Measles

Who's at increased risk of measles?

• Babies under one year
• People whose immune system is suppressed, for example by cancer or HIV
• Malnourished people
• Children with vitamin A deficiency
• Pregnant women - the infection may cause miscarriage or premature delivery

What are the symptoms?

Symptoms take about ten to 14 days to develop after exposure to the virus (the incubation period). Early symptoms are like a cold, with runny nose, cough, conjunctivitis and fever.

A couple of days later, tiny white spots surrounded by red (Koplik spots) may develop on the inside lining of the cheeks, so they are difficult to see.

The measles rash appears a day or two later, starting behind the ears or on the face and spreading down across the body. It's a fine red rash which becomes blotchy and confluent, fades after three to four days and may peel off after a week or so.

Abdominal symptoms may include nausea and vomiting, abdominal pain and diarrhoea. Symptoms usually last about 14 days in all and it's recommended that children stay off school for five days after the start of the rash.

The infection isn't usually serious but there are potential complications that can be fatal, even for otherwise healthy children. These include otitis media, pneumonia, hepatitis, conjunctivitis and encephalitis (inflammation of the brain, which occurs in about one in 5,000 cases).

Although complications involving the nervous system occur in fewer than one in 1,000 cases, the long-term effects can be devastating.

Encephalitis or inflammation of the brain may develop a few days after the rash has appeared, and a quarter of those who get this complication will be left with brain damage. A devastating but extremely rare progressive illness called subacute sclerosing panencephalitis (SSPE) may develop many years after the first bout of measles and is eventually fatal. Fortunately, it's very rare, occuring in fewer than one in 100,000 cases.

What's the treatment for measles?

See your doctor to confirm the diagnosis. Children may be treated at home with pain and fever-reducing syrups such as paracetamol and they should be encouraged to drink fluids.

Hospital treatment, with antiviral drugs, may be needed in more serious cases. In developing countries vitamin A may also be given to help the immune system.

Although rare, complications can be very dangerous. Encephalitis, for example, typically develops after about eight days, with headaches, lethargy and irritability, progressing to convulsions, coma and death in 15 per cent and long-term health problems in nearly half of survivors. If your child shows any worrying symptoms during measles get urgent medical advice.

The child is infectious from one day before the onset of symptoms until about four days after the start of the rash, so let friends, family and other potential contacts know.

The facts about measles

• Measles can, and does, kill and do long-term harm but vaccination prevents this risk
• Measles is a notifiable disease - if you think your child may have it, see your doctor at once, who can confirm the diagnosis with a simple saliva test who and must then let the local health authority know
• Some children may possibly be at risk from vaccination - for example, a child who's had febrile fits or existing nervous system problems
• A vaccine for each infection may be given instead of the MMR vaccine in certain cases, for example, if your child has an allergy, but it's extremely difficult to get hold of the separate vaccines
• Ask your GP for advice if you think your child may be at risk from the vaccine

How is measles spread?

The measles virus is highly contagious. Measles is spread through droplet transmission from the nose, throat, and mouth of someone who is infected with the virus. These droplets are sprayed out when the infected person coughs or sneezes. Among unimmunized people exposed to the virus, over 90% will contract the disease. The infected person is highly contagious for four days before the rash appears until four days after the rash appears. The measles virus can remain in the air (and still be able to cause disease) for up to two hours after an infected person has left a room.

 Is measles deadly?

Measles can cause death. In 2008, approximately 164,000 people died of measles in the world. However, measles is rarely fatal in the United States. This is due to the fact that most people are immunized, which results in very infrequent outbreaks. Also, people most likely to have complications (including death) are those who are malnourished or who have weakened immune systems.

 - Measles can be complicated by ear infections, pneumonia, or encephalitis.

-  Measles infection of the brain (encephalitis) can cause convulsions, mental retardation, and even death.

-  Measles in pregnant women can cause miscarriages or premature delivery.

 What is measles?

Measles is a highly contagious viral disease that can be fatal. Although an uncommon disease in the United States of America, in 2008, measles killed 164,000 children worldwide. In most people, the disease produces fever (temperature > 101 F [38.3 C]), a generalized rash that last greater than three days, cough, runny nose(coryza), and red eyes (conjunctivitis). The complications of measles that result in most deaths include pneumonia and inflammation of the brain (encephalitis).

