[Natural transmission of microsporidia (Encephalitozoon cuniculi) by way of the chicken egg].

100 chicken embryos were examined for naturally occurring infections with Encephalitozoon cuniculi (E.c.). Two embryos were found to be dead, the others were killed at an age of 18 days. Samples from the oesophagus, intestine, liver, kidneys, heart and brain were collected and examined by immunohistochemical methods. E.c. was found in about 40% of the embryos. This microsporidian was observed in all organs, particularly, however, in the oesophagus, intestine, brain and heart. The number of E.c. was significantly larger in the two embryos that died than in the others. The investigations demonstrated, that E.c. may be transmitted naturally to the chicken egg. Further, the results suggested that E.c. may be a cause of death in chicken embryos. In most cases, however, E.c. infections are inapparent in embryos. Such inapparent infections may be an important way of contamination of chicken production units with E.c.