Estimating seroprevalence and variation to four tick-borne infections and determination of associated risk factors in cattle under traditional mixed farming system in Mbeere District, Kenya
Estimating seroprevalence and variation to four tick-borne infections and determination of associated risk factors in cattle under traditional mixed farming system in Mbeere District, Kenya
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DOI：
10.1016/j.prevetmed.2010.03.015
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发表时间：
2010-07-01
影响因子：
2.6
通讯作者：
Skilton, R. A.
中科院分区：
文献类型：
--
作者：
Gachohi, J. M.;Ngumi, P. N.;Skilton, R. A.
在肯尼亚Mbeere地区的传统小农混合农场进行了牛对蜱传疾病（TBD）寄生虫（小泰勒虫、变形泰勒虫、边缘无形体和双芽巴氏杆菌）的血清抗体应答的横断面研究。目的是估计感染的血清阳性率和变异，并确定相关的危险因素。共440头牛在80个农场，选择分层随机抽样的四个分区在该地区，进行了调查。通过使用标准化问卷进行个人访谈，获得有关动物和每个农场管理实践（特别是蜱虫控制实践）的信息。采用酶联免疫吸附试验（ELISA）技术测定血清抗体的患病率。采用标准Logistic回归模型和混合模型，以农场作为随机效应，通过多变量分析评估TBD血清阳性率和危险因素之间的关系。血清阳性率的总体估计及其95%置信限为：T。parva（19% [14%，25%]），T.变形杆菌（25% [20%，29%]）、A.边缘型（58% [52%，64%]）和B型。二联胎（19%[15%，23%]）。方差分析（ANOVA）中存在额外二项变异的分析得出T的农场内相关系数（ICC）（0.3）和方差膨胀因子（VIF）（2.35）值相对较大。parva比其他寄生虫[范围，0.05-0.07（ICC）和1.02-1.32（VIF）]。农场和地区水平的变量对所有感染都有显著和巨大的影响，但这些对T。细小病毒血清阳性率。纳入农场随机效应导致T的农场方差分量估计值显著较高。与其他感染[范围，0.29-0.56]相比，parva感染（1.73），ICC值与ANOVA分析[范围，0.08-0.35]下的ICC值相当，并且比标准多变量logistic回归更好地拟合。上述结果作为可能的指标存在的地方性不稳定的研究TBD感染在该地区。在病媒适宜生境中可能存在不同的生态和气候变异性，特别是T。Mbeere区可能存在细小病媒，这可能会影响整个地区的农场蜱虫控制管理。本文还讨论了基于设计的抽样和分析对上述结果的影响。(C)2010爱思唯尔有限公司版权所有。
A cross-sectional study of serum antibody responses of cattle to tick-borne disease (TBD) parasites (Theileria parva, Theileria mutans, Anaplasma marginale and Babesia bigemina) was conducted on traditional smallholder mixed farms in Mbeere District in Kenya. The objective was to estimate the infections' seroprevalence and variation and identify associated risk factors. A total of 440 cattle in 80 farms, selected by stratified random sampling from the four divisions in the district, were surveyed. Information on animal and on each farm's management practices, particularly on tick control practices, was obtained by personal interview using a standardized questionnaire. Prevalences of serum antibodies were determined using the enzyme-linked immunosorbent assay (ELISA) technique. The relationship between TBDs seroprevalence and the risk factors was assessed by multivariable analysis using standard logistic regression models and mixed models using the farm as a random effect. Overall estimation of seroprevalences and their 95% confidence limits were: T. parva (19% [14%, 25%]), T. mutans (25% [20%, 29%]), A. marginale (58% [52%, 64%]) and B. bigemina (19%[15%, 23%]). Analysis in presence of extra-binomial variation under Analysis Of Variance (ANOVA) yielded relatively larger intra-farm correlation coefficient (ICC) (0.3) and variance-inflation factor (VIF) (2.35) values for T. parva than for the other parasites [range, 0.05-0.07 (for ICC) and 1.02-1.32 (for VIF)]. Both farm- and area-level variables had variably significant and large effects on all infections, but these were more pronounced on T. parva seroprevalence. Inclusion of farm random effect resulted in substantially higher estimate of farm variance component for T. parva infection (1.73) compared to other infections [range, 0.29-0.56], comparable ICC values with those under ANOVA analysis [range, 0.08-0.35] and a substantially better fit than the standard multivariable logistic regressions. The above results serve as possible indicators of existence of endemic instability for the studied TBD infections in the district. A probable differential ecological and climatic variability in vector suitability habitats, particularly for T. parva vector, was likely in Mbeere District and this was suggested to influence farm tick control management across the area. Implications of the design-based sampling and analyses on the above results are also discussed. (C) 2010 Elsevier B.V. All rights reserved.