Health Institute of the State of Mexico


  • Rabies is a preventable disease through vaccination that affects more than 150 countries and territories.
  • In the vast majority of rabies deaths in humans, the dog is the source of infection. In 99% of cases of transmission to humans, the disease is spread by these animals.
  • It is possible to eliminate this disease by vaccinating dogs and avoiding their bites.
  • Rabies causes tens of thousands of deaths every year, mainly in Asia and Africa.
  • 40% of people bitten by an animal suspected of having rabies are children under 15 years old.
  • Immediate and thorough washing of the wound with soap and water after contact with a suspicious animal is essential and can save lives.
  • WHO, the World Organization for Animal Health (OIE), the Food and Agriculture Organization of the United Nations (FAO) and the World Alliance for Rabies Control (GARC) have established the global partnership «United against Rabies »to develop a common strategy to ensure that, by 2030, there is no human death due to rabies

Rabies is an infectious viral disease that ends up being fatal in almost all cases once clinical symptoms have appeared. In up to 99% of human cases, the virus is transmitted by domestic dogs. However, the disease affects both domestic and wild animals and is spread to people normally by saliva through bites or scratches.

It is a disease present on all continents except Antarctica, but more than 95% of human deaths are recorded in Asia or Africa.

Rabies is one of the neglected diseases that primarily affects poor and vulnerable populations living in remote rural areas. Although there are immunoglobulins and vaccines for humans that are effective, people who need them do not have easy access to them. In general, deaths caused by rabies are rarely reported, and children ages 5 to 14 are frequent victims.
The average cost of prophylaxis after exposure, which is around US $ 40 in Africa and US $ 49 in Asia, regions where the average daily income is US $ 1-2 per person, is extremely high for populations poor

Vaccines are administered every year after a bite to more than 15 million people worldwide, thus preventing hundreds of thousands of deaths per year from rabies.

Elimination of canine rabies

Rabies can be prevented by administering a vaccine. Vaccination of dogs is the most profitable strategy to prevent rabies in humans. Not only will deaths attributable to rabies be reduced, but also the need for prophylaxis after exposure as part of care for patients bitten by dogs.

Rabies awareness and prevention of dog bites

Education about dog behavior and bite prevention, both for adults and children, is essential in any rabies vaccination program if it is intended to reduce its incidence in humans and the cost of treatment of the bites It is necessary to improve the knowledge of the communities regarding prevention and fight against rabies, specifically on the responsibility of having a pet, the prevention of bites and the way of acting when they occur. The commitment of the communities and their participation in preventive programs contribute to improving coverage and receiving the most important information.

Preventive human immunization

There are rabies vaccines that can be used as pre-exposure immunization. It is recommended to administer them to people who have high-risk occupations, such as laboratory personnel who work with rabies virus and other live lysaviruses and people who perform professional or personal activities in which they may have direct contact with bats, carnivorous animals and other mammals in areas affected by rabies. For example, it is the case of staff working in programs to combat zoonoses and rangers.

It is also recommended to vaccinate people who travel to remote areas where rabies is transmitted that will spend a lot of time doing outdoor activities, such as caving or mountaineering. Likewise, foreigners living in countries where the disease is transmitted should be vaccinated and travelers who are forced to stay for long stays in high-risk areas if access to biological products for the prevention of human rabies is limited. Finally, the possibility of vaccinating children who reside or visit high-risk areas should be considered, since they are at greater risk because they usually play with animals. Children may suffer more serious bites and not even say they have been bitten.

The incubation period of rabies is usually 1 to 3 months, but it can range from a week to a year, depending on factors such as the location of the inoculation point and the viral load. The first manifestations are fever accompanied by pain or paraesthesia at the site of the wound. Paresthesia is a sensation of tingling, itching or burning unusual or not explainable by another cause. As the virus spreads through the central nervous system, progressive inflammation of the brain and spinal cord that causes death occurs.

The disease can take two forms:

  • In the first, furious rage, the patients show signs of hyperactivity, excitement, hydrophobia (fear of water) and, sometimes, aerophobia (fear of air currents or the outdoors), and death occurs to the few days due to cardiac arrest.
  • The other form, paralytic rabies, represents approximately 30% of human cases and has a less severe and usually more prolonged evolution. The muscles gradually become paralyzed, starting with those closest to the bite or scratch. The patient slowly goes into a coma and ends up dying. Often, the paralytic form is not diagnosed correctly, which contributes to the underreporting of the disease.


Current diagnostic tools do not allow rabies to be detected before the onset of the clinical phase and, unless there are specific signs of hydrophobia or aerophobia, the clinical diagnosis can be difficult to establish. Rabies in humans can be confirmed in life and post mortem by different techniques that allow the detection of whole viruses, viral antigens or nucleic acids present in infected tissues (brain, skin, urine or saliva).


Infection in people usually occurs through the deep bite or scratch of an infected animal, and transmission by rabid dogs is the source of 99% of human cases. Asia and Africa are the regions with the highest burden of this disease and where more than 95% of rabies deaths occur.

In the Americas, bats are the main source of infection in fatal cases of rabies, since transmission to humans by biting rabid dogs has been almost completely interrupted. Bat rage has recently become a threat to public health in Australia and Western Europe. Mortal cases in humans from contact with foxes, raccoons, skunks, jackals, mongooses and other infected wild carnivorous hosts are very rare, and there are no known cases of transmission through rodent bites.

