Rabies( Hydrophobia) - Causes, symptoms and treatment. MF.

Rabies disease has been known since ancient times, and the first mention of a disease transmitted through the bite of dogs and very resembling the description of rabies, found in cuneiform clay tablets of Ancient Mesopotamia - refer to III BC.Positive changes in the study and control of these diseases since 1885 - when Louis Pasteur developed an antirabic vaccine and, thanks to these vaccinations, many deaths were prevented. A little later than 1892 and 1903( almost immediately), Bebest and Negri described intracellular inclusions in the neurons of those killed by rabies, at about the same time the viral nature of the causative agent was proved by the scientist Remlege.

The causative agent of rabies:

RNA-containing virus, the family Rabdaviridae, the genus Lyssavirus - thanks to this knowledge it is possible to evaluate the characteristics of the causative agent:

• the particles are surrounded by a two-layer lipid membrane with protruding spines - the presence of this layer may protect the pathogen from phagocytosis.

• the presence of glycoprotein G - is responsible for the adsorption and introduction of the virus into the cell - if antibodies are produced to this structure, the virus is neutralized by the body;

• The pronounced inhibition of protein biosynthesis in the cell by the organism of the infected leads to a loss of regeneration capacity, and this plays a role in the formation of the lethal outcome, since almost all the cells of our body have a white structure in their composition;

• The presence of tropicity( selectivity) of the virus to neurons and salivary gland cells - this feature justifies the specificity of symptoms: tropism to the cells of the nervous system, including the central nervous system, affects the hippocampus - the structure responsible for the behavior, and if it is damaged, the person becomes uncontrollablehe wants to bite everyone. And the infection of the salivary glands leads to the fact that the desire to bite becomes deadly to others, even if there is just a muffle( because at the contact points there may be microtrauma).

Sustainability: The virus is not stable in the external environment, the only thing it can do is to survive in the corpses of animals up to 4 months and at low temperatures. The death of the virus causes: boiling for 2 minutes;temperature 60 ° C - for 5 minutes;the effect of UVI, as well as disinfectants, causes an almost instantaneous death of the virus.

Susceptibility to rabies is high for all warm-blooded. Sexual, age and geographical limitations are not present, rabies is common on all continents. Hope to avoid infection after a bite is in those who are vaccinated( especially recently).Autumn-summer seasonality is noted because of the increased frequency of people's contacts with wild animals and stray dogs.

Causes of infection by rabies

The source and reservoir of infection are mostly wild mammals, but may be urban( dogs and other domestic animals).Routes of transmission of rabies are contact, ie only after direct mucosal injury to the skin / mucous membranes.

Try to follow the behavior of animals, namely, strangeness manifests itself in the following: wolves are calm and walk alone among people, and then suddenly attack;Foxes become more affectionate;In dogs( and in other animals) there is abundant salivation and the tail can be pinched. But the "strangeness" of behavior is not a guarantee of rabies.

Symptoms of rabies

The incubation period is from 7 days to a year or more, but more often 30-90 days. This is the time from the introduction of the pathogen to the first symptoms of rabies. The duration of this period will be hanged from several factors: from localization, from depth and from the vastness of the bite, and also from the age of the victim. Especially localization and age - directly predetermines the speed of propagation of the pathogen, and the localization of the bite closer to the head( ie damage in the area of ​​the arms / neck / face), the faster reaches the brain causative agent, precisely because of the short path, and gives specific symptoms. The younger age also speeds up the appearance of symptoms, because in children the rate of excitation is higher than in adults and this helps to move the virus further along the nerve fibers.

During this period, the virus penetrates the site of the bite and there is primary reproduction, then the virus penetrates into the muscle tissue( with strong bites immediately into the muscle tissue), there is a connection with neuromuscular synapses, penetration into nerve fibers and the spread of pathogensto the central nervous system and salivary gland cells and, as soon as the pathogen reaches the CNS structures, a period of clinical manifestations( prodromal or forerunner period, excitation period and paralysis period) occurs.

The prodromal period lasts an average of 1-3 days and one of the first signs is tissue changes at the site of the bite and along the nerve pathways from it, namely, swelling occurs. Redness and itching in the area of ​​the scar / bite site. These manifestations are possible against a background of a small febrile syndrome. There is insomnia, depression and irritability, a sense of fear, anguish, increased sensitivity to auditory and visual irritants, hyperesthesia of the air and a sense of lack of air.

The period of excitation is characterized by the onset of acute encephalitis: attacks of psychomotor agitation, alteration of consciousness, hallucinations, aggression, riot, delusions, muscle spasms, convulsions. During this period, the pathogen reaches the structures of the central nervous system and divergent behavior indicates damage to the hippocampus - this is characterized by attempts by the patient to escape, bite, and attack with fists. It is also worth mentioning the uncontrolled strength that arises in infected people, because it reaches such a scale that patients begin to pull pipes, tear off doors, etc.

Once the causative agent reaches the stem structures and upon reaching the cranial nerves, focal neurological symptoms develop: diplopia, facial paresis, optic neuritis, impaired swallowing - each of these symptoms has its own specific manifestation, depending on which pair of cranial nerves is damaged. For example, the brightest symptom is salivation and foam from the mouth is characteristic for damage to the glossopharyngeal nerve, because there is a violation of the tone of the salivary gland duct and a violation of swallowing. Because of fluid loss through saliva and possible vomiting, patients want to drink, but can not because of hydrophobia( fear of water), in addition to recording aerophobia( fear of air, his breath), there is also a fear of bright light( photophobia) or loud sound(acoustophobia) - all these fears can cause the occurrence of more and more seizures. Attacks are not constant, but are easily provoked and often grow with shortening of the intervals of occurrence and concomitant convulsions( often generalized).

