Hardy W D, Hess P W, Essex M, Cotter S, McClelland A J, MacEwen G
Bibl Haematol. 1975(40):67-74. doi: 10.1159/000397519.
Traditionally, cancer has not been considered an infectious disease although some multiple cases of leukemia in man and cattle have been reported. The discovery that feline lymphosarcoma was associated with an RNA virus (feline leukemia virus(FeLV)) meant that infectious transmission of the disease was a possibility. The critical question was whether the predominant method of transmission from one animal to another was 'vertical' (via the gametes) or 'horizontal' (via contagion or infection). A number of epidemiological studies have shown that the chances of healthy cats contracting lymphosarcoma are greatly increased when a cat with the disease lives in close proximity. It does not matter whether the healthy cats are related to the sick animal or not. It has also been established that viremic normal cats have an approximately 900 times greater chance of developing leukemia than cats whose FeLV status is unknown. Infectious FeLV is present in the excretions and blood of viremic animals. In the natural environment, feline lymphosarcoma occurs in clusters. The results in pet cats have been supported by experiments with cat colonies under controlled conditions and prove that horizontal transmission of FeLV occurs. This does not mean that epigenetic (infection in utero or via the milk) or vertical transmission cannot also occur. It should be possible to break the cycle of horizontal transmission of the virus by vaccination and thus control FeLV-related diseases.
传统上，癌症一直未被视为一种传染病，尽管已有人类和牛群中多例白血病病例的报道。猫淋巴瘤与一种RNA病毒（猫白血病病毒（FeLV））有关这一发现意味着该疾病存在传染性传播的可能性。关键问题在于，疾病从一只动物传播到另一只动物的主要方式是“垂直”（通过配子）还是“水平”（通过接触或感染）。多项流行病学研究表明，当患有淋巴瘤的猫与健康猫近距离生活时，健康猫感染淋巴瘤的几率会大幅增加。健康猫与患病动物是否有亲缘关系并不重要。研究还证实，病毒血症正常的猫患白血病的几率比FeLV状况未知的猫高出约900倍。传染性FeLV存在于病毒血症动物的排泄物和血液中。在自然环境中，猫淋巴瘤呈聚集性发生。在受控条件下对猫群进行的实验支持了宠物猫的研究结果，并证明FeLV存在水平传播。但这并不意味着表观遗传（子宫内感染或通过乳汁感染）或垂直传播不会发生。通过接种疫苗有可能打破病毒水平传播的循环，从而控制与FeLV相关的疾病。
