Researchers in Siberia have reported that rising temperatures are causing permafrost to melt thereby exposing mass graves of people who died in smallpox epidemics back in the 1890s. This is not the first time melting permafrost has given rise to modern illness. One child was killed and thousands of reindeer slaughtered due to an outbreak of the bacterium anthrax which was thought to be the result of infected bodies being released from the permafrost.
So far the smallpox virus itself has not been found but the bodies bear skin lesions consistent with those caused by smallpox and fragments of viral DNA have been found in tissue samples. Scientists are saying it’s possible that the virus could still be alive in these circumstances and therefore that smallpox could make a comeback! Okay, it sounds a bit unlikely but the scientific community hadn’t expected Ebola to be on the scale it was two years ago so maybe it’s time for a refresher…better to be to be safe than sorry.
Smallpox was [thought to be] eradicated in the 1970s. The last naturally occurring case was in Somalia in 1977. Following eradication of naturally occurring smallpox the World Health Organisation ordered the destruction of all remaining examples of the virus except for those kept at the Centre for Disease Control (CDC) in Atlanta, USA, and some in the State Research Centre of Virology and Biotechnology, Koltsovo, Russia.
It is thought that these are the only remaining examples of live virus...however there was a laboratory acquired case at the University of Birmingham in 1978! A photographer, Janet Parker, was infected from airborne virus that was extracted via air ducts from a research laboratory on the floor below. Janet died from the virus 4 weeks after contracting it, her mother who was also infected survived, but her father died of a heart attack during the incident and the head of the laboratory committed suicide! This tragic laboratory acquired case marked the end of an infectious disease era...or did it?
In 2014, 6 vials of live smallpox virus were found in a cardboard box by someone cleaning out a fridge in a laboratory in Bethseda, Maryland, USA. That must have been a heck of a shock! You can just see them coming to a laboratory manager saying “I’ve just found these in the back of the fridge, what should I do with them?” As the colour drained from the manager’s face they probably said something along the lines of “Please put those back where you found them, close the door and don’t let anyone else in… I’m off for a strong drink and then I’ll phone the CDC.”
It was possible to eradicate smallpox for two reasons:
- Humans are the only species that can carry the smallpox virus and therefore if you can interrupt transmission in humans you can prevent it spreading
- There was a very effective vaccine against smallpox which could be used to protect anyone at risk of exposure thereby interrupting transmission
In theory, for the same reasons, we could eradicate Rubella as well but as Rubella does not cause such severe infection this is not a global priority.
So would I spot a case of smallpox if I saw it?
The simple answer is probably not. As it is nearly 40 years since the last case in the world, it is very unlikely that anyone in current clinical practice has ever seen a case. So maybe it’s time to remind ourselves how to recognise it… just in case…
There are two distinct forms of smallpox depending on the type of smallpox virus acquired; Variola minor and Variola major. Variola major is more severe and has a mortality of 30%, with most deaths occurring between days 5 and 7, whereas the mortality from Variola minor was around 1%. A small proportion of patients with Variola major developed haemorrhagic smallpox in which the skin lesions are absent and the patients have signs of bleeding into the skin or from the mucous membranes. Haemorrhagic smallpox is almost universally fatal. Although this should all be written in the past tense!
The main differential diagnosis for smallpox is Varicella Zoster (chicken pox). The clues to distinguishing smallpox from Chicken Pox are:
If smallpox is suspected then national and international authorities should be notified immediately; this would be of major international public health significance. This would be Public Health England (PHE) in the UK and also the World Health Organisation (which would be done by PHE). A whole storm of attention would rapidly follow, including a bioterrorism concern, so hospital senior managers should also be aware.
Most of the old techniques for detecting smallpox have been superseded by the development of molecular methods and now PCR fluid from the skin lesions would be the mainstay of diagnosis. This high risk organism would be processed in a specialist reference facilities which in the UK would be the laboratory at Porton Down.
Treatment of smallpox
There is no specific treatment for smallpox available however it is likely that someone somewhere has an experimental treatment that might be available on a named patient basis if a case presented, which is what happened with Ebola. This is another reason for alerting international organisations as they will know who might have such a treatment available; according to the WHO the experimental drugs Brindofovir and Tecovinimat might be available to use…obviously someone is still researching this virus hopefully with better ventilation than in Birmingham in the 1970s!!!
Infection Control Implications
There is no specific guidance on the infection control aspects of smallpox because there has not been a case for nearly 40 years however we do know how it is spread and therefore can propose sensible precautions. Smallpox is spread by droplets and patients are infectious from the development of the prodromal illness until all of the scabs have disappeared. Whilst smallpox is much less contagious than chicken pox the disease is much more severe and as there is no treatment, infection control precautions need to be stricter than for chicken pox. The following is how I would manage a case of smallpox: