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Swine Flu:A new pandemic?


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im just saying that there are many high up people saying the world is overpopuilated and trying to put in the publics minds that thats the truth and i think that if the govt wants more control they will kill off people but most likely they will use a virus to do that, or nuke, or world war 3,

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INFLUENZA A (H1N1) - WORLDWIDE (31)

***********************************

New H1N1 rumour

 

A ProMED-mail post

<http://www.promedmail.org>

ProMED-mail is a program of the

International Society for Infectious Diseases <http://www.isid.org>

 

In this update:

[1] New H1N1 rumour

[2] Estimation of R

[3] Source of novel H1N1

 

******

[1] New H1N1 rumour

Date: Fri 15 May 2009

Source: Swine Flu Archives, ScienceInsider, Science [edited] <http://blogs.sciencemag.org/scienceinsider/swine-flu>

 

 

A New, New H1N1 in Mexico?

--------------------------

This odd exchange took place at today's press conference with the US

Centers for Disease Control and Prevention (CDC):

 

David Brown, The Washington Post: There's a report that there is yet

another new H1N1 virus that has been found in the states of Durango,

Zacatecas, and Jalisco that is distinct from both this swine H1N1 and the

seasonal Brisbane H1N1. Have you heard of this and can you tell us anything

about this?

 

Daniel Jernigan, CDC's deputy director of influenza division: We've heard

of some reports about that, but I've not had any direct information about

the specifics of that case. There's ongoing dialog between us and the folks

that are in Mexico, and as we know more about that, we'll be able to let

people know.

 

ScienceInsider is investigating but has yet to learn anything substantive.

It was aired in a public venue, though, and likely will receive media

attention, regardless of whether it turns out to be false.

 

"We heard a rumor but think it may be a misinterpretation of some lab data

by a non-lab person," Nancy Cox, head of CDC's influenza division, tells

ScienceInsider. "We are following up."

 

[byline: Jon Cohen]

 

--

communicated by:

Kunihiko Iizuka

<edcvfr3464@yahoo.co.jp>

 

******

[2]

Date: Thu 14 May 2009

Source: Eurosurveillance, Volume 14, Issue 19, 14 May 2009 [edited] <http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=19212>

 

 

Why are Mexican data important?

-------------------------------

This issue of Eurosurveillance contains an article by a French team on the

transmission of the new influenza A(H1N1) in Mexico, which uses published

figures from the outbreak to estimate important parameters for

transmission, among them the reproduction rate, R (1). Such studies may

have important implications for public health action in Europe. [This

article has been reproduced previously in ProMED-mail; see Part [3],

Influenza A (H1N1) - worldwide (29) 20090515.1824]

 

What is R?

----------

The growth rate of an epidemic is determined by 2 factors: the number of

new persons infected by each case and the time from start of infectiousness

in one case to start of infectiousness in the secondary cases caused by

him/her. The 1st factor is called "reproduction rate" and is usually

denoted R. If the disease is spreading in a population that is totally

susceptible the term "basic reproduction rate" (Ro) is used. R is the

product of four terms: the risk of transmission in one single contact

between an infectious and a susceptible person, the frequency of such

contacts in the population, the duration of infectivity of a case, and the

proportion of susceptibles in the population. If R is greater than 1 this

means that each case infects more than one new person, and the outbreak is

likely to continue. If R is less than 1 the outbreak will eventually die

out, even if there may be a number of cases before that. The time from

infectiousness in one case to infectiousness in his/her secondary cases is

called "generation time" (Tg) and is basically a biological constant, even

if its exact value depends on how it is estimated.

 

Values for the factors that determine R can be calculated on the basis of

scientific knowledge of the disease, its context of transmission, and the

immunity status of the population. However, during an epidemic an R value

usually has to be derived from the analysis of the epidemic curve or by the

study of transmission chains.

 

Several studies have now tried to estimate R (or Ro) and Tg for the new

influenza A(H1N1) virus from Mexican data. In the one published in this

issue of Eurosurveillance [1], the authors use one exponential fitting and

one real-time estimation model to arrive at an estimate of R between 2.2

and 3.1. This is higher than the value found in an article in Science [2],

which estimated Ro to be 1.4-1.6 using 3 models: one exponential fitting,

one genetic analysis, and 2 standard SIR models for a confined outbreak in

La Gloria. Another analysis of the minor genetic changes in the virus over

time arrived at a Ro estimate of 1.16 [3].

 

Why is Ro important in public health?

-------------------------------------

The reproduction rate reflects effectiveness of transmission, and therefore

has important implications for the efforts that public health authorities

would have to make in implementing health measures aiming at containing or

mitigating the outbreak. For example, with a Ro of 1.16, preventing 14 per

cent of cases will result in eventually interrupting transmission, while

with a Ro of 3.1, preventing 68 per cent cases would be needed -- assuming

a total random mixing of contacts in the population.