There may also be transmission to humans through direct contact with mucous membranes or recent skin wounds with infectious material, usually saliva. Transmission from person to person by bites is theoretically possible, but has never been confirmed.

Although rare, the disease can also be contracted by transplanting infected organs or inhaling aerosols containing the virus. Ingestion of raw meat or other tissues of infected animals is not a confirmed source of human infection.

Post-exposure prophylaxis

Post-exposure prophylaxis is the immediate treatment after a bite. The goal is to prevent the infection from entering the central nervous system, which would cause immediate death. This prophylaxis consists of:

  • thorough cleaning and local treatment of the wound as soon as possible after exposure,
  • the application of a potent and effective rabies vaccine according to WHO standards, and
  • administration of rabies immunoglobulin, if indicated.

Effective treatment immediately after exposure can prevent the onset of symptoms and death.

Integrated bite case management

If possible, veterinary services should be alerted and the attacking animal found to be quarantined during the observation period, provided they are healthy dogs or cats. If this is not the case, the animal should be euthanized for immediate examination in the laboratory. Prophylaxis should be administered during the observation period of 10 days or until the results of the tests performed in the laboratory are obtained. If it is concluded that the animal does not have or did not have rabies, the treatment should be discontinued. When the suspect animal cannot be caught or the tests cannot be performed, complete prophylaxis should be administered.

Collaboration "United against Rabies": a global platform with a catalyst function to achieve "zero human deaths from rabies by 2030"

WHO, the World Organization for Animal Health (OIE), the Food and Agriculture Organization of the United Nations (FAO) and the World Alliance for Rabies Control (GARC) joined in 2015 to adopt the common strategy destined to ensure that, by 2030, there is no human death due to rage, and they formed the "United against Rabies" collaboration.

This initiative is the first in which the human and animal health sectors come together to promote and prioritize investments in rabies control and to coordinate global efforts to eliminate this disease. A global strategic plan called Zero for 30, guide and support countries in formulating and implementing their national rabies elimination plans, based on the concepts of A health and of intersectoral collaboration.

Zero for 30 It focuses on improving the access of bite victims to prophylaxis after exposure, informing about the prevention of bites and expanding the vaccination coverage of dogs in order to reduce the risk of human exposure.

Monitoring and surveillance should be central components of anti-rabies programs. It is essential to report cases of mandatory notification diseases, so that operational mechanisms are established to transmit data from the community level to national authorities and, subsequently, to the OIE and WHO. In this way the degree of effectiveness of the programs will be known and measures can be taken to remedy their deficiencies.

The reserves of canine and human rabies vaccines have had a catalytic effect on countries' efforts to eliminate the disease. WHO is collaborating with its partners to anticipate the needs of human and canine vaccines and rabies immunoglobulins, determine global manufacturing capacity and study the wholesale purchasing options that countries have through the mechanisms established by WHO and UNICEF, in the case of vaccines and immunoglobulins for human treatment, and OIE and WHO, in vaccines for animals.

In 2016, the WHO Group of Experts on Strategic Immunization Advisory (SAGE) created a working group on rabies vaccines and immunoglobulins that is analyzing available scientific data, relevant programmatic considerations and the costs associated with its use. Specifically, they will evaluate the supply of intradermal vaccines, reduced vaccination programs and the possible effects of new biological products. In October 2017, the SAGE will review the recommendations of this working group to update WHO's position on rabies vaccination.

WHO-supported studies in countries where rabies is endemic

With the help of WHO, certain countries in Africa and Asia are conducting prospective and retrospective studies to collect data on dog bites, cases of rabies, post-exposure prophylaxis, surveillance, vaccine needs and various options. for the execution of programs.

Preliminary results of studies conducted in Cambodia, Kenya and Viet Nam confirm:

  • that children under 15 have a higher risk of exposure to rabies and that most exposures are due to dog bites,
  • that the availability of biological products and the costs of prophylaxis after exposure are factors that influence the observance of treatment, and
  • that notifications based on the health system underestimate the detection of cases of human and canine rabies, compared to community-based systems.

In addition, data from suppliers of biological products on formulations, procurement and use of rabies vaccines and immunoglobulins is expected in India and Viet Nam.

Once complete, the data will provide more evidence to support the need to invest in anti-rabies programs and that will be crucial to support global and regional strategies aimed at ensuring that, by 2030, there is no human death from rabies. Likewise, the data will be used by the GAVI Alliance to support the inclusion of rabies vaccines in its Vaccine Investment Strategy. The decision in this regard is scheduled for 2018.

Examples in countries and regions

Since 1983, countries in the WHO region of the Americas have reduced the incidence of rabies by more than 95% in humans and 98% in dogs. This achievement was mainly the result of the application of effective policies and programs focused on coordinated canine vaccination campaigns at the regional level, on the awareness of society and on the wide availability of post-exposure prophylaxis measures.

Many countries in the WHO South-East Asia Region have initiated elimination campaigns consistent with the regional disease elimination goal by 2020. An elimination program was presented in Bangladesh in 2010 and, thanks to the attention to dog bites , mass canine vaccination and increased availability of free vaccines, human deaths from rabies decreased by 50% between 2010 and 2013.

