Rabies

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59,000 deaths occur worldwide each year, primarily in Asia and Africa

In 2016, nearly 4,200 people received a treatment in France

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Cause

The rabies virus (Lyssavirus genus) is found in the saliva of animals (dogs and other wild animals) in the latter stages of the disease. It is usually transmitted through a bite or scratch from a contaminated animal, and can also be spread if the animal licks broken skin or mucosa. Human-to-human transmission (through organ transplants or mother-to-fetus transmission) is extremely rare.

Symptoms

The rabies virus is neurotropic: it infects the nervous system and stops it from functioning properly. It does not cause visible lesions in the brain but it disrupts neurons, especially those regulating autonomic functions such as heart rate and breathing. After the incubation period, which can be just a few days but is usually a few months, the infected individual develops encephalitis symptoms. The symptomatic phase often begins with dysphagia (difficulty swallowing) and various neuropsychiatric disorders, especially anxiety and agitation. The patient may develop hydrophobia (as a result of the dysphagia). Once the symptoms appear, the disease leads to coma and death (often by respiratory arrest) within a few hours or a few days. Apart from a few documented cases, the outcome is always fatal after the onset of clinical signs.

Exceptional cases of survival without post-exposure treatment  

In 2004, an American teenager survived rabies. She was bitten by a bat on the American mainland and was given no post-exposure preventive vaccination. After receiving aggressive treatment in intensive care, she survived and recovered with few after-effects. Although this girl's recovery opened up new possibilities for treatment, her survival cannot be attributed to the treatment she received. The reason she was able to overcome the disease has still not been identified to this day – no other patient treated in the same way on other continents has survived since.

Epidemiology

Rabies is responsible for around 59,000 deaths worldwide each year, mainly in Asia and Africa, most often following a bite from a rabid dog. Every year, approximately 17 million people receive treatment following exposure to suspected rabid animals.

No human cases of rabies contracted on the French mainland have been reported since 1924. In 2008, a human case probably caused by a bat bite was reported in French Guiana. Human cases contracted outside France and diagnosed within the country have also been recorded. The last patient to die from rabies in France (a 10-year-old child in east-central France; city of Lyon) was diagnosed in October 2017, after presenting the first clinical signs, following a lengthy stay in Sri Lanka.

Anyone traveling to an endemic area – mainly Asia and Africa, and also to a lesser extent Central Europe, the Middle East and South America – should take precautions to avoid wild and domestic animals.

Treatment

Preventive post-exposure rabies treatment begins with non-specific treatment of the wound, involving cleansing and the application of an antiseptic. A course of antibiotics and a tetanus booster (if needed) are also recommended after a bite. Post-exposure prophylaxis itself consists of a vaccination, sometimes combined with serum therapy. The treatment should be administered as soon as possible after exposure, before the appearance of the first symptoms, which signal the start of an inevitably fatal decline. Prophylaxis involves 4 or 5 intramuscular vaccine injections over the course of a month and is well tolerated. In a growing number of (endemic) countries, the intradermal route is now considered to be just as effective.

In 2016, 4,223 people received post-exposure treatment in France. This does not necessarily mean that these people had been exposed to the rabies virus, but rather that the risk of transmission could not be ruled out and prophylaxis was administered as a precaution.

At the Institut Pasteur

The National Reference Center for Rabies, based at the Institut Pasteur (led by Hervé Bourhy) which is also a WHO Collaborating Center (page in French), is responsible for the epidemiological surveillance of rabies in France. Every year, it analyzes more than a thousand suspected samples from humans and animals. It also coordinates the extensive network of anti-rabies treatment centers across France (90 centers and hospitals/clinics with rabies facilities). In 2016, 1,835 consultations were carried out at the Anti-Rabies Center in the Institut Pasteur Medical Center, and 56% of these patients received post-exposure rabies prophylaxis. Three research laboratories (the Lyssavirus Dynamics and Host Adaptation Unit, the Viral Neuro-Immunology Unit, and the Antiviral Strategies Unit) are also carrying out additional research on the rabies virus as well as the disease in France and in developing countries, where rabies represents a daily risk.

Surveillance and public health: National Reference Center for Rabies

At the Institut Pasteur in Paris:

Dans le Réseau international des instituts Pasteur :


October 2017

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