The various types of influenza virus are clearly illustrated in the above figure. Solid squares show the appearance of a new strain causing recurring influenza pandemics. The dotted line indicates the unidentified strains.

The H1N1 form of swine flu is one of the descendants of the Spanish flu that caused a devastating pandemic in humans during 1918 -1919. It would have been persisting in pigs and was then circulated into humans during the 20th century, contributing to the normal seasonal epidemics of influenza.

This virus constantly changes its form, thereby eluding the protective antibodies that people may have developed in response to previous exposures to influenza vaccines. Every two or three years, the virus undergoes minor changes.

But at intervals, a bulk of world’s population has developed some level of resistance to these minor changes and it easily infect populations around the world, often infecting hundreds of millions of people whose antibody defenses are unable to resist it.

In 1957, an Asian flu pandemic infected 45 million Americans and killed 70,000. It caused about two million deaths globally. Once again, the cycle turns back in 2009. So far, 300 peoples in Mexico have been infected by the influenza A swine strain. Thus making evident, the outbreak of swine flu and making contingency plans for a possible global pandemic.

The infectious agent responsible is a virus CSFV (previously called hog cholera virus) of the genus Pestivirus in the family Flaviviridae ([1]). CSFV is closely related to the ruminant pestiviruses which cause Bovine Viral Diarrhoea (BVDV) and Border Disease (BDV).^[1]

The effect of different CSFV strains varies widely, leading to a wide range of symptoms. Highly virulent strains correlate with acute, obvious disease and high mortality, including neurological symptoms and hemorrhages within the skin.

Less virulent strains can give rise to subacute or chronic infections that may escape detection, while still inducing mortality in fetuses and new-borns.

Infected piglets birthed from infected but subclinical sows help maintain the disease within a population. Other symptoms can include lethargy, fever, immunosuppression and secondary respiratory infections. The incubation period of CSFV ranges from 2 to 14 days but symptoms may not be apparent until after 2 to 4 weeks. Animals with an acute infection can survive 2 to 3 months before their eventual death.

Eradicating CSF is problematic. Current programmes revolve around rapid detection and diagnosis, and preventive culol, possibly followed by emergency vaccination. Possible sources for maintaining and introducing infection include the wide transport of pigs and pork products, as well as endemic CSF within wild boar and feral pig populations.

CLASSICAL SWINE fever (CSF), otherwise known as hog cholera (also sometimes called pig plague based on the German word Schweinepest), is a highly contagious disease that comes from pigs and wild boar. It is caused by Pestivirus, which belongs to the family Flaviviridae.

Swine fever causes fever, skinlesions, convulsions particularly in young animals and fatality within 15 days. The disease is endemic in much of Asia, Central and South America and parts of Europe and Africa. According to the reports of the United Kingdom Husbandry, it was eradicated in animals. This statement was also confirmed by the United States Animal Husbandry in 1978. The major symptom of this virus infection in pigs is the pinpoint hemorrhages on the kidneys.