulk milk samples were used to demonstrate that the seroprevalence in a group of animals can be estimated with this ELISA. A cut-off was selected for the specific detection of herds having a seroprevalence > or =10%. About 90% of the dairy herds located in Rhineland-Palatinate were examined. An overall prevalence of bulk milk-positive herds of 7.9% (95% confidence interval 7.0-8.9%), respectively, was determined. Major regional differences in the distribution of bulk milk-positive herds were observed. Prevalences were higher in regions with an increased degree of urbanisation. Logistic regression was applied to model the prevalence of bulk milk-positive herds on a district and city level. Variables describing the dog density, mean temperature in July, mean temperature in January and the total yearly precipitation in districts and cities were able to explain most of the observed variability in the regional prevalences. Our results provide evidence that in addition to risk factors related to individual farms also risk factors related to the farm location such as dog density in the surrounding and climate factors are important in the epidemiology of bovine neosporosis.

Seroprevalence and associated risk factors of neosporosis in beef and dairy cattle in Italy

A cross-sectional serological survey for Neospora caninum was carried out on beef and dairy cattle in southern and northern Italy. A total of 111 herds and 1140 animals were tested using an ELISA assay (CHEKIT-Neospora) to detect anti-N. caninum antibodies. Management and individual data were collected and analysed both by linear and logistic multiple-regression models in order to find good predictors of the cattle seroprevalence and anti-N. caninum antibody level. At least one seropositive animal was found in 49 herds (44.1%), of which 31 (39.7%) from southern Italy and 18 (54.5%) from northern Italy. A total of 126 head of cattle (11%) were found to be seropositive and the seroprevalence was lower in southern (8.7%) than in northern Italy (16%). One of the best predictors of neosporosis seroprevalence in this study was the practice of self-rearing replacement heifers. Further risk factors were linked to higher stocking density, i.e. animals farmed in large herds and with no summer or permanent grazing practices were more likely to be seropositive than others. Farms with two or more dogs had higher herd seropositivity than farms with one or no dogs and this factor interacted significantly with the farm size and presence of poultry. Among individual characteristics, seropositivity was higher in animals sampled in mid- or late-pregnancy compared to animals either in early pregnancy or not pregnant. There was a significant interaction between the factors for pregnancy status and grazing practices. None of the epidemiological data recorded was a good predictor of the anti-N. caninum antibody level.

Reproductive Losses due to Neospora caninum in a Beef Herd in Argentina

Reproductive losses in a beef herd of 857 heifers with a pregnancy rate of 86.3% are described. After pregnancy testing, 69 abortions were seen during a 3 month period. Before calving season, three heifers had delivered pre-mature non-viable calves. Serum samples from 58 of 69 aborted heifers were available for serological tests. In order to compare the seroprevalence in non-aborted vs. aborted heifers, 214 pregnant animals were bleed during the abortion storm. In addition, blood samples were collected from two heifers with pre-mature calves and from 16 heifers with their calves prior to colostrum intake. All available serum samples were tested for Neospora caninum antibodies using an indirect fluorescence antibody test (IFAT). Fifty-nine of 290 (20.3%) evaluated heifers were seropositive. Heifers that aborted and heifers with pre-mature calves were more likely to be seropositive than pregnant heifers and heifers with normal calves [odds ratio (OR), 12.01; 95% CI, 6.18-23.30]. Vaginal mucus from four aborted heifers, and samples from two aborted foetuses and three pre-mature calves were available. Laboratory tests for Tritrichomonas foetus, bacterial and viral isolation, and histological examination were performed. Culture from vaginal mucus and foetal samples were negative. Histological lesions consistent with neosporosis and positive immunohistochemistry (IHC) to N. caninum were found in one aborted foetus and in one pre-mature calf. It is the first description of reproductive losses because of N. caninum in beef herds in Argentina.