Determinants ambientals del virus de la grip aviar
Afra Boix, Marc Rubio, Jonathan Serrano i Francesc Vidal
Tema: Els determinants ambientals de virus de la grip aviar
1.
Introduction
1.1 Avian flu
The flu or influence is an infectious disease, which is
produced for influenza virus. The avian influenza was first discovered in free
living ducks in 1972. Avian influenza is part of the Orthomyxoviridae group,
which is single-stranded RNA virus.
When an infected person talk, stress or sneeze and expel
the virus to the air the flu viruses are transmitted easily from person to
person. It can also be infected with touch surfaces virus contaminated and
touching the face after (eyes or nose) without washing your hands properly.
There are a vaccine against the flu. That is the better
precaution to combate this illness, that is called anti-influenza vaccine, and
the resolds depends of the person’s age and the risk.
2. Body text
2.1 Origin of the avian flu.
The avian flu epidemic began probably in the meridional
Xina as the New Scientist magazine.
The epidemic began in the first semester of 2003, probably
in China.
As the magazine wrote, the vaccine in all the chickens
allowed the dissemination of H5N1 virus, who is in different countries in Asia.
After the sacrifice of all the chickens in Hong Kong for prepare the advance of
the epidemic in 1987 which affected 18 persons, 6 of them died, the chineese
products began to vaccinate their animals with a vaccine from the virus H5N1
inactivate.
That could be a mistake. If the vaccine not correspond at
the virus, for example the strain of the virus who is propagate from all ASIA,
the virus could keep multiplicity no matter if the animals will not show all
symptoms.
2.2 Virus
structure
Image 1: Flu
virus structure.
Ortomixovirus, group of virus what represents the
Orthomyxoviridade family, its genome is formed by RNA. Before its was known by
mixovirus, virus of mocous and all was included at the oromixovirus. However
after the study of its structure they have qualified in two families.
The RNA from the viral particle is segmented in 8 fragments
that codified the protein presents in her. The nucleocapsida is spiral and his
diameter there is between in 80 to 100nm. In the external part of the wrapper
lipidic appears for separate two kind of glicoproteins, hemaglutinina (H) and
neuraminidasa (N). The first responsable of the aglutination of hematis in the
presence of the virus and the second there is an enzyme who intervens in the
final fase from the virus’s freedom.
In fact to have and a RNA fragmented it does that the
antigenic combinations been more numerous giving rise a different virus strains
for the people who not presents antibodies.
For these reason, the specific immunity won by a virus
strains in particular does not works for the new ones.
The influenzavirus type A is the most common causer of
pandemics (epidemic of wide extension), the type B cause’s for the most part
local epidemics and that type C, of animal origin rarely is pathogenic.
2.3 Different kind
of aviar virus
There are several classifications of avian influenza
according to various parameters, such as its virulence or depending on the
species that it affects.
Depending on their virulence, they can be classified in
highly pathogenic avian influenza
(HPAI) or light or non-pathogenic avian influenza (MPAI).
They are differentiated because the HA protein from HPAI is synthesized by
enzymes found in most cells of the organism, but HA proteins of the MPIA are
synthesized exclusively by enzymes found in the respiratory system.
In the other side, the classification based in the vector
transmition differences the avian influenza into three types: A, B and C. The
type A affects animals like wild and domesticated birds, ducks, gulls, seabirds
and mammals (humans, pigs, horses). Types B and C influenzas only affect
humans.
2.4 Since they affect the environmental
determinants to the virus of the avian flu.
The avian grip
is commonly transmitted by direct contact between infected birds and healthy
birds. It can also spread indirectly through contact with surfaces that have
been contaminated. The avian flu virus is found in the secretion of the
nostrils (nostrils), mouth, eyes and feces of infected birds.
Contact with
contaminated feces is the most common means of transmission. The feces of the
wild ducks can introduce the avian flu virus into domestic flocks reared in the
open air. Avian flu can be transmitted by contact between and with poultry and
their feces, feathers,
guts and
blood. The greatest risk of infection for people is through the handling and
killing of infected live birds.
