Smith K E, Zimmerman J J, Patton S, Beran G W, Hill H T
Department of Microbiology, Immunology, Iowa State University, Ames 50011.
Vet Parasitol. 1992 May;42(3-4):199-211. doi: 10.1016/0304-4017(92)90062-e.
Multiparous sows from 19 central Iowa swine farms were tested for antibodies against Toxoplasma gondii by the modified direct agglutination test. Antibody titers of 1:32 or greater were considered positive. Rodents, domestic cats, opossums (Didelphis virginiana), raccoons (Procyon lotor) and striped skunks (Mephitis mephitis) were live-trapped on each farm and similarly tested for antibodies. The overall prevalence of T. gondii antibodies in the species tested was 39/273 (14.3%) swine, 31/74 (41.9%) cats, 2/588 (0.3%) house mice (Mus musculus), 0/21 mice of the genus Peromyscus, 0/9 Norway rats (Rattus norvegicus), 1/34 (2.9%) opossums, 4/14 (28.6%) raccoons and 2/7 (28.6%) striped skunks. The overall prevalence was significantly greater in adult cats versus juvenile cats, adult male cats versus adult female cats, and adult raccoons versus juvenile raccoons. The prevalence of T. gondii antibodies in sows was compared with the prevalence in each non-swine species on a farm basis in order to identify existing associations. The prevalence in sows (and each of the non-swine species) was also analyzed on a farm basis for association with farm characteristics or swine management practices, including the degree of confinement of swine, population size and average parity of breeding female swine, estimated cat population size, and estimated mouse and rat abundance. Average titers of seropositive animals were compared on a species basis. The prevalence in sows which were totally and continuously confined was lower than that in sows which were not totally and continuously confined. The prevalence in sows from farms with an average parity of less than 2.0 was significantly lower than that in sows from farms with an average parity of 2.0 or greater. These results suggested that the prevalence of T. gondii antibodies in swine increased with age and that prevalence in swine could be reduced through total confinement. No associations could be established between prevalence in sows and prevalence in non-swine species or other farm characteristics/swine management practices. However, the high prevalence of T. gondii antibodies in cats suggested that fecal contamination of the environment by cats may be the most significant source of toxoplasmosis for swine. The extremely low prevalence of T. gondii antibodies in house mice suggested that this species was not an important source of T. gondii for swine in Iowa.
通过改良直接凝集试验，对来自爱荷华州中部19个养猪场的经产母猪进行了抗刚地弓形虫抗体检测。抗体效价为1:32或更高被视为阳性。在每个农场对啮齿动物、家猫、负鼠（弗吉尼亚负鼠）、浣熊（北美浣熊）和条纹臭鼬（北美臭鼬）进行活体诱捕，并同样检测抗体。在所检测的物种中，刚地弓形虫抗体的总体流行率为：猪39/273（14.3%）、猫31/74（41.9%）、家鼠（小家鼠）2/588（0.3%）、白足鼠属的小鼠0/21、褐家鼠0/9、负鼠1/34（2.9%）、浣熊4/14（28.6%）和条纹臭鼬2/7（28.6%）。成年猫与幼年猫、成年雄性猫与成年雌性猫以及成年浣熊与幼年浣熊之间的总体流行率差异显著。为了确定现有的关联，在农场层面将母猪中刚地弓形虫抗体的流行率与每个非猪物种中的流行率进行了比较。还在农场层面分析了母猪（以及每个非猪物种）中抗体流行率与农场特征或养猪管理实践之间的关联，包括猪的圈养程度、种群规模、繁殖母猪的平均胎次、估计的猫种群规模以及估计的小鼠和大鼠数量。按物种比较了血清阳性动物的平均效价。完全且持续圈养的母猪中的流行率低于未完全且持续圈养母猪中的流行率。平均胎次小于2.0的农场的母猪中的流行率显著低于平均胎次为2.0或更高的农场的母猪中的流行率。这些结果表明，猪中刚地弓形虫抗体的流行率随年龄增加，并且通过完全圈养可降低猪中的流行率。在母猪中的流行率与非猪物种中的流行率或其他农场特征/养猪管理实践之间无法建立关联。然而，猫中刚地弓形虫抗体的高流行率表明，猫对环境的粪便污染可能是猪感染弓形虫病的最重要来源。家鼠中刚地弓形虫抗体的极低流行率表明，该物种不是爱荷华州猪感染刚地弓形虫的重要来源。
