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- April 2010, tilapia streptococcus disease in Hainan
Province, which was dotted occurred, indicating the
occurrence of streptococcal disease in the extended
season, also means streptococcus may be widespread in
2010.
□ Text / Figure Freshwater Fisheries Research Institute of
Fujian Province, Hai-Ping Fan
1, Streptococcus Overview
Worldwide death of fish caused by streptococcal infection
in the twentieth century has been sporadic seventies and
eighties reported nineties the rise, now has become a major
streptococcal pathogens of fish. Primary infection of
Streptococcus fish head, fish brain damage, then damage
the blood circulation through the liver, kidney, spleen and
other organs caused systemic hemorrhage, is a bacterial
disease, contagious, high mortality, treatment difficulties
and the higher the temperature the more severe disease.
- Streptococcus cultured species have a certain selectivity,
occur mainly in salmonids, tilapia, catfish, carp and
freshwater pomfret, and grass carp, carp, silver carp and
bighead carp have not been reported. Streptococcus
infection reported in literature tilapia strains are mainly
dolphins Streptococcus (S.iniae) and Streptococcus
agalactiae (S.agalaciate), the domestic strains of
Streptococcus isolated from Streptococcus mostly dolphins,
Fujian Institute of Freshwater Fisheries S. agalactiae was
first reported outbreak of deaths caused by tilapia.
Robinson and Meyer in 1966, first reported in U.S.
freshwater fish golden bream (Notemigonus crysoleucas)
an isolated group B Streptococcus.
Subsequently, Plumb and Baya isolated from fish such
as multiple strains of non-hemolytic streptococcus
group B, but not sure is right. 1994, Eldar, etc. to be
called Streptococcus difficile. Wilkinson, Elliott, and
Vandamme, etc. to isolation and identification of
streptococci, mostly assigned to group B Streptococcus
agalactiae. 2002, Evans and other re-reported hemolytic
Streptococcus agalactiae is the major pathogen of fish. In
- 2005, Kawamura and other proposed re-division of S
difficilis attribution, identified as Streptococcus agalactiae
synonyms. 2006, Evans and other marine mammals from
isolated Streptococcus agalactiae. Streptococcus agalactiae
is considered the sole owner of group B Streptococcus-
specific antigen.
Second, an overview of Tilapia Streptococcus
Streptococcus disease occurs mainly in poor water quality,
breeding density of water, low-cost long-term use of low-
quality feed is also contributory factors. In addition, there is
a lot of streptococcal bacteria in water also has a direct link.
Sometimes in the natural incidence of ovarian broodstock
can be detected in the presence of pathogens, so there may
be pathogens in tilapia in the possibility of vertical
transmission. Streptococcal disease of fish disease control
are mainly drugs control, ecological control and immune
control.
Chemical drugs and Chinese herbal medicine the most
- direct and simple control yes De Kongzhishouduan,
However prolonged use of chemicals inevitably Shi
resistant pathogens Chan Sheng Xing, Daozhifangzhi
failure, Tong Shi Ye Keneng lead to products of the
drug residue Yinqizhiliang health safety Wen Ti.
Therefore, the ecological control and immune control as an
important means of control. Streptococcus agalactiae is a
major pathogen of fish, but also one of zoonotic pathogens
in aquaculture should place no pathogen carrying seed,
maintain good water quality, full fed high-quality feed, the
tracing of pathogens source of infection, cut off the route of
transmission is the important work of ecological control.
Streptococcus disease in the event, both the brain
infection, brain damage, but also damage the liver,
kidneys and other organs, affect the fish's own immune
function, vaccines and immune activator control the
research and development is caused by Streptococcus
agalactiae non-Luo Fish of the Epidemic mainstream.
3, tilapia streptococcus epidemic Overview
- Tilapia streptococcus often long-term high temperature,
oxygen, or breeding density is too large outbreaks such
circumstances, in the spring, summer and autumn, is the
peak was from May to September, popular water
, in particular water temperature
temperature 25-37
, easily lead to disease outbreaks; main
higher than 30
hazards broodstock and 100g or more juvenile and adult
fish. Contagious, the incidence rate is 20-30%, the
incidence of fish mortality rate of 80%, and duration of
long duration, mortality continued to peak 2-3 weeks; In
winter, the mortality rate is relatively low, but longer
duration . China's major farming areas such as tilapia
Hainan, Guangdong, Guangxi, Fujian and other areas in
recent years, outbreaks of different degrees, resulting in a
more serious losses.
IV symptoms and pathological changes
Tilapia streptococcus main symptoms: prevalence disease
fish losing balance, some tumbling in the water, some
sideways movement to do a circle; serious condition, the
- dying disease fish in channeling the water around on tour or
intermittent; abdominal surface with a point-like or plaque
bleeding or ulcers, jaw and two lower edge of gill cover
diffuse bleeding, liver, gallbladder, spleen swelling,
bleeding, severe erosion; intestine and the stomach or the
product water yellow mucus, anal outstanding; eye
congestion, swelling, prominent, serious corneal opacity
white, or even eye loss. Pathology revealed a small piece
gill congestion, edema, necrosis, respiratory epithelial
hyperplasia, fusion, capillary swelling, congestion,
congestive enlargement of the end of the gill filaments,
lymphocyte infiltration; epicardial rupture, muscle fiber
breakage, disorder, loose myocarditis edema, lymphocyte
infiltration; granular degeneration and fatty degeneration of
the liver, arterial pipe and liver cell separation, wall
accumulation of blood cells and liver cell nuclei and blood
iron flavin calm, hepatocellular cloudy swelling, necrosis;
intestinal epithelial necrosis, loss, natural meningitis
leukocyte infiltration; spleen hemorrhage, edema,
lymphocytes decreased, the organization has a large
number of hemosiderin deposition; purulent foci within the
- kidney, there are a large number of neutrophils infiltration,
renal swelling and kidney central capillary blood
sedimentation capsule lacunar increased renal tubular cells
increased, irregular, hyaline degeneration of small arterial
wall, formation of micro vascular thrombosis, necrosis of
epithelial cells; periosteum choroidal and orbital
inflammatory injury occurs, the lens fiber fracture and
separated from the capsule and the lens was severe
necrosis, corneal ulceration occurs, retina damage.
