The hygiene mythbuster

13 October 2014

This issue Seán Derrig, scientific director at Chemex International, explains why we have have more to fear from mosquitos than Ebola

We’re all used to media hysteria about ‘new’ plagues. While SARS, H1N1 and MERS–CoV all generated their fair share of fact-free headlines if you want real top-notch ill-informed panic, Ebola is in a class of its own. Derrig’s Law states the more overexcited the reporting the less perilous the organism. And so it is with Ebola. It’s wreaking havoc in West Africa but it’s still not a candidate for a global pandemic.

But viral haemorrhagic fevers (VHFs) such as Ebola, Marburg, Lassa and Hanta do hit a nerve in the public consciousness probably due to their superficial resemblance to zombie plagues where the mere touch of someone infected spreads exponentially and a couple of airline flights later you have a global pandemic. Yes, Ebola is a ghastly, often fatal ‘Category 4’ organism, which means there is no effective prevention or treatment and if it gets into the community it can spread rapidly. But contagion and fatality do not a zombie plague make.

Ebola is actually pretty inefficient. It’s not contagious before symptoms appear and it’s spread via body fluids, not droplets (like flu or measles are) so you won’t get it from an asymptomatic carrier sneezing on a bus or an insect bite. Also, outbreaks of rapidly-fatal diseases tend to burn out quickly. We might see isolated cases imported into the UK but further spread is very unlikely.

This outbreak is spreading in Africa because sources are not isolated as they would be in the UK and local health infrastructure, education and awareness of basic hygiene are all shockingly poor. But it’s not just Ebola or ignorance that’s killing people. Healthcare workers are most at risk so fear has shut down much of the health system; clinics are closed and people are dying from what are usually entirely preventable causes.

To put Ebola in context its all-time death toll remains in the low thousands yet malaria kills 500,000 people a year in sub-Saharan Africa alone. TB kills 1.3 million. H1N1 infected 60 million and killed about 250,000 in a single season. A more concerning viral haemorrhagic fever is dengue which infects 50-100 million annually and kills over 20,000 – and it’s moving north with the Aedes mosquito as global warming opens up new habitats for it.


Half of all human deaths ever are due to mosquito-borne diseases. So don’t worry about sharks or zombie plagues – it’s the mozzies that are coming to get you.