How contagious is measles as the outbreak of Texas grows? – Public Media in Houston

AP Photo/Julio Cortez

As an outbreak of measles It continues to expand Many people wonder in West Texas and New Mexico.

Well, the first thing you need to know is that measles is one of the most contagious diseases on the planet. That means more than Ebola, natural PO, or other infectious diseases.

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Most people developed measles as children before widespread vaccinations eliminated the disease in the United States. And 400-500 children died every year.

However, once vaccination rates drop sufficiently, the power of the vaccine to defeat the outbreak of measles will begin to collapse. We asked scientists to help decipher how low vaccination rates will affect them and what it means for the current outbreak.

Measles mathematics has expanded

It helps you understand the basic breeding numbers, or scientific concept known as r nought, to understand how easily measles is spreading. It is, on average, the number of people a single infected person can communicate the illness.

The r of measles ranges from 12 to 18. This means that if one person is infected, on average, it infects as many as 18 people. This is much higher than other infectious diseases, such as Ebola 2.

However, r nought is the theoretical number. “It's not a magic constant.” Justin Wrestleran epidemiologist at the University of North Carolina Gillins School of Global Public Health.

I'm assuming that No one is immune to certain diseases. Like zero immunity, it refers to “waste”. It helps to compare the infectious potential of different diseases. But in the real world, many different factors can change how easily measles is sent.

This brings us to a concept known as: Effective Replication number. This is the number of people who are able to infect a particular population with illness. It changes as more people become immune through infection or vaccination.

It also depends on how people behave. Will infected people be quarantined? Are vulnerable and unvaccinated people interacting with each other and coming together? Such a situation “gives the opportunity for the virus to be present in a place,” says Wrestler.

And the most effective firewall for transmission is vaccination.

The graphics below are the theoretical group of kindergarteners who gather together on weekdays in classrooms every day, showing how much a decrease in vaccination rates can affect the spread of measles.

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If the number of disease breeds is less than 1, the infection spreads slowly and the outbreak eventually disappears. This is because each infected person spreads because on average, it is less than the others.

On the other hand, there is a possibility that exponential case growth can occur here. Measles occurs when the effective number of views is 3, as shown in the graphics above. That may not be too bad until you consider these three people will infect the other three.

In fact, the original strain of the virus that causes Covid is about 3 breeding numbers and we all say we saw how it went, Matt FerrariProfessor of Biology and Director of the Center for Infectious Disease Dynamics at Penn State University.

“It's not unreasonable to think that measles can spread just as quickly [pre-vaccine] In the SARS-COV-2 population, particularly in the school setting, children are vaccinated in 80-85%,” says Ferrari.

Vulnerable Texas County

Vaccination rates for measles kindergartens in Gaines County, the epicenter of Texas' current outbreak, are just below 82%. This is well below the 95% vaccination rate threshold required to protect communities from measles outbreaks, according to the Centers for Disease Control and Prevention.

Nationally, measles vaccination rates have been declining for years, currently at 92.7%. In some communities, vaccination rates in kindergartens are much lower, creating pockets of opportunities for measles to spread.

About half of Texas counties are below its 95% threshold of vaccination rates for kindergartens. In Ford County, Texas, the fee is just under 67%. In that vaccinated classroom, one infected child on average contracts measles to five other non-vaccinated classmates.

Drill down to school level and you can find even lower vaccination rates. One private school in Fort Worth, Texas reported that kindergarten vaccination rates are just over 14%. That's not to say outbreaks will reach places like this, but if they do, they are very vulnerable.

Wrestlers say a number of factors determine how far this outbreak will spread and how big it will grow. This includes those who are vaccinated in response to outbreaks, whether the exposed people are quarantined, and whether the exposed people are in good contact to prevent others from getting infected.

And that's important. This is because people infected with measles can be transmitted from 4 days before the rash of the Telltail from 4 days to 4 days after it appears. Dr. Carla Garcia Carrenoa pediatric infectious disease expert with Plano, a pediatric medical center in Texas.

“So you can spread it out without knowing that you have measles,” says Kareno. Measles people can release infectious particles that remain in the air for up to two hours for a long time after leaving the room. “That's why it's difficult to control.”

Wrestle states that unvaccinated people are grouped together, such as close-up rural communities. Current outbreaks are spreading mostly – Measles can cause a reasonable size outbreak. However, he believes that firewalls provided by higher vaccinations and immunity levels for a larger population will ultimately curb the outbreak.

“Are we at risk of filing thousands or tens of thousands of cases from this outbreak like we did back then? That's probably pretty unlikely,” says Wrestler. ” [vaccination] The firewall is still quite strong at such a wide level. ”

However, if measles vaccination rates continue to decline Increased anti-vaccine sentimenthe says the era in which measles outbreaks include thousands of cases could return within the next five to ten years.