International Livestock Research Institute (ILRI), P.O. Box 30709, GPO 00100, Nairobi, Kenya.
Prev Vet Med. 2013 Jun 1;110(2):198-205. doi: 10.1016/j.prevetmed.2012.11.012. Epub 2012 Dec 7.
We describe a horizontal survey of African swine fever virus (ASFV) prevalence and risk factors associated with virus infection in domestic pigs in two contrasting production systems in Kenya. A free range/tethering, low input production system in Ndhiwa District of South-western Kenya is compared with a medium input stall fed production system in Kiambu District of Central Kenya. Analysis of variance (ANOVA) of data derived from cluster analysis showed that number of animals, number of breeding sows and number of weaner pigs were a significant factor in classifying farms in Nhiwa and Kiambu. Analysis of blood and serum samples using a PCR assay demonstrated an average animal level positivity to ASFV of 28% in two independent samplings in South-western Kenya and 0% PCR positivity in Central Kenya. No animals were sero-positive in either study site using the OIE indirect-ELISA and none of the animals sampled exhibited clinical symptoms of ASF. The farms that contained ASFV positive pigs in Ndhiwa District were located in divisions bordering the Ruma National Park from which bushpig (Potamochoerus larvatus) incursions into farms had been reported. ASFV prevalence (P<0.05) was significantly higher at distances between 6 and 16km from the National Park than at distances closer or further away. One of the 8 bushpigs sampled from the park, from which tissues were obtained was PCR positive for ASFV. The data therefore indicated a potential role for the bushpig in virus transmission in South-western Kenya, but there was no evidence of a direct sylvatic virus transmission cycle in Central Kenya. ASF control strategies implemented in these areas will need to take these epidemiological findings into consideration.
我们描述了一项在肯尼亚两个截然不同的生产系统中对家猪进行非洲猪瘟病毒（ASF）流行情况和与病毒感染相关的风险因素的横向调查。在肯尼亚西南部恩迪瓦区的自由放养/拴系、低投入生产系统与肯尼亚中部基安布区的中等投入圈养生产系统进行了比较。聚类分析得出的数据的方差分析（ANOVA）表明，动物数量、繁殖母猪数量和断奶猪数量是区分恩迪瓦和基安布农场的重要因素。使用 PCR 检测法对血液和血清样本进行分析表明，在肯尼亚西南部的两次独立采样中，ASFV 阳性动物的平均阳性率为 28%，而在肯尼亚中部则为 0%PCR 阳性。在两个研究地点均未使用 OIE 间接 ELISA 检测到动物呈血清阳性，也未采样到任何表现出 ASF 临床症状的动物。在恩迪瓦区含有 ASFV 阳性猪的农场位于与鲁马国家公园接壤的地区，据报道，丛林猪（Potamochoerus larvatus）已入侵这些农场。距离国家公园 6 至 16 公里的农场的 ASF 流行率（P<0.05）明显高于距离更近或更远的农场。从公园获得组织样本的 8 头丛林猪中有 1 头 PCR 检测为 ASFV 阳性。因此，数据表明丛林猪可能在肯尼亚西南部传播病毒，但在肯尼亚中部没有证据表明存在直接的森林病毒传播循环。在这些地区实施的 ASF 控制策略将需要考虑这些流行病学发现。
