Hantavirus – What you need to know, from a Doctor

Hantavirus advice from Private GP in Wessex

Here we go again. Reports of sickness and death in far-away places. An illness behaving in troublesome ways. Memories of a time so near that it hardly needs recalling, but so far in its experience from the life we know, that it seems like a dream.

Is Hanta the next COVID? The short answer is… ‘probably not’… the (slightly) longer answer is, ‘only time will tell for sure…’

Not very reassuring, I suppose, but in a world in which we constantly and deftly manage unclear and ever-evolving risk, it isn’t really that different from the daily commute.

What is Hantavirus?

The Hantaviruses are a family of disease-causing nasties defined by their structure (they are enveloped viruses with a negative‑sense, single‑stranded RNA genome, for those who care to know). A defining characteristic is their predilection for infecting certain animals, especially rodents, which carry them without becoming unwell.

Humans are typically infected by breathing it in from contaminated rodent urine, faeces, or saliva. In contrast to many related viruses, hantaviruses are not spread by insects. There is only one strain of hantavirus where an infected human can pass it on to another, the strain currently under scrutiny, the ‘Andes’ strain.

How do pandemics happen?

Human to human transmission of an illness is not necessary for it to cause misery. Indeed malaria, which must be in the top 5 most appalling illnesses by almost any measure, can only be spread by blood. In the overwhelming majority of cases, this is through mosquito bites, other means of transmission such as via blood transfusion have been documented very rarely.

All this to say, you aren’t going to catch Malaria by sitting next to someone on the bus who has it, no matter how cough-y or mask-free that person is. Human to human transmission is necessary for a disease to become a pandemic. Moreover, that transmission has to be quite likely. The practical measure of this likelihood is the ‘R value’ of an illness (remember that?). The R value is the number of people an infected person is expected to pass the disease on to under present conditions. If R is more than 1, we all have a bad time as the number of infected people grows. If it is less than 1, the illness peters out.

Why are we concerned now?

I think, by and large, we are concerned now because of what happened with COVID. We (and by we, I mean largely the non-medical media) see the similarities but not the differences and know that, given the huge impact COVID had on our collective consciousness, stories about a potentially similar situation will sell newspapers and drive clicks. SARS-CoV-2 was a virus, unknown to the general public, with a history of confirmed human-to-human transmission, that causes illness and death. The Andes strain of hantavirus is a virus, unknown to the general public, with a history of confirmed human-to-human transmission, that causes illness and death.

However, here the similarities stop. Whereas SARS-CoV-2 was an entirely new thing, the Andes strain is not, and current evidence suggests that this virus is not behaving significantly differently than it has before.

What happened in the past?

Previous outbreaks have demonstrated transmission between people, some of whom have died. This sounds ominous, but it is actually quite reassuring. We have seen all this before, including deaths, without a pandemic. The Andes strain of hantavirus simply wasn’t that transmissible in the past; outbreaks happened, but they were relatively easily contained.

Hantavirus Case Study:

In 2018–19 in and around Epuyén, Argentina, the Andes hantavirus caused 34 (confirmed) infections and 11 deaths. According to a 2020 study, transmission was mostly driven by three people who went to crowded social events while symptomatic. The outbreak was halted through isolation, quarantine, and contact tracing, reducing the reproduction number below 1.

Could things be different this time?

Yes, they could. We shouldn’t be complacent by any means. Viruses can evolve over time, and past behaviour is not a guarantee of future patterns. This is why there is some dissonance between the messaging coming from trusted organisations like the WHO, which are trying to project an image of calm confidence, and the attire of medical workers on the ground. People dressed up in full hazmat suits don’t visibly signal a virus that is difficult to catch.

Nevertheless, according to all the evidence we have now, the virus really is difficult to catch, but how stupid we would look, how hindsight would shame us, if it turned out that this virus had changed and we hadn’t taken sensible precautions. This, especially after the lessons our leaders are supposed to have learned during COVID. Hazmat suits are inconvenient. A pandemic is devastating.

So what should I do?

Nothing different. Avoid searching for daily updates on this; it doesn’t warrant it at present and will only cause unnecessary worry. Significant news will filter through, and should be sought from trusted sources like the WHO or WPGP (of course). If you have any concerns, we are here for you as always.