Great progress has also been made in the Philippines, the United Republic of Tanzania and South Africa. In these countries, preliminary demonstration studies have been carried out within the framework of the Bill and Melinda Gates Foundation project led by WHO, which recently allowed us to conclude that it is possible to reduce rabies in humans through a combination of consistent interventions in the vaccination of dogs, the improvement of access to post-exposure prophylaxis and the increase in surveillance and public awareness.

The keys to maintaining and expanding rabies control programs into new territories have been to start small, offer incentive packages to strengthen local rabies control programs, demonstrate good results and cost effectiveness of the programs, and ensure the involvement of governments and affected communities.

Prevention and Action against Rabies

How to prevent rabies?

  • Vaccinating all your dogs and cats against rabies, at one month of birth, then at three months and then every year. REMEMBER TO KEEP YOUR VACCINATION CERTIFICATE UNTIL YOUR NEXT VACCINE
  • Avoid contact with puppies or unknown or stray animals and even more so if they are sick or injured. Avoid adopting them and don't let children play with them.
  • Do not let your pet go loose on the street, take it for a walk with its leash and lift its waste.
  • Become aware and lead to sterilize your dogs and cats, in this way we will avoid more stray animals and increased risk of rabies
  • Avoid buying animals that do not have a vaccination certificate
  • If you no longer want your pet, do not leave it on the street, better take it to the nearest rabies center
  • Report to the authorities the presence of animals suspected of suffering from rabies
There are pirate vaccinators who charge for deworming and offer you the vaccine at low cost or free,

Where can I vaccinate my pet?

The objective of the mass vaccination program is to interrupt the cycle of rabies transmission by immunizing at least 80 of the dogs in the community. For the immunization of dogs and cats, a vaccine with live inactivated virus is used and is performed at one month of age, at three months of age and subsequently every year. Remember that there are two national weeks of vaccination (March and September) where all your pets (dogs and cats) will receive the rabies vaccine completely free at your nearest health center or vaccination post. Vaccination is permanent and free in health centers.

What to do in case of being bitten, scratched or licked by an animal suspected of rabies?

  1. Immediately wash the wound with plenty of soap and water for 10 minutes and dry the wounds with sterile gauze and cover. For the mucosa of the eyes or nose, irrigate with boiled water for 5 minutes.
  2. Go immediately to the nearest health unit, to be evaluated by a doctor, he will determine, if it is a slight, serious or risk-free risk and will administer the type of treatment. Currently, rabies treatment is no longer painful and consists of the application of a vaccine in the arm or leg in turn (3 to 5 doses), it is highly effective, safe and of excellent quality.

What to do with the Animal Aggressor?

  • Locate and identify the aggressor animal and establish date of aggression
  • Assess the conditions and circumstances in which the aggression occurred
  • Verify that you have rabies vaccination and that it is in force
  • Observe the dog or cat for 10 days after the assault

Do not kill the attacking animal, and if possible keep it under observation, if it is a stray or unknown animal, call the local anti-radic center immediately.

What is canine rabies?

The term "rage" comes from the adjective in Latin Rabidus, which is translated as "delusional", "furious" or "fierce", due to the characteristic behavior of animals that suffer from this pathology, which show aggressive behaviors.

As we have advanced in the introduction, rabies is caused by a family virusRhabdoviridae, which mainly affects the central nervous system (CNS), spreading and accumulating in large quantities in the dog's salivary glands, which cause excessive production of saliva, infected with the virus. This disease is present in the infected animal and can last in the carcasses of deceased animals for up to 24 hours.

Forms of contagion of rabies in dogs

The Rage it is usually spread by bite of an infected animalHowever, it can also be transmitted through saliva, for example if the animal licks an open wound, or if they occur scratches in certain areas, such as mucous membranes. However, these are rare situations.

Do not forget that this disease can affect the human being in case of a bite, so it is so important to make an adequate preventive medicine plan and inform us about the symptoms and forms of infection, with the aim of ensuring the health of the dog, of other domestic animals and that of the guardians themselves.

Causes of rabies in dogs

Dogs are considered the main carriers from rabies, those dogs that have not been vaccinated and those that come into contact with wild animals, such as foxes and bats, are vulnerable. However, the most common form of infection is by biting domestic mammals, like cats, dogs and rabbits.

Direct contact with the skin (without wounds), blood, urine or feces is not a risk factor, except in bats, however, it is rare for domestic animals to come into contact with these small mammals.

Currently, attempts are made to control rabies in countries around the world, focusing on prevention in dogs and cats, thanks to vaccination campaigns and multiple protection measures. However, rabies remains a frequent pathology that appears in a timely manner, even in countries where it is practically eradicated.

Phases of rabies in dogs

To understand the progress of the canine rabies virus, it is essential to pay attention to the phases of this pathology. During the bite, the virus present in saliva enters the body and it is installed inside muscles and tissues, while it multiplies in that place.

Then, the virus begins to spread through the surrounding structures, usually those closest to the nervous tissue, since it is a neutropic virus, that is, it has an affinity for nerve fibers. It is important to note that it does not use blood as a means of diffusion.

The dog rage presents several phases:

  • Incubation: refers to the period from the bite to the appearance of the first symptoms. At this stage the dog seems to be fine and is asymptomatic, that is, it has no symptoms of disease. We talk about a phase that can last from one week to several months.
  • Prodromal: At this stage the dog begins to manifest the incipient symptoms of the disease, showing more nervous, scared, anxious, tired and even withdrawn. It can last from 2 to 10 days.
  • Aggressiveness: This is the phase that characterizes rabies disease. The dog becomes irritable, excessively, even biting its owners. It is a high risk stage.
  • Paralysis: is the final stage of rage. In it the dog is paralyzed and can have spasms and even go into a coma, until death occurs.

