Researchers from the World Health Organization (WHO) say that the H5N1 bird flu virus strain has mutated a bit after samples from a family cluster in Sumatra, Indonesia, were studied. However, WHO stresses that the mutation has not increased the chances of a human pandemic threat at all.

Seven members of the same family became infected with bird flu last month. An eighth person, also a member of that family, died. However, she was buried before samples could be taken. It is therefore presumed that it was most likely a cluster of eight. WHO scientists say that samples taken from a 10-year-old boy indicate that the virus mutated slightly and that the boy infected his father.

WHO scientists said the H5N1 in that cluster did not infect anyone else. In other words, it not spread. This is the first time compelling evidence has been found of H5N1 transmitting from one human to another.

WHO added that viruses are always changing slightly. This current slight mutation is nothing to be alarmed about. The virus can mutate in many different ways, one of which could be in the direction that may become a threat to human public health – this has not happened in this case. The fact that H5N1 died within that cluster means the mutated virus probably died there as well.

Detecting this mutation shows how advanced our surveillance system is becoming.

The H5N1 bird flu virus strain has always had the potential of transmitting from human to human – albeit with great difficulty. For one human to infect another ?continuous close physical contact’ is needed. The family cluster lived together in a very small room. If some of the members were infected and they slept together, the likelihood of human-to-human transmission would have been much greater.

Scientists were intrigued that only ?blood-relatives’ were infected. This means that if a boy and his father got infected, the father’s wife and her blood relatives didn’t.

Investigators still have not been able to find the source of the infection for the cluster – an animal source. They have combed the area and come up with nothing. It is probable that wherever there had been an infected bird had been thoroughly cleaned before the inspectors arrived.

Good surveillance is essential if we want to combat the spread of bird flu. The H5N1 virus needs an environment where lots of humans are getting infected for it to mutate. The most likely way the bird flu virus could pick up the ability to become human transmissible is to infect a person who is sick with the normal human flu virus. H5N1 could exchange genetic information with the human flu virus and acquire its ability to easily spread from human-to-human.

Humans cannot get ill easily because H5N1 needs to get deep down in the human lung to cause illness. It does not infect the upper-respiratory tract. This, for us has two bonuses:

1. We cannot catch it easily as it is difficult for it to get deep down into the lung(s).

2. A sick human cannot pass it on easily as his coughs and sneezes contain hardly any H5N1s, for the same reason – they are too deep down.

For the virus to become easily human transmissible it will most likely need to infect the upper respiratory tract. It will need to mutate to do this. Then infections would be easier to get and sick people would cough and sneeze larger quantities of the virus. Even so, on a good note, upper-respiratory tract infections are much easier to treat than ones deep down in the lungs. Therefore, if the virus mutates it will spread among humans more easily, but should not be so deadly. This is only a well calculated theory. Nature sometimes follows different paths.

Written by: Christian Nordqvist
Editor: Medical News Today