<table align="left" width="270" style="font-size:10px;font-style:italic;color:gray;">
<tr>
<td>
<img loading="lazy" src="http://www.scientificamerican.com/media/inline/contagion-controversy-erupts_1.webp" width="250" alt="Colorized transmission electron micrograph of Avian influenza A H5N1 viruses (seen in gold) grown in MDCK cells (seen in green). Avian influenza A viruses do not usually infect humans; however, several instances of human infections and outbreaks have been reported since 1997. When such infections occur, public health authorities monitor these situations closely" />
</td>
<td>
&nbsp;&nbsp;
</td>
</tr>
<td>
Colorized transmission electron micrograph of Avian influenza A H5N1 viruses (seen in gold) grown in MDCK cells (seen in green). Avian influenza A viruses do not usually infect humans; however, several instances of human infections and outbreaks have been reported since 1997. When such infections occur, public health authorities monitor these situations closely. (Image: Cynthia Goldsmith)
</td>
<td>
&nbsp;&nbsp;
</td>
<tr>
</tr>
</table>

Epidemiologists have long debated the pandemic potential of H5N1, a.k.a. avian bird flu. On one hand, the virus spreads too inefficiently between humans to seem like much of a threat: it has caused less than 600 known cases of human flu since first emerging in 1997. On the other hand, when it does spread, it can be pretty deadly: nearly 60 percent of infected humans died from the virus. For years now, the research has suggested that any mutations that enhanced the virus’s ability to spread among humans, would simultaneously make it less deadly. But in a recent batch of as-yet-unpublished studies, two scientists - <a href="http://www.vetmed.wisc.edu/people/kawaokay/" target="_blank" class="news_link" title="Yoshihiro Kawaoka">Yoshihiro Kawaoka</a> from the University of Wisconsin, Madison and <a href="http://www.erasmusmc.nl/MScMM/faculty/CVs/fouchier_cv?lang=en" class="news_link" title="Ron Fouchier" target="_blank">Ron Fouchier</a> of Erasmus Medical Center, in the Netherlands – have shown otherwise.



Working separately, they each hit on a combination of mutations (five, in Dr. Fouchier’s case) that makes H5N1 airborne (enabling it to spread readily between humans), without making it less deadly. In laboratory experiments, ferrets infected with this mutant strain passed it to other ferrets in nearby cages (ferrets are a common subject of flu studies because they react to flu viruses in a similar way to humans). A significant proportion of infected subjects died.


Efforts to publish those findings have been fraught. Critics say that making the methodology or gene sequences widely available, amounts to giving would-be bioterrorists an easy recipe. They also worry that these manmade strains might escape from the lab.



<a href="http://www.scientificamerican.com/article.cfm?id=contagion-controversy-erupts" class="news_link" title="Source" target="_blank">
Continue reading at source Scientific American
</a>

Contagion: Controversy Erupts over Man-Made Pandemic Avian Flu Virus