ndividual effects of cichlidogyriasis and streptococosis induced on the blood biochemistry of tilapia Oreochromis niloticus

Abstract

In this study, we propose to evaluate the blood biochemistry as diagnosis technique of a pathologic process in tilapias Oreochromis niloticus by means of infections induced by Streptococcus sp. or by the activation of the immune response induced by antigens of Cichlidogyrus spp. Specifically, variations of some metabolites from the blood biochemistry were evaluated in experimentally infected tilapia Oreochromis niloticus. The organisms were intraperitoneally challenged (IP) with individual antigenic extracts of Streptococcus sp. (STREP Group, n = 10) and Cichlidogyrus spp. (C-EXP Group, n = 10), respectively, while 10 other tilapia were inoculated with a saline solution buffer (SS Group) and were used as immunization control. Another group of 70 tilapias was maintained in aquaculture conditions included the baseline group (LB). The negative control (CN) included 10 fish free of infection. The blood chemistry (metabolites and ions) were tested in a microplate format. No differences were observed between the LB and the CN groups (p > 0.05). Only fish injected with Streptococcus sp. (STREP) and Cichlidogyrus spp. (C-EXP) were significantly different with the values of glucose, total proteins, albumin, and globulins, when comparing with LB fish (p < 0.05). Furthermore, the cholesterol, calcium and the chlorine changed significantly in the STREP fish (p > 0.05). The results from the induced infections with Streptococcus sp. and Cichlidogyrus spp., respectively, modified some parameters of the blood biochemistry of tilapia that could be used for some preliminary diagnosis of infectious diseases.