Menelaos Lefkaditis1, Zoi Athanasakopoulou1, Rustem Bayramoglou2, Marina Sofia1, Dimitris C Chatzopoulos3, Vassiliki Spyrou4 and Charalambos Billinis1,3*
1Faculty of Veterinary Science, Greece
2Private practice veterinarian, Greece
3Faculty of Public and One Health, Greece
4Faculty of Animal Science, Greece
*Corresponding author: Charalambos Billinis, Faculty of Veterinary Science, Greece
Submission: January 20, 2022;Published: January 31, 2022
ISSN: 2576-9162 Volume8 Issue5
Neospora caninum is a major cause of reproductive problems in cattle worldwide. The aim of the present study was to describe the rate of N. caninum infection among cows that presented reproductive problems in Greece. Nine hundred and thirty-one blood samples were collected from an equal number of dairy cows that had presented abortion or decreased reproductive performance and were subjected to serological detection of IgG N. caninum antibodies. Subsequently, brain tissue samples from aborted fetuses were collected from cows that were found positive for N. caninum antibodies and were molecularly tested for the presence of the parasite. Antibodies against N. caninum were found in 200 of the blood samples tested and the presence of the parasite was genomically confirmed in all the examined fetal brain tissue samples. This report provides evidence of N. caninum role as a cause of cattle reproduction problems in Greece and underlines the need for the implementation of effective preventive measures.
Keywords:Neospora caninum; Neosporosis; Cattle; Reproductive problems; ELISA
Neospora caninum (Sarcocystidae) is a protozoan parasite which is the etiological agent of neosporosis [1-3]. This apicomplexan parasite was initially recognized in 1984 from dogs in Norway  and was described as a new genus and species in 1988 . In the N. caninum life cycle, dogs and other related canids are, beside their role as intermediate hosts, the only definitive hosts that shed through their feces the oocysts for a variable period of time into the environment [6-9]. N. caninum has been reported in a large number of intermediate hosts worldwide, such as ruminants, horses, rabbits, mice, deer, badgers, polecats, ferrets and mink [10-12], while it is not considered as a zoonotic agent although antibodies against N. caninum have been reported in human tissues . Neosporosis has emerged as a serious disease only in cattle and dogs. Regarding cattle, neosporosis is recognized as one of the most important causes of cow reproductive and infertility problems and abortions worldwide while it can also cause increased mortality in newborn calves [8,10]. When a cow becomes infected from dog feces, the infection spreads via tahyzoites to other tissues of the body and to the placenta in cases of pregnancy, where damage to the placenta or vertical transmission through the placenta to the fetus can occur. Vertical transmission of N. caninum is considered the principal route of infection in cattle  while a cow may pass the infection to multiple offspring . Abortion may be a result of both the primary damage and the immune mediated inflammatory response of the cow [15,16]. Calves that are infected in utero may be born weak, underweight and with neurological symptoms such as ataxia, decreased reflexes and exophthalmia [3,8]. Neosporosis has a serious economic impact within a flock especially if the prevalence is high. This results from direct costs such as the value of fetuses and indirect costs, including veterinarian support, costs associated with rebreeding, possible loss of milk yield, and replacement costs if aborted cows are culled [17,18]. The aim of this study was to describe the rate of N. caninum infection among cows that presented reproductive problems in Greece.
During 2018-2021, blood samples were collected in Greece from 931 dairy cows that presented reproductive problems, including abortions (n=384) and decreased reproductive performance (n=547). All samples were examined by an indirect Enzyme-Linked Immunosorbent Assay (ELISA) for the detection of IgG antibodies against N. caninum (IDVet, Montpellier, France). In addition, tissue samples from aborted fetuses were collected from cows that were found positive for N. caninum antibodies and were examined by nested polymerase chain reaction (PCR) for N. caninum. The presence of the NC-5 gene was evaluated using the primers and conditions described by Corbellini .
Antibodies against N. caninum were found in 200 (21.5%) of the 931 samples tested (Table 1). Eighty-seven of the positive samples originated from cows that had aborted and 113 from cows with decreased fertility. Among the cows that presented abortion, 48 had aborted in the first lactating period, 10 in the second and 29 in early gestation (32-70 days). Nested PCR for N. caninum in seven brain samples, which were collected from the aborted fetuses of an equal number of positive for N. caninum cows, recorded a positive result. Brain samples were not collected from the fetuses of all the cows that had aborted either due to early abortion (32-70 days) and subsequent insufficient development of the brain (n=29) or due to advanced autolysis of the fetus (n=51).
Table 1: Characteristics of the farms included in the study.
Abortions and neonatal mortality are a major problem in livestock. Neosporosis is recognized as one of the most important causes of reproductive problems and abortion in cattle worldwide [8,10,20,21]. Abortions and neonatal mortality can cause severe financial losses, especially when the disease is endemic or epidemic. In this study a large amount of reproductive problem cases was investigated using the combination of two techniques (ELISA and PCR). The results recorded in our research showed the spread of Neosporosis among 21.5% of the dairy cows that had such problems. Previous studies have shown prevalence of N. caninum infection among cows presenting abortion that varies from 12 to 42% [22-25]. Abortions due to N. caninum have been described to occur starting in month three of gestation and until delivery [10,21,26] in an epidemic or endemic manner . Of note, our study records several cases occurring between the first 32 to 70 days of gestation. In addition, the present study records that most miscarriages due to neosporosis occurred during the first lactation period, which indicates that the infections were recent and that preventive measures should be implemented on the infected farms. N. caninum can also cause fetal viability disorders or neurological birth defects in newborn calves [28,29] and calves younger than 2 months of age . The N. caninum-infected young calves may present neurologic signs, low birth weight , difficulties to rise and stand, flexed or hyperextended hind and/or forelimbs, and in some cases exophthalmia or asymmetrical appearance of the eyes. However, most of the calves born congenitally infected remain clinically healthy [31-33]. The aforementioned situations lead to additional financial losses for the breeders and, thus, the employment of preventive measures is necessary . In cattle, the transplacental transmission is the most frequent route of infection, being observed in up to 93.7% of cases . Dogs play an important role in the horizontal transmission and maintenance of N. caninum infection in dairy cattle [6-8] and subsequently keeping dogs away from infected breeding is recommended .
Neosporosis is a very important parasitic disease which can cause infertility, abortions, neonatal mortality and other clinical symptoms in dairy cattle. Frequent preventive laboratory tests are needed to determine the causes of infertility, miscarriages and birth of calves with characteristic clinic symptoms. Preventive measures and special management are needed in infected flocks with N. caninum.
This research has been co‐financed by the European Regional Development Fund of the European Union and Greek national funds through the Operational Program Competitiveness, Entrepreneurship and Innovation, under the call RESEARCH– CREATE–INNOVATE (Acronym: the summer cow, project code: T1EDK-01078).
© 2022 Charalambos Billinis. This is an open access article distributed under the terms of the Creative Commons Attribution License , which permits unrestricted use, distribution, and build upon your work non-commercially.