Paralytic stage of the disease: convulsions and excitement stop, and against the background of complete well-being, which is imaginary, death occurs - often due to paralysis of the vasomotor or respiratory center.

All 4 periods can vary very much, but there would not be one outcome - death. The emergence of specific symptoms "includes a life timer" and people live no more than a week.

Diagnosis of rabies

I will say right away that diagnosis is often posthumous, because due to the lightning current and tissue destruction of neurocytes, diagnostics and even treatment are meaningless and are conducted only to prevent the spread of the disease and rescue those who have not yet begun clinical manifestations.

• pH( neutralization reaction) is directed to the determination of specific antibodies against glycoprotein G( description in the subtitle "causative agent"), with the material for the study - corneal prints, the biopsy of the occiput, in unvaccinated patients there is a fourfold increase in antibodies in the study of paired sera. Vaccinated patients show an absolute level of specific antibodies, which are determined not only in peripheral blood, but also in cerebrospinal fluid.

Posthumous methods of diagnosis of rabies( ie only after death):

• PCR( polymerase central reaction) is aimed at detecting RNA virus, taken from brain biopsies.

• Histological method aimed at the detection of Babes-Negri bodies( specific eosinophilic inclusions and their appearance is caused by the difficulty of ripening of virions in the neurocytes) in the smears-prints of the brain.

• The biological method is based on infecting laboratory animals and finding the same Babes-Negri bodies, but already in the brain tissues of dead animals. For laboratory tests, in addition to pieces of brain tissue, still use biopsies of salivary glands and cornea.

Treatment of rabies

There is no specific treatment. The help is based only on eliminating the pathogenesis, ie the treatment is symptomatic: the installation of the nasogastric tube and the conduct of the probe nutrition, also carry out infusion therapy, anticonvulsant and sedative therapy, if necessary, inject muscle relaxants and narcotics, and carry out mechanical ventilation. But such treatment does not allow to avoid a fatal outcome.

Therefore, immediately after the bite of any animal, it is necessary to conduct treatment-and-prophylactic immunization in case the animal is sick.

Prevention of rabies

The main goal of prophylaxis is immunization, which can be prophylactic or preventive:

Prophylactic is carried out for people at risk of infection: veterinarians, foresters, hunters, dogs, slaughterhouse workers, laboratory staff working with rabies virus;

Treatment-and-prophylactic immunization is carried out by contact and bites of people rabid, suspicious of rabies or unknown animals. In this case, there are no contraindications for vaccination, even during pregnancy and feeding it should still be carried out - "the head that has lost his head does not cry".

Principles of prevention: the edges of the wound are not excised and not sutured in the first 3 days, exceptions are only a few cases - extensive wounds, suturing on bleeding vessels, suturing of the wounds of the face. After the initial surgical treatment, an antirabic culture concentrated concentrated purified inactivated dry vaccine( COCAV) is used - it is administered 1 ml each into the deltoid muscle, and children - into the thigh muscle. The course of administration falls on 0, 3, 7, 14, 30 and 90 days in total, instead of the notorious "40 injections in the stomach" in the past, the rate of immunization is only 6 injections.

Antibiotic immunoglobulin heterologous( equine) or homologous( human) neutralizes rabies virus. Enter it with severe multiple bites and dangerous localization. It is administered in the first hours after the bite, but no later than 3 days in order to create passive immunity. Before the immunization, in order to avoid an anaphylactic reaction, the rules for the administration according to Bezredko are used, and the dose of the administered vaccine is determined from the calculation of 40 ME / kg - when the heterologous is administered, and 20 ME / kg - when a homologous immunoglobulin is introduced. To administer the required dose of immunoglobulin, the weight of the victim should be multiplied by 40( 20) IU and divided the resulting number by the activity of the immunoglobulins indicated on the label. The calculated dose is infiltrated around wounds and in the depth of the wound( if the whole dose is impossible to enter for anatomical reasons - the eye area, the auricle, etc., the remaining dose is administered intramuscularly to other places).After application of the vaccine, immunoglobulin is not administered, joint administration is possible in severe cases( oslusination and / or mucosal sting, head area, hands, just multiple bites) and moreover, the immunoglobulin is administered before the vaccine.

The bitten animal is observed for 10 days and, when the first signs of the disease appear, its head is sent to the laboratory for immunofluorescence of the brain biopsy, in order to detect a rabies virus. If, within 10 days of observation, there were no symptoms on the part of the animal, then the person stops the immunization started. If the victim was previously immunized and after less than a year of immunization, only 3 injections of 1 ml per day, 3, 7 days are prescribed. If more than a year has elapsed from immunization, then a full immunization is carried out.

The vaccinated should be aware that treatment with glucocorticoids and immunosuppressants should be suspended, otherwise rabies immunization will be ineffective, alcohol will not be used throughout the immunization period and for 6 months after the end. Eliminate all stressful reactions.

Complications of rabies:

fatal outcome.

Frequently Asked Questions for Rabies

Question: Is the patient dangerous to others?
Answer: yes. The patient with rabies is not only contagious, but also aggressive.

Question: Is immunity remaining after immunization?
Answer: due to absolute mortality, postinfectious immunity has not been studied, but it is known that post-vaccination immunity persists for a year.

Doctor therapist Shabanova IE