It’s another shift in Virchester ED. You’ve picked up the next card; a 12 year old has stepped on a nail in her grandparents’ garden. You have a look, there’s only a small scratch and it happened yesterday, but her dad has brought her in today as he’s concerned “she might need a tetanus”.
You seem to remember reading something about a green book, and that there are vaccines and boosters and immunoglobulins, and learning all about them for that exam you had last week, but all that knowledge has popped right out of your head. You excuse yourself to ‘go and look at her obs on the computer’.
Let’s go through what you need to know.
What is Tetanus?
The Clostridium genus of bacteria is probably one of the most unfortunate to get infected with. Not content with just having Clostridium difficile (C. diff) in the family, they also have C. botulinum (botulism), C. perfringens (gas gangrene), and, more relevant to this post, C. tetani.
Clostridium tetani is gram positive, anaerobic, and shaped like tennis rackets (if you squint carefully). It survives well outside of the body, and is commonly found in soil and manure, making it essentially impossible to eradicate as there’s always somewhere it can hide.
It produces tetanospasmin – the potent neurotoxin that causes tetanus. The LD50 of tetanus toxin has been measured to be around 2.5-3ng/kg (albeit in mice), making it the second deadliest toxin known to man after botulinum toxin (see, we told you Clostridium was bad!)1
The bacteria can get into your body through puncture wounds, scratches, burns or bites. Also body piercings and tattoos with unsterile and contaminated needs, or injecting contaminated drugs. Tetanus isn’t contagious thankfully, but it does have a 10-90% mortality, highest in infants and the elderly. Its incubation period is around 10 days (4-21) so symptoms generally appear around this time after exposure.
Of course this varies country to country, but in the UK2 we use three primary immunisations and two boosters. The primary immunisations are given at 2, 3 and 4 months old as combined vaccines with diphtheria, pertussis, polio and Haemophilus influenzae type b (DTaP/IPV/Hib). The first booster (DTaP/IPV) is given three years after the primary course is complete, so usually at age 3 and a half. The second booster (Td/IPV) is given ten years after the first booster – aged 14.
The American and Australian schedules are fairly similar, though have one extra administration of DTaP – at 2, 4, 6, 18 months, and 4-6 years, with a booster at age 11-12 years old. This is also the schedule the WHO recommend.3 In the US you’ll also get an adult booster every ten years!
“But Chris…”, you probably aren’t asking, “why are there so many different capital and small case letters?”
And that’s a great question, and one I spent literally minutes finding the answer to, so you’re going to be sure I’ll tell you too. You might be wondering why there’s DTaP, Tdap, and Td. Seems a bit strange. Well, DTaP stands for diphtheria, tetanus and acellular pertussis. The capital letters indicate a normal dose of the inactivated toxoid. In Tdap and Td there are reduced levels of the toxoids for diphtheria and pertussis, and so they get small letters.
Hope that all makes sense now. Let’s find out how we help our patients in the emergency department.
In order to manage ED patients with regards to tetanus, we need to ask two questions:
- What’s their immunisation status?
- Is this a tetanus-prone wound?
Hopefully we now know what immunisations are needed and when, and by taking a history we can find out whether the patient has had, and is up to date with their primary immunisations and boosters. Don’t forget that in some patients we won’t know their immunisation status and it can be tricky in travellers from other countries who may not know what was in the vaccines they or their children have been given.
To answer the second question, we can turn to the Green Book. In the UK, Public Health England have published a guide to immunisation against infectious disease, the so-called Green Book (because the front cover is green – don’t say us Brits aren’t original…).4
A wound is tetanus-prone if it meets any of the following criteria:
- Requires surgical intervention that is delayed for more than six hours
- Significant degree of devitalised tissue or a puncture-type injury, particularly if contact with soil or manure
- Contains foreign bodies
- Compound fractures
- In patients with systemic sepsis
If it’s none of these, it’s a clean wound!
The Green Book helpfully puts these two questions together in a handy table, to give the quick guide to management in the ED.
