Vitamin B12 deficiency in newly weaned goat kids associated with clinical infection with Eimeria arloingi

Abstract A severe outbreak of diarrhea associated with poor growth was reported in ten newly weaned goat kids that originated from a research farm (Group A). Two of these kids underwent necropsy examination. Five goat kids of the same age maintained in the same pen showed no clinical signs (Group B). The clinical, gross pathological and histopathological features of the clinically sick animals were consistent with severe coccidiosis. Group A animals had significantly lower levels of serum vitamin B12 (<200 pg/ml) compared with group B animals (2000 pg/ml). In addition, kids belonging to group A had significantly higher Eimeria arloingi oocysts per gram (OPG) of faeces (101,400/g) compared with kids of group B (9,154/g). Microscopy and molecular tools (18S rRNA and COI genes) confirmed that the goat kids were infected with the caprine protozoan parasite E. arloingi. This study provides a definitive association between low levels of serum vitamin B12 and clinical E. arloingi infection, and also provides support to our previous studies that demonstrated how low levels of serum vitamin B12 leads to an impairment of neutrophil function and thereby potential lowered immunity to pathogens.

摘要：某科研农场的10头刚断奶山羊羔暴发了伴随生长不良的严重腹泻疫情（A组）。其中2头山羊羔接受了尸体剖检。同栏饲养、年龄一致的5头山羊羔未表现出任何临床症状（B组）。患病动物的临床症状、大体病理及组织病理学特征均与严重球虫病相符。A组山羊的血清维生素B₁₂水平（<200 pg/ml）显著低于B组山羊（2000 pg/ml）。此外，A组山羊每克粪便中的艾美尔球虫（Eimeria arloingi）卵囊数（每克粪便卵囊数，oocysts per gram，简称OPG）为101400个/克，显著高于B组山羊的9154个/克。显微镜检查与分子检测技术（18S rRNA和COI基因）证实，该批山羊羔感染了山羊源原生动物寄生虫艾美尔球虫（E. arloingi）。本研究明确了血清维生素B₁₂水平低下与临床型艾美尔球虫感染之间的确定性关联，同时为我们此前的研究提供了支撑——此前研究表明，血清维生素B₁₂水平低下会损伤中性粒细胞功能，进而降低机体对病原体的免疫能力。