Dr Harvey Pynn reviews the latest guidance from Public Health England (PHE) on rabies post exposure treatment. PHE’s 31 page pdf document was published in January 2015 and is available in full free on line. In addition, in Harvey’s Medical Director Bulletin No. 5 he offers a 12 point summary of the information below which can be read here. (BR to insert link when MDB is published.)
WMT constantly strives to ensure WMT courses provide tuition to facilitate the highest level of safe practice in austere overseas environments. For more than two decades, we have maintained that well trained laypeople can learn to provide a high level of care to ill or injured patients when other medical help may not be readily available in a foreign, wilderness setting.
Rabies is an acute viral infection (causing encephalomyelitis) transmitted in the saliva of infected animals (especially dogs). Once symptoms in humans develop, it is incurable. Whilst the UK is free of rabies in terrestrial animals, it is still endemic in many countries popular for foreign travel.
Worldwide more than 55,000 people die of rabies each year (WHO, 2010). Every year, more than 15 million people worldwide receive a post-exposure preventive regimen to avert the disease – this is estimated to prevent 327 000 rabies deaths annually (WHO, 2010). Most cases are in developing countries, particularly India (Plotkin et al., 2008). In the UK, deaths from classical rabies continue to occur in people infected abroad. Such instances are, however, rare, with 25 deaths having been reported since 1946, five of which have occurred since 2000 and the most recent was in 2012. None had received appropriate post-exposure prophylaxis. From my weekly tropical medicine update, there is still the occasional case suspected in the UK:
Pre-travel vaccination is effective and reliable at priming the immune system should an infected bite be subsequently sustained. In 95% patients receiving a course of vaccine, the immunity will be long lived and no further boosters will be required especially if intramuscular vaccine has been administered (versus intradermal).
Pre-exposure vaccine is administered by a 1.0ml intramuscular injection on day 1,7 and 21-28. The vaccine can be given intradermally by a suitably qualified operator in the same dosing regimen using a 0.1ml dose though this route is off licence. However, it allows the vial and therefore the cost to be shared amongst a group. The only definite contraindication to the intradermal route is if the patient is taking chloroquine as an anti-malarial though many providers do not routinely vaccinate children using this route.
Most travellers are infrequently exposed to potential rabies and thus the recommendations regarding pre-exposure vaccination is that a course of primary vaccination should be administered but no blood tests or booster are routinely required subsequently.
Post-exposure management normally consists of wound treatment and risk assessment for appropriate post exposure prophylaxis. Treatment and immunisation after a possible rabies exposure will depend on the circumstances of the exposure, including the local incidence of rabies in the country involved and the immune status of the individual.
Wounds should be thoroughly cleaned with sterile water or preferably povidone iodine to which rabies virus is extremely sensitive. Wounds should not be closed until post exposure treatment (PET) has occurred.
Regardless of whether pre-travel vaccination has occurred, if a bite from a potentially infected animal is sustained, PET will be required in the form of vaccine or immunoglobulin (HRIG). All such PET vaccines should be given via the intramuscular route.
Rabies vaccine and HRIG for use in post-exposure treatment are available free of charge to patients in the UK.
PHE have stratified risk relating to bites separately for terrestrial mammals and bats. The remainder of this bulletin will relate to the management of exposure from terrestrial animals (cavers and others who are at high risk of exposure to bats should read the full document available on line). Exposure is classified from 1 (licks, minor scratches – lowest risk) to 3 (bites, saliva contact with mucous membranes – highest risk).
Dogs that are shedding virus in their saliva are likely to be in the terminal phase of their illness and so not behaving normally. If an animal is still alive 15 days post bite, it will not have transmitted virus in that bite.
The incubation period for rabies is typically 1-3 months though can be as little as 1 week and as long as 2 years. Due to the potentially long incubation period for rabies, there is no time limit for commencing PET though the earlier the better.
All episodes of animal bite in an area where rabies is endemic should be risk assessed – is there a pet owner, has the animal been vaccinated, was the animal behaving normally are some of the questions that must be asked to help inform a decision as to whether PET is required.
There are five possible PET options after risk assessing the bite:
1. No risk so no PET
2. Vaccine and HRIG – for those who have not had pre-exposure immunisation
3. Vaccine only – for those who have had pre-exposure immunisation (those who have had a complete pre-exposure course will need 2 3. PET vaccines and those with partial pre-exposure course will need 5 PET vaccines)
4. Vaccine and blood test 1 week later – those who have had pre-exposure immunisation more than 10 years ago will need 2 PET vaccines followed by a blood test to check antibody levels to determine whether further vaccines are required
5. Observation of animal (domestic pets only)
Day 0 is the day of 1st vaccine NOT necessarily the day of exposure.
If pre-travel immunisation has occurred, two doses of vaccine will be required, even if there has been a high risk exposure. Vaccine is available in most countries of the world.
HRIG, however, is unavailable in most countries of the world. It is expensive (approx £300 per vial in the UK) and depending on a patient’s weight, 4-6 vials may be required for treatment. As such, if a bite is suffered, a course of post exposure prophylaxis vaccine should be commenced followed by travel back to the UK and then HRIG as soon as possible thereafter (within 7 days of first vaccine).
With this in mind, if travelling to remote areas of the world and returning to the UK will be problematic, a course of pre-exposure immunisation is recommended so that getting HRIG is not required regardless of the bite received.
This is a summary of the PHE guidance for routine wilderness travel. If you are planning to work with animals or likely to come into contact with bats (I.e cavers), please read the document in full on line.
My final recommendations would be to have a pre-travel course of vaccine if travelling to a region of the world where rabies is endemic. Consider having the injections intradermally if part of a group to save costs. Boosters after an initial pre-exposure course of vaccine are no longer recommended for routine travel.
Dr Harvey Pynn
Medical Director, Wilderness Medical Training
June 2015
Footnotes
1. PET vaccine required on days 0,3,7,14 and 28 with HRIG within 7 days of starting treatment
2. PET vaccine required on days 0 and 3
3. PET vaccine required on days 0,3,7,14 and 28
4. PET vaccine required on days 0 and 3 then blood test before deciding whether to give further vaccine on days 7,14 and 28
References:
1. Public Health England Guidance on Rabies Post Exposure Treatment, Jan 2015
2. Green Book Chapter 27 (Version 3), 2012