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expert reaction to news that a Briton has died from rabies following a cat bite in Morocco

Expert reactions to news that a British national has died after contracting rabies following a cat bite in Morocco.

 

Dr Michael Tildesley, Associate Professor in Mathematical Epidemiology, University of Warwick, said:

Q: How is it kept under control in some places?

“In countries where rabies has been controlled, this is typically achieved through repeated high-coverage mass vaccination campaigns of the reservoir population. This requires significant financial and logistical resources to carry out these campaigns, that must continue even after it appears that the disease has been eliminated as rabies can persist unobserved circulating at very low incidence. This is particularly challenging for low- and middle-income countries where technical limitations and repeat vaccine shortages result in less effective vaccination campaigns.”

Q: What it actually does to the body?

“The symptoms of rabies can vary depending upon the person infected, but usually include fever and headaches, confusion, irritability and abnormal behaviour. Later symptoms can include overt aggressiveness, overproduction of saliva (leading to frothing at the mouth) and in some cases lethargy and paralysis. If not treated promptly, rabies is almost 100% fatal.”

Q: How it’s contracted?

“Rabies is usually transmitted to humans through saliva from infected animals, which typically occurs through animal bites. Transmission can also occur when infected saliva gets into an open wound, for example through licks. Human to human transmission is exceedingly rare, though is possible through bites or due to organ transplantation.”

Q: Whether it’s just dogs and cats that are reservoirs?

“Rabies can affect any mammalian species. However, around 99% of human cases are a result of exposure to rabies-infected dogs. In some countries (such as the USA), rabies has been eradicated in the domestic dog population but still circulates amongst terrestrial wildlife and bats.”

 

Kristyna Rysava, PhD Candidate in Disease Ecology and Control, University of Warwick, said:

Q: Why is it not kept under control in others?

“In many countries around the world, rabies is extremely challenging to control. It circulates in mostly free roaming dog populations with fast demographic turnover, so infected animals have high potential to spread infection to other animals and humans and are more difficult to vaccinate. There is a lack of awareness of the risks associated with biting dogs and many people do not seek treatment in the event of an animal bite. Most importantly, in countries where the disease circulates endemically resources to vaccinate dogs in large numbers and consistently over longer periods of time are strained, which presents a significant obstacle to controlling and eliminating the disease.”

Q: How much we know about the illness?

“We know a lot about the symptoms associated with rabies, how it progresses in the body upon infection and the need for post-exposure vaccination in the event of exposure. However, rabies epidemiology at population level, including the scale of rabies transmission and persistence, remains a very active subject of scientific research. This is especially challenging for rabies compared to many other human diseases as in most endemic countries the disease is extremely under-reported, providing a sparse representation of the system.”

Q: How uncommon it is to contract nowadays?

“Rabies is extremely uncommon in the high-income countries. The disease has been eliminated in both domestic dogs and wildlife in most parts of Europe, and humans that have become infected were typically exposed to a rabid animal in other parts of the world where the disease is still present. Particularly in Sub-Saharan Africa and Southeast Asia the virus circulates endemically with around 60,000 human death from rabies worldwide every year. Unfortunately, some of the most affected places and communities are also most neglected with little or no access to post-exposure treatment, ultimately leading to preventable deaths.”

 

Dr Katie Hampson, Reader at Institute of Biodiversity Animal Health & Comparative Medicine, University of Glasgow, said:

Why is rabies so deadly?

“The virus infects the nervous system and before reaching the brain replicates slowly in a way that does not trigger the immune system. When the virus reaches the brain it replicates rapidly, and that’s when symptoms become evident. At that point it is too late and death is inevitable. Death involves muscle spasms, brain inflammation, and coma, although victims go in and out of lucidity, which makes it even more traumatic.

 

How is it kept under control in some places?

“The most common source of rabies is free roaming unvaccinated dogs. The vast majority of dogs in low- and middle-income countries where rabies is prevalent are free roaming. But rabies can be easily controlled through dog vaccination, since most dogs are owned and accessible through well-organized campaigns. Rabies has not been a problem in most high-income countries for decades as it has been eliminated entirely from dog populations through dog vaccination.

 

Why is it not kept under control in others?

To deliver large-scale dog vaccination requires a strong veterinary sector committed to controlling a public health problem and/or a medical sector that is willing to invest in veterinary control efforts.

 

That has not happened in low-income countries – where vaccinating kids has been a struggle never mind dogs. These days childhood vaccination is central to healthcare around the world – but veterinary services have much smaller budgets than Ministries of Health. They are typically required to control diseases for trade (e.g. Foot-and-Mouth-Disease) or require livestock owners to pay for disease control. But this is not the model that has successfully controlled childhood vaccine-preventable infections. When dog owners are charged for vaccination, it is very difficult to vaccinate enough dogs to have an impact.

