Some Person To Person Transmission Possible In Pakistan Bird Flu Cluster

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Main Category: Bird Flu / Avian Flu
Also Included In: Infectious Diseases / Bacteria / Viruses;  Respiratory / Asthma
Article Date: 19 Dec 2007 - 8:00 PDT

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According to the World Health Organization (WHO), the eight people in Pakistan who became infected with the H5N1 bird flu strain probably got ill as a result of contact with poultry and some degree of human-to-human transmission. The WHO stressed that nothing has been confirmed yet.

This latest cluster will not make the WHO raise the level of pandemic alert. A WHO spokesperson informed Reuters that in all probability there is one index case - a veterinarian - and while the others had the illness passed on to them from poultry.

Human-to-human transmission of H5N1 bird flu is extremely rare, but not unheard of.

In this latest cluster eight people have become infected with the H5N1 bird flu virus strain in the North West Frontier Province, Pakistan - one of the patients has died. There could be another case, the deceased brother, who also died. But confirmation of bird flu may never come as samples were not taken.

What is H5N1?

H5N1 is a strain of the bird flu virus - the strain everybody is worried about because human beings have no immunity against it, it is very virulent (powerful and dangerous).

Scientists are afraid that the H5N1 bird flu virus strain will sooner or later transform and become easily human transmissible. This has not happened yet. It is still exceedingly difficult for birds to infect humans, and even harder for a human to infect another human.

It is thought that one of the ways H5N1 could mutate would be by infecting a person who is ill with the normal human flu virus. The bird flu virus would then have the chance to exchange genetic information with the human flu virus and acquire its ability to spread easily from human-to-human (become easily human transmissible). If this happened, we could be facing a serious, global flu pandemic.

If we can keep the number of outbreaks among birds down to a minimum, then the number of humans becoming infected is also low - giving the bird flu virus fewer opportunities to mutate.

One theory is that the main reason humans do not catch it easily is that it has to reach deep down into the lung(s) to take hold and make the person sick - for this to happen exposure must be close (contact) and there has to be a lot of the virus about. It is even harder for a human to infect another human because the infected person expels hardly any viruses when he/she coughs for the same reason - the virus is deep down in the lungs. If H5N1 mutated so that it could infect higher up the respiratory tract it would then spread more easily as more of it would be expelled after each cough/sneeze and it would not have to go so deep down into the next human in order to make him/her sick. However, if this happened the flu would probably be less deadly as upper-respiratory tract infections are spotted earlier on and can be treated earlier compared to lung infections that are deep down. This is all theory - things could develop in a completely different way.

Written by - Christian Nordqvist
Copyright: Medical News Today
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