After mad cow and avian influenza, it is now the swine flu that has caused worldwide panic about the possibility of a potential human pandemic, caused by an ailment of animal origin.
Over 150 people have already lost their lives in Mexico, the US and elsewhere, prompting the World Health Organisation to proclaim the flu as a 'public health emergency of international concern'.
While the mad cow and bird flu could pass on from animals to humans through either direct contact with the diseased animals or on consumption of the under-cooked flesh of sick livestock, the swine flu virus A-H1N1 is easily transmittable from animals to humans and vice versa, as well as from one person to another -- like any common human influenza infection which can spread even through coughing and sneezing.
This particular strain is deemed more perilous also because it has been found to have characteristics common to swine flu, human flu and bird flu, all of which are, singly or collectively, present in several pockets of the globe.
Moreover, though pigs still can't fly, the birds and humans moving across the world can and do, and therefore carry the virus to distant places.
That explains the quick spread of this infection from its epicentre (Mexico) to as far and geographically isolated an area as New Zealand. Coming at a time when the first signs of an economic recovery had appeared on the horizon, the swine flu can potentially send important parts of the world economy back into a tailspin.
The immediate worry is with regard to prevention, and not so much the cure of swine flu.
For, the vaccines available for warding off the common human flu are ineffective or only partially effective against this strain, which is believed to have evolved through the swapping of genes between influenza viruses of different species.
Mercifully, however, once the flu has caught on, it is curable if detected in time. In its present form, the H1N1 virus has been found to be immune to only two (amantadine and rimantadine) of the available four antiviral drugs.
The other two -- oseltamivir (Tamiflu) and zanamivir (Relenza) -- are said to be capable of treating this disease in human beings.
In the absence of an effective vaccine, the only way to curb the spread of this plague is through increased vigil at airports and other entry points where people from the infected regions cross into other territories, and speedy isolation and treatment of infected persons.
Such surveillance will be needed against not only swine flu but also against bird flu, which is still present in virulent form in several countries -- having caused the death of a woman in Vietnam just last week. Any further admixture of the swine and bird flu viruses with human flu strains will heighten the danger of their mutating into new viral forms which could then pose fresh, wholly unpredictable, challenges.
Considering the increasing incidence of human health hazards due to the frequent outbreaks of animal diseases in recent years, livestock management and breeding policies may well need a fresh look.
The single breed-based industrialisation of the livestock sector may have contributed to the perpetuation of animal diseases as pathogens, more particularly influenza viruses, tend to change form to suit the abundantly available hosts.
Diversification of livestock breeds in commercial animal farms can reduce such risks. At the same time, the efforts to evolve and mass-produce strain-specific vaccines against emerging viruses need to be redoubled.