Tuesday, 22 January 2013

Polio and measles : Human Enterovirus and Morbillivirus

This one is going to be massive...

Poliovirus: any of three serotypes of the particular virus that causes polio; it us an enterovirus, meaning it infects the gastrointestinal tract and is excreted in fecal matter.
Poliomyelitis: an acute viral disease that may include central nervous system involvement and result in paralysis and/or muscle atrophy.
Poliovirus enters through mouth and multiplies in the throat and gastrointestinal tract, then moves into the bloodstream and is carried to the central nervous system where it replicates and destroys the motor neutron cells.  Motor neutrons control the muscles for swallowing, circulation, respiration, and the trunk, arms and legs.  When poliovirus encounters the nerve cells, the protruding receptors attach to the virus particle and the infection begins.  Once inside the cell the virus hijacks the cell’s assembly process and makes thousands of copies of itself in hours. The virus kills the cell and then spreads to infect other cells.

Poliovirus invades the nervous system, and can cause total paralysis in a matter of hours. The virus enters the body through the mouth and multiplies in the intestine. Initial symptoms are fever, fatigue, headache, vomiting, stiffness in the neck and pain in the limbs.
There is no cure for polio, it can only be prevented. Polio vaccine, given multiple times, can protect a child for life.
Global Caseload:
Polio cases have decreased by over 99% since 1988, from an estimated 350 000 cases in more than 125 endemic countries then, to 650 reported cases in 2011. In 2012, only parts of three countries in the world remain endemic for the disease–the smallest geographic area in history–and case numbers of wild poliovirus type 3 are down to lowest-ever levels.
Future benefits of polio eradication:
Once polio is eradicated, the world can celebrate the delivery of a major global public good that will benefit all people equally, no matter where they live. Economic modelling has found that the eradication of polio in the next five years would save at least US$ 40–50 billion, mostly in low-income countries

- Polio (Poliomyelitis) mainly affects children under five years of age.
- One in 200 infections leads to irreversible paralysis. Among those paralysed, 5% to 10% die when their breathing muscles become immobilized.
- Polio cases have decreased by over 99% since 1988, from an
- estimated 350 000 cases then, to 650 reported cases in 2011. The reduction is the result of the global effort to eradicate the disease.
- In 2012, only three countries (Afghanistan, Nigeria and Pakistan) remain polio-endemic, down from more than 125 in 1988.
- As long as a single child remains infected, children in all countries are at risk of contracting polio. Failure to eradicate polio from these last remaining strongholds could result in as many as 200 000 new cases every year, within 10 years, all over the world.
- In most countries, the global effort has expanded capacities to tackle other infectious diseases by building effective surveillance and immunization systems.

->  Many types of human cells have receptors that fit the poliovirus; no one knows why the virus favors motor neurons over other cells for replication.
->  For every 200 or so virus particles that encounter a susceptible cell, only one will successfully enter and replicate.
-> in tissue culture, poliovirus enters cells and replicates in six to eight hours, yielding 10,000 to 100,000 virus particles per cell.
->  A person who gets polio is immune to future infection from the virus type that caused the polio.


Poliovirus (Human Enterovirus):
The genus Enterovirus consists of 10 species: Human enterovirus A, Human enterovirus B, Human enterovirus C, Human enterovirus D, Simian enterovirus A, Bovine enterovirus, Porcine enterovirus B, Human rhinovirus A, Human rhinovirus B and Human rhinovirus C. A further two species have been proposed, "Enterovirus F" and "Enterovirus J".
 The Enterovirus type species is Human enterovirus C.
The three poliovirus serotypes now belong to the species Human enterovirus C and the species Poliovirus no longer exists.

Human enterovirus C:
The species Human enterovirus C  (proposed new name "Enterovirus C") consists of 23 types: poliovirus (PV) 1, PV-2, PV-3, coxsackievirus A1 (CV-A1), CV-A11, CV-A13, CV-A17, CV-A19, CV-A20, CV-A21, CV-A22, CV-A24, EV-C95, EV-C96, EV-C99, EV-C102, EV-C104, EV-C105, EV-C109, EV-C113, EV-C116, EV-C117 and EV-C118.

http://www.picornaviridae.com/ > Enterovirus > …

Measles a.k.a Rubeola, morbilli (paramyxovirus)

Measles is a highly contagious viral disease, which affects mostly children. It is transmitted via droplets from the nose, mouth or throat of infected persons. Initial symptoms, which usually appear 10–12 days after infection, include high fever, runny nose, bloodshot eyes, and tiny white spots on the inside of the mouth. Several days later, a rash develops, starting on the face and upper neck and gradually spreading downwards.
There is no specific treatment for measles and most people recover within 2–3 weeks. However, particularly in malnourished children and people with reduced immunity, measles can cause serious complications, including blindness, encephalitis, severe diarrhoea, ear infection and pneumonia. Measles can be prevented by immunization.
Key facts
> Measles is one of the leading causes of death among young children even though a safe and cost-effective vaccine is available.
> In 2011, there were 158 000 measles deaths globally – about 430 deaths every day or 18 deaths every hour.
> More than 95% of measles deaths occur in low-income countries with weak health infrastructures.
> Measles vaccination resulted in a 71% drop in measles deaths between 2000 and 2011 worldwide.
> In 2011, about 84% of the world's children received one dose of measles vaccine by their first birthday through routine health services – up from 72% in 2000.

there is more on its way... 

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