Laboratory of Parasitology, Graduate School of Infectious Diseases, Faculty of Veterinary Medicine, Hokkaido University, Kita-18, Nishi-9, Sapporo, Hokkaido, 060-0818, Japan; Department of Veterinary Pathobiology, Faculty of Veterinary Medicine, Lilongwe University of Agriculture and Natural Resources, P.O. Box 219, Lilongwe, Malawi.
Mikolongwe College of Veterinary Sciences, P.O. Box 5193, Limbe, Blantyre, Malawi.
Acta Trop. 2022 Jul;231:106413. doi: 10.1016/j.actatropica.2022.106413. Epub 2022 Mar 17.
Malawi has an estimated cattle population of 1,884,803 heads, the indigenous Malawi zebu breed accounts for 91.2%, while the exotic and crossbred accounts for the remaining 8.8%. Although ticks and tick-borne diseases are widespread in Malawi, no molecular study has been conducted to investigate the tick-borne Anaplasmataceae and piroplasms infecting cattle. To provide an insight into the current status of tick-borne pathogens (TBPs) of cattle, a molecular survey was conducted in the central and southern regions of Malawi. A total of 191 cattle of which 132 were Malawi zebu, 44 were Holstein Friesian and 15 were Holstein-Friesian/ Malawi zebu crosses were screened for Anaplasmataceae and piroplasms using the heat shock protein groEL gene and 18S rDNA, respectively. A new 18S rDNA multiplex PCR assay was designed for Babesia and Theileria species identification without sequencing. Overall, 92.3% (n = 177) of the examined animals were infected with at least one TBP. Anaplasmataceae-positive rate was 57.6% (n = 110) while for piroplasms it was 80.1% (n = 153). The detected Anaplasmataceae were Anaplasma bovis 2.6% (n = 5), Anaplasma marginale 24.6% (n = 47), Anaplasma platys-like 13.6% (n = 26), uncharacterized Anaplasma sp. 14.1% (n = 27), and uncharacterized Ehrlichia sp. 16.2% (n = 31). The detected piroplasms were Babesia bigemina 2.6% (n = 5), Theileria mutans 73.8% (n = 141), Theileria parva 33.0% (n = 63), Theileria taurotragi 12.6% (n = 24), and Theileria velifera 53.4% (n = 102). Mixed infection rate was found in 79.6% (n = 152) of the samples analyzed. This study has shown a high burden of TBPs among cattle in Malawi which highlights the need to conceive new methods to control ticks and TBPs in order to improve animal health and productivity. The newly developed multiplex PCR assay would be a useful tool especially in resource limited settings where sequencing is not available and when mixed infections are expected.
马拉维估计有 1884803 头牛，本地的马拉维瘤牛品种占 91.2%，而外来品种和杂交品种占 8.8%。尽管在马拉维 ticks 和 tick-borne 疾病很普遍，但尚未进行分子研究来调查感染牛的 tick-borne Anaplasmataceae 和 piroplasms。为了深入了解牛的 tick-borne 病原体 (TBPs) 的现状，在马拉维中部和南部地区进行了一项分子调查。共筛选了 191 头牛，其中 132 头是马拉维瘤牛，44 头是荷斯坦弗里生牛，15 头是荷斯坦弗里生/马拉维瘤牛杂交牛，分别使用热休克蛋白 groEL 基因和 18S rDNA 检测 Anaplasmataceae 和 piroplasms。设计了一种新的 18S rDNA 多重 PCR 检测方法，无需测序即可鉴定巴贝虫和泰勒虫种。总的来说，检查的动物中有 92.3%（n=177）至少感染了一种 TBP。Anaplasmataceae 的阳性率为 57.6%（n=110），而 piroplasms 的阳性率为 80.1%（n=153）。检测到的 Anaplasmataceae 包括牛无浆体 2.6%（n=5）、边缘无浆体 24.6%（n=47）、平胸无浆体样 13.6%（n=26）、未鉴定的无浆体 14.1%（n=27）和未鉴定的埃立克体 16.2%（n=31）。检测到的 piroplasms 包括双芽巴贝斯虫 2.6%（n=5）、突变泰勒虫 73.8%（n=141）、小泰勒虫 33.0%（n=63）、塔陶泰勒虫 12.6%（n=24）和 Velifera 泰勒虫 53.4%（n=102）。分析的样本中有 79.6%（n=152）存在混合感染。本研究表明，马拉维牛群中 TBPs 的负担很重，这突出表明需要构思新的方法来控制 ticks 和 TBPs，以提高动物的健康和生产力。新开发的多重 PCR 检测方法将是一种有用的工具，特别是在资源有限的环境中，那里无法进行测序，并且预计会存在混合感染。
