2014-10-30

#obese more likely to die from #flu

10.21: web.health/hormonics/obese more likely to die from flu:
summary:
. the obese were more likely to get the H1N1 flu
and to subsequently die from it;
so, would that apply to any flu?
. usa's Advisory Committee on Immunization Practices
added morbid obesity to the list of conditions that
increase the risk of influenza-related complications,
including hospitalization and death .
. some say the obese should be urged to get flu vaccine,
while others claim vaccines may not work in the obese
because they are less like to mount an immune response .
. also, vaccines work surely only by herd immunity,
because, vaccines are not 100% effective,
so if you are obese surrounded by
thin people who don't get vaccinated,
getting a flu vaccine is not surely going to protect you from flu .
. vaccines aren't without risk,
so, it would be wise to minimize them .
. instead of flu vaccines,
we could vaccinate only the care providers
of those who stay home with the vulnerable
(infants and elderly)
and reduce the size of our obese population
by putting a huge tax on high-glycemic foods
and also on the high-fructose low-fiber foods .

Exp Biol Med (Maywood). 2010 
The burden of obesity on infectious disease.
Studies in obese humans have repeatedly demonstrated
impaired immune function,
including decreased cytokine production,
decreased response to antigen/mitogen stimulation,
reduced macrophage and dendritic cell function,
and natural killer cell impairment.
Recent studies have demonstrated that the
impaired immune response in the obese host
leads to increased susceptibility to infection
with a number of different pathogens such as
community-acquired tuberculosis, influenza,
Mycobacterium tuberculosis, coxsackievirus,
Helicobacter pylori and encephalomyocarditis virus.
While no specific mechanism has been defined,
several obesity-associated changes
could affect the immune response, such as
excessive inflammation, altered adipokine signaling,
metabolic changes and even epigenetic regulation.

Clin Infect Dis. 2011:
Obesity and Influenza.
The association between obesity and influenza
was first noted during the early phase of
the 2009 influenza A(H1N1) pandemic,
when data from many countries around the world indicated that
obese persons were more likely to be among the
influenza-associated hospitalizations and deaths .
Worldwide, annual influenza epidemics result in
an estimated 3–5 million cases of severe illness
and 250,000–500,000 deaths every year .
. in 2008, more than 500 million adults were obese
[ World Health Organization estimate ].
. during influenza seasons, obese persons had
increased odds for all hospitalizations
but not those due to external injury;
and conversely, when influenza was not in season,
there was no association between obesity and
risk of hospitalization due to respiratory illness .
. persons who are obese during seasonal influenza periods
are at increased risk for respiratory hospitalizations
and, for persons with severe obesity (BMI≥ 35),
the association was present even for those
without other known chronic medical conditions;
however,
perhaps the same condition that causes obesity
is also causing hidden flu risk factors
such as immunosuppression, neurological disorders,
hematological conditions, or diabetes .
. many of the obese are also undiagnosed diabetics,
and diabetes is another risk factor for flu complications:
is the risk from the obesity or their hidden diabetes?
When infected with influenza, diet-induced obese mice
had higher mortality, immune dysregulation,
and more lung pathology compared with lean controls.
One explanation could be that
adipose tissue produces adiponectin, an adipokine,
which reduces macrophage activity and cytokine production
and contributes to a proinflammatory state in obesity
and may predispose to infection.
. usa's Advisory Committee on Immunization Practices
added morbid obesity to the list of conditions that
increase the risk of influenza-related complications,
including hospitalization and death,
and for which prompt empiric influenza antiviral treatment
is recommended during influenza seasons .
Vaccination is the primary tool to prevent influenza infection
and should be encouraged in
patients who are obese or morbidly obese,
with or without presence of recognized comorbidities.

International Journal of Obesity 2013:
. obesity has been shown to be associated with
adverse outcome in pandemic H1N1 infection.
Obesity is an established risk factor for
surgical-site infections, nosocomial infections,
[Hospital-acquired infection]
periodontitis and skin infections.
There are no data on the association between
obesity and high risk from the common flu;
but, obesity is associated with impaired
immune response to flu vaccination;
and, there is such data from animal studies:
diet-induced obese mice have been shown to be
more susceptible than lean mice
to morbidity and mortality during influenza infection
due to altered innate immune responses
(impaired natural killer cytotoxicity
minimal induction of interferon-alpha/beta,
delayed expression of proinflammatory cytokines and chemokines,
and impaired dendritic cell presentation).
. Immune system and fat-storage cells
have similarities in structure and function
such as the production of various inflammatory mediators.
fat-storage cells mediate interactions with immunity cells
by the secretion of adipokines [fat-storage cell's hormones],
for example, leptin.
Obesity results in dysregulated immune response,
impaired chemotaxis [immune cell movement in response to toxins]
and altered macrophage differentiation;
[ about macrophage differentiation:
http://www.biomarkerres.org/content/2/1/1
Monocytes are immunity cells that can differentiate
into either inflammatory or anti-inflammatory subsets.
Upon infection, monocytes can differentiate into
tissue macrophages (infection eaters)
or dendritic cells (immune response communicators).]