The Americas is the first of the World Health Organization's six regions to eliminate transmission of the virus, which used to be known as the German measles or the three-day measles. Like measles, it triggers a diffuse red rash over the bodies of those who contract it.
Here are five things you should know about rubella, and about Wednesday's announcement:
IT LOOKS LIKE MEASLES BUT....
Rubella infection produces a widespread red rash similar to measles and is also spread when infected people cough and sneeze.
The disease in children is usually mild, with a low fever — typically under 38.3 Celsius. Symptoms last two or three days and are milder in younger children than in older kids and adults.
Like measles, it can be preventable by vaccination. The rubella vaccine is bundled into one shot that also protects against measles and mumps.
Rubella is contagious, but not as contagious as measles, which is one of the most infectious diseases known. In the days before vaccine use, one person with measles would, on average, infect between 12 and 18 others. For rubella, the estimate was five to seven.
THIS VIRUS IS DANGEROUS FOR PREGNANT WOMEN AND THEIR FETUSES
A woman who contracts rubella during the early stages of pregnancy may miscarry or give birth to a stillborn. If she carries to term, the risk is high that her baby will be born with multiple birth defects.
Birth defects seen in cases of congenital rubella syndrome — the name for the condition these children suffer from — include deafness, blindness, intellectual disabilities and heart defects.
The Public Health Agency of Canada says as many as 85 per cent of babies born to women who had rubella in the first trimester of their pregnancy will have a birth defect. The risk does not completely disappear after the first trimester, but it diminishes over time.
THIS VIRUS IS TRICKY
People with rubella are most contagious when they have the accompanying rash. But people who are infected can spread the virus for seven days before they develop a rash.
And here's the thing: About half of the people who are infected don't develop evident symptoms. Yet those people can still transmit rubella, the U.S. Centers for Disease Control says.
THE SIGNIFICANCE OF WEDNESDAY'S ANNOUNCEMENT
Officials of PAHO announced that ongoing spread of rubella has been stopped in the countries of the Americas. The official process to certify that accomplishment takes several years.
In fact, the region's last known cases of endemic rubella and congenital rubella syndrome occurred in 2009 in Argentina and Brazil respectively.
Canada used to have tens of thousands of rubella cases a year, before the vaccine went into wide use. There are still occasional cases, sparked when viruses are imported into the country in sick people.
Last year, there was only one case of rubella reported in Canada.
STOPPING ENDEMIC SPREAD DOESN'T MEAN NO MORE RUBELLA
When public health authorities say they've stopped endemic spread of a virus, it means that ongoing person-to-person spread in a country or a region has been halted.
When spread is stopped in a country or region, authorities say the virus has officially been "eliminated."
But that's not the same as eradicated; that term is reserved for describing the complete wiping out of a pathogen.
Smallpox was declared eradicated in 1980, and remains the only human disease to have been completely obliterated. Work is underway to eradicate several others, most notably polio.
Until rubella has been eliminated in other parts of the world, the Americas could still experience cases.
An infected traveller could bring the virus to one of the PAHO countries, or someone from the region could contract it overseas. But if vaccination rates remain high, rubella is unlikely to spread far.
Short-term spread from an imported rubella case would not erase the region's elimination status.
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