Experimental Infection of Pacific White Shrimp Litopenaeus vannamei with Necrotizing Heptopancreatitis (NHP) Bacterium by Per os Exposure
Document Type
Article
Publication Date
11-4-2004
Department
Coastal Sciences, Gulf Coast Research Laboratory
Abstract
Necrotizing Hepatopancreatitis Bacterium (NHPB), which causes Necrotizing Hepatopancreatitis, was successfully transmitted in individually isolated Kona stock Litopenaeus vannamei through per os exposure. Animals (140) were individually exposed orally to a 0.05 g piece of an NHPB-infected hepatopancreas and 120 control animals were each exposed to a 0.05 g piece of NHPB-negative hepatopancreas. Shrimp were maintained in Sterilite(R) containers with approximately 4 1 of artificial seawater at 30parts per thousand salinity and 30degreesC for 60 d. Mortality of infected shrimp was observed from Day 16 to Day 51 post-exposure. Infected animals sustained reduced feeding activity and displayed empty guts. Some infected animals developed a pale hepatopancreas noticeable through the carapace. Survival probabilities fit a Weibull distribution and parametric survival analysis revealed lowered survival due to NHPB infection. Median survival time of NHPB-infected animals was 34.5 d. After correcting for background daily mortality in the controls, mean acute daily mortality of NHPB was estimated at 0.09, a value much lower than that estimated for other diseases in Kona stock L. vannamei such as White Spot Syndrome Virus (0.40) and Taura Syndrome Virus (0.30). A chronic, or carrier, state was not demonstrated in NHPB epizootics because all NHPB-positive animals experienced mortality and no animals surviving to 60 d post-exposure were diagnosed NHPB-positive through PCR or histology.
Publication Title
Diseases of Aquatic Organisms
Volume
61
Issue
3
First Page
227
Last Page
233
Recommended Citation
Vincent, A. G.,
Breland, V.,
Lotz, J. M.
(2004). Experimental Infection of Pacific White Shrimp Litopenaeus vannamei with Necrotizing Heptopancreatitis (NHP) Bacterium by Per os Exposure. Diseases of Aquatic Organisms, 61(3), 227-233.
Available at: https://aquila.usm.edu/fac_pubs/2980