Rabies has been largely ignored by development agencies – most deaths are not seen because they occur in rural and poor communities where people cannot afford or access lifesaving vaccines. Rabies post-exposure vaccines are some of our most effective vaccines – if delivered immediately after a bite they are 100% effective in preventing death. But bite victims need access to these vaccines, which are expensive and often out of stock.

 

Many in the UK and all high-income countries are now aware this disease is still such a problem in low-income countries – where one person dies every 10 minutes from an infected dog bite. It seems like such a Victorian disease and it was a major problem previously in the UK. Travellers may also have the impression that wildlife is the main risk. Any mammal can transmit rabies, so spillover into other species does occur, with cats commonly infected form dog-transmitted rabies.

 

WHO and partners, including the Global Alliance for Rabies Control recently launched a global strategy ‘Zero by 30’ aiming to completely end human deaths from dog-mediated rabies by the end of 2030. The main tool for this strategy to work is dog vaccination, which can eliminate the disease at source – stopping spill over into humans, cats, wildlife and livestock.

 

 

Professor Tom Solomon, Professor of Neurology at the University of Liverpool, said:

“Rabies is the most deadly of all diseases. Humans become infected following the bite or scratch of an infected animal. If they receive vaccine soon after, then the disease can be prevented. But once someone develops the clinical features of the disease, the death rate is almost 100%, despite the best efforts at treatment. It is so deadly because there is no proven antiviral drug against rabies. The virus works its way through the nervous system destroying nerve cells; once those that control breathing, and the heart rate and blood pressure are affected, death inevitably follows.

 

“Rabies virus is transmitted in nature among dogs, cats and other mammals. In some countries, such as the UK, this has been controlled by restricting the entry of animals from endemic areas, and by vaccinating. In parts of Asia and Africa wild dogs and other wild animals contribute to the spread of the disease. However campaigns to vaccinate such animals have proved successful to help bring the disease under control.”

Dr Jonathan Stoye FRS, Senior Group Leader, Francis Crick Institute, said:

“The most common source of rabies is ownerless, unvaccinated dogs. Thus areas with high numbers of such animals, for instance certain areas of the African continent are those where there is the greatest risk and the highest number of cases. Canine vaccination is a highly effective means of controlling rabies and the Global Alliance for Rabies Control has set a target for eliminating canine rabies in endemic areas by 2030 using vaccination.”

 

Dr Edward Wright, Senior Lecturer in Microbiology, University of Sussex, said:

“Rabies virus is found on every continent, with the exception of Antarctica. However, it is a real concern in Africa, Asia and the Middle-East where 95% of the annual 59,000 human deaths from rabies occurs. Infection follows transmission of the virus via the bite or scratch from an infect animal. The most commonly infected animals vary depending where you live in the world but 95% of human cases are cause by dogs. Other animals, such as foxes, skunks and bats can also spread the virus.

“Once infected the virus will replicate within the host and invade the nerve tissues. Eventually it will make its way to the brain. At this point symptoms will start which can include hallucinations, partial paralysis, and brain inflammation and dysfunction.  It is also very difficult to treat the disease once the brain is infected. Once symptoms have developed death results in over 99.9% of infections.

“This is the most tragic statistic of rabies disease.  There are vaccines and post-exposure drugs that targeted the virus.  These have been shown to be highly effective in protecting humans and animals against rabies virus. They’ve even been used to eliminate rabies from some communities. However, the cost of these treatments can be several time higher than the average monthly income in the areas where the virus is endemic.  Therefore, they are underused.

“The UK is considered rabies free, with sporadic case imported in unvaccinated travellers who have become infected following contact with infected animals in countries where the virus is known to circulate.  If travelling to any areas where rabies is present it is essential to receive the vaccine prior to travel.  This normally requires 3 jabs so must be started at least 4 weeks ahead of the trip. Vaccination is also recommended for bat handlers in the UK. While we have a rabies free status, a rabies-related virus capable of causing the same fatal disease as rabies, has been repeatedly found in UK bats. However, the rabies vaccines provide protection against this virus too.”

 

Prof Geoffrey Smith, Wellcome Trust Principal Research Fellow, Head of Department of Pathology, University of Cambridge, said:

Q: How much do we know about the illness?

“We know a lot about the illness caused by infection by rabies virus. After the infection is started, usually by being bitten by a rabies-infected animal, the virus travels up the nerves to the central nervous system where it infects the Perkinji cells of the cerebellum. The infection of these cells causes the aggressive behaviour associated with hydrophobia. The final place where the virus replicates is in the salivary glands and it is from here that the virus in spread to new hosts by biting.”

Q: Which animals are reservoirs?

“It is not just dogs and cats that are reservoirs for rabies virus. Virtually all mammals can be infected by rabies virus and a large reservoir is in bats. Indeed, the last person to die of rabies in UK was a bat handler who was bitten by a bat and then refused to be vaccinated. In US skunks and raccoons are a source of the virus, and vampire bats are reported to have spread the infection to cattle.”

