söndag 20 september 2009

Prevention of cross-species transmission of infections

In this era of rapid global transport as well as poorly planned urbanization and overcrowding in many parts of the world, infections such as influenza, severe acute respiratory syndrome (SARS), Ebola, HIV can get transmitted much faster than ever. I think it is necessary to note that these infections and many others causing human diseases have emerged as human pathogens when virus established in animals switched (jumped) host into humans, with subsequent within-species (human-to-human) transmission, ultimately leading to the analogous nature of epizootic diseases among the humans. About three fourths of emerging infectious diseases are known to have zoonotic origin. Possibility of original animal virus to acquire even higher pathogenicity in humans of course, is a cause of concern. Timely containment of infections at the spot of origin can prove to be an efficient strategy to prevent large scale epidemics and pandemics. Tropical forests with wide range of animal and plant species diversity associated with higher likelihood of greater diversity of viral strains and their contact with humans in their vicinity - is a most likely link of cross-species jump of many such infections. Bushmeat hunters are known to be a perfect "virus interface" due to their close contact with animals, mostly primates. Besides, activities of bushmeat transportation, butchering, sales, purchase and consumption are also other important risk factors. Tribal populations that traditionally survive on bushmeat are another interface for animal viruses. Recently ongoing H1N1 influenza pandemic has underscored need of more stronger surveillance on one more interface of viral hosts to contact the humans- swine and poultry farms.




US National Institute of Health funded Global viral forecasting project aims at building a network of virus-discovery projects by monitoring hunters and wild-game markets in some of the potential locations in Congo, Malaysia, Laos, Madagascar, Paraguay, and China. Undoubtedly, this project is anticipated to be a valuable effort in preventing spread of zoonoses to human populations by timely intervention using global viral forecasting.

However, utilization of similar volume of resources for preventing global bushmeat trade, discouraging use of bushmeat among tribals- can prove even more cost-effective strategy to prevent cross-species transmission of infections. It is surprising that none of the projects so far aims towards completely ending bushmeat hunting.

In addition to the concern about infections, bushmeat industry is estimated to cause loss of more than 579 million animals annually only in the Central Africa. Biomass of mammals in parks has got downsized by 70% since 1967 due to bushmeat "harvesting". Many species are facing extinction. Bushmeat hunting also threatens local livelihood. There are some projects such as Bushmeat crisis task force working on prevention of commercial hunting and towards conservation of wild-life. Scale of their operation appears much weaker in comparison to the intensity of bushmeat hunting.

In this view, policy framework promoting vegetarianism at global scale is likely to have a far greater potential as a global public good for health compared to any one of the GPGH policies of the WHO. Since vegetarianism might not only help in significantly reducing disease burden of many chronic diseases (particularly in the developing nations experiencing health transition and increasing burden of non-communicable diseases) but also helps in effective prevention of cross-species transmission of infections with potential of causing pandemics, conservation of biodiversity, reduction of carbon foot-print and ultimately restoring ecological equilibrium.