Time- and dose-dependent development of humoral immune responses to Ascaridia galli in experimentally and naturally infected chickens.

•Worm-specific IgY levels initially depend heavily on the initial infection dose.•Reinfection is responsible for further elevated IgY levels.•Number of larvae is associated with increasing IgY in plasma and egg yolks.•Reinfection eliminates most differences resulting from the initial infection dose.•Retrospective IgY levels show only a weak association with worm burden.