Granuloma disease in a flock of free range productive layers in the Netherlands in 2017 is described. The disease resembled granuloma outbreaks in layers caused by Tetratrichomonas gallinarum in 2013 and occurred in the same area in which the rearing farm considered as the source of the 2013 outbreaks was located. Between 55 and 84 weeks of age mortality was 20.3% (breeder’s norm 3.9%). All dead hens examined (n = 20) showed granulomas especially in liver and ceca. Nine hens with or without liver and/or ceca granulomas were examined for trichomonads in mentioned organs by in situ hybridization (ISH), nested PCR, and cloning and sequencing. Ceca were also examined by culture. T. gallinarum ISH was positive in all livers and ceca with granulomas and negative in case granulomas were absent. T. gallinarum strain 13/16632, which caused the 2013 outbreaks was found in 4/8 hens with granulomas. Moreover, other trichomonads were detected: a T. gallinarum strain GPO-like and a Simplicimonas sp. strain GABC1-like. Mixed infections also occurred. Infectious causes of granuloma disease other than the afore-mentioned trichomonads could be excluded. Trichomonad DNA was not detected in environmental samples and wild ducks originating from the farm of concern, except for one duck in which the same Simplicimonas sp. as in hens was detected, leaving the source of the T. gallinarum infection in hens unknown. It is concluded that the herein described granuloma disease likely was caused by T. gallinarum strain 13/16632. However, the pathogenicity of the other trichomonads found remains to be clarified.

描述了2017年荷兰一群自由放养生产层中的肉芽肿病。该病类似于2013年由四角毛猴引起的肉芽肿暴发，并发生在被认为是2013年暴发源头的饲养场所在的地区。在55至84周龄之间，死亡率为20.3％（育儿标准为3.9％）。检查的所有死亡母鸡（n  = 20）均显示肉芽肿，尤其是在肝脏和盲肠。通过原位杂交（ISH），巢式PCR以及克隆和测序检查了9头有或没有肝和/或盲肠肉芽肿的母鸡的毛滴虫。盲肠也通过文化检查。鸡毛锥虫ISH在所有肉芽肿肝和盲肠中均为阳性，如果没有肉芽肿则为阴性。在4/8例肉芽肿鸡中发现了导致2013年暴发的T. gallinarum菌株13/16632。此外，还检测到其他滴虫：T。gallinarum菌株GPO样和Simplicimonas sp。菌株GABC1样。混合感染也发生了。除上述滴虫以外，还可以排除肉芽肿疾病的传染原因。在环境样品和相关养殖场的野鸭中未检出滴虫DNA，只有一只鸭子具有相同的Simplicimonas sp.。就像在母鸡中被检测到一样，留下了T. gallinarum的来源母鸡的感染情况未知。结论此处所描述的肉芽肿疾病可能是由引起T.鹑鸡应变16632分之13。然而，发现的其他滴虫的致病性仍有待澄清。