Breaking the species barrier

An animal specie can be the unwilling host for a virus or other pathogen. It then serves as a reservoir from which the virus can expand, survive and thrive. When working with the World Animal Health Organization, also known as the OIE a Paris based IGO, I actually learned a lot about this subject. The fact that there are such diseases as the West Nile Virus, Avian influenza, foot and mouth disease or the Henza virus for example that have the capacity to infect humans, is a cause of great   concern. This happens when the disease breaks or jumps the species barrier. Rabies is a typical example.

Source American Society for Microbiology http://mmbr.asm.org/content/72/3/457/F5.expansion.html
We just need to think of the H5N1 pandemic to realize their damaging potential to humans, the economy and therefore our societies. Some food borne pathogens such as E.coli or Campylobacter Jejuni, are carried by poultry and livestock . These biological agents or pathogens can also affect public confidence in the food supply. An international network of disease outbreak surveillance is needed to detect outbreaks early on and limit their extent. This also underlines the need for well stocked vaccine banks. It is essential that the behavior and ecology of organisms that serve as vectors and reservoirs be well studied and understood. Obviously if one were to disallow animal research such defensive or safeguarding systems would become useless and our level of risk increased accordingly.
See this article about the Hendra virus found in bats.

For certain diseases such as malaria for example the host specie can be both human or animal (apes) and the disease transmission vector is the mosquito. A good site about malaria , its origins, treatments etc is found here.
The WHO publishes reported malaria cases on a per country basis here. The reduction of the disease is part of the UN millennium development goals (#6C).

Source US CDC

The United States Centers for Disease Control (CDC) reports WHO estimates of mortality ranging from 708,000 - 1,003,000 deaths for 2008. Current treatments are derived from plant species according to the CDC site. Take a look here for the malaria's parasite life cycle.

The micro organism responsible is called Plasmodium and there exist over a hundred species of them, four of which are known to infect humans (Source USCDC visited 2101-05-31).
A limiting factor for the spread of the disease appears to be cold temperatures (below 20 deg. C) as it prevents the completion of the anopheles mosquito's growth cycle.

So beware of global warming, for over the coming years the boundaries of the disease may spread well beyond its current areas of occurrence. Genetic mutations and viral recombination too make it possible to break the species barrier. One more reason to keep a close eye on what is happening, via animal research, with the evolution of these micro organisms and to get a vaccine ready for a potential outbreak. Aren't we all worth it?

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