 

Why are Ro estimates so different for influenza?

------------------------------------------------

A few studies have tried to measure Ro for seasonal influenza [4], and

found it to be in the order of 1.2 to 1.4. However, for most of the

seasonal strains, there is already some immunity in the population from

past seasons, which lowers the reproduction rate (and it should thus really

not be called Ro in this situation). For any epidemic of a disease that

leads to immunity after infection the initial Ro will also be higher than

the actual R at any later stage, since the proportion still susceptible in

the population will decrease. It should also be realised that delayed

reporting of cases will affect an estimate of R; a problem that adheres to

the study in this issue and the others cited above.

 

What influences Ro?

-------------------

The risk of transmission in a contact when an infective meets a susceptible

is basically a biological constant (even if it varies over the time course

of the infection), as is the duration of infectiveness. However, frequency

of contacts varies considerably between populations and population groups.

For example, among children in schools or day care, the contact frequency

is higher than among adults [5], and it also varies by culture, by family

size in a society, by types of social interaction, etc.

 

Why is the Ro from Mexico important?

------------------------------------

One could question why there is so much interest around studies of R and Ro

based on Mexican data. Would they apply to Europe? One could guess that

contact density might be higher in a Mexican setting, but on the other

hand, since the epidemic has already run its course for some time there,

the proportion of non-susceptibles would be higher in Mexico and the

European situation would more approach a "true" (higher) Ro, with a totally

susceptible population.

 

In a graph [not reproduced here] of the daily reported cumulative number of

cases in Mexico, Canada, US and EU/EFTA countries, outbreak of new

influenza A(H1N1), April-May 2009, we have just compared the daily reported

cumulative number of cases in Mexico, Canada, United States, and European

Union and European Free Trade Association (EU / EFTA) countries. On a

semi-logarithmic scale it is evident that the slope for Europe is very much

the same as for Mexico. It is difficult to estimate the time lag for

Europe, but it seems that we are some 1-2 months behind. If the generation

times are the same for both epidemics -- which seems highly plausible

***--then an estimate of Ro for Mexico would apply also to Europe. A Ro just

above 1 could mean that a containment strategy might be successful.

 

The European Centre for Disease Prevention and Control (ECDC) is

continuously monitoring the situation and with more data being available

every day in Europe we will obviously be able to have a better picture here

soon as well. Nevertheless, the similarities of the shapes of the epidemics

indicate that lessons from Mexico could apply also to Europe.

 

References

----------

1. Boelle PY, Bernillon P, Desenclos JC. A preliminary estimation of the

reproduction ratio for new influenza A(H1N1) from the outbreak in Mexico,

March-April 2009. Euro Surveill 2009; 14(19): pii=19205. Available from:

<http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=19205>

2. Fraser C, Donnelly CA, Cauchelmes S, Hanage WP, Van Kerkhove MD,

Hollingsworth TD, et al. Pandemic potential of a strain of influenza A

(H1N1): early findings. Published 11 May 2009 on Science Express. DOI:

10.1126/science.1176062. Available from:

<http://www.sciencemag.org/cgi/content/abstract/1176062>

3. Rambaut A. Human/Swine A/H1N1 flu outbreak - BEAST analysis. Available

from:

<http://tree.bio.ed.ac.uk/groups/influenza/wiki/178c5/BEAST_Analysis_29_Apr_2008_-_Andrew_Rambaut.html>

 

4. Chowell G, Miller MA, Viboud C. Seasonal influenza in the United States,

France, and Australia: transmission and prospects for control. Epidemiol

Infect 2008; 136(6): 852-64.

5. Keeling MJ, Eames KT. Networks and epidemic models. J R Soc Interface

2005; 2(4): 295-307.

 

[byline: D Coulombier and J Giesecke

At: European Centre for Disease Prevention and Control, Stockholm, Sweden]

 

--

communicated by:

ProMED-mail

<promed@promedmail.org>

 

******

[3]

Date: Sat 9 May 2009

Source: The Veterinary Record, May 9 2009 [abbreviated and edited] <http://veterinaryrecord.bvapublications.com/cgi/content/full/164/19/577>

[subscription required]

 

 

Novel H1N1 influenza in people: global spread from an animal source?

--------------------------------------------------------------------

The rapidly unfolding and evolving events, on a worldwide scale, relating

to the human-to-human transmission of a novel H1N1 influenza A virus have

dominated the news media in the past 2 weeks. In Europe to date, as in

North America and Canada, there have been cases of laboratory-confirmed

H1N1 infection in people returning from recent foreign travel in South

America, specifically Mexico. In the vast majority of cases in people who

are not from Mexico, the reported clinical presentation has been mild.