The virus is
spread mainly by the movement of poultry, its products, people and vehicles
used for transport. The virus does not spread by air.
The time that
the virus lives in the feces varies according to the amount of virus they
contain, the temperature and the moisture content. The virus dies more quickly
at high temperatures and lower humidity.
2.5. Propagation
The flu propagation occurs when an infected person talk,
stress or sneeze and expel the virus to the air the flu viruses are transmitted
easily around people. It can also be infected with touch surfaces virus
contaminated and touching the face after without washing your hands properly.
3. Conclusion
In conclusion, bird flu is an infectious disease of birds
caused by type A strains of influenza virus. In birds, the infection can
manifest itself in various forms, from mild symptoms that can go unnoticed, to
a disease that quickly leads to death and can cause a serious epidemic.
Bird flu viruses do not normally infect humans. However,
there have been cases of hyperpathogenic strains (A (H5N1) and A (H7N9)) that
have caused serious respiratory diseases in humans. In most cases, the infected
persons had been in direct contact with infected poultry or objects
contaminated by their feces. However, there is concern that the virus could
mutate and acquire the ability to transmit easily between humans, which would
increase the risk of a flu pandemic.
Therefore, in order to reduce the risk to human health, it
is essential to control and monitor the disease in animals and people.
http://www.medisur.sld.cu/index.php/medisur/announcement/view/1506 https://www.monografias.com/trabajos35/virus-gripe-aviar/virus-gripe-aviar.shtml https://microbewiki.kenyon.edu/index.php/Avian_influenza https://www.who.int/topics/avian_influenza/es/ https://espanol.cdc.gov/enes/flu/avianflu/avian-in-birds.htm http://www.fao.org/avianflu/es/qanda_es.html https://www.comb.cat/cat/actualitat/publicacions/bonapraxi/praxi22.pdf
Tot i tractar-se de l’esborrany hauria estat convenient afegir-hi imatges i taules. Ambdues ajuden molt a la comprensió d’alguns continguts i fa el treball més atractiu per la seva lectura. Heu de comentar la particularitat que, al ser un virus RNA, la replicació del RNA implica sempre una taxa de mutació més alta que en el cas dels virus que tenen DNA. És a dir, les RNA polimerases que repliquen els genomes RNA “s’equivoquen” més sovint, la taxa de mutació és més alta, la qual cosa fa que aquests virus mutin amb més freqüència i apareguin soques noves fàcilment de manera que dificulta obtenir una vacuna efectiva (com passa amb el virus de la grip, que cal renovar anualment la vacuna, ja que la soca vírica que ha afectat a la població a partir dels mesos de novembre o desembre, és diferent a la soca que infecta els mesos de febrer-març, la segona és una soca que deriva de la primera).
ResponderEliminarUn altre aspecte que ha de quedar clar és, com s’explica que havent-hi especificitat entre les soques víriques i els organismes que infecten, resulti que hi ha soques que passen d’aus a mamífers (humans)?. Com s’explica l’aparició de soques noves que passen a mamífers?. Els virus que passen d’aus a humans poden infectar abans altres mamífers?. Es pot donar aleshores contagi de mamífers a humans?. Les causes de transmissió de la malaltia a nivell global estan relacionades amb el comerç de les aus i el seu control o bé més directament amb rutes migratòries de les aus i per tant hi ha un factor que no es pot controlar?.
Caldria que expliqueu de forma molt breu com es fa el control de la presència de virus en aus, tot i que es mantenen mesures de control que són bàsicament mesures preventives de contagi, mesures higièniques....com es determina la presència del virus en aus que són infectades?. Per exemple, quan es porten aus a un zoològic, segurament se’ls fa una anàlisi per diagnosticar l’estat de salut de l’animal. O bé si es detecten aus mortes en un aiguamoll.... Algunes d’aquestes coses ja les apunteu a l’apartat de Conclusions, però caldria desenvolupar-les abans.
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