Maas J, Lincoln S D, Coan M E, Kuttler K L, Zaugg J L, Stiller D
Am J Vet Res. 1986 Mar;47(3):528-33.
The prevalance of Anaplasma marginale-infected cows, as determined by use of the modified rapid card agglutination (MRCA) test, was measured during a 4-year period (1980-1983). The prevalence of A marginale-infected cows, defined as positive reactors on the MRCA test, remained constant (31%-37%). The apparent incidence of A marginale transmission to susceptible cows was approximately 7% from 1980 to 1981, 8% from 1981 to 1982, and no transmission from 1982 to 1983. The occasional MRCA-positive cow became negative on the MRCA test, and 1 cow was determined to be free of A marginale infection by subinoculation of 100 ml of the cow's blood into a susceptible, splenectomized calf. Dermacentor andersoni, a known vector of A marginale, was often found on the cattle and in their environment. However, A marginale was not transmitted to susceptible, splenectomized calves, using collected ticks. Of 56 calves born to MRCA-positive cows, 82% were MRCA-positive within the first 3 months of life. These calves converted to MRCA-negative status and were determined to be free of A marginale infection by subinoculation of their blood into susceptible, splenectomized calves, indicating the passive transfer of colostral antibodies.
在1980年至1983年的4年期间，使用改良快速卡片凝集试验（MRCA）测定了边缘无形体感染奶牛的流行率。边缘无形体感染奶牛的流行率（定义为MRCA试验中的阳性反应动物）保持恒定（31%-37%）。1980年至1981年，边缘无形体向易感奶牛的表观传播率约为7%，1981年至1982年为8%，1982年至1983年无传播。偶尔有MRCA阳性的奶牛在MRCA试验中变为阴性，通过将100毫升奶牛血液接种到易感的脾切除小牛体内，确定1头奶牛无边缘无形体感染。边缘无形体的已知传播媒介安德逊革蜱经常在牛及其环境中被发现。然而，使用收集到的蜱虫，边缘无形体并未传播给易感的脾切除小牛。在MRCA阳性奶牛所生的56头小牛中，82%在出生后的前3个月内为MRCA阳性。这些小牛转变为MRCA阴性状态，并通过将其血液接种到易感的脾切除小牛体内确定无边缘无形体感染，这表明初乳抗体的被动转移。
