Here’s a measles infographic prepared using a range of sources and some feedback from the public. It aims to present measles symptoms and the levels of the virus and white blood cells in your blood over time. Here, I add the words to help interpret it better.

The measles virus causes measles, the disease

I’m not going to present a big review of the measles literature here – this has been done well by your local public health-focussed organisations, for example, here, here, here, and here. And there are a ton in the scientific literature.

This is to provide the visual learners with a graphical way of seeing some of the key events from initially inhaling an infectious dose of measles virus (MeV) through to clinical recovery. Even if MeV RNA can be detected for months after you’re well.

A follow-up piece will talk more about the development of “immune amnesia” following a measles virus MeV infection. It has its own infographic from which this one budded off.

The first version of the measles infographic

By the time I got to writing this blog, the graphic was already at version 1.6 – thanks to all those who provided feedback on social media. I’m happy to continue making changes if they help more people understand what this needs to convert – within my skillset, anyway.

Below is the measles infographic image. Click on it to enlarge it further.

It’s a line graph

This infographic is a line graph. It shows MeV levels (red straight line) in an unvaccinated person’s blood rising, peaking, and then falling over time.

When there’s virus travelling around in the blood, it’s called viraemia.

Some very important MeV-fighting immune response-producing white blood cells are called lymphocytes. They are also shown as an orange dotted line. Their levels drop slowly, then suddenly rise back up to levels above where they were to start with, before settling back down.

What are the vertical and horizontal lines (axes) telling me?

Time is shown along the bottom line x-axis and the levels of virus or It starts on the left when an infectious dose of measles virions is inhaled at the bottom left of the graph infection to the time when the infectious virus can no longer be cultured. However, MeV RNA may still be detectable using RT-PCR methods dashed (red line trailing to the right) for months.

What are all those lines linking the words to the shaded boxes at the bottom?

You ask a lot of questions!

At the bottom of the graphic, I’ve tried to highlight the key windows of time when important things are happening.

Keep in mind that these numbers are a range and just there to provide a rough idea. A good infographic aims to simplify a whole lot of scientific data without dumbing it down too far.

There are bullet lists of each description linked by lines to a blue bar that makes it easier to underline and highlight how long each thing lasts and when that thing occurs. You can then relate when those signs and symptoms occur back to changes in MeV and lymphocyte numbers.

What might make this confusing is that some of the blue bars overlap.

For example, the incubation period overlaps the time when pre-rash symptoms (the prodrome period) and the rash period occur. Huh?

The overlap is because we’re human, and so we don’t all start getting sick at exactly “X” days or developing a rash at “Y” days after infection.

The time after infection but before symptoms show up is the incubation period – it can be 7 days long for some people or anywhere up to 18 (or more) days long for others. So that total span of time is shown.

Symptoms usually show up around 10 days (marked with a yellow arrow). Again, I’ve used a bar to show the total possible prodrome period (2-4 days) and also added a yellow arrow to show the average start time of around 10 days after infection.

The same kind of method shows the average time it takes for a rash to start to appear (the result of immune cells eliminating the virus from the skin). If we look back at the main infographic, I’ve added a yellow arrow to mark the most common time for the rash to start, also shown with a shaded red box. The red colouring fades as the rash fades. Rash can last a week, but again, when it starts for you could be anytime across a 12-day period.

Infectious dose

This bit of the infographic is not based on humans; it’s from rhesus macaque (monkey) data. These animals have been used as a model that reflects human measles, so I still think it’s a valuable model to think about.

The two grey curved lines on either side of the red MeV curve aim to show that if you inhale a lot of virus, your levels of virus in the blood start to rise earlier (left-hand grey curve) than if you inhaled a smaller dose (right-hand grey curve).

But interestingly, in the interpretation and the primary study this comes from, the peak height didn’t change with infectious dose. That may be different in humans – or not – it’s not ethical to run a human infection study for pretty obvious reasons. But these are the data we have.

Rash and symptoms fade as lymphocyte numbers recover and the measles virus gets owned

The peak of viraemia drops back down as our body releases new cells that are programmed to destroy infected cells and to produce antibodies to MeV to prevent further infections and to remember MeV forever. These quickly ramp up and comprise a lot of the new lymphocytes produced to recover from the deaths of their infected forbears due to targetted MeV killing.