Nevertheless, the emergence of this novel H1N1 influenza virus, and its

rapid and worldwide spread, facilitated by the normal movement of people

across international boundaries, highlights some important epidemiological

features. It is relevant to note that while this H1N1 influenza virus has

been termed "swine influenza" (or "swine flu"), the definitive scientific

evidence base to support its origin in pig populations has not yet been

confirmed. Furthermore, in the absence of contemporaneous reports of

clinical disease in pigs infected with this virus, it is not possible to

confirm the clinical signs that may be observed in infected animals. In

common with other influenza A infections of pigs, where a range of clinical

presentations can occur, asymptomatic infection with this virus is also a

theoretical possibility.

 

Epidemiology

------------

The epidemiology of swine influenza in pigs is itself not straightforward.

However, a number of consistent features exist:

-- swine influenza is an important, contagious disease of pigs that occurs

worldwide, and is typically caused by infection with influenza A viruses;

-- virus subtypes H1N1, H1N2 and H3N2 are endemic in many pig populations

around the world, and pigs serve as major reservoirs of these viruses;

-- interspecies transmission, including zoonotic infections, with the

recognised endemic swine influenza viruses does occasionally occur

(reviewed by Brown 2000).

 

The maintenance of these influenza viruses in pigs, and the frequent

introduction of new influenza viruses from other species, could, therefore,

contribute to the generation of strains of human influenza virus with

pandemic potential (Alexander and Brown 2000). Historical evidence of this

suggests that, to date, the risk has been low. In addition, there is

significant genetic and antigenic variability within each of the endemic

swine influenza subtypes, which can often be dependent on geographical

region. More specifically, before the emergence of this novel H1N1 virus,

there has been a clear genetic distinction between North American and

Eurasian lineages of swine influenza viruses. This new variant of H1N1

virus contains 3 of 8 gene segments (encoding for the neuraminidase and

matrix protein genes) that do not appear typical of the genes seen in

current North American strains. It has been postulated that these 3 gene

segments have derived from Eurasian swine influenza viruses. It is not

known if the particular genotype of H1N1 virus that appears putatively to

have originated in Mexico is circulating in North American pigs, but its

close similarity to other strains of swine influenza known to be

circulating in the region (sharing 6 of 8 gene segments) has led to the

assumption that this novel H1N1 strain is derived from pigs.

 

[insert in text: Influenza A virus ecology with relevance to swine

Influenza A viruses

--------------------------------------------------------------------------------------

 

Influenza A viruses infect a large variety of animal species, including

mammals and birds, and, given the worldwide animal-human interface, there

is potential for interspecies transmission of influenza viruses in nature.

Phylogenetic studies of influenza A viruses have revealed species-specific

lineages of viral genes and have also demonstrated the frequency of

interspecies transmision depends on the animal species. Aquatic birds are

known to be the source of all influenza viruses for other species.

 

Pigs are an important host in influenza virus ecology as they are

susceptible to infection with both avian- and human-origin influenza A

viruses, and are often involved in interspecies transmission, facilitated

by regular close contact with people and/or birds. Following transmission

to and independent spread of avian or human influenza viruses in pigs,

these viruses are general referred to as being "avian-like" or "human-like"

swine influenza viruses, reflecting both their previous and current hosts.

After reassortment with other influenza A viruses, some of the genes of

these viruses may be maintained in the resulting progeny viruses.

Therefore, the evolution of influenza genes in species-specific lineagesis

an invaluable characteristic in studying and determining influenza virus

epidemiology.]

 

Influenza viruses in pigs in Europe

-----------------------------------

A number of countries in Europe conduct routine surveillance of pig

populations for swine influenza, but, as this is not a notifiable disease

in the EU, the surveillance programme is not consistent across the region.

A European Swine Network for Influenza in Pigs (ESNIP2), funded by the EU,

has been proactively monitoring the influenza situation in the European pig

population for several years, and has demonstrated that subtypes H1N1, H3N2

and H1N2 co-circulate.

 

There are also some significant differences in epidemiology in terms of the

virus subtypes involved within the EU. For example, currently in Great

Britain (GB) "avian-like" swine H1N1 viruses co-circulate with H1N2, but

H3N2 has apparently disappeared since the mid-1990s [Data tabulated in the

original text]. This is in contrast, for example, to the situation in

Italy, where these viruses are still widespread (Van Reeth and others 2008).

 

The genotypic diversity of the influenza viruses in the European pig

population is also well recognised, and periodically genotypic variants are

identified. However, broadly, the endemic strains retain common genotypes

and the new reassorted variants appear to have poor viability for long-term

sustainability and transmission within the swine population (Brown 2008).

This is in contrast to the current situation in North America, where

multiple genotypes of several different subtypes have emerged within the

past 10 years, creating a complex aetiology with respect to swine influenza

in these populations.

