Jacobson Caroline, Al-Habsi Khalid, Ryan Una, Williams Andrew, Anderson Fiona, Yang Rongchang, Abraham Sam, Miller David
School of Veterinary and Life Sciences, Murdoch University, Murdoch, Western Australia, 6150, Australia.
School of Veterinary and Life Sciences, Murdoch University, Murdoch, Western Australia, 6150, Australia.
Vet Parasitol. 2018 Aug 30;260:30-37. doi: 10.1016/j.vetpar.2018.07.005. Epub 2018 Jul 10.
Cryptosporidium and Giardia are common parasites of ruminant livestock worldwide. These parasites are associated with diarrhoea outbreaks in young goats (pre-weaning), but the impacts on health and productivity for older goats (post-weaning) are not well understood. Here we show Cryptosporidium faecal shedding is associated with reduced growth and diarrhoea in goats aged approximately 9-15 months. Goats were sampled four times at one-month intervals. Faecal shedding for a range of pathogens were determined using quantitative PCR and sequencing (Cryptosporidium, Giardia, Eimeria, Salmonella, Campylobacter), and microscopy (trichostrongylid nematode worm egg count and Entamoeba). Cryptosporidium faecal shedding was associated with 1.5 kg lower growth for the one-month period following sampling. Specifically, C. xiaoi was associated with 1.9 kg lower growth in the following month. This is the first report of production impacts associated with C. xiaoi in ruminants older than 3 months of age. Cryptosporidium shedding was associated with an over 4-fold increase in risk of diarrhoea, with C. parvum associated with 10-fold and C. ubiquitum associated with 16-fold increase in risk of diarrhoea. Notably, C. xiaoi shedding was not associated with increased risk of diarrhoea. Giardia shedding was associated with looser faecal consistency, but not diarrhoea. Higher Eimeria oocyst counts were weakly associated with lower live weight, poorer body condition and looser faecal consistency. Shedding of other enteric pathogens were not associated with impacts on live weight, growth or diarrhoea risk. This study challenges the two notions that Cryptosporidium infections only impact health and productivity of goats during the pre-weaning period, and that Cryptosporidium (and specifically C. xiaoi) infections in the absence of diarrhoea are asymptomatic. Recognising the potential for impacts of Cryptosporidium infection on growth rates in the absence of diarrhoea will support improved design for experiments testing impacts of Cryptosporidium on ruminant health and production. Improved understanding of the role of protozoan infections on animal health has implications for the management of goats in order to reduce adverse impacts on farm profitability, animal welfare and public health risk.
隐孢子虫和贾第虫是全球反刍家畜常见的寄生虫。这些寄生虫与幼龄山羊（断奶前）腹泻暴发有关，但对老龄山羊（断奶后）健康和生产力的影响尚不清楚。在此我们表明，隐孢子虫粪便排放在约9至15月龄山羊中与生长减缓及腹泻有关。山羊每隔一个月采样四次。使用定量PCR和测序（隐孢子虫、贾第虫、艾美耳球虫、沙门氏菌、弯曲杆菌）以及显微镜检查（毛圆线虫虫卵计数和内阿米巴）确定一系列病原体的粪便排放情况。在采样后的一个月期间，隐孢子虫粪便排放与生长降低1.5千克有关。具体而言，微小隐孢子虫在下个月与生长降低1.9千克有关。这是关于微小隐孢子虫对3月龄以上反刍动物生产影响的首次报告。隐孢子虫排放与腹泻风险增加4倍以上有关，其中微小隐孢子虫腹泻风险增加10倍，泛在隐孢子虫腹泻风险增加16倍。值得注意的是，微小隐孢子虫排放与腹泻风险增加无关。贾第虫排放与粪便质地变稀有关，但与腹泻无关。较高的艾美耳球虫卵囊计数与较低的活体重、较差的体况及较稀的粪便质地弱相关。其他肠道病原体的排放与对活体重、生长或腹泻风险的影响无关。本研究对两个观点提出了挑战，即隐孢子虫感染仅在断奶前影响山羊的健康和生产力，以及在无腹泻情况下隐孢子虫（特别是微小隐孢子虫）感染是无症状的。认识到在无腹泻情况下隐孢子虫感染对生长率的潜在影响，将有助于改进测试隐孢子虫对反刍动物健康和生产影响的实验设计。更好地理解原生动物感染对动物健康的作用，对于山羊管理具有重要意义，以便减少对农场盈利能力、动物福利和公共卫生风险的不利影响。
