Tag: disease

Should I Stop Calling Chickenpox and Measles Diseases?

Sherri Tenpenny wants us to stop calling chickenpox and measles diseases.

She thinks that we should call them infections instead…

Should I Stop Calling Chickenpox and Measles Diseases?

If you are like most people, you are probably thinking to yourself and maybe even shouting at your computer screen right now, “who cares what you call them, just get vaccinated and stop the outbreaks!”

When you vaccinate to avoid an infection, what you are potentially doing is preventing a death!
When you vaccinate to avoid an infection, what you are potentially doing is preventing a death!

Believe it or not, there is actually some precedent for changing the way we talk about diseases. While you may still refer to them as STDs, or sexually transmitted diseases out of habit, the prefererable term is actually STI, or sexually tranmistted infection.

Of course, this has nothing to do with Tenpenny’s reasoning.

“Why the change? The concept of ‘disease,’ as in STD, suggests a clear medical problem, usually some obvious signs or symptoms. But several of the most common STDs have no signs or symptoms in the majority of persons infected. Or they have mild signs and symptoms that can be easily overlooked. So the sexually transmitted virus or bacteria can be described as creating ‘infection,’ which may or may not result in ‘disease.’ This is true of chlamydia, gonorrhea, herpes, and human papillomavirus (HPV), to name a few.

For this reason, for some professionals and organizations the term ‘disease’ is being replaced by ‘infection.'”

ASHA on STDs/STIs

In fact, their definitions sound nothing like Tenpennys…

Unfortunately, many STIs, even if they aren’t causing symptoms and disease, can still be contagious.

Measles and chickenpox don’t do that. Although you can be contagious just before you start to have symptoms, you will very quickly develop symptoms.

It is true that some viruses and bacteria can lead to subclinical infections, in which you develop immunity without ever developing symptoms, but that doesn’t usually happen with measles and chicken pox.

Polio is one of the best examples of when it does happen. Remember, nearly 75% of kids who got polio never had any symptoms. Tragically, those symptoms could be severe in the small percentage who did.

So as usual, Sherri Tenpenny is wrong.

Chickenpox and measles are infections that cause disease. And while most people recover after 7 to 10 days of symptoms, including a high fever and rash, some don’t.

Both also put you at risk for long-term complications, namely shingles and SSPE.

Remember, if you listen to folks like her and skip or delay your child’s vaccines and they get chickenpox or measles, the only thing you are doing is causing more people to get sick. A catchy slogan won’t prevent that or keep your kids healthy.

More on Diseases vs Infections

Do Vaccines Prevent Disease or Infection?

What kind of question is that?

Do you avoid vaccinating your kids because you believe in the sanctity of human blood?!?

It sounds like something from one of those folks who say that vaccination is not immunization, doesn’t it?

“A remark in passing: it has become cliché to say that vaccines prevent only disease, not infection.”

Stanley A. Plotkin on Correlates of Vaccine-Induced Immunity

Oh, it’s one of those kinds of questions

“Although that may be often the case, it is not a general truth. If the presence of antibodies is sufficient to prevent colonization of mucosal surfaces, vaccines can produce “sterile” immunity. Vaccines against polio, measles, rubella, Hib, pneumococcus, meningococcus, and probably human papillomavirus are all capable of preventing infection as well as disease.”

Stanley A. Plotkin on Correlates of Vaccine-Induced Immunity

The bottom line, whether they are preventing disease or infection, vaccines work to keep you from getting sick.

But just so you know, since talking about vaccines preventing disease vs infection is a thing, many vaccines do both.

More on Vaccines that Prevent Disease and Infection

Can Vaccinated Children Be Asymptomatic Carriers of Pertussis?

Why do anti-vaccine folks like to talk about baboons so much?

“Did you know that a study showed that baboons injected with whooping cough vaccine became infected with whooping cough anyway – and silently spread the disease to other baboons for 35 days?”

Anti-vaccine Meme

Is it because baboons are used in the study of vaccines?

That’s part of it, at least when they can find a study where they can cherry pick the results to suit their needs.

The Baboon Study

Like most anti-vaccine talking points, this one about baboons, has some truth to it.

An adult male baboon.
An adult male baboon. Photo by Elizabeth Miller

There was a baboon study with the pertussis vaccine and it found that previously vaccinated baboons could develop asymptomatic carriage of the pertussis bacteria after they were intentionally infected.

Here is where it is important to note that an infection is different than a disease.

The example that many people are familiar with is tuberculosis. It is common to have a TB infection without any signs or symptoms and to not feel sick. The only reason we know that they have TB is because they had a positive TB test.

Unfortunately, about 5 to 10% of these people with TB infections can eventually develop TB disease, with coughing, weight loss, night sweats, fever, and chest pain, etc.

It is kind of the same with the baboons in the study. Twenty-four hours after two previously vaccinated baboons were inoculated with pertussis bacteria in the back of their nose and trachea, an unvaccinated baboon was put in each of their cages.