Q: How uncommon is it to contract rabies nowadays?

“In the UK it is extremely uncommon. Cases in UK citizens are usually associated with travel to an endemic country and then being bitten by a rabies infected animal there. It is common to be vaccinated against rabies before travelling to an endemic country.”

Q: What is the treatment?

“Vaccination against rabies is safe and effective, and rabies is one of the few diseases in which vaccination after infection can be effective. But this depends on how soon this is done and also where the patient is bitten. After a bite on the foot, there is more time to vaccinate before the virus reaches the brain by travelling along nerve cells, than if one was bitten on the back if the neck.”

 

Dr Daniel Horton, Senior Lecturer in Veterinary Virology and Research Director, Department of Pathology and Infectious Diseases, University of Surrey, said:

Q: How much do we know about the illness?

“Rabies is one of the oldest recognised zoonotic diseases (diseases transmitted from animals to people) but still causes tens of thousands of deaths every year, in 150 countries across the world. Although knowledge of the virus and illness have improved, the actual number of animal rabies cases is poorly understood in many areas- which means predicting the chance of getting the disease if bitten is very difficult.”

Q: What does it actually do the body?

“Rabies is caused by a virus which travels up the nerves from a bite or scratch, to the brain. Changes in the brain then cause the symptoms of rabies, which include anxiety, headaches, fever and famously a fear of water (hydrophobia) and difficulty swallowing. The virus then spreads back down the nerves to many organs, including the salivary glands. Unfortunately once symptoms have developed, rabies is almost always fatal.”

Q: How is it contracted?

“Rabies in humans is contracted when the virus, usually from the saliva of an infected animal, enters a wound. The majority of cases are caused by bites or scratches from dogs and cats.”

Q: Which animals are reservoirs?

“Although the majority of human cases are caused by dog bites, in many parts of the world wildlife also get rabies and can act as a reservoir- for example, fox rabies in Europe and racoon rabies in North America. Bats also carry similar viruses capable of causing rabies.”

Q: How uncommon is it to contract rabies nowadays?

“Rabies remains a globally important problem, with tens of thousands of human cases every year. Unfortunately many of these cases are in children. The UK and Western Europe is currently free from dog rabies, and all five human cases in the UK since 2000 have been acquired abroad.”

Q: What is the treatment?

“Once clinical signs develop the disease is almost always fatal. To prevent the disease developing any bite or scratch should be cleaned thoroughly with soap and water and medical attention sought immediately. Post exposure treatment may be given, which can consist of vaccine and passive immunisation according to international standard protocols.”

 

Dr Pierre Nouvellet, Reader in Evolution, Behaviour and Ecology, University of Sussex, said:

“A great deal is actually known about the virus, its pathology, its transmission cycle… a vaccine has been available since the 1880’s! However, the majority of cases occur in place where surveillance is very poor.

“Rabies develops and multiplies in the muscle, then migrates to the brain via the nervous system. It then causes encephalitis (inflammation of the brain). After first symptoms occur, death happens within days (2-10).

“All mammals can be infected but dogs are the main problem in term of transmission to humans and typical exposure is from infected dogs – >90% of human cases.

“Despite the vaccine, it’s not that uncommon to contract rabies nowadays. Credible estimates from 2015 put the burden at around 60,000 human deaths. Also it’s estimated that almost half of cases are in children less than 15!

“Treatment is in the form of preventive or post-exposure vaccination – recommendations from WHO:”

 

Prof Jonathan Ball, Professor of Molecular Virology, University of Nottingham, said:

Q: How much do we know about the illness?

“We know lots about it. Much pioneering work was done by Louis Pasteur who developed and used the first rabies vaccine (even though he didn’t know he was working with a virus back then).”

Q: What does it actually do the body?

“It affects the nervous system, particularly the brain and eventually causes total paralysis and therefore death. It is nearly always fatal in humans.”

Q: How is it contracted?

“Through the bite of scratch of an infected (rabid) mammal, such as dog, fox, wolf, cat etc.”

Q: Which animals are reservoirs?

“A variety of mammals can be infected but it is usually contact with a rabid dog that results in human infections.”

Q: How uncommon is it to contract rabies nowadays?

“It isn’t uncommon in places around the world where rabies is endemic, but in the UK and Europe it is pretty rare.”

Q: What is the treatment?

“We have very effective vaccines that can be used post-exposure, but have to be used before a person starts to develop symptoms. You can also be given antibody therapy post exposure.”

Q: How is rabies kept under control?

“Vaccination of pets (eg. Dogs and in some places (e.g. North Europe) by wildlife vaccination programmes (which was how they controlled rabies in wild mammal populations in parts of northern Europe)”

Q: Why is it not kept under control in some places?

“Because vaccination programmes aren’t adequately deployed. It is on the list of WHO’s priorities (http://www.who.int/neglected_diseases/news/WRD_2017_Press_release/en/)”

 

  

Declared interests

None received

 

 

 

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