The deadly H5N1 virus prefers to reside deep within the lung cells rather than in the upper respiratory tract, unlike other human influenza strains, as revealed by two recent studies.
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| The possibility of human-to-human transmission of H5N1 is highly unlikely (Image: ecplanet) |
This may explain why human-to-human transmission of this avian influenza virus has not occurred to date—and may not happen in the future, Forbes.com reported yesterday.
Since 2003, the H5N1 virus has emerged in Asia, Europe, Africa, and the Middle East, leading to the culling of tens of millions of poultry. Although infections are currently limited to birds, the virus has killed 103 people through bird-to-human transmission.
However, scientists are concerned that this deadly virus could mutate into a form that is much more easily transmitted from human to human, which could lead to a global human influenza pandemic.
One of the two studies released this week investigated this possibility, conducted by scientists from the University of Wisconsin and the University of Tokyo. The team found that H5N1 has very little likelihood of residing in the upper respiratory tract. Instead, it penetrates much deeper and remains resilient in the lungs, making it more difficult for the virus to spread and be treated.
In contrast, common human influenza strains tend to inhabit cells in the upper respiratory tract. This means that whenever a person coughs or sneezes, droplets from this area can easily spread into the air, facilitating human-to-human transmission.
The findings of the Japanese-American researchers were corroborated by a Dutch research team, which is expected to publish their results in the journal Science tomorrow. The scientific group from Erasmus University Rotterdam once again found that avian influenza prefers to hide in cells deep within the lungs while avoiding the upper respiratory tract.
Both studies suggest that the likelihood of human-to-human transmission of H5N1 is very low, at least for now. However, any mutation could change that situation.
T. An