Contains public sector information licensed under the Open Government Licence v3.0.
Now there’s a lot of words there, so what it really comes down to is, if the patient…
- …has had the primary immunisations at 2/3/4 months, and the wound is low-risk, do nothing!
- …has had the primary immunisations, and the wound is high-risk, just give tetanus immunoglobulin (TIG).
- …has not had the primary immunisations, or is unsure, give both and follow up with their primary practitioner to complete the course.
- …is immunosuppressed, treat them as if they’re not immunised, even if they’ve had the full course.
The tetanus vaccine generally used in the UK is Revaxis (Td/IPV), prescribed as 0.5ml IM.
TIG is given as 250 units IM ordinarily, or 500 units IM if it’s been longer than 24 hours since the injury, or if there is heavy contamination or burns.
I mentioned earlier that in some parts of the world adults get tetanus boosters every ten years, and certainly in departments in the UK you’ll hear people asking “have you had a tetanus in the last ten years?”. What’s the evidence for this though?
A study by Mark Slifka and team in Oregon5 looked at adult serum antibody titres, which predicted immunity to tetanus for >30 years in 95% of fully vaccinated individuals. They have proposed a change to the US vaccination schedule such that adults would get boosters at age 30 and 60. As well as saving a predicted $1 billion in vaccine costs over the first four years, it would certainly take some of the guesswork out of when patients had their last booster. Their proposals need to be reviewed by the Advisory Committee on Immunisation Practices, so it’s not going to happen soon, but maybe in the near future the US will see a change in their tetanus regimes.
In the UK, and other countries, we don’t routinely give boosters beyond the full five-dose course. The Green Book recommends a booster if you haven’t had one in the last ten years and you’re going to a country where immunoglobulin might not be routinely available, but otherwise the consensus is the childhood immunisations confer immunity for life.
Are you feeling lucky?
In 2016, there were just four cases of tetanus in the whole of England and Wales6 (a population of around 56 million). This means that clinicians who have diagnosed a case of tetanus are few and far between.
Tetanus is a clinical diagnosis7, defined as trismus with one or more of the following:
- Respiratory distress
- Muscle spasms
- Autonomic dysfunction
It’s graded on a scale of 1 (mild) to 3b (very severe), and you can read more about that here.
If you’re unlucky enough to suspect a case, based on the signs and symptoms above, together with the clinical history, get help. The patient will need early airway management and supportive therapy, and the wound will need to be debrided as soon as possible.
In the ED, we can start metronidazole which stops bacterial replication and thus production of new toxin, and diazepam or midazolam to control muscle spasms. The mainstay of treatment is intravenous TIG, however this is hard to obtain in the UK and US. If TIG is not available then intravenous Human Normal Immunoglobulin (HNIG) should be used, at a dose of 5,000 units in patients under 50kg, and 10,000 units in those over.8
It’s important to take serum samples before administering immunoglobulin, as these will need to be sent for testing, however treatment should never be delayed to wait for the lab result.
If you made it this far, well done, here’s the summary.
Tetanus is a significant condition, with a high mortality, but the incidence is very low thanks to vaccination. There are some fantastic guidelines to help you out when you’re not sure about wounds and the tetanus thing, but generally the only thing you might need to give is immunoglobulin in high-risk wounds. IV drug users are at a higher risk of tetanus than the rest of the population so don’t forget about it. A clinical case of tetanus requires early airway management, and in the ED we can take serum samples and give metronidazole, benzodiazepines, and IV immunoglobulin. The patient’s best chance is early recognition, so keep it in your mind, it’s very unlikely you’ll see an actual case though.
So, what about our patient? After using a well-known search engine to look up the guidelines, you take a good history, establish that she received her primary immunisations and her first booster, but hasn’t had her second yet, so she’s well on schedule. The wound is very superficial, certainly not a significant puncture, and meets none of the criteria for a high-risk wound. You give it a good clean, stick a plaster on it, and reassure dad that the obs you checked on the computer are fine, and no further treatment is needed. They go home happy.
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