Now that you know the phases of canine rabies, we will explain what are the symptoms of rabies in dogs, fundamental to the suspicion that our dog may be infected.

"Chuchos" of others

All dog breeds can bite. And the mere fact that a dog is small and seems friendly does not imply that it cannot cause any other injuries. Even the friendliest and best-educated companion dog can try to bite if someone startles, scares, threatens, or bothers you or if you are angry, upset or dominated by hunger.

As much as you think you know a dog, always supervise your child when in contact with a foreign pet. To reduce the risk of bites, teach your child the following safety rules:

  • Always ask the owner whether or not the dog can be petted.
  • Wait for the dog to see and sniff before petting.
  • Do not run to the dog or run away from him.
  • If an unknown dog is approaching, keep calm, do not look directly into the eyes that stay still or slowly move away from it.
  • If a dog tries to bite, place any object between your body and the dog's. If a dog knocks him down, he has a ball, cover his face and stay still.

How to prevent rabies in dogs

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Teach your child the basic safety rules for relating to dogs

A dog expert has developed the following seven safety tips that children can follow to prevent dog bites. If you form the word "NOTHING BAD"With your initials, you will find it easier to remember:

Nor disturb the dog
TOcaress it only with permission
Dgive it space
TOctuar slowly
MKeep calm and ask for help whenever a dog attacks you
hTOsta good dogs can bite
Lyou fingers always together

Symptoms of rabies in dogs

The canine rabies virus has a long incubation period, which can range between three and eight weeks, although in some cases it can be even more extensive, which is why it is not always detected quickly. In humans, for example, symptoms usually appear around 3 and 6 weeks after the bite.

The symptoms of this condition mainly affect the SNC and at brain, and although the phases mentioned above usually occur, not all symptoms are always manifested, which is why it is so important to be aware of the signs that indicate that our dog may be sick.

Here we show you rabies symptoms in dogs more common:

  • Fever
  • Aggressiveness
  • Irritability
  • Apathy
  • Vomiting
  • Excessive salivation
  • Photophobia (aversion to light)
  • Hydrophobia (water aversion)
  • Difficulty to swallow
  • Face paralysis
  • Seizures
  • General paralysis

Anger easily confused with other neurological diseases and, therefore, it is always necessary to consult with a veterinarian before the appearance of any of the symptoms of rabies in mentioned dogs, or if we suspect that our dog may have come into contact with an infected animal.

Manual for the dog master

Much of the responsibility to prevent dog bites rests with the dog's master. Before acquiring a dog, talk to a professional (such as a veterinarian, a caretaker or the owner of a dog shelter) who has a good reputation to tell you which type of dog breed is best for your home. Ask questions about the temperament and health of the dog. A dog with a history of aggressive behavior is not suitable for a family with children.

If your family already has a dog, make sure the pet keeps up its vaccination schedule and takes it to the veterinarian regularly. Also, sterilize or chase it. Consider enrolling your dog in a training center or school to promote his sociability and obedience, which will greatly reduce the chances of him biting someone.

When you take your dog for a walk, always take it on the leash so you can control it. Carefully supervise your child when interacting with your dog and never leave a baby or small child (up to two and a half years old) alone with the family pet.

Even if you don't have dogs at home, make sure your child understands some "never" about how to interact with dogs:

  • Never squeeze a dog too hard, do not throw it in the air, do not jump on it or jump on it.
  • Do not annoy a dog or pull its ears or tail.
  • Do not disturb a dog while eating, sleeping or taking care of its young.
  • Never remove a toy or bone from a dog or play fighting with it.
  • Never feed a dog using your fingers. Always place the food on the palm of the hand while keeping all the fingers well together.
  • Never corner a dog against a corner.

How to know if my dog ​​has rabies?

If you suspect that your dog may have been bitten by a stray dog, a homeless cat or come into contact with a carrier wild mammal, you may want to find out how to know if a dog has rabies. Pay attention to the next step by step:

  1. Look for wounds or bite signs: This disease is usually transmitted through saliva, so if your dog has fought with another dog or pet you should, look immediately the wounds that could have caused him.
  2. Pay attention to possible symptoms: Although during the first phase no obvious signal is manifested, after a few weeks after the bite the dog will begin to show strange behaviors and, although they are not symptoms that can confirm the transmission, they can alert you. Remember that dogs may have muscle aches, fever, weakness, nervousness, fear, anxiety, photophobia or loss of appetite, among other symptoms. In a more advanced stage, your dog will begin to show a furious attitude that is the most characteristic of the disease and that gives it the name "rabies". The symptoms you will present will be that of excessive salivation (It can present the typical white foam with which the disease is related), an uncontrollable desire to bite things, excessive irritability (before any stimulus the dog will become aggressive, growl and try to bite us), loss of appetite and hyperactivity. Some less common symptoms may be lack of orientation and even seizures.
  3. Advanced phases: If we have not paid attention to the previous symptoms and we have not taken the dog to the veterinarian, the disease will enter the most advanced stage, although there are dogs that do not even suffer them, because before they are euthanized or die. At this stage the dog's muscles will begin to paralyze, from their hind legs to the neck and head. He will also be lethargic, continue to foam white mouth, bark abnormally and have difficulty swallowing due to muscle paralysis.

