Investigations by PCR analysis of neospora caninum prevalence and co-infection with toxoplasma gondii in naturally infected populations

Neospora caninum and Toxoplasma gondii are closely related intracellular protozoanparasites associated with abortion in mammals. TV! caninum was identified in 1984, describedas a new species in 1988 and often previously misidentified as T. gondii.hi this study molecular techniques were used to investigate the presence of TV. caninum and T.gondii in naturally infected populations.To facilitate this a nested PCR technique, targeting the Nc5 region of N. caninum, wasdeveloped. Using this and an established T. gondii specific PCR the prevalence ofN. caninumand co-infection with T. gondii were investigated hi naturally infected mammals.The fox has been identified as a potential definitive host of TV. caninum. PCR analysis of DNAextracted from tongue tissue determined a low prevalence of 1.4% (1/70) hi British foxes.None of these foxes had detectable T. gondii DNA. Small mammals are a potential source ofTV. caninum infection. TV. caninum was present in the brain tissues of all species investigated:Mus domesticus 3.1% (4/130), Rattus norvegicus 4.4% (2/45), Apodemus sylvaticus 3.4%(4/118) and Oryctolagus cuniculus 10.5% (6/57). T. gondii prevalences were significantlyhigher in all species tested. Co-infection was observed hi all species except Rattus norvegicus.Investigation of vertical transmission of T. gondii in wild Mus domesticus, determined it wasa common occurrence with 74.6% of foetuses from infected dams having detectable parasiteDNA.A relatively high frequency of infection with TV. caninum was detected hi brain tissue ofaborted lambs (18.9%). No significant relationship was found between TV. caninum and T.gondii infection. Detection of TV. caninum DNA was restricted to the brain in aborted lambsbut was more widely distributed in rabbits. T. gondii DNA was detected in multiple tissues ofboth host species.These studies demonstrate that TV. caninum is widely distributed in natural populations ofmammals