[Looking at the picture to see the disease]The symptoms and prevention methods of Koi herpes virus d
First, because KHV is sensitive to temperature, keeping the temperature of the water body constant, proper control of the water temperature can prevent the occurrence of koi herpes virus disease to a certain extent.At the same time, "Jinquan" (probiotics and targeted nutrients) is regularly added to the water body to maintain a stable water quality environment, which can effectively prevent common bacterial diseases such as koi rotten gills.
Koi herpes virus disease occurs frequently in spring and autumn.The optimal temperature for KHV to proliferate in cells is 20°C to 25°C. It cannot proliferate above 30°C and below 4°C. The minimum temperature requirement is 10°C.However, the virus persists in the cell at non-permissible temperatures. When it is returned to the appropriate temperature, the transcription of the viral gene is activated again, resulting in cytopathy.
Koi herpes virus disease has a rapid onset and rapid death, which brings great challenges to treatment. Once KHV is found, the treatment methods that can be found so far are to kill the fish and cut off the virus source.Therefore, it is of great significance to prevent the disease.
2.Pathological changes: The most obvious damage to the diseased fish is in the gills.On the second day after infection, the gill slices decreased, accompanied by infiltration of inflammatory cells; on day 6, the gill structure disappeared, the blood vessels in the gill arch were congested, and the gill rake became thinner.Gill damage is earlier than other tissues.Except for the gills, the most important lesions occur in the kidney.On the second day after infection, there was inflammatory infiltration around the renal tubules; on the sixth day, there was severe interstitial inflammation accompanied by vascular congestion.The inflammation subsequently worsened, accompanied by a slight degeneration of tubular epithelial cells of some nephrons.In addition, other organs also have different lesions.Liver parenchyma showed a slight inflammatory infiltration, and brain tissue sections showed focal meningeal and parameningeal inflammation.
1.Clinical symptoms: unresponsiveness, loss of appetite, difficulty breathing, often swimming on the water surface or outlet; gill hemorrhage and necrosis, sunken eyes, atrophy of the skull, gray spots on the skin, increased mucus secretion; scales with blood, no obvious damage to the surfaceAfter 7 to 10 days of infection, death began, and the mortality rate reached 100% after 2 to 3 weeks.Other species of fish in the same pond will not be sick.
The molecular biological techniques for detecting Koi herpesvirus mainly include PCR method, probe detection and loop-mediated isothermal amplification technology (LAMP).The LAMP detection method has three major advantages: First, it is fast, simple, cheap, and the reaction can be observed with the naked eye, and does not require a special PCR reaction instrument, which is very suitable for on-site diagnosis; Second, high sensitivity, the required test sample (from gills)The amount of virus DNA extracted from the tissue is extremely small and will not cause damage to the Koi carps; third, whether the virus is carried can be detected without the clinical symptoms of the Koi carps.
When the water temperature is 16 ℃ ~ 27 ℃, Koi herpes virus disease is the most prone to outbreak, depending on the water temperature, the incubation period of the disease is about 7 to 21 days.At a low temperature of 13°C, the fish will be infected with KHV, but will not get sick.If the fish has been infected with KHV, the longer the water temperature is 18℃~27℃, the greater the possibility of disease outbreak.
Second, improve the fishs own immunity.Long-term administration of probiotics and immune polysaccharides can enhance fish immunity and improve disease resistance.golden arowana Grandma Township&What to pay attention to,Efficacy of Little Golden dragon fish Gum!Golden Dragon Fish Grandma Township Advertisement*How to raise the golden dragon/How to feed arowana grows fast"How to raise the small fish bred from Arowana)What food do Arowana eat mainlyTaboo for goldfish.