Quarantine for rage

In Spain there is a action protocol before the bites or aggressions of domestic animals, with the objective of minimizing the risk of contagion towards other animals and people. Se hace un estudio sobre el caso, se realiza una evaluación inicial y se mantiene en observación al animal durante un período de 14 días, fundamental para asegurar que el mamífero no era infectivo en el momento de la agresión, aún si no presentara síntomas de rabia en perros.

Después, si el animal ha dado positivo, se realiza un período de investigación epidemiológico de 20 días. Además, existen varios niveles de alerta según la presencia de rabia en el territorio, ya hablemos de animales domésticos y terrestres, que comprenden unos métodos de actuación u otros.

Tratamiento de la rabia en perros

Desafortunadamente, la rabia canina no tiene cura ni tratamiento, pues la intensidad de los síntomas de la rabia en perros y su rápida propagación provocan la muerte certera del animal, sin embargo, sí es posible prevenir el contagio de esta patología mediante la vacunación del perro. Por ello, ante un animal infectado el veterinario nos aconsejará proceder a la eutanasia del perro, con el objetivo de evitar el sufrimiento animal y un posible contagio.

Recordamos que tras la mordedura de un animal infectado nos exponemos a padecer la rabia en humanos, por ese motivo resulta de vital importancia lavar la herida con agua y jabón y acudir cuanto antes a un centro médico para recibir de forma pronta la vacuna antirrábica.

¿Cómo prevenir la rabia en perros?

Mediante el seguimiento estricto del calendario de vacunación del perro podemos prevenir que nuestro can padezca esta terrible enfermedad mortal. Generalmente se aplica la primera dosis alrededor de las 16 semanas y, de forma anual, se aplica un refuerzo para que el organismo del perro se mantenga activo contra el virus. Así mismo, antes incluso de la aparición de los primeros síntomas de la rabia en perros, si hemos observado que nuestro can ha sido mordido por otro perro o animal silvestre debemos go to the vet.

¿Cuánto vive un perro con rabia?

No es posible determinar de forma exacta cuánto tiempo vive un perro con rabia ya que la fase de incubación puede variar enormemente dependiendo de la localización y gravedad de la mordedura. Por ejemplo: el virus transmitido por un mordisco profundo en la pata se extenderá mucho rápido que en una herida superficial en la cola.

Debemos saber que la esperanza de vida de un perro con rabia es relativamente corta, pues puede variar entre 15 y 90 días, siendo más corta aún en cachorros. Así mismo, una vez afectado el SNC y tras una manifestación evidente de los síntomas de rabia en perros, la muerte del can ocurre entre los 7 y 10 días.

En cualquier caso, si sospechas que tu perro pueda padecer la rabia acude cuanto antes a tu veterinario para aislar adecuadamente al animal, hacerle las pruebas pertinentes y evitar así el riesgo de propagación hacia otros animales y hacia las personas mediante la eutanasia.

This article is purely informative, at we have no power to prescribe veterinary treatments or make any kind of diagnosis. We invite you to take your pet to the veterinarian in case he presents any type of condition or discomfort.

If you want to read more articles similar to Rabia en perros – Síntomas, contagio y tratamiento, we recommend that you enter our section of infectious diseases.

Prevención de la rabia

Para evitar el contagio de la rabia y prevenir su propagación se recomiendan una serie de medidas:

  • Vacunar a todos los mamíferos que se tengan como mascota siguiendo las recomendaciones del veterinario.
  • No entrar en contacto con animales callejeros o salvajes de los que se desconozca cuál es su estado de salud.
  • Se puede recomendar la vacuna directamente a las personas que viajen a zonas de alto riesgo durante largo tiempo o trabajen en contacto con animales con riesgo.
  • Si compra animales en otros países infórmese de si pueden cruzar fronteras y si están correctamente vacunados.
  • Cuando entre en contacto con mamíferos sospechosos de rabia consulte al médico, incluso cuando no haya herida.

Síguenos en:

La rabia es una zoonosis de etiología viral que cuando afecta al hombre le produce una encefalomielitis aguda, siempre mortal. Ocupa el décimo lugar entre las enfermedades infecciosas mortales. En el presente trabajo se aborda la etiología, patogenia, epidemiología, diagnóstico, medidas profilácticas y tratamiento de la rabia.

La rabia se transmite a través de mordedura o contacto directo de mucosas o heridas con saliva del animal infectado. También se ha demostrado su adquisición a través de trasplante corneal de donador muerto infectado por el virus y no diagnosticado. No obstante, no se ha documentado su transmisión por mordedura de humano a humano, pero se ha aislado de la saliva de los pacientes afectados de rabia. Este virus también se ha identificado en sangre, leche y orina. No se ha documentado transmisión transplacentaria.

La rabia fue descrita por Aristóteles y por Celso, y no fue hasta 1885 cuando Pasteur consiguió la primera vacuna antirrábica, salvando al niño Joseph Meister de una muerte segura tras sufrir múltiples mordeduras de un perro rabioso.

