When the lights go out

What happens when highly contagious, life-threatening diseases that were once controlled make a comeback?

- TANYA MEESON

In May this year, the UK reported the first significant outbreak of polio since 1984. In the same month, UNICEF reported a 79% increase in measles infections between 2021 and 2022. In June, Australia saw its first case of diphtheria since 1992.

To post-2020 sentiments, these numbers might seem insignificant; the diseases themselves no more than footnotes to the almost three-year global COVID pandemic we've faced.

It therefore bears reminding the devastation these diseases can wreck: Approximately 1 in 25 people who contract polio will get meningitis, 1 in 200 will suffer permanent paralysis, many will die; measles, which causes fevers, a rash, blindness and encephalitis, is one of the most contagious viruses in the world and killed some 2.6 million people annually before 1963; diphtheria, which became known as the 'strangling angel of children', causes paralysis, suffocation and death, and in 1980 was still infecting almost 100 000 people every year.

The difference between these diseases making daily headlines and affecting your life directly is due to one primary mechanism: vaccines.

Thanks to the discovery and continual improvement of vaccines and global uptake of vaccination drives, polio, measles and diphtheria are just some of the terrible diseases that have long been considered eliminated as epidemic threats in all but a handful of countries. So why are we starting to see their re-emergence?

The slow spread

'When we discuss re-emerging diseases, what we're talking about, frankly, is that wealthier countries that thought they'd eliminated these diseases, or had them under control, are now seeing a return,' explains Dr Alastair McAlpine, a South African infectious diseases paediatrician, currently working at BC Children's Hospital in Vancouver, Canada. 'We've only ever eradicated smallpox and some, like polio, we got close to eradicating, but never quite got there.