5, tilapia streptococcus disease diagnosis
Anatomical disease fish sterile equipment, were taken gill,
liver, kidney, spleen, gonad, eye and other organs of the
small piece of tissue or fluid membrane inside the gill
cover, smear on clean glass slides and dried, Gram stain,
microscopic examination in the oil, can be found in the
chain of Gram-positive bacteria, found more bacteria for in
pairs, in a serious condition may find the typical chain of
bacteria, symptoms can be combined with the basic
diagnosis of fish. Types of pathogens can be identified by
- bacterial pathogens isolated or immunological detection
methods confirmed.
6, and the outbreak of factor analysis
Culture environment, breeding patterns and breeding
species and is closely related to the incidence of
Streptococcus, breeding density, breeding water pollution
by livestock to maintain high levels of feeding whole high
incidence of artificial feed; high temperature and disease
outbreaks and lead to high closely related mortality, and
once the temperature dropped, the death rate decreased
significantly; cultured species has a relationship with the
incidence rate, which may be fish food consumption with
high, fast growth, the; and specifications related to fish,
100g or more of the fish disease high, which may also
related to food consumption and rapid growth; onset of
segregation is not the fish, diseases and breeding ponds in
different areas of horizontal transmission; Also, in some
natural disease of broodstock gonads can sometimes detect
pathogens, the existence of vertical transmission also need
- further research. As for the zoonotic pathogen
Streptococcus one, livestock pollution is the source of
infection is also worth exploring.
7, tilapia streptococcus disease prevention and control
measures
Since the pathogen was Gram-positive bacteria, the
prevention and treatment than Gram-negative bacteria more
difficult. Prevention and control of Streptococcus main
measures:
1, strengthen the culture water environmental control of
microbial and sediment quality improver, regulate water
quality, maintain good water quality environment. Disease
outbreaks in the warm seasons, lower stocking density,
increase the oxygen machine to open the time, maintain
good water quality, particularly water contaminated by
livestock and poultry breeding areas, should be strictly
controlled the flow of contaminated water, and reduce the
amount of baits, in the case of conditions can reduce the
water temperature.
- 2, to enhance disease management, dead fish promptly
remove, as harmless, and to strengthen the disease in
isolation incidence pool and health pool of water, tools and
personnel.
3, in season and easy to outbreaks of epidemics season,
strengthening the control of the number of pathogens, such
as the environment and control the number of fish
pathogens. Breeding environment using disinfectants such
as chlorine preparations, antioxidants, such as hydantoin,
disinfecting water, reducing the number of environmental
pathogens and the infection rate; fish carrying the pathogen
commonly used oral medication to control sensitivity, but
the use of oral medication, you should pay attention to
medication the type, dose and administration period, to
choose the type of drug-sensitive drugs or compounded
preparations, such as the use of penicillin, ampicillin, and
more West tetracycline, minocycline, sulfonamides and
other drugs on the G + bacteria sensitive; drug dose to
ensure Drug use is able to effectively kill and inhibit the
reproduction of the dose of pathogen, the general dose of
50mg/kg to achieve more than the fish; drug use cycle,
- generally up to 7-10 days.
4, to improve fish's body, strengthen the improvement of
non-specific immune function. Such as dietary vitamin C
and immune polysaccharides, enzymes and other immune
enhancer, improve fish function, effective against
pathogens harmful to the body.
5, in the treatment of disease, they should pay attention to
environmental conditions and body function improvement,
while in the application of these drugs, fish liver and other
organs function improved, such as the use of 654-2 (trade
name), Glucurolactone ( trade name), etc. Oral, auxiliary
control the disease have significant effects.
6, immunization prevention and treatment of Di research
techniques are being carried out, in order to be truly
effective in controlling the disease's Chuanbo, immune
prevention and treatment always the most important resort
in Xianjie Duan Guo Nei Guangxi Fisheries Yanjiu Suo,
Zhongshan University, Pearl River Fisheries Research
Institute, Freshwater Fisheries Research Institute of Fujian
Province were carried out streptococcal vaccines.
- 8, Problems
Because tilapia streptococcus study also is not deep
enough, as it exists vertical transmission? Whether
livestock pollution is unknown. Breeding species are
sensitive pathogen-related issues and needs further
confirmation.
In 2010, Hainan Province in April that spotty
occurrence, indicating the occurrence of streptococcal
disease in the extended season, also means streptococcus
may be widespread in 2010, therefore, need competent
trade authorities, scientists and aquaculture industry
mutual coordination and efforts to strengthen the
epidemiological investigation and surveillance,
strengthen the collection and analysis of pathogenic strains
can the immune control techniques of research,
development and provide necessary basic materials.
Although the disease can not confirm whether vertical
transmission, seed quarantine will not only support the
existence of vertical transmission, but also effectively
- control the spread of the disease, therefore, I propose
that the unit should carry out seed quarantine.
nguon tai.lieu . vn