A pesar de la eficacia y la inocuidad del tratamiento actual, entre 35.000 y 50.000 personas mueren cada año de rabia debido a que no son tratadas. La rabia ocupa el décimo lugar entre las enfermedades infecciosas mortales.

El virus de la rabia pertenece a la familia Rhabdoviridae , género Lyssavirus . Es un rhabdovirus de 180 nm de longitud por 75 nm de anchura con forma de bala de fusil o de proyectil cilíndrico. Tiene una extremidad redondeada y la otra plana con una muesca como el talón de una flecha. Asimismo, posee una nucleocápside y envoltura. Esta última es una doble capa bilipídica perfectamente definida.

La mordedura o arañazo de un animal rabioso trae como consecuencia la presencia de saliva infectada con virus rábico en la musculatura estriada. Éste se multiplica en los miocitos hasta lograr una concentración infectante necesaria para alcanzar las terminaciones nerviosas sensitivas y las placas neuromusculares motoras. Se une a los receptores de acetilcolina, penetrando en las fibras nerviosas periféricas, donde es descapsidado, y comienza así el proceso de replicación viral.

La rabia es una zoonosis de distribución mundial (excepto en Australia, Reino Unido, Japón y Nueva Zelanda), y se calculan alrededor de 15.000 casos anuales. El principal reservorio de los virus son los animales salvajes, a partir de los cuales la infección se extiende a otros animales salvajes y a los domésticos. Todos los seres de sangre caliente pueden experimentar el virus rábico.

Los principales reservorios dependen del área geográfica: en Europa son los zorros y los lobos, en América, la mofeta, el zorro y el mapache, en África, la mangosta y el chacal, y en Asia, el lobo y el chacal. Mención especial requieren los murciélagos, que muerden y chupan la sangre de bóvidos y équidos durante la noche, transmitiéndoles la rabia. En América existen vampiros portadores del virus que hacen que se les consideren los verdaderos reservorios de la enfermedad. En Europa Central y Occidental es el zorro rojo o común la causa principal de la propagación de la rabia.

En cuanto a la rabia urbana, los animales domésticos son la principal fuente de infección. El perro es, en el 90% de los casos, el principal atacante del hombre, principalmente el perro vagabundo. Los gatos, de vida mucho más incontrolada, transmiten la enfermedad por múltiples arañazos y su peligro de transmisión es más alto.

El diagnóstico de la rabia puede realizarse en el hombre o en el animal mordedor. Estamos ante una enfermedad mortal la mayor parte de las veces. Por esta razón, es necesario realizar el diagnóstico durante el período de incubación, circunstancia sólo posible en el animal mordedor. Por ello, en el hombre tiene poco interés en el diagnóstico. No obstante, se puede establecer directamente por la demostración del virus a partir de la saliva, esputo, exudados traqueal y nasal, orina y LCR.

En otras ocasiones se pueden detectar antígenos virales, por inmunofluorescencia, en células del epitelio corneal y piel de la her >post mortem , el aislamiento, la investigación de antígenos y la búsqueda de corpúsculos de Negri pueden realizarse en el tejido cerebral.

La detección de anticuerpos tiene poco interés en los casos de período de incubación corto. Si, por el contrario, éste es largo, pueden aparecer anticuerpos en sangre y en el LCR al iniciarse el cuadro clínico. Se detectan mediante reacciones de fijación del complemento, inmunoflurescencia indirecta y pruebas de neutralización. Recientemente se han empleado también las de inhibición de la fluorescencia y el test de reducción de placas.

El principal reservorio de los virus son los animales salvajes, a partir de los cuales la infección se extiende a otros animales salvajes y a los domésticos

Como la vacuna VEP (vacuna de embrión de pato), que se obtiene por cultivo en embrión de pato y cuya inactivación se hace con betapropiolactona. Es muy empleada en Estados Unidos.

Vacunas obtenidas de tejido cerebral de animales inmaduros

­ Vacuna de fuenzalida. Se obtiene del cerebro del ratón lactante y la posterior inactivación con rayos ultravioleta. Es muy inmunógena. Se recomienda una dosis diaria durante 14 días con dosis de 0,5 ml en niños menores de 3 años, y de 1,0 ml en adultos por vía subcutánea en la región periumbilical interescapulovertebral. Las reacciones secundarias generalmente son locales, como dolor, eritema e induración en el sitio de la aplicación. Se calcula que 1 de cada 8.000 receptores de vacunas pueden presentar alguna complicación neurológica como encefalitis, mielitis transversa, neuropatías periféricas y neuritis. Las complicaciones están en relación directa con el número de dosis de vacunas y la edad del paciente. En caso de presentarse cualquiera de estas reacciones adversas, debe suspenderse este tipo de vacuna y continuar con la de células diploides.

­ Vacuna de Rossi . Se obtiene del cerebro del carnero y la posterior emulsión en solución salina mertiolada y fenolada.

­ Vacuna de Gispen . Se obtiene del cerebro del conejo lactante.

Vacunas obtenidas de cultivos tisulares

No presentan las complicaciones encefalíticas de hipersensibilidad a la mielina que aparece en las vacunas obtenidas a partir de tejido cerebral. Existen muchas vacunas de este tipo, a saber:

­ Vacuna de Abelseth . En células de riñón de cerdo.

­ Vacuna de Atanasiu . Células BHK/21.

