Foot-and-mouth disease (FMD) is a highly contagious animal disease caused by an RNA virus subdivided into seven serotypes that are unevenly distributed in Asia, Africa, and South America. Despite the challenges of controlling FMD, since 1996 there have been only two outbreaks attributed to serotype C, in Brazil and in Kenya, in 2004. This article describes the historical distribution and origins of serotype C and its disappearance. The serotype was first described in Europe in the 1920s, where it mainly affected pigs and cattle but as a less common cause of outbreaks than serotypes O and A. No serotype C outbreaks have been reported in Europe since vaccination stopped in 1990. FMD virus is presumed to have been introduced into South America from Europe in the nineteenth century, although whether serotype C evolved there or in Europe is not known. As in Europe, this serotype was less widely distributed and caused fewer outbreaks than serotypes O and A. Since 1994, serotype C had not been reported from South America until four small outbreaks were detected in the Amazon region in 2004. Elsewhere, serotype C was introduced to Asia, in the 1950s to the 1970s, persisting and evolving for several decades in the Indian subcontinent and for eighteen years in the Philippines. Serotype C virus also circulated in East Africa between 1957 and 2004. Many serotype C viruses from European and Kenyan outbreaks were closely related to vaccine strains, including the most recently recovered Kenyan isolate from 2004. International surveillance has not confirmed any serotype C cases, worldwide, for over 15 years, despite more than 2,000 clinical submissions per year to reference laboratories. Serology provides limited evidence for absence of this serotype, as unequivocal interpretation is hampered by incomplete intra-serotype specificity of immunoassays and the continued use of this serotype in vaccines. It is recommended to continue strengthening surveillance in regions of FMD endemicity, to stop vaccination against serotype C and to reduce working with the virus in laboratories, since inadvertent escape of virus during such activities is now the biggest risk for its reappearance in the field.

中文翻译：

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口蹄疫病毒血清型C的历史：第一个已知的灭绝血清型？

口蹄疫 (FMD) 是一种高度传染性的动物疾病，由一种 RNA 病毒引起，该病毒分为七种血清型，在亚洲、非洲和南美洲分布不均。尽管控制口蹄疫面临挑战，但自 1996 年以来，仅在 2004 年在巴西和肯尼亚发生了两次由血清型 C 引起的暴发。本文描述了血清型 C 的历史分布和起源及其消失。该血清型于 1920 年代在欧洲首次被描述，主要影响猪和牛，但与血清型 O 和 A 相比，它是一种不太常见的暴发原因。自 1990 年疫苗接种停止以来，欧洲没有报告血清型 C 暴发。口蹄疫病毒是推测是在 19 世纪从欧洲引入南美洲，尽管血清型 C 是在那里进化还是在欧洲进化尚不清楚。与欧洲一样，这种血清型的分布较不广泛，比血清型 O 和 A 引起的暴发也少。自 1994 年以来，直到 2004 年在亚马逊地区发现四次小规模暴发，南美洲才报告了血清型 C。在其他地方，血清型 C 是在 1950 年代到 1970 年代引入亚洲，在印度次大陆持续和发展了几十年，在菲律宾持续了 18 年。C 血清型病毒也在 1957 年至 2004 年间在东非流行。来自欧洲和肯尼亚暴发的许多 C 血清型病毒与疫苗株密切相关，包括最近从 2004 年发现的肯尼亚分离株。国际监测尚未在全球范围内确认任何 C 血清型病例，超过 15 年，尽管每年有超过 2,000 份临床提交给参考实验室。血清学为不存在这种血清型提供了有限的证据，因为免疫测定的不完整的血清型内特异性和在疫苗中继续使用这种血清型阻碍了明确的解释。建议继续加强口蹄疫流行地区的监测，停止针对 C 型血清的疫苗接种，并减少在实验室中使用该病毒，因为在此类活动中病毒的意外逃逸现在是其在该领域再次出现的最大风险。