What is rubeola?

Rubeola is the scientific name used for measles. It should not be confused with rubella (German measles).

SCRIPT in progress.

Introduction:

(TITLE shows)
FIVE DEADLY VIRUSES

(White board)
(Written on the white board)
What is a Virus? A Virus is an infectious agent that replicates only within the cells of living hosts: composed of an RNA or DNA core, a protein coat, and, in more complex types, a surrounding envelope.

(Life Cycle, Animation)

When a virus comes in contact with a target cell it enters what is known as the attachment phase.  Using it’s forged protein signature it makes use of the cells active transport system called endocytosis which inducts the virus into the cell inside of a vesicle.  Once inside the cell the DNA or RNA inside the virus is transcribed into the cell’s nucleus and then translated by the golgi apparatus.  This new RNA is then brought to the ribosomes where proteins are constructed and new viruses are built.  

(Exits whiteboard view)

(Microscope appears)

(Cell view begins)

(First slide)
(World Map indicating virus spread)

HIV

What happens through HIV infection?

The infection leads to low levels of CD4 T cells - which are the host of aid HIV replication  through three main mechanisms. The first mechanism directs viral killing of infected cells. Next it increases rates of apoptosis (cell death) in the infected cells. Followed by the killing of infected CD4 T cells by CD8 cytotoxic lymphocytes. A cytotoxic T cell is a type of white blood cell that kills cancer cells and cells that are infected especially with viruses, or cells that are damaged in other ways. As the CD4 T cell numbers decline below a critical level; the cell-mediated immunity is lost, and the body becomes progressively more susceptible to opportunistic infections.

Measles Virus

Measles virus targets immune cells that express glycoprotein, which serve as an entry receptor for measles.  Measles virus infects epithelial cells, and endothelial cells and neurons. The first infected cells transports virus to nodes where T and B cells become infected. Measles virus is highly cytolytic. In peripheral tissues, adjacent infected calls may fuse together forming giant cells, or syncytia. This process occurs through the action of the viral fusion protein, which is expressed on the surface of infected cells. The skin rash is immune-mediated due to infection of dermal capillary endothelial cells and immune complex formation. Infection of lung epithelial cells that occurs late during the infection cycle mediates transmission to other hosts.

Influenza Virus

When the influenza virus infects a host cell, its goal is to produce many copies of itself that go on to attack even more cells. A viral polymerase both copies the genetic material of the virus and steers the host cell machinery towards the synthesis of viral proteins. It steals a cap from host cell RNA molecules then adds it onto its own. The cap is a short extra piece of RNA that much is present at the beginning of all messenger RNAs  to direct the cell’s protein-synthesis machinery to the starting point. The viral polymerase binds to host cell RNA via its cap, cuts the cap off and adds it to the beginning of its own RNA. This process is known as ‘cap snatching’.

H1N1 Virus (Swine Flu)

-       The swine flu virus uses its antigens to attach to the surface of cells in the nose, throat and lungs.The cell engulfs the virus. The virus is able to pierce the bubble of cell membrane that encloses it and release its RNA cargo into the cell. In the nucleus, copies of the viral RNA are made. Viral messenger RNA (mRNA) causes the cell to make viral proteins. These proteins and RNA migrate to the cell’s surface where they are assembled into new virus particles.  New virus start budding off from the cell surface.

Life cycle of swine flu, H1N1 can be initiated very easily because it is known to live outside of humans for 2 to 8 hours. It can attach itself to any surface touched by an infected person. 

Rabies Virus

Rabies begins the replication process at the site of inoculation, usually as the result of a bite.  By having its translation occur inside the cytoplasm the virus can propagate very quickly.  Rabies will first attack the central nervous system and then later spread to other tissues in the body. The highest concentration of of rabies propagation takes place in the soft tissues of the mouth, creating the tell tale foaming saliva of a rabies victim.  Most rabies victims will die 2-10 days after the first symptoms appear.  The main cause of death is usually dehydration or asphyxiation as selective paralysis takes place in the throat and diaphragm.