­ Vacunas en células diploides . Como la WI38 del Instituto Wistar de Filadelfia y la vacuna VCDH (vacuna de células diploides humanas) del Instituto Merieux de Lyon). En el caso de la vacuna VCDH se administran 4 o 5 dosis de 1 ml por vía intramuscular los días 1, 3, 7 y 14 (el día 28 es opcional).

Es posible distinguir tres estrategias de vacunación diferentes:

­ En áreas libres de rabia, se recomienda la inmunización preexposición a los sujetos de alto riesgo por motivos laborales.

­ En los países desarrollados con rabia salvaje, hay que evitar la transmisión de la rabia mediante la vacunación y otras medidas de control de los perros. El tratamiento preexposición se aplica como en las áreas libres de rabia y el tratamiento postexposición se aplica rara vez.

­ En los países en vías de desarrollo con rabia urbana es prioritaria la inmunización canina y la erradicación de animales callejeros. El tratamiento postexposición es frecuente, pero las vacunas disponibles son poco inmunógenas y provocan graves reacciones adversas.

La OMS ha establecido algunas recomendaciones sobre la profilaxis preexposición. Tres dosis de 2,5 U administradas por cualquier vía generan niveles de anticuerpos neutralizantes casi en el 100% de los individuos. Si se emplean vacunas celulares, la inmunización consiste en la aplicación por vía intramuscular de 3 dosis de 1 ml en los días 0, 7, 21 y 28. En zonas donde las limitaciones económicas dificultan la disponibilidad de vacunas se pueden inocular por vía intradérmica 3 dosis de 0,1 ml en los días 0, 7, 21 y 28.

Muchas autoridades sanitarias, incluidas las de la OMS, recomiendan una serología de 2-4 semanas después de la última inyección para asegurar una seroconversión satisfactoria. Es fundamental realizar este control en individuos que tienen un elevado riesgo de contraer la rabia, en los sometidos a tratamiento inmunosupresor y en los que reciben múltiples vacunas simultáneamente. Si existe una exposición continua al virus de la rabia se deben efectuar determinaciones de anticuerpos neutralizantes cada 6-12 meses y administrar dosis de recuerdo si los títulos son inferiores a 0,5 U/ml.

En cuanto a las indicaciones de la profilaxis preexposición, queda restringida a aquellos individuos que tienen un elevado riesgo de exposición: personal de laboratorio, veterinarios, granjeros, manipuladores de animales y personas que viajan a zonas endémicas. Especial interés presenta el estudio de la profilaxis preexposición en los viajeros.

La vacunación preexposición elimina la necesidad de administrar inmunoglobulina y reduce el número de dosis de vacuna postexposición, pero no elimina la necesidad de tratamiento postexposición, sólo lo simplifica

La vacunación antirrábica no es un requisito obligatorio para entrar en ningún país, pero aquellas personas que viajan a países donde la rabia es endémica deben ser informadas del riesgo de contraer esta enfermedad y de la conducta que deben seguir en caso de mordedura. Se recomienda el tratamiento preexposición para aquellos que viven o visiten durante más de 30 días zonas endémicas de rabia en las que no es posible obtener un tratamiento óptimo para una mordedura. Estas zonas incluyen casi todos los países de América central y Sudamérica, la India, el sureste asiático y la mayor parte de África. Sin embargo, un grupo de expertos recientemente ha desaconsejado la profilaxis preexposición para los que viajen a zonas endémicas durante largo tiempo. Según este grupo de trabajo, la vacunación previa debe limitarse a individuos sometidos a un elevado riesgo de exposición y a niños incapaces de comprender la necesidad de evitar los animales o de comunicar un contacto con éstos.

Finalmente, decir que la vacunación preexposición elimina la necesidad de administrar inmunoglobulina y reduce el número de dosis de vacuna postexposición, pero no elimina la necesidad de tratamiento postexposición, sólo lo simplifica.

Es muy efectiva si se combinan el tratamiento local de la herida, la inmunización pasiva y la vacunación de forma correcta.

Sólo está indicada si ha existido exposición realmente. Así, las caricias a animales rabiosos o el contacto con sangre, orina o heces de un animal con rabia no se considera exposición.

El mayor riesgo corresponde a mordeduras en zonas ricas en terminales nerviosas o próximas al SNC. Sin embargo, la localización de la mordedura no debería influir en la decisión de iniciar el tratamiento.

Las exposiciones que no son mordeduras rara vez provocan rabia. El mayor riesgo se corre cuando ha existido exposición a grandes cantidades de aerosoles que contienen virus de la rabia, en trasplantes de órganos y por arañazos de animales rabiosos. Se han descrito casos en trasplantes de córnea. No se han descrito casos de transmisión digestiva, transplacentaria, ni mediada por artrópodos.

La OMS ha establecido tres categorías en función del grado de exposición (tabla 1). Se ha sugerido una cuarta categoría que incluye a aquellos pacientes que han sufrido mordeduras graves en la cara, la cabeza, los brazos y las manos, casos en los que puede ser inadecuado el volumen de inmunoglobulina recomendado.

El objetivo de la infiltración de la herida con inmunoglobulina es neutralizar el virus antes de que penetre en las terminaciones nerviosas periféricas y estimular la respuesta de linfocitos T

Tratamiento local de la herida

La herida debe lavarse inmediatamente con agua y una solución jabonosa al 20% para evitar contraer la rabia. En la actualidad no se aconseja el uso de ácido nítrico o los derivados de amonio cuaternario, porque su efectividad es inferior a la solución de jabón al 20%.

