African Swine Fever spreads throughout Africa, Russia

May 30, 2012 — 

The African Swine Fever (ASF) virus is not a new disease. In fact, it has been around for decades. However, the bleeding disorder has recently been showing up more often, rearing its head in regions where it has not been seen before. With growing presence in Africa and Russia, the European Union (EU) could be the next nation to be affected by ASF. [Agri-view, May 24, 2012]

According to Jose Manuel Sanchez-Vizcaino, one of the World Organization for Animal Health’s (OIE) ASF experts, the virus has been moving around Africa actively over the past 15 years. It is also present on the Italian island of Sardinia, in Russia and in some of Russia’s neighboring post-Soviet countries like Georgia and Armenia.

“Africa and Russia are considered a potential risk for the introduction of ASF in the EU,” Sanchez-Vizcaino says. As trade relationships for Africa and Russia grow between other countries, there is fear that ASF could become endemic. A higher presence of the virus in Africa means more contaminated animals and products being transferred around the continent, thus leading to new outbreak areas. ASF has been present in Russia since 2007, he says, calling the situation “out of control.” Though imports of both live pigs and products have been restricted from affected countries, illegal trade activities may contribute to the ongoing spread of the disease, as well as a lack of biosecurity measures. The wild boar population has also been known to contribute to the migration of the disease. Currently, there is no vaccine to prevent hogs from becoming infected with ASF, nor is there an effective treatment. Some strains of the virus cause as much as 100 percent mortality.

Compared to other contagious diseases like foot and mouth disease or classical swine fever, ASF tends to move more slowly, Sanchez-Vizcaino points out. He warns, however, that if control measures are not taken, the virus could become endemic, especially as outbreaks occur near the borders of the EU. ASF can be difficult to diagnose because its symptoms often resemble other bleeding disorders; therefore, a necropsy is needed to properly identify the disease. The virus can persist in blood, tissue and feces for long periods of time, and when infected carcasses are not properly disposed of, or infected pork products are fed to other pigs, transmission can occur.

In its least severe form, ASF results in death around 20 days post-infection with few clear signs of sickness. A necropsy would reveal hemorrhagic lesions in the lymph nodes and bleeding or irregularities in organs like the lungs, kidneys, heart and stomach.

Hogs infected with the acute form of ASF show more outward symptoms. Skin disorders, including a rash on the abdomen, ears and snout, may be visible. Edema of the lungs may also cause pigs to exhibit breathing difficulty. Hemorrhages and possibly hemorrhagic shock resulting in nasal discharge or diarrhea may also be signs of ASF. Feverish animals will display huddling behavior due to being cold and suffering from the injuries noted. ASF outbreaks in Russia have typically been presenting themselves as the acute form, causing death within seven to 15 days after infection.

In its most severe form, hyperacute ASF shows very few signs before causing death. Beyond fever and feverish behavior, pigs with ASF do not exhibit any other symptoms. Death can occur in less than one week post-infection.

Early detection and rapid implementation of control measures are critical in preventing the large economic losses that can occur as a result of ASF. In late 2011, the Ukraine slaughtered 14,000 pigs to prevent the spread of the disease. They also banned imports of all pork products from Georgia, Armenia and five other Russian districts. Since 2007, 273 outbreaks in the Russian Federation region have been reported to the OIE with death losses mounting 76,000 hogs.

As outbreaks inch their way west toward the EU, Sanchez-Vizcaino says that farmers, veterinarians and policy makers together would play key roles in controlling and eradicating ASF. Increased biosecurity measures, monitoring of the movement of live hogs and pork, eliminating infected animals and economic compensation would all be components of a plan to isolate and control an ASF outbreak.

“Definitely, at present the risk of ASF for Europe is the highest since 2007, and we must be prepared, our best defense being information,” Sanchez-Vizcaino says.

Source:
Agri-view, May 24, 2012
BY PEGGY COFFEEN, DAIRY/LIVESTOCK EDITOR