| n the spring of 1993, seven farms with histologically confirmed outbreaks of proliferative gill disease (PGD) in their fish populations were selected from references from fish diagnostic labs at the Delta Research and Extension Center at Stoneville, MS and at the College of Veterinary Medicine at Mississippi State University. At each farm two ponds were sampled, one histologically confirmed as having a clinical PGD outbreak (positive pond), and a second which had shown no signs of PGD (control pond). Samples collected included fish, water, and sediment. Ponds were sampled during the outbreak and quarterly for a year following the outbreak. Histological examinations of catfish collected from control ponds revealed that 4 of 7 control ponds had PGD in their catfish populations. Since no losses attributed to PGD had occurred in those ponds they were noted as subclinical outbreaks. More subclinical outbreaks occurred through the year of the study with PGD observed at some time in the catfish populations of 12 of 14 ponds. Ten species of actinosporea were observed and described from the ponds sampled. Aurantiactinomyxon ictaluri was found to be significantly (P... |
