Background

Porcine circovirus (PCV) is an emerging global disease with a massive impact on the swine industry causing severe economic loss. PCV is associated with the post-weaning multisystemic wasting syndrome (PMWS) characterized by respiratory distress, weight loss, jaundice, etc. The strain associated with PMWS is pathogenic and designated as PCV2 and the non-pathogenic strain as PCV1. PCV2 infection is ubiquitous and is circulating in the pig population for more than a decade. Recently, a novel species PCV3 has been reported in pigs having porcine dermatitis nephropathy syndrome, acute myocarditis, and multisystemic inflammation, etc. PCV2 has a wide geographic distribution as an emerging swine pathogen. In India, PCV2 has also been reported from different parts. In Uttar Pradesh, swine farm having a history of mummification, stillbirth, neonatal mortality, and decreased litter size from 12 out of 70 piglets were positive for PCV2. PCV is transmitted through different routes. PCV2 are secreted in body secretion like nasal, bronchial, tonsilar and ocular secretions, urine, faeces, saliva, and milk of infected animals. The most efficient route of virus transmission is direct contact with the infected animals. Generally, the oronasal route is the most favorite route of transmission. Native pigs, when fed on uncooked tissues of infected pigs were infected. When pigs are kept in adjacent pens, then the indirect transmission of the virus occurs. Infected sows also shed PCV in milk, which can transmit the virus to the offspring through the oral route. The most effective method to prevent viral disease is vaccination using a safe and effective vaccine. The commercially available vaccine is effective in controlling the severity of the disease and improves production parameters. The commercially available vaccines are based on whole inactivated PCV2 virus or immunogenic protein.

Cause

A virus disease caused by Porcine circovirus 2 (PCV2)

Host Species

Pigs

• The virus is secreted through the nasal discharge, feces and urinary secretions.
• Ingestion by fecal/oro-fecal route is the common method of spread.
• It is secreted intermittently in semen because the virus resides within macrophages which are extruded into the semen via the local lymphoid tissues particularly the bulbourethral glands.
• Transplacental infection usually occurs in the field and stillbirths in pigs may be associated with the PCV2 infections.
• Clinically healthy pigs from post-weaning multi systemic wasting syndrome affected pigs developed the disease when transported and commingled with clinically affected pigs.

• There will be progressive loss of weight, wasting and failure to thrive.
• There may be slight fever, pallor, and diarrhea. Jaundice may be observed occasionally.
• There may be evidence of respiratory disease in the form of cough, difficulty in respiration and/or rapid respiration.
• Sick pigs may be there along with healthy pigs.
• There may also be signs of heart failure with pericardial effusions and myocardial dysfunction.
• The most characteristic clinical feature is the presence of swollen inguinal lymph nodes.
• In growing and finishing pigs, PCV2 associated PRDC is characterized by slow and prolonged growth along with dyspnea that does not respond to antibiotic therapy.
• There is also a marked increase in mortality from single/concurrent bacterial infection(s).
• The co-infection of PCV-2 and PRRSV causes abortion at midgestation, stillbirths, mummification of fetuses, and early embryonic death.
• The intrauterine infection may produce fetal deaths and abortions.
• The abortion is typically sporadic and characterized by increased numbers of mummified fetuses. Transplacental infection with PCV2 is generally associated with reproductive failure in a gilt.
• PCV2 is associate with reproductive failure at all stages of gestation.

Management

• No specific treatment is there for porcine circovirus.
• Only following supportive treatment will help.
• Sick animals should be isolated.
• Antibiotic is prescribed to prevent secondary bacterial infections.
• Corticosteroid is useful to alleviate stress.

Preventive measures

• The control measures of the disease are based on following principles
• Good maintenance of health.
• Reduce the stocking density.
• All in/all out management of the rooms of buildings with cleaning and disinfection before the next batch.
• Reduction of entry of new stock with in each 3 months for replacement gilts.
• Avoid contact between animals.
• Avoid any form of fostering if possible.
• Avoid frequent handling of piglets to reduce stress.
• Increase the hygiene practices in the farrowing quarters.
• Enhancement of natural immune response. Make sure that the piglets have an adequate colostrum intake. Make sure that they are a good body weight at weaning.
• Avoid vaccinating piglets at an early age to be avoided.
• Generate the right environmental conditions particularly for temperature and humidity. It should be regulated with the stage of growth. Avoid overcrowding.
• Provide good quality feed.
• Control parasites in animals house.

Control

• Regular vaccination is the only effective way to control the disease

Type of vaccines

Recombinant Inactivated chimaeric PCV1/2 vaccine

Oil adjuvanted inactivated PCV2 vaccine

Vaccination schedule

The vaccination against porcine circovirus is recommended to pigs at the age of 3 weeks and annual vaccination is needed if animals are reared more than 8 months or above.

Dose

1mL I/M route or following manufacturer's instructions

Note: Deworming is must at least 15 days before vaccination

Source/manufacturer of vaccine in India

Boeuringer Ingelhein India Pvt. ltd., Mumbai, India