The recent death of a British woman from rabies after a holiday in Morocco is a sobering reminder of the risks posed by this almost universally fatal disease , once symptoms begin.
Author
- Dan Baumgardt
Senior Lecturer, School of Physiology, Pharmacology and Neuroscience, University of Bristol
If you're considering travelling to a country where rabies is endemic , understanding how rabies works - and how to protect yourself - may go a long way in helping you stay safe.
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Rabies is a zoonotic disease - meaning it is transmitted from animals to humans - and is caused by a viral infection. In 99% of cases the source of the infection is a member of the canidae family (such as dogs, foxes and wolves). Bats are another animal group strongly associated with rabies, as the virus is endemic in many bat populations.
Even in countries that are officially rabies-free , including in their domestic animal populations - such as Australia, Sweden and New Zealand - the virus may still be found in native bat species. Other animals known to transmit rabies include raccoons, cats and skunks.
Rabies is caused by lyssaviruses (lit. rage or fury viruses), which are found in the saliva of infected animals. Transmission to humans can occur through bites, scratches or licks to broken skin or mucous membranes, such as those in the mouth. Once inside the body, the virus spreads to eventually reach the nervous system.
Because it causes inflammation of the brain and spinal cord, symptoms are primarily neurological, often stemming from damage to the nerve pathways responsible for sensation and muscle control.
Patients who develop rabies symptoms often experience altered skin sensation and progressive paralysis. As the virus affects the brain, it can also cause hallucinations, and unusual or erratic behaviours. One particularly distinctive symptom - hydrophobia, a serious aversion to water - is believed to result from severe pain and difficulty associated with swallowing.
Once rabies symptoms appear, the virus has already caused irreversible damage. At this stage, treatment is limited to supportive intensive care aimed at easing discomfort - such as providing fluids, sedation and relief from pain and seizures. Death typically results from progressive neurological deterioration, which ultimately leads to respiratory failure.
It's important to note that rabies symptoms can take several weeks, or even months, to appear. During this incubation period , there may be no signs that prompt people to seek medical help. However, this window is crucial as it offers the best chance to administer treatment and prevent the virus from progressing.
Another danger lies in how the virus is transmitted. Even animals that don't appear rabid - the classical frothing mouth and aggressive behaviour for instance - can still transmit the virus.
Rabies can be transmitted through even superficial breaks in the skin, so minor wounds should not be dismissed or treated less seriously. It's also important to remember that bat wounds can often be felt but not seen . This makes them easy to overlook, should there be no bleeding or clear mark on the skin.
The vaccine
The good news is that there are proven and effective ways to protect yourself from rabies - either before travelling to a higher-risk area, or after possible exposure to an infected animal.
Modern rabies vaccines are far easier to administer than older versions, which some may recall - often with discomfort. In the past, treatment involved multiple frequent injections (over 20 in all) into the abdomen using a large needle. This was the case for a friend of mine who grew up in Africa and was one day bitten by a dog just hours after it had been attacked by a hyena.
The vaccine can now be given as an injection into a muscle, for instance in the shoulder, and a typical preventative course requires three doses. Since the protective effect can wane with time, booster shots may be needed for some individuals to maintain protection.
Sustaining a bite from any animal should always be taken seriously. Aside from rabies, animals carry many potentially harmful bacteria in their mouths, which can cause skin and soft tissue infections - or sepsis if they spread to the bloodstream.
First aid and wound treatment is the first port of call, and seeking urgent medical attention for any bites, scratches or licks to exposed skin or mucous membranes sustained abroad. In the UK, this also applies to any injuries sustained from bats.
A doctor will evaluate the risk based on the wound, the animal involved, whether the patient has had previous vaccines, and in which country they were bitten, among other things. This will help to guide treatment, which might include vaccines alone or combined with an infusion of immunoglobulin infusions - special antibodies that target the virus.
Timing is crucial. The sooner treatment is started, the better the outcome. This is why it is so important to seek medical help immediately.
In making the decision whether you should get a vaccine before going on holiday, there are recommendations , but ultimately the choice is individual. Think about what the healthcare is like where you are going and whether you'll be able to get treatment easily if you need it.
Vaccines can have side-effects , though these tend to be relatively minor, and the intended benefits vastly exceed the costs. And of course avoid contact with stray animals while on holiday, despite how tempting it may be to pet them.
Several rules of thumb can counteract the dangers of rabies: plan your holiday carefully, seek travel advice from your GP, and always treat animal bites and scrapes seriously.
Dan Baumgardt does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
