Analysis of management factors influencing Anaplasma marginale transmission

IF 2 2区农林科学 Q2 PARASITOLOGY Veterinary parasitology Pub Date : 2024-08-06 DOI:10.1016/j.vetpar.2024.110283

Nicolás Morel , Mariano Mastropaolo , Susana Torioni de Echaide , Marcelo L. Signorini , Atilio J. Mangold , Maria E. Primo

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Abstract

The aim of this study was to identify factors that play a key role in the epidemiology of bovine anaplasmosis by adapting a model primarily developed for cattle babesiosis. A cross-sectional observational study was conducted to study the proportion of calf herds in endemic stability/instability for A. marginale in a semi-arid area of Argentina. The A. marginale inoculation rate (h) was calculated from age-specific seroprevalence using double-antigen sandwich ELISA in 58 herds of 4.5–8.5-month–old calves. Herds were considered to be in endemic instability (EI) at h < 0.005 and, therefore, at risk of anaplasmosis outbreaks. A generalized linear model was performed to explore husbandry practices associated with differences in A. marginale transmission. Additionally, spatial clustering of herds with the same immunological status was analyzed using spatial scan statistics (SatScan, Bernoulli model). Spearman's correlation was used to explore a possible association between A. marginale h and Babesia bovis and B. bigemina h (data obtained in previous works). Almost half (43 %) of the herds were in the EI zone for A. marginale. Calves raised under forage combinations had a greater risk of being in EI (OR = 5.41, CI95 %OR = 1.43–20.41) than those reared exclusively on permanent pastures, where cattle density is higher (P = 0.01). Moreover, calves from herds treated only with pyrethroids to control ticks had more chances of being in EI (OR = 4.16, CI95 %OR = 1.12–15.38) than calves from herds receiving different acaricide combinations (P = 0.03). Calves from herds subjected to more than two treatments against Haematobia irritans had higher odds for EI (OR = 5.69, CI95 %OR = 1.24–26.11) than those from herds using fewer than two treatments (P = 0.02). The spatial analysis revealed no spatial clustering of the immune status of the herds (P = 0.67 and P = 0.74 for low and high incidence rates, respectively). A significant variation between farms was observed in A. marginale h (CV = 90.38 %). The correlation analysis revealed a strong epidemiological link of A. marginale h with B. bovis h (Rho=0.794, P<0.001) and B. bigemina h (Rho=0.839, P<0.001). Given that R. microplus is the only vector of B. bovis and B. bigemina in the region, the results of this work strongly suggest an active and significant role of R. microplus in the transmission of A. marginale.

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影响边缘疟原虫传播的管理因素分析。

本研究旨在通过调整主要针对牛巴贝斯虫病开发的模型，找出在牛无形体病流行病学中起关键作用的因素。研究人员开展了一项横断面观察研究，以了解阿根廷半干旱地区处于边缘体病流行稳定/不稳定状态的犊牛群比例。在 58 个饲养 4.5-8.5 个月大犊牛的牛群中，使用双抗原夹心酶联免疫吸附法根据年龄特异性血清流行率计算出了边缘疟原虫接种率（h）。当 h < 0.005 时，牛群被认为处于地方性不稳定（EI）状态，因此有爆发无形体病的风险。采用广义线性模型探讨了与边鞭毛虫传播差异相关的饲养方法。此外，还利用空间扫描统计（SatScan，伯努利模型）分析了具有相同免疫状态的畜群的空间聚类。斯皮尔曼相关性被用来探讨边缘疟原虫 h 与牛巴贝斯虫和比格犬巴贝斯虫 h 之间可能存在的联系（数据来自之前的研究）。几乎有一半（43%）的牛群处于边缘疟原虫的 EI 区。与完全在牛群密度较高的永久性牧场上饲养的犊牛相比，在草料组合下饲养的犊牛出现 EI 的风险更高（OR = 5.41，CI95 %OR = 1.43-20.41）（P = 0.01）。此外，仅使用除虫菊酯类杀虫剂控制蜱虫的牛群中的犊牛与使用不同杀螨剂组合的牛群中的犊牛相比，出现 EI 的几率更高（OR = 4.16，CI95 %OR = 1.12-15.38）（P = 0.03）。与使用两种以上杀螨剂的牛群的犊牛相比，使用两种以上杀螨剂的牛群的犊牛发生 EI 的几率更高（OR = 5.69，CI95 %OR = 1.24-26.11）（P = 0.02）。空间分析表明，猪群的免疫状况没有空间聚集性（低发病率和高发病率的空间聚集性分别为 P = 0.67 和 P = 0.74）。观察到不同猪场的边缘型甲虫发病率差异很大（CV = 90.38 %）。相关性分析表明，A. marginale h 与 B. bovis h 有很强的流行病学联系（Rho=0.794，P.

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来源期刊

Veterinary parasitology 农林科学-寄生虫学

CiteScore

5.30

自引率

7.70%

发文量

126

审稿时长

36 days

期刊介绍： The journal Veterinary Parasitology has an open access mirror journal,Veterinary Parasitology: X, sharing the same aims and scope, editorial team, submission system and rigorous peer review. This journal is concerned with those aspects of helminthology, protozoology and entomology which are of interest to animal health investigators, veterinary practitioners and others with a special interest in parasitology. Papers of the highest quality dealing with all aspects of disease prevention, pathology, treatment, epidemiology, and control of parasites in all domesticated animals, fall within the scope of the journal. Papers of geographically limited (local) interest which are not of interest to an international audience will not be accepted. Authors who submit papers based on local data will need to indicate why their paper is relevant to a broader readership. Parasitological studies on laboratory animals fall within the scope of the journal only if they provide a reasonably close model of a disease of domestic animals. Additionally the journal will consider papers relating to wildlife species where they may act as disease reservoirs to domestic animals, or as a zoonotic reservoir. Case studies considered to be unique or of specific interest to the journal, will also be considered on occasions at the Editors'' discretion. Papers dealing exclusively with the taxonomy of parasites do not fall within the scope of the journal.