Sporozoans produce simple resistant spores with a special apical complex used in the invasion of the host cell. They can occur in the intestinal organs, muscle tissue and skin of fish.
Gregarines (3.5-4 x 8-16 µm) (Fig. 5-19)
Gregarines may be detected in the digestive tract microscopically.
EFFECTS ON HOST:
Large numbers of the parasite attached to filter apparatus of shrimp may possibly interfere with filtration of particles moving towards hepatopan-creatic ducts or passing through the stomach. There is a considerable growth retardation. Infection rate in pond-grown shrimps was reported to reach 94%.
Microscopic or histological examination of the digestive tract of the host.
PREVENTION AND CONTROL:
• In the hatchery, filter or chlorinate seawater used for rearing
• In grow-out ponds, eliminate the molluscan intermediate host
Copyright © 2018-2020 BrainKart.com; All Rights Reserved. Developed by Therithal info, Chennai.