The vaccinated baboons continued to have pertussis bacteria in their noses, which the researchers had put there, for up to 35 days. And they were able to eventually pass the pertussis bacteria to the unvaccinated baboons in their cages. Vaccinated baboons also became infected or colonized after they were put in a cage with an intentionally infected unvaccinated baboon.

“…animals did not cough and showed no reduction of activity, loss of appetite, or other outward signs of disease.”

Warfel et al on Acellular pertussis vaccines protect against disease but fail to prevent infection and transmission in a nonhuman primate model

The vaccinated baboons were infected, but they never did develop symptoms of pertussis.

What Does The Baboon Study Mean?

One thing that is for sure – the baboon study found that the pertussis vaccines work. Only unvaccinated baboons got sick with pertussis.

But does this study explain our current outbreaks of pertussis?

Are vaccinated people becoming colonized and then getting others sick?

I guess it is possible, but we are not baboons in a cage with other baboons. How would we spread a respiratory disease, even if we did become colonized with the bacteria, if we don’t have symptoms?

It may explain part of our outbreaks though.

If vaccinated people do commonly become colonized with pertussis bacteria, then they might very well test positive for pertussis even though they don’t have symptomatic pertussis disease. So when they develop a cold or bronchitis and are found to have a positive pertussis test, then couldn’t that test just indicate that they have a pertussis infection and not disease, even though something else is actually causing their symptoms?

That’s what we think happens with strep carriers, right?

That’s kind of what the baboon study found. All of the baboons tested positive, but only the unvaccinated baboons had symptomatic pertussis disease.

“Baboons vaccinated with wP vaccines exhibit a level of protection that is intermediate between convalescent animals and aP-vaccinated animals. They exhibit no outwards signs of disease and are initially colonized to the same high level as aP-vaccinated animals but clear the infection more rapidly.”

Pinto et al on Pertussis disease and transmission and host responses: insights from the baboon model of pertussis.

It is interesting to note that the baboon study also found that baboons who had received whole cell pertussis vaccines also became carriers. They just didn’t stay carriers for as long as the baboons who got the newer acellular pertussis vaccine. But since they were still carriers, if asymptomatic transmission is such a big problem, wouldn’t it have been a big problem back in the day when everyone got whole cell pertussis vaccines?

The Debate Over Asymptomatic Carriage

Most vaccines prevent the spread of disease.

Do the pertussis vaccines?

Most folks still think so.

“The baboon model pioneered by Warfel et al. is without question a game-changer, shedding light on the impact of vaccination on disease and infection. However, the view it affords is clearer with respect to immunity and pathology than with respect to transmission. We point out that the extrapolation of the possibility of transmission from vaccinated baboons in the laboratory to the probability of transmission from vaccinated humans in the population is unwarranted. More work is needed to elucidate the relative transmissibility of infections in vaccinated vs. unvaccinated hosts. The evidence adduced above suggests, however, that vaccination with aP must have a strong effect on transmission as well as disease.”

Matthieu Domenech de Cellès et al on Epidemiological evidence for herd immunity induced by acellular pertussis vaccines

Even the author of the baboon study has said that “We agree that these data should not be directly extrapolated to pertussis transmission in humans. Although baboons are >96% genetically similar to humans, there are likely differences in how the species respond to vaccination and infection. We also agree that aP-vaccinated infected people are likely less efficient at transmitting pertussis compared with unvaccinated infected people, although it is not clear to what extent.”

Others think that asymptomatic carriage of pertussis might behind a lot of our recent outbreaks. Or at least what helps them grow so large.

Still, it is important to remember that unvaccinated folks do play a role in these outbreaks too. In a pertussis outbreak at a Florida preschool, in which most kids were vaccinated, the outbreak was started by a vaccine-exempt toddler.

And we have seen this in many other areas and it has been confirmed by many studies. Whatever else is contributing to pertussis outbreaks, like waning immunity, they are also associated with vaccine refusal.

“Counties with higher exemption rates had higher rates of reported pertussis among exempted and vaccinated children when compared with the low-exemption counties.”

Imdad et al. on Religious exemptions for immunization and risk of pertussis in New York State, 2000-2011.

But what if the DTaP and Tdap vaccines do cause folks to be asymptomatic carriers?

Even if that is true, understand that these vaccines don’t actually infect you, making you a carrier. They just might not prevent you from becoming a carrier if you are exposed to someone else with pertussis. While that might be a good reason to develop a new and better pertussis vaccine, it certainly isn’t a reason to skip or delay your child’s vaccines now.

Remember that even with our current outbreaks, rates of pertussis were much higher in the pre-vaccine era.

What to Know About Vaccines and Asymptomatic Carriers of Pertussis

The role of asymptomatic carriers and pertussis is controversial, but it certainly isn’t a reason to skip or delay your child’s vaccines.

More on the Vaccines and Asymptomatic Carriers of Pertussis