La sutura primaria de la herida sin infiltración previa de inmunoglobulina puede provocar la entrada del virus en las terminaciones nerviosas. Por ello debe evitarse la sutura primaria, y se hará siempre después de la limpieza e infiltración con inmunoglobulina. La sutura secundaria podría hacerse 2 semanas después, cuando el paciente dispone de anticuerpos neutralizantes.

La inmunoglobulina antirrábica está indicada en todos los contactos de la categoría III de la OMS y se inoculará si es posible en las primeras 24 horas. La inmunización siempre debe ir acompañada de una pauta vacunal completa.

Las inmunoglobulinas antirrábicas homólogas aprobadas por la FDA de Estados Unidos se obtienen por fraccionamiento con etanol frío a partir de plasma de donantes hiperinmunizados.

La dosis recomendada por la OMS es de 20 U/kg de peso corporal de inmunoglobulina humana y de 40 U/kg de peso corporal de inmunoglobulina equina. Se administrará la mayor cantidad posible localmente alrededor de la herida, siempre que sea posible. El resto se administrará en la región glútea. El objetivo de la infiltración de la herida con inmunoglobulina es neutralizar el virus antes de que penetre en las terminaciones nerviosas periféricas y estimular la respuesta de linfocitos T.

Cuando el volumen de inmunoglobulina es insuficiente para infiltrar todas las heridas (categoría IV), existen dos posibilidades: administrar la dosis calculada alrededor de heridas más graves o incrementar la dosis. Pero existen evidencias de que un incremento de la dosis suprime la producción de anticuerpos. Por ello se ha considerado adecuado diluir la inmunoglobulina en suero salino hasta disponer de un volumen suficiente para infiltrar todas las heridas.

Tras la administración de inmunoglobulinas de origen humano puede presentarse dolor local y fiebre. La inmunoglobulina heteróloga se ha asociado a edema angioneurótico, síndrome nefrótico y anafilaxia. Las preparaciones de origen equino se asocian con frecuencia a la enfermedad del suero, pero las usadas hoy día son inocuas.

La inmunoglobulina humana, en dosis de 20 U/kg, apenas interfiere en la producción de anticuerpos inducidos por la vacuna de células diploides humanas. Un incremento en la dosis de inmunoglobulina o su asociación con otras pautas vacunales pueden provocar fenómenos de interferencias.

La OMS desaconseja las vacunas de tejido nervioso y no da la recomendación sobre la pauta vacunal que se debe seguir.

El régimen de vacunación postexposición más usado en los países desarrollados incluye la administración por vía intramuscular de 5 dosis de 1 ml de vacuna de células diploides humanas o de vacuna purificada de embrión de pato. La primera dosis puede administrarse después de la exposición, las restantes en los días 3, 7, 14, y 30 posteriores a la primera dosis. Para evitar interferencias, la vacuna no será inoculada con la misma jeringuilla o en la misma localización que la inmunoglobulina. Los lactantes y niños pequeños deben recibir la misma cantidad y dosis vacunales que los adultos. Durante el embarazo la vacuna no está contraindicada. Por su elevada eficacia no se recomienda la comprobación de marcadores posvacunales, excepto en inmunocomprometidos.

Asimismo, si el paciente ha recibido profilaxis preexposición y/o existe constancia de una adecuada respuesta de anticuerpos, el tratamiento postexposición consistirá en la inoculación de dos dosis de refuerzo los días 0 y 3.

Para terminar, decir que la combinación del tratamiento local de la herida, junto con la inmunización pasiva y activa, asegura una protección adecuada contra la rabia.

Estas enfermedades mantienen una prevalencia considerable y ocupa el décimo lugar entre las enfermedades infecciosas mortales.

La labor del farmaceútico es importante en la prevención y el adecuado tratamiento de las her > Lyssavirus. Su consejo y conocimiento farmacológico harán que en cada momento pueda decidir sobre la prioridad o no de administrar inmunoglobulinas, sueros o vacunas, así como las más adecuadas.

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Si a su hijo le muerde un perro

Si a su hijo le muerde un perro, póngase en contacto con el pediatra, sobre todo si no se trata del perro de su familia. Algunas mordeduras de perro deben tratarse en servicios de urgencias. La fuerza de una mordedura de perro puede, de hecho, provocar fracturas o roturas de hueso. Algunas mordeduras de perro pueden parecer de escasa importancia cuando se ven por fuera, pero pueden conllevar lesiones más profundas en músculos, huesos, nervios y tendones.

Aunque se trata de algo sumamente infrecuente, una mordedura de perro puede contagiar la rabia y otros tipos de infecciones bacterianas que trasmiten los perros, de modo que se deben tratar lo antes posible. Asegúrese de preguntarle al pediatra de su hijo si necesita antibióticos para prevenir este tipo de infecciones. No todos los cortes y desgarros provocados por una mordedura de perro se corrigen con puntos de sutura, ya que este tipo de tratamiento puede incrementar el riesgo de infección. El pediatra de su hijo decidirá qué tipo de heridas deben o no deben recibir puntos.

Intente disponer de la información que figura a continuación para ayudar al pediatra de su hijo a determinar el riesgo de infección y el tipo de tratamiento (en caso de que requiera alguno) que necesita: