Authors: Zoe Campbell, Future Science Group
People will generally wait an average of 10 days before seeking medical advice following exposure to potentially rabid animals overseas. These findings, presented at the European Congress of Clinical Microbiology & Infectious Diseases (13—16 April 2019; Amsterdam, Netherlands), are of great importance as there is only a short window of opportunity for individuals to receive treatment before rabies can become fatal.
Rabies is a zoonotic infection that can cause rare but life-threatening infections in the brain and nervous system in humans. Resulting from a bite, scratch, or lick from an infected animal, the virus is estimated to kill around 59,000 people globally, every year.
Rabies is not commonly found in wild or domestic animals in the UK, however some bat species can carry rabies-like viruses, such as the European Bat Lyssavirus type 1 and type 2. In England, around 150 people are treated after being bitten by a bat every year. The study found that people in the UK wait an average of 3 days before seeking treatment following bat exposure.
“Preventive treatments are 100% effective if given promptly after exposure,” explained co-author Kevin Brown, Head of Rabies and Immunoglobulin Service for Public Health England (PHE, Collingdale, UK). “That’s why seeking prompt care is so important, even if the wound or incident seems very trivial. If you are bitten, scratched, or licked by an animal you must wash the wound or site of exposure with plenty of soap and water and seek medical advice without delay. Travellers should not delay waiting for treatment until they return to the UK.”
Symptoms typically take 2—3 months to appear, but in cases where the individual receives a severe bite to the head it can take as little as a week. People who believe they have been exposed to rabies are advised to seek immediate treatment – a series of rabies vaccinations with or without immunoglobin, an antibody treatment that gives immediate short-term protection while the vaccines start to work.
The data for this study was provided by a treatment-issuing center in Manchester (UK). The medical staff conducted a review of all requests for rabies post-exposure treatment at their labs between June 2015 and June 2018.
Of the total 200 patients who received treatment, over 79% received treatment after returning to the UK from 43 different countries. 1 in 5 individuals reported exposure to a bat in the UK. Brown noted, “While the risk of catching rabies in the UK is extremely low, it is important that all potential bat bites are risk-assessed and treated as necessary. Bat bites in the UK often do not leave a mark and are felt rather than seen.”
The incubation time for rabies in the UK is much longer than it is for those exposed abroad; yet despite this, it is recommended individuals receive prompt treatment, although it is never considered too late to receive post-exposure treatment.
A separate study, from PHE Doctors, saw a 7.5-fold increase in the number of risk assessments performed for rabies post-exposure in England since 2001 – increasing from 390 to 2949 by 2018.
The vast majority of these were from dog bites in South and South East Asia, and of these individuals, 40% did not seek this treatment whilst overseas but waited until their return to the UK. Similar to the results from Manchester, more than 60% of those with bat bites sought treatment within 2 days.
An update on rabies treatment guidance
In addition to the national rabies advice and guidance provided through the Rabies and Immunoglobulin Service within PHE, they also provide rabies vaccine and rabies immunoglobulin for all potential rabies exposures in England.
The guidance on post-exposure treatment for rabies was updated in mid-2018, reducing the routine vaccine schedule for unimmunized individuals from five doses to four. A composite rabies risk was also calculated for each exposure – assigning them a red, amber, or green risk – based on the country, the animal and the category of exposure.
Rabies immunoglobulin was only recommended in cases with a ‘red’ composite rabies risk, which is a category 3 exposure (bite or laceration) in a high-risk country in combination with a high-risk animal. Rabies immunoglobulin is also no longer given for bat bites in the UK, although still advised for non-UK bat bites.
Analysis of the first 6 months following these guideline changes showed that there was a significant increase in the number of calls about possible cases of rabies, compared to the same period in 2017. However, it was also found that fewer vaccines and vials of immunoglobulin were issued as treatment.
“Those completing the risk assessment found the process easier to follow and there was less risk of inappropriate treatment given. The new guidance has led to a significant reduction in the costs of running the program, whilst still ensuring appropriate treatment for those at potential risk of rabies,” concluded Brown.
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Sources: Goodwin L, Davies EA, Fariiq HZ et al. A three year retrospective review of cases requiring rabies post-exposure treatment administration from a large regional PHE virology laboratory in Manchester, UK. Public Health England. Presented at ECCMID (13–16 April, Amsterdam, the Netherlands); Brown E K & Russell K. Trends in rabies post-exposure treatment in England, 2001—2008. Public Health England. Presented at ECCMID (13–16 April, Amsterdam, the Netherlands).