Porcine circoviral disease (PCVD) and porcine circovirus associated disease (PCVAD), is a

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

seen in

domestic pig The pig (''Sus domesticus''), often called swine, hog, or domestic pig when distinguishing from other members of the genus '' Sus'', is an omnivorous, domesticated, even-toed, hoofed mammal. It is variously considered a subspecies of ''Sus ...

s. This disease causes illness in piglets, with clinical signs including progressive loss of body condition, visibly enlarged lymph nodes, difficulty in breathing, and sometimes

diarrhea Diarrhea, also spelled diarrhoea, is the condition of having at least three loose, liquid, or watery bowel movements each day. It often lasts for a few days and can result in dehydration due to fluid loss. Signs of dehydration often begin w ...

, pale skin, and jaundice. 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 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

Universidade Federal do Rio Grande do Sul The Federal University of Rio Grande do Sul ( pt, Universidade Federal do Rio Grande do Sul, UFRGS) is a Brazilian public federal research university based in Porto Alegre, Rio Grande do Sul. UFRGS is among the largest and highest-rated univers ...

, Rio Grande do Sul,

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

. 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