 

Based on current evidence from surveillance programmes in several European

countries, the variant of H1N1 virus recently isolated in human beings has

never been reported, and therefore does not appear to be present in the

European pig population.

 

Swine influenza surveillance in Great Britain

---------------------------------------------

In Great Britain, the Veterinary Laboratories Agency (VLA) has run a

national swine influenza scanning surveillance programme since 1991, funded

by the Department for Environment, Food and Rural Affairs (DEFRA). This

programme is targeted, based on clear criteria using a standardised case

definition, selection algorithm and sampling protocol, and provides

free-of-charge laboratory testing for the detection of swine influenza

viruses in clinical samples from affected pigs submitted by veterinary

surgeons to VLA regional laboratories (RLs) and Scottish Agricultural

College (SAC) Veterinary Services. Further information can be found on the

VLA website at <http://www.defra.gov.uk/vla/diseases/dis_si.htm>, or from

local VLA *** RLs or SAC disease surveillance centres. It is important for

vigilance to be maintained within both the swine and human sectors for the

emergence or spread of the newly reported H1N1 virus. The recent report of

human-to-pig transmission in Alberta, Canada, highlights the importance of

reverse zoonosis, a recognised phenomenon in influenza virus epidemiology.

Ongoing close liaison and collaboration is also occurring between the VLA

and public health institutes and delivery agencies to ensure rapid and

robust information exchange.

 

Capacity for change

-------------------

The global human-animal interface is complex and dynamic, with the

potential for zoonotic transmission of known pathogens, variants thereof

and emergent infectious agents. In turn, animal reservoirs and people, both

with the capacity for rapid global movement and distribution in time and

space (intrinsic properties of globalisation), face these shared infectious

challenges, not forgetting the propensity of some pathogens for 2-way

exchange between species.

 

While the novel H1N1 influenza virus is assumed to be of animal origin, it

is now clearly spreading between humans and has already entered the EU, as

well as other parts of the world. However, to date, human-to-animal

transmission has not been identified or reported by EU member states. The

case of human-to-pig transmission in Canada followed contact of an infected

occupationally exposed worker, apparently incubating H1N1 virus infection

following return from travel to Mexico. It also seems inevitable that more

human cases will be detected worldwide. It is important to note that the

potential host range for this virus is currently unknown. Potential changes

in the virus characteristics need to be closely monitored by both public

health and veterinary institutes. The world is watching on as international

scientific and sociopolitical efforts attempt to better understand and

combat an historical foe with seemingly limitless capacity for change and

variation, and to evade predictions -- the influenza virus.

 

[byline: Richard Irvine and Ian Brown Veterinary Laboratories Agency]

 

References

----------

1. Alexander DJ, Brown IH. Recent zoonoses caused by influenza A viruses.

OIE Scientific and Technical Review 2000; 19: 197-225.

2. Brown IH. The epidemiology and evolution of influenza viruses in pigs.

Veterinary Microbiology 2000; 74: 29-46

3. Brown IH. The role of pigs in interspecies transmission. In: H-D Klenk,

MN Matrosovich, J Stech (editors). Avian Influenza. Monogr Virol. Karger,

2008; 27: 88-100.

4. Van Reeth K, Brown IH, Darrwald R, Foni E, Labarque G, Lany P, et al.

Seroprevalence of H1N1, H3N2 and H1N2 swine influenza viruses in seven

European countries in 2002-2003. Influenza and Other Respiratory Viruses

2008; 2: 99-105.

 

--

communicated by:

ProMED-mail

<promed@promedmil.org>

 

[see also:

Influenza A (H1N1) - worldwide (30): case counts 20090516.1831 Influenza A (H1N1) - worldwide (29) 20090515.1824 Influenza A (H1N1) - worldwide (28): case counts 20090515.1822 Influenza A (H1N1) - worldwide (27): case counts 20090514.1800 Influenza A (H1N1) - worldwide (26) 20090514.1798 Influenza A (H1N1) - worldwide (25): case counts 20090513.1785 Influenza A (H1N1) - worldwide (24): case counts 20090512.1772 Influenza A (H1N1) - worldwide (23) 20090511.1764 Influenza A (H1N1) - worldwide (22): case counts 20090511.1759 Influenza A (H1N1) - worldwide (21) 20090510.1749 Influenza A (H1N1) - worldwide (20): case counts 20090510.1741 Influenza A (H1N1) - worldwide (10): case counts 20090504.1675 Influenza A (H1N1) - worldwide 20090430.1636]

 

.......................cp/ejp/sh

 

 

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I haven't really been following this mainly because I think it's bullshit, but the paper today said (basically) the reason I never got swine flu is because the government did such a good job at handling it.

 

 

 

 

 

Ever since I've come back to America I've started to dislike it more and more.

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