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Detecting Human-to-Human Transmission of Avian Influenza A (H5N1)

L

Laidback Al

Well-known member
Detecting Human-to-Human Transmission
of Avian Influenza A (H5N1)​

Yang Yang,* M. Elizabeth Halloran,*† Jonathan Sugimoto,*† and Ira M. Longini, Jr.*†
*Fred Hutchinson Cancer Research Center, Seattle, Washington, USA; and †University of Washington, Seattle,
Washington, USA​

Highly pathogenic avian influenza A (HPAI) subtype H5N1 has caused family case clusters, mostly in
Southeast Asia, that could be due to human-to-human transmission. Should this virus, or another
zoonotic influenza virus, gain the ability of sustained human-to-human transmission, an influenza
pandemic could result. We used statistical methods to test whether observed clusters of HPAI (H5N1)
illnesses in families in northern Sumatra, Indonesia, and eastern Turkey were due to human-to-human
transmission. Given that human-to-human transmission occurs, we estimate the infection secondary
attack rates (SARs) and the local basic reproductive number, R0. We find statistical evidence of human-to-
human transmission (p = 0.009) in Sumatra but not in Turkey (p = 0.114). For Sumatra, the estimated
household SAR was 29% (95% confidence interval [CI] 15–51). The estimated lower limit on the local R0
was 1.14 (95% CI 0.61–2.14). Effective HPAI (H5N1) surveillance, containment response, and field​
evaluation are essential to monitor and contain potential pandemic strains.

Please see below for uploaded document and new link -
 
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Re: Detecting Human-to-Human Transmission of Avian Influenza A (H5N1)

Take Indonesia for example.....who would be able to use this new software application? The World Health Org.? Scientists from NAMRU-2?

Page 9 of 14

We have developed a software application, TRANSTAT, for implementing these
analyses. This application provides a stand-alone environment for the entry, storage, and analysis of data from outbreaks of acute infectious diseases. A partial list of the input information is given in the Table. The statistical methods presented here can be applied to the data along with several standard epidemiologic tools. This information system would allow for real-time analysis and evaluation of control measures for an outbreak. We would encourage outbreak investigators to
use this tool, taking care to input data on the exposed nonpatients as well as case-patients. The authors will provide a link to this software upon request.
 
Re: Detecting Human-to-Human Transmission of Avian Influenza A (H5N1)

I have not read this article yet, and likely all my questions would be answered by it.

However, why would TRANSTAT be more advantageous over abother product? I beleive CDC has developed a field usable statistics program. And what of the normal programs - Excell, SPSS - nearly everything can run on a PC now, and has a form entry systemen rather than a spreadsheet. Perhaps the value-added is in the questions or prompts used to lead the researcher in the right direction - but this could also be a question template or a checklist.

And why do we need stats at all to confirm H2H? Isn't this a microbio question about droplet or airborne transmission and an evidence question based on the circumstances?

J.
 
Re: Detecting Human-to-Human Transmission of Avian Influenza A (H5N1)

This appears to be an interesting scientific exercise with little practical application. In a very real sense, we will recognize human-to-human transmission very quickly once there is an epidemic. There will be no need to collect epidemiological data to confirm an epidemic. This approach appears to be useful when you have a small cluster of human cases that has either been contained or burned itself out. It might help to distinguish true H2H from multiple infections from a common reservoir.

It seems that some of the variables in the Table require a priori guesses or else numbers that can only be known after the start of an epidemic. (e.g. Latent/incubation period and Infectious period). So I am not sure how this statistical approach to detecting H2H transmission has any bearing on a goal "to monitor and contain potential pandemic strains."
 
Re: Detecting Human-to-Human Transmission of Avian Influenza A (H5N1)

Study confirms 2006 human-human spread of bird flu

Tue Aug 28, 2007 11:37PM BST

WASHINGTON (Reuters) -
A mathematical analysis has confirmed that H5N1 avian influenza spread from person to person in Indonesia in April, U.S. researchers reported on Tuesday.

They said they had developed a tool to run quick tests on disease outbreaks to see if dangerous epidemics or pandemics may be developing.
Health officials around the world agree that a pandemic of influenza is overdue, and they are most worried by the H5N1 strain of avian influenza that has been spreading through flocks from Asia to Africa.

It rarely passes to humans, but since 2003 it has infected 322 people and killed 195 of them.

Most have been infected directly by birds. But a few clusters of cases have been seen and officials worry most about the possibility that the virus has acquired the ability to pass easily and directly from one person to another. That would spark a pandemic.

Ira Longini and colleagues at the Fred Hutchinson Cancer Research Center in Seattle looked at two 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 case was human-to-human transmission, but were eager to see more proof.

"We find statistical evidence of human-to-human transmission in Sumatra, but not in Turkey," they wrote in a report published in the journal Emerging Infectious Diseases.

"This does not mean that no low-level human-to-human spread occurred in this outbreak, only that we lack statistical evidence of such spread."
In Sumatra, one of Indonesia's islands, a 37-year-old woman appears to have infected her 10-year-old nephew, who infected his father. DNA tests confirmed that the strain the father died of was very similar to the virus found in the boy's body.

"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," he added.

The researchers estimated the secondary-attack rate, which is the risk that one person will infect another, was 20 percent. This is similar to what is seen for regular, seasonal influenza A in the United States.

The researchers developed a software product called TranStat and said they would provide it free of charge on the National Institutes of Health's Models of Infectious Disease Agent Study, or MIDAS, Web site.

"We know the key to preventing a pandemic is early detection, containment and mitigation with antiviral therapy and this tool will enable those on the front lines, such as physicians, epidemiologists and other public-health officials, to carry that out efficiently," said Elizabeth Halloran, who worked on the study.


http://uk.reuters.com/article/scienceNews/idUKN2829220820070828
 
Re: Detecting Human-to-Human Transmission of Avian Influenza A (H5N1)

Detecting Human-to-Human Transmission of Avian Influenza A (H5N1)
Yang Yang,* M. Elizabeth Halloran,*† Jonathan D. Sugimoto,*† and Ira M. Longini, Jr.corresponding author*†


link to study:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2857285/
(my file: karo3.pdf)

comment by CDC (Uyeki,Bresee):
http://wwwnc.cdc.gov/eid/article/13/12/07-1153_article


Uyeki,Bresee:
> ...but this (proof of h2h) suggestion is misleading.
> ... determination of h2h requires detailed field epidemiologic investigations

response by the original authors:
> we found statistical evidence of human-to-human transmission (p = 0.009) in Sumatra. (no "proof")




they quote Declan Butler in nature
(4) http://www.nature.com/nature/journal/v442/n7099/full/442114a.html

> The possibility that HPAI (H5N1) was transmitted
> from the nephew to his father is also supported by genetic
> sequencing data (4).

but these sequences were likely wrong, as discussed here:
http://www.flutrackers.com/forum/showthread.php?t=7465

This was also confirmed by Elodie Ghedin who did the sequencing for Butler.
nature had acknowledged that in email but refused to post a correction
Declan Butler never replied.

however, the study above doesn't rely on the sequences
 
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