International Journal of Aquaculture, 2018, Vol.8, No.20, 151-155
151
Research Report Open Access
Histopathology of
Aeromonas caviae
Infection in Challenged Nile Tilapia
Oreochromis niloticus
(Linnaeus, 1758)
Anwesha Roy, Jasmine Singha, Thangapalam Jawahar Abraham
Department of Aquatic Animal Health, Faculty of Fishery Sciences, West Bengal University of Animal and Fishery Sciences, 5, Budherhat Road, Chakgaria,
Kolkata-700094, West Bengal, India
Corresponding author Email
International Journal of Aquaculture, 2018, Vol.8, No.20 doi
Received: 15 Jun., 2018
Accepted: 13 Jul., 2018
Published: 31 Aug., 2018
Copyright © 2018
Roy et al., This is an open access article published under the terms of the Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Preferred citation for this article
:
Roy A., Singha J., and Abraham T.J., 2018, Histopathology of
Aeromonas caviae
infection in challenged Nile tilapia
Oreochromis niloticus
(Linnaeus, 1758),
International Journal of Aquaculture, 8(20): 151-155 (doi
Abstract
Aeromonas caviae
is one of the predominant motile aeromonads in Nile tilapia,
Oreochromis niloticus
. In this study, the
histopathological alterations in the kidney, liver and pancreas of
O. niloticus
juveniles experimentally challenged with α-haemolytic
A. caviae
is described. The Nile tilapia experienced 60% mortalities at a challenge dose of 6×10
8
cells/fish. Post-challenge,
well-defined histopathological changes were observed with nephritis and the loss of structural integrity of the kidney tissues. The
liver was dispersed, necrotized and had fatty changes in the hepatic parenchyma. Inflammation of the pancreas, as well as pancreatic
acinar cells and disintegration of intrahepatic exocrine pancreatic tissues, were also noted. The results, thus, demonstrated that
A.
caviae
can cause severe damages in the kidney, liver and pancreas of
O. niloticus
, similar to those of other known fish bacterial
pathogens.
Keywords
Aeromonas caviae
;
Oreochromis niloticus
; Histopathology; Nephropathy; Inflammation
Background
Disease is one of the major problems that affect the tilapia production and livelihood of the farmers. The bacteria
that cause diseases and mortalities in tilapia are
Flavobacterium columnare
,
Edwardsiella tarda
,
Aeromonas
spp.,
Vibrio
spp.,
Francisella
spp.,
Streptococcus agalactiae
, etc (Zamri-Saad et al., 2014; Huicab-Pech et al., 2016).
The genus
Aeromonas
includes ubiquitous bacteria found in aquatic habitats and at least 31 species have been
described (Chen et al., 2016).
Aeromonas
spp. are considered to be opportunistic pathogens and capable of
producing disease only in weakened populations of fish or as secondary invaders in fish suffering from other
diseases (Harikrishnan and Balasundaram, 2005; Austin and Austin, 2012).
Aeromonas
spp. are divided into two
principal subgroups: the non-motile and psychrophilic species (
A. salmonicida
) and the motile and mesophilic
species namely
A. hydrophila
,
A. sobria
,
A. veronii
,
A. caviae
and others (Austin and Austin, 2012). Several
species of the genus
Aeromonas
frequently cause problems in both feral and cultured fish and are responsible for
heavy economic losses due to high mortality (El-Sayed, 2006; Martins et al., 2008; Austin and Austin, 2012).
The Nile tilapia
O. niloticus
is reportedly sensitive to streptococcosis and also motile
Aeromonas septicemia
(MAS). Diseases associated with streptococcosis and MAS are, however, most severe among fish that are cultured
under intensive conditions (El-Sayed, 2006; Martins et al., 2008; Zamri-Saad et al., 2014). In a study by Martins
et al. (2008),
A. caviae
was associated with mortalities of Nile tilapia held in cages, wherein they isolated large
numbers
A. caviae
in the liver and kidney. Saleh et al. (2017) reported
A. caviae
as one of the predominant species
of motile aeromonads in Nile tilapia. As the Nile tilapia culture is fast picking up, we started investigating the
diseases of cultured tilapia in West Bengal, India. In our earlier studies, streptococcal (Adikesavalu et al., 2017)
and
A. hydrophila
(Julinta et al., 2017) infections in Nile tilapia were reported. In this study, we report the
histopathological alterations in the kidney, liver and pancreas of
O. niloticus
juveniles caused by experimental
A.
caviae
infection.
1 Materials and Methods
1.1 Bacterial challenge in
Oreochromis niloticus
juveniles
Healthy
Oreochromis
niloticus
(14.50 ±0.50 g; 11.20 ±0.57 cm) were brought from Naihati, North 24 Parganas
