Study confirms human-human spread of bird flu

[KimMC]

 

http://news.sympatico.msn.ctv.ca/TopStorie...bird_flu_070829

 

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A new analysis has confirmed that bird flu spread from person to person in Indonesia in April, U.S. researchers report in what appears to be a disturbing development for the infectious disease.

 

 

 

 

Health officials around the world have been closely monitoring the H5N1 strain of avian influenza spreading among birds from Asia to Africa to Europe.

 

So far, the strain rarely infects humans. But infectious disease experts are worried if it evolves so that it can spread easily from person to person, it may be the source of the next influenza pandemic, for which the globe is thought to be well overdue.

 

Since 2003, H5N1 has infected 322 people and killed 195. Most have been infected directly by birds. But a few clusters of cases have been noted for which no other explanation can be found except person-to-person transmission.

 

Biostatistician Ira Longini and colleagues at the Fred Hutchinson Cancer Research Center in Seattle looked at two such recent clusters -- one in which eight family members died in Sumatra in 2006, and another in Turkey, in which eight people were infected and four died.

 

Experts were almost certain the Sumatra cases were human-to-human transmission, but were eager to see more proof. Longini's team claims they have found that proof, reporting in the journal Emerging Infectious Diseases.

 

Using a computerized disease-transmission model that took into account the number of infected cases, the number of people potentially exposed, the viral-incubation period and other parameters, the researchers produced the first statistical confirmation of humans contracting the disease from each other.

 

How the cluster likely spread

 

The cluster likely began with a 37-year-old woman, who had been exposed to dead poultry and chicken feces, the presumed source of infection. She then probably passed the virus to her 10-year-old nephew who then passed it to his father.

 

The possibility that the boy infected his father was supported by genetic sequencing data. Other person-to-person transmissions in the cluster were backed up with statistical data.

 

All but one of the flu victims died.

 

Local health authorities eventually placed more than 50 relatives and close contacts under voluntary quarantine and the infections stopped. But Longini's team does not believe the quarantine did the trick; they believe the virus simply burned out.

 

"It went two generations and then just stopped, but it could have gotten out of control," Longini said in a statement.

 

"The world really may have dodged a bullet with that one, and the next time, we might not be so lucky."

 

The researchers now estimate the secondary-attack rate, which is the risk that one person will infect another, is at about 29 per cent. This is similar to what is seen for regular, seasonal influenza A in the United States.

 

As for the cluster in Turkey, Longini's team could not find statistical evidence of human-to-human transmission.

 

"There probably was person-to-person spread there as well but we couldn't get all the information we needed for the analysis," biostatistician Yang Yang said.

 

Longini's team also says they have developed a tool to run quick tests on disease outbreaks to see if dangerous epidemics or pandemics may be developing. The software product, called TranStat, would be available free of charge on the National Institutes of Health's Models of Infectious Disease Agent Study, or MIDAS, website.

 

[Cat]

The pig illnesses that are in China are another disturbing trend... too much like before 1918.

 

 

 

[cookiejar]

Originally Posted By: Cat

The pig illnesses that are in China are another disturbing trend... too much like before 1918.

Can I ask how the pig illness correspond? specially in reference to 1918...?

[Vic303]

It's actually not a biochemical study--it was a mathematical analysis of probabilities. They even admit later in the article that the strain the Dad had was DIFFERENT than the Son he supposedly contracted it from.

[Cat]

Cookie, I'll have to do some looking. I've got a lot on my plate right now.

 

But off the top, I seem to remember that the place where it started in the US had pig/animal deaths when it all began.

 

[Mother]

Vic is correct, the strain was different in the dad but it has been the subject of much debate whether it was different because it had mutated. It is my belief that what we read and hear is only the tip of the iceberg. This subject has been fairly hush hush for some months now with very little mention of new cases and no media hype over it. That does NOT mean it is a non issue.

 

We can not personally stop this or any pandemic from coming but we can be ready to cope with it and it's aftermath when it does come. Just as we prepare for other possible disasters, we prepare for this, to the best of our resources. Perhaps it is time to reread some of the back posts here on this subject to refresh ourselves on what that might be.

 

Winter colds and flu season will be here sooner than we expect and it won't hurt to be prepared for that. In turn we will be better prepared for a possible pandemic also.

 

((( )))

[mom11]

Pigs are suseptible to both human and avian flu viruses. They are often the mixing vessel and can unleash a human virus, if they contract both human and avian viruses at the same time. There are also lots of other viruses pigs can contract. They just need to be watched.

 

The longer this virus struggles, the better prepared we can be, if we use our time wisely. New studies show, the virus may need 13 mutations to become a pandemic and so far it has only made several. Of course, we still don't know if the virus can swap a segment and many mutations at one time, but this study does give us a little hope, that we may have some more time....BUT use it wisely. We must keep our eyes on the ball! We also don't know what else is out there, that may just pop up, out of no where. then we need to factor in the droughts, floods, terrorists, etc., etc. ,etc. I guess the best thing to do, is make prepping our lifestyle and just not worry so much.

[cookiejar]

Originally Posted By: Cat

Cookie, I'll have to do some looking. I've got a lot on my plate right now.

But off the top, I seem to remember that the place where it started in the US had pig/animal deaths when it all began.

Wasn't thinking chica


For you and Mom11:
J Virol. 1989 November; 63(11): 4603-4608


Avian-to-human transmission of the PB1 gene of influenza A viruses in the 1957 and 1968 pandemics.
Y Kawaoka, S Krauss and R G Webster
Department of Virology/Molecular Biology, St. Jude Children's Research Hospital, Memphis, Tennessee 38101-0318.

ABSTRACT

We determined the origin and evolutionary pathways of the PB1 genes of influenza A viruses responsible for the 1957 and 1968 human pandemics and obtained information on the variable or conserved region of the PB1 protein. The evolutionary tree constructed from nucleotide sequences suggested the following: (i) the PB1 gene of the 1957 human pandemic strain, A/Singapore/1/57 (H2N2), was probably introduced from avian species and was maintained in humans until 1968; (ii) in the 1968 pandemic strain, A/NT/60/68 (H3N2), the PB1 gene was not derived from the previously circulating virus in humans but probably from another avian virus; and (iii) a current human H3N2 virus inherited the PB1 gene from an A/NT/60/68-like virus. Nucleotide sequence analysis also showed that the avian PB1 gene was introduced into pigs. Hence, transmission of the PB1 gene from avian to mammalian species is a relatively frequent event. Comparative analysis of deduced amino acid sequences disclosed highly conserved regions in PB1 proteins, which may be key structures required for PB1 activities.

and so my question is answered...