Porcine Circovirus-2
| Porcine Circovirus-2 | ||||||||||||||||||
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| Porcine circovirus 2 | ||||||||||||||||||
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The Porcine circovirus (PCV) type 2 is a virus, which is found in pigs. It belongs to the virus family Circoviridae , genus Circovirus and has a circular, single-stranded DNA with ambisense polarity as its genome . The PCV has no virus envelope ; it is therefore very stable to the environment and difficult to inactivate with disinfectants .
PCV-2 infection is one of the most important problems encountered by companies that have been bought in. The pathogens have been detected since 1962, but outbreaks have only occurred since around 1998. It is still unclear how this is possible.
Symptoms
Symptoms include sneezing, coughing, nasal and eye discharge, fever up to 41 ° C and growth arrest at the age of 4 to 16 weeks. Miserable ones often emerge 1 to 2 weeks after weaning. Sometimes the symptoms of sneezing, sniffing and worrying already occur in the farrowing pens, there can also be abortions in all stages of pregnancy. The piglets have thickened, reddened eyes and black traces of tears (conjunctivitis). The lymph nodes in the thigh gap are massively enlarged, but normally they are not visible. There are also severe respiratory problems.
The PCV-1 is closely related with the PCV-2, but non-pathogenic.
Connection with other diseases
PRRS and PCV-2 often coexist, making the disease worse. PCV-2 often causes PMWS ( Postweaning Multisystemic Wasting Syndrome = "epidemic worries after weaning") and PDNS ( Porcine Dermatitis and Nephropathy Syndrome = skin changes, kidney damage and thus high losses); PMWS and PDNS very often occur together. PCV-2 often occurs at the same time as a mycoplasma infection, so that this co-infection can be treated with antibiotics, but not the virus infection with PCV-2 itself.
Factor disease
PCV-2 is a factor illness, which means that there is not a single trigger, but that the illness is influenced by various factors. She is z. B. strongly favored by epidemiological and hygienic factors such as a pig-dense region, PRRS, a continuous occupancy of compartments, litter compensation of older piglets, the relocation of piglets in younger groups, the mixing of different origins, poor integration of gilts and stock increases.
Investigations on cell cultures indicate that a disease caused by PCV-2 is caused by the simultaneous presence of PCV-1 and a cooperative pathogenicity of both viruses.
Prevention
The most important countermeasures are management optimization and compliance with strict disease hygiene measures. Litter compensation must be minimized, the injection needles must be changed after each litter, and the castration set must be disinfected after each litter. The farrowing pens and piglet rearing should only be occupied in a consistent all-in-all procedure, so that smaller piglets are not allowed to be moved back into younger groups. Sick piglets must be separated immediately and, if necessary, also killed in good time. The housing conditions must be optimized (suitable occupancy density, good air quality, etc.). The piglets must only receive high-quality feed and water, and the integration of gilts must be optimized, gilts should be integrated no more than six times a year, they should be given at least 6 weeks of integration time during which they are kept separate from the rest of the herd. Here the gilts must also receive the best possible immune prophylaxis. The measures on the piglet in the first week of life should be reduced as much as possible, since stress promotes the diseases. Observations also suggest that immune stimulation in the first week of life such as For example, vaccination increases the risk of PCV-2 infection and thus also the risk of PMWS and PDNS, but this has also been associated with insufficiently sterile conditions during vaccination and transmission of PCV-2. Animals with an existing infection should not be vaccinated or stressed in any other way, but you have to weigh up, because timely and consistent treatment is very important.