Porcine circoviral disease (PCVD), also known as porcine circovirus associated disease (PCVAD), is a

disease A disease is a particular abnormal condition that adversely affects the structure or function (biology), function of all or part of an organism and is not immediately due to any external injury. Diseases are often known to be medical condi ...

seen in

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s. This disease causes illness in piglets, with clinical signs including progressive loss of body condition, visibly enlarged

lymph node A lymph node, or lymph gland, is a kidney-shaped organ of the lymphatic system and the adaptive immune system. A large number of lymph nodes are linked throughout the body by the lymphatic vessels. They are major sites of lymphocytes that includ ...

s, difficulty in breathing, and sometimes

diarrhea Diarrhea (American English), also spelled diarrhoea or diarrhœa (British English), is the condition of having at least three loose, liquid, or watery bowel movements in a day. It often lasts for a few days and can result in dehydration d ...

, pale skin, and

jaundice Jaundice, also known as icterus, is a yellowish or, less frequently, greenish pigmentation of the skin and sclera due to high bilirubin levels. Jaundice in adults is typically a sign indicating the presence of underlying diseases involving ...

. PCVD is very damaging to the pig-producing industry and has been reported worldwide. PCVD is caused by ''Porcine circovirus 2'' (PCV-2). The North American industry endorses "PCVAD" and European use "PCVD" to describe this disease.

PMWS and PCV-2

''Postweaning multisystemic wasting syndrome'' (''PMWS'') is the classic PCVD entity, caused by PCV-2. PCV-2 has a near universal distribution – present in most pig herds. In contrast, PMWS is more sporadic in its distribution. Experimental induction of PMWS has not been achieved by PCV-2 infection alone, using infectious

DNA Deoxyribonucleic acid (; DNA) is a polymer composed of two polynucleotide chains that coil around each other to form a double helix. The polymer carries genetic instructions for the development, functioning, growth and reproduction of al ...

clones of the virus or a pure form of PCV-2 derived from infectious DNA clones. Therefore, it is assumed that PMWS is a multifactorial disease. PCV-2 is necessary but not sufficient for the development of PMWS. However, viral infection by itself tends to cause only mild disease, and co-factors such as other infections or immunostimulation seem necessary for development of severe disease. For example, concurrent infection with porcine parvovirus or PRRS virus, or immunostimulation lead to increased replication of PCV-2 and more severe disease in PCV-2-infected pigs. There is no significant correlation of the disease with virus sequence variation with affected and control pigs.
Porcine circovirus type 1 (PCV1
was first identified in 1974 and was recognized as a non-disease-causing agent that frequently occurred in laboratory tissue cultures.

Clinical signs

Both PMWS and ''porcine dermatitis and nephropathy syndrome'' (''PDNS'') are associated to PCV-2. Many pigs affected by the circovirus also seem to develop secondary bacterial infections, like Glässer disease ('' Haemophilus parasuis''), pulmonary pasteurellosis, colibacilosis, salmonellosis and others. Postmortem lesions occur in multiple organs, especially in lymphoid tissues and lung, giving rise to the term "multisystemic".Harding & Clark, 1997 Lesions may also affect the skin, kidney, reproductive tissue, brain, or blood vessels. Wasting pigs is the most common sign of PMWS infection, increasing the mortality rate significantly.

Management practices to decrease severity of PMWS

François Madec, a French author, has written many recommendations on how reduce PMWS symptoms. They are mostly measures for disinfection, management, and hygiene, referred to as the "20 Madec Points" adec & Waddilove, 2002 These measures have recently been expanded upon by Dr. David Barcellos, a professor at the Veterinary College in the

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. He presented these points at "1st Universidade Federal do Rio Grande do Sul Symposium about swine management, reproduction, and hygiene". He divided his points by pig growth stage, and they can be loosely summarized as: *keep the gutters clean *increase feeder space *use pens or small cages with solid dividers *avoid mixing pigs from different origins *improve the quality of air *decrease maximum capacity, giving each pig more room *separate sick animals as soon as possible, and treat them in a hospital pen. If they do not respond to antibiotics in three days, they should be culled *control access of people and other animals *reduce environmental stress factors such as gases and air currents *use immunizations and preventive medications for secondary agents commonly associated with PMWS

PMWS and PCV-2

Clinical signs

Management practices to decrease severity of PMWS

See also

References

Further reading