Role of stressors in histomoniasis transmission and development in turkeys

The aim of the current study was to evaluate the influence of stressors on histomoniasis development and lateral transmission of Histomonas meleagridis. In the following experiments, half of the birds in each pen were inoculated with H. meleagridis to study disease transmission and progression. Birds were infected at 5 wk of age (experiments 1 and 3) or at 2 wk of age (experiment 2). Disease progression was evaluated by infection rate, mortality rate, and pathologic lesions in the ceca and liver. Reported results were applicable for directly infected birds as lateral transmission was not induced in these experiments. In experiment 1, the results showed high electrolyte, low-density diet (HE + LD), feed withdrawal (FW), caused higher infection rates and increase lesion scores in the liver and ceca compared to con. Experiment 2 further investigated the influence of low-density diet (LD) in conjunction with coccidiosis (LD + C) or feed withdrawal (LD + FW). All treatments had higher infection rates, mortality rates, ceca and liver scores compared to PC. In experiment 3, birds were fed diets containing naturally occurring aflatoxin at 0 ppb (AFLB1), 6.26 ppb (AFLB1 Low), or 19.82 ppb (AFLB1 High). No significant differences among treatments were observed. Though lateral transmission was not induced by theses stressors, the results of these experiments demonstrated that low-density diets, feed withdrawal and/or coccidial infection facilitated more severe histomoniasis infection.