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Classical Swine Fever
What is it?
Classical swine fever (CSF), also known as hog cholera or swine fever, is a highly contagious viral disease of pigs. It is clinically similar to African swine fever, but is caused by a different virus.
CSF virus can remain infective in frozen pig carcases and cured or salted pigmeat products for long periods. It can also persist in contaminated pig pens for up to two weeks.
Where is it found?CSF is found in parts of Germany and some Eastern European countries. The disease is also present in eastern and central Africa, the Indian subcontinent, China, East and Southeast Asia, Central America and most of South America. CSF first occurred in Sumatra in 1994 and gradually spread across the Indonesian archipelago, reaching Java in early 1995, Bali and Kalimantan in late 1995, East Timor in 1997 and Papua, on the island of New Guinea, in 2004.
Outbreaks of CSF occurred in Australia in 1903, 1927–28, 1942–43 and 1960–61. In each case the disease was eradicated. The first three outbreaks were caused by virulent strains and resulted from imported pigmeat or food refuse from ships being swill-fed to pigs. The last outbreak was caused by a low virulence strain, and was characterised by milder illness and increased mortalities associated with bacterial infections in poorly run piggeries.
What are its effects?
CSF is highly contagious and spreads rapidly in faeces, urine, nasal secretions and tears. Direct contact of infected pigs with susceptible pigs is the most important means of spread, but the virus can also be transmitted on contaminated pens, pig crates, trucks or clothing.
Swill-feeding of pigs with infected meat scraps is also an important means of spreading CSF to new areas or countries, as shown by the history of its introduction to Australia.
Acute CSF causes sudden fever. Affected pigs first appear drowsy but are later severely depressed and off their feed. They huddle together, stagger and occasionally have convulsions and trembling; vomiting, coughing and diarrhoea are common. There is often also red or purple blotching on the skin of the ears, snout, limbs and abdomen of infected animals. Mortalities can reach 90 per cent.
The chronic form of the disease produces similar clinical signs, though in milder form; death usually results after 30 days or more and is often associated with secondary bacterial infections.
In the mild form, clinical signs may be absent altogether or affected pigs may fail to thrive. Pregnant sows may abort or give birth to stillborn piglets. Piglets that survive often have congenital tremors or deformities. They may show few other clinical signs for several months and then develop signs of acute disease, terminating in death.
What’s the threat to Australia?
A CSF outbreak would have serious consequences for Australia’s domestic and export production of pigmeat, since outbreaks can only be controlled by slaughter, by strict controls on the movement of pigs and equipment and by long-term vaccination programs.
22 Feb 2008