A longitudinal research was performed inside a Swedish dairy herd where Neospora caninum had been isolated from a stillborn calf. external illness in the herd could not be recognized. Keywords: Neospora caninum, parasite, cattle, transmission, abortion, antibodies, IgG avidity Intro Neospora caninum is definitely a cyst-forming coccidian parasite which may infect several mammalian species although it is definitely clinically most important in cattle where it can cause abortion, stillbirth and the birth of feeble calves [15]. In the bovine, transplacental transmission of N. caninum from dam to foetus is considered the most important mode of illness and can happen in consecutive pregnancies [1,4]. However, post natal N. caninum illness has also been observed in cattle herds [8,13,17,33]. The dog, a definitive sponsor of the parasite [20], has been suggested like a source of such a transmission [16]. The risk of abortion is generally higher in cows congenitally infected with N. caninum than in non-infected animals [4,32]. However, abortion outbreaks have also been associated with recently acquired N. caninum illness [21,22]. The presence of antibodies to N. caninum in the serum of an individual indicates that it is, or has previously been, infected with the parasite. Antibodies can be shown by different serological checks [7], including the IgG avidity ELISA that can be used to discriminate between recent and chronic N. caninum infections [6]. With this paper, we describe a long-term serological investigation of the dynamics of N. caninum illness inside a Swedish dairy herd, and its effects on reproduction. Materials and methods Animals A herd of Swedish reddish and white breed dairy cattle, in which N. caninum was isolated from a stillborn calf [26], was investigated inside a longitudinal study from 1994 to 1999. The farm, situated in central Sweden, included around 40 milking cows. The heifer calves were kept for dairy replacement and the bull calves were reared until slaughter. The herd was free from bovine disease diarrhoea disease (BVDV) illness when it joined the TMC 278 Swedish control system for BVDV in 1993 [18], and offers remained free since then. The milking cows were housed indoors in tie stalls during winter season and were pastured during summer season. Heifers and bull calves were kept outdoors inside a loose housing system in winter season and were pastured during the summer season. Calves more youthful than 3 months had been held indoors in pens. The pets had been given hay and focus regarding to Swedish criteria. The heifers TCF3 and cows were inseminated artificially. Heifers were included in a bull if inseminations were unsuccessful repeatedly. Pregnancies had been diagnosed by TMC 278 transrectal palpation at 6C8 weeks. A lot of the calvings occurred during autumn or summer. Calvings that happened during summer months or early fall occurred on pasture, even though through the cool period the cows calved in another calving container TMC 278 indoors. The cow and calf spent together at least 4 times. Placentas, if retrieved, had been usually removed outdoors without special caution taken up to prevent usage of scavengers and predators. Eleven from the 1-year-old heifers within the herd in 1994 acquired suckled foster dams for an interval during the prior year. As the cows and calves moved freely the calves could have suckled cows apart from the foster dam also. All foster cows have been culled at our initial trip to the plantation, and weren’t sampled. All pets in the herd had been descendants of 2 cows, among which have been bought in 1933, as well as the various other in the 1940s. Several cows have been presented in the 1970s but by 1994 no descendants of the continued to be in the herd. In 1994 a puppy was purchased January. Before that now there have been no canines on the plantation at least since 1952. In March 1998 another pup was bought. The canines had been working canines and had free of charge.