Lymphocytes involved in the new response were of the same type that MeV killed off during the heat of replication. The orange dotted line shows total lymphocyte numbers, but within that are all sorts of subsets of these cells – that’s really a story unto itself.

A lot of the immunological memory we carried before this infection- for example, between 11 to 73% of the different antibody-producing cells that helped moderate disease from viruses, bacteria and fungi we had previously been infected with- can be wiped out. And yes, that can include vaccine-produced immune memories.

We can still make and release new cells in our bone marrow, though, and we do. Those hot, sore and swollen lymph nodes you get during measles are a testament to the body’s awesome ability to produce new defences, quickly. But for any immune memories that were erased, we’ll have to go through a new round of infection – and possibly illness – all over again to produce a new expert cellular army.

All of that serious immune memory loss doesn’t seem to happen after vaccination because the virus in the vaccine has been severely weakened, and its dose is controlled.

Breaking down some technical terms

Prodome

Early signs or symptoms that signal the beginning of disease.

Coryza

Inflammation of the lining of the nasal cavities which leads to sneezing and a runny, stuffy or blocked nose.

Viraemia

The presence of virus in the blood.

Conjunctivitis

Also called “pink eye”; an inflammation of the lining (conjunctiva) of the eyelid and eyeball.

When are we contagious?

To be safe, the window describing when we’re most likely to transmit our infection to others spans from 4 days before to 4 days after the rash.

In Australia, our national guideline notes 24 hours before prodromal symptoms – which ends up in about the same place to 4 days after!

This ends up looking like a big period of time because of the broad range spanned by the rash window, which can be 7 days long and start 7 days after the prodrome. The bars overlap.

We can be contagious before we experience symptoms, and that’s expected for measles as much as for SARS-CoV-2 and influenza viruses.

MeV genetic material lingers in some people for months

Sensitive PCR-based methods can detect the presence of MeV RNA for months after infection. This is shown in the infographic using a dashed red line drifting off the central red downward curve.

The source of this RNA – whether it is a low-level replication, production of MeV proteins that keep prompting the immune system or production of non-infectious genome sequences – remains unclear but could be related to sustaining high levels of protective virus-neutralising antibodies.

After vaccination, RNA detection can also persist. No onward transmission has been reported to date.

Vaccine safety studies continue to show that the measles vaccine has an excellent safety profile

Making the graphic accessible to all

So, it takes a lot of words to explain a measles infographic huh?

Apart from posting the infographic on Bluesky, Mastodon and Threads, I’ve also placed the image (.png format) and the editable vector graphic (.svg format; I use the wonderful Inkscape for these graphics) version of it onto my Figshare page at https://figshare.com/articles/figure/Measles_and_lymphycytes_-_an_infection_timeline/28658399

All the versions are there, so make sure you use the most recent one or contact me via here or a social channel to check what’s most shiny.

This page includes a CC BY 4.0 open-access license, which lets you share and adapt the image and only asks you to credit the source and indicate any changes you make. 

Other references used to inform the measles infographic

1. Measles virus, immune control, and persistence
   https://academic.oup.com/femsre/article/36/3/649/635473?login=false
2. Measles immunity and immunosuppression
   https://linkinghub.elsevier.com/retrieve/pii/S1879625720300699
3. Measles virus infection diminishes preexisting antibodies that offer protection from other pathogens
   https://www.science.org/doi/10.1126/science.aay6485
4. STUDIES ON IMMUNITY TO MEASLES
   https://linkinghub.elsevier.com/retrieve/pii/S0022-3476(65)80112-3
5. Incomplete genetic reconstitution of B cell pools contributes to prolonged immunosuppression after measles
   https://www.science.org/doi/10.1126/sciimmunol.aay6125
6. Measles – CDNA National Guidelines for Public Health Units
   Used for incubation, prodrome and rash timings
   https://www.health.gov.au/resources/publications/measles-cdna-national-guidelines-for-public-health-units?language=en