rabies
Synonyms
Anger sickness, hydrophobia, Greek: Lyssa, Latin: Rabies French: La Rage
definition
rabies is a Infectious disease of central nervous system. The pathogen is that to the Rhabdoviruses belonging Rabies virus and becomes more infected from a bite, the virus im saliva excreted animals such as dogs or foxes.
Pathogen
The rabies virus is a virus that Neurons infected and multiplied there (neurotropic virus). He belongs to the group of Rhabdoviruses. Rhabdoviruses have a shell made of protein molecules, a single strand of a copy of the DNA (RNA) and are usually rod-shaped. The virus is widespread among wildlife and domestic animals. Affected animals are: foxes, deer, dogs and cats. But bats, ferrets, badgers, raccoons, skunks and wolves can also be vectors.
transmission
The transmission takes place via the infected saliva or urine animals suffering from rabies, especially with bite and scratch injuries, but also with trusting licking in areas of small skin injuries. The intact skin cannot be penetrated by the virus, but intact mucous membranes such as the oral mucosa can. They are also found in the milk of the sick animals Viruses. Any animal that behaves atypically in an area at risk of rabies is considered to be rabies. The leading symptom of an infected animal is lack of shyness in front of humans in the wild. Veterinarians, foresters, hunters, forest workers, butchers and laboratory staff are particularly at risk.
The very different incubation times are between 10 days and several months. The closer the virus entry point is to the central nervous system, the shorter it is.
Epidemiology
rabies is a very rare infectious disease. The incidence of the disease is around 1: 100,000,000 worldwide. Between 1977 and 1992 there were four deaths from rabies in Germany. The last time a man was diagnosed with rabies was in 2007, who was infected by a dog bite while in Morocco. There are 50,000 rabies deaths annually in India.
There was a transmission of rabies viruses in the summer of 2004 in one Organ transplant in the USA. All organ recipients died as a result of the infection. In 2005, such an incident also occurred in Germany: The organ donor transmitted the virus to the recipient. Three of them died of rabies, the other three survived. The donor had previously been in India.
history
Rabies is one of the longest known infectious diseases. Already around 2300 BC. was known that the disease could be transmitted through a bite. In ancient times, Aristotle and Euripides, a Greek playwright, dealt with the disease, and in Greek mythology, for example, Artemis, the goddess of the hunt, was a rogue or victim of rabies. Augustine of Hippo, Roman philosopher of the Middle Ages, suspected the origin of rabies in the devil. Sirius (Greek: Dog), the main star in the constellation of the Big Dog, got its name from the belief that it spreads the plague. Therefore, in midsummer, when Sirius was particularly close to the sun, dogs suspected of having rabies were tortured and killed. Rabies has long been accompanied by myths, superstitions, and fantasies of people, mainly because it inevitably led to death. The origin of the belief in werewolves is also closely related to the disease, as rabies was transmitted through the bite of wolves and an infected person became “wolf-like”. Rabies was treated with the Hubertus key, which was consecrated to St. Hubertus, the patron saint of hunting. This instrument was a key or nail that was made to glow over charcoal and then used to burn out the bite wound. However, in 1828 the use of the Hubertus key was forbidden by the church. In 1885 the vaccine was made by Louis Pasteur (1822-1895), French medic and bacteriologist. For this he used attenuated Rabies viruses in the Spinal cord from rabbits, the rabbits developed antibodies against the viruses and Pasteur made the first vaccine against rabies from the dried spinal cord.
causes
The virus first multiplies at the point of entry in muscle - and connective tissue, to then along the nerves into the spinal cord and into the brain to get. There they attack the nerve cells and multiply again. This leads to acute inflammation (Encephalitis) and so-called Negri bodies develop, some of which consist of immature viruses. When a certain number of viruses are reached, they spread again along the nerves, causing paralysis of the body and ultimately death. Salivary and lacrimal glands can also be affected, so that the virus can be excreted with their secretions. But only in 30 to 40% of those infected does the disease break out, which then always ends fatally. In the aggressive form, the brain is particularly affected, while the silent form causes inflammation of the spinal cord (Myelitis).
Symptoms
rabies is inflammation of the brain (Encephalitis) with the three most important symptoms (Triad of symptoms) States of excitement, cramps and paralysis.
The disease has three stages:
- Prodromal stage (melancholy stage): This stage varies in length and is characterized by pain in the wound, a non-specific feeling of illness, a slight increase in temperature, a headache, Nausea, depressed mood and personality changes such as nervousness.
- Excitation stage: Pain and disturbing sensations such as tingling (tingling) develop (Paresthesia) in the area of the wound, as well as breathing disorders, high fever, Anxiety, Confusion and mental excitability that increase on the slightest occasion Tantrums leads. In addition, there is an increased flow of saliva and tears, whereby the saliva can no longer be swallowed properly due to the paralysis of the throat muscles and therefore runs out of the mouth. The sight of liquid triggers violent pharyngeal muscle spasms, which can be seen as an aversion to drinking (Hydrophobicity) referred to as. The hydrophobicity and swallowing hindrance prevent the virus from diluting, which increases the virus's toxic effects.
- Paralytic stage: After 1-3 days there is a decrease in excitability and progressive Paralysis of the muscles (motorized) and the senses of touch (sensitive). Death comes from central respiratory paralysis and circulatory failure. At this stage the fatal outcome cannot be stopped.
diagnosis
The Diagnosis of rabies is difficult with initially unspecific symptoms. First of all, the suspicion of rabies results from observing the symptoms and asking the patient about his or her previous history (anamnese).
The DNA of the rabies virus can be found in saliva, cornea of the Eye and Cerebral fluid (Cerebrospinal fluid) by means of the polymerase chain reaction (PCR), a method of reproducing the DNA, be detected. Pathogen and antibody detection can only be used to a limited extent, however, since negative pathogen detection does not exclude rabies and antibodies are only detectable in blood and liquor after a delay of about 7 to 10 days. After death, the aforementioned Negri bodies can be found in the tissue of the brain.
therapy
There is no specific therapy, only the symptoms can be treated (symptomatic therapy). The bite wound must first be rinsed extensively with water and cleaned with soap. It is then disinfected as usual and must be kept open. Tissue may need to be surgically removed from the wound (Excision). Furthermore, intensive medical measures can help the patient in the end-stage of the disease. To do this, he is admitted to the intensive care unit, where the vital signs are monitored, the patient is made calm and sleepy with medication and finally ventilated.
If there is justified suspicion of rabies, a simultaneous vaccination must be carried out immediately, which means that the patient receives rabies antibodies (passive vaccination) and the rabies vaccine (active vaccination) at the same time. Around half of the rabies antibodies should be injected around the wound so that the viruses remaining in the tissue are directly neutralized. The vaccination is only effective during the early stage, the prodromal stage. In addition, the tetanus protection must be checked.
It is also possible after contact with the pathogen to take a measure to protect the body and thus to escape the outbreak of the disease. For detailed information, read our article: Post exposure prophylaxis - the salvation?
Note:
The suspicion, the illness and the death from rabies are notifiable and must be reported to the health department within 24 hours!
prophylaxis
People at high risk are vaccinated against rabies. Of the HDC- vaccine (Human diploid cell) contains inactivated rabies viruses that can no longer trigger the disease. The viruses are grown in human cells or in chicken cells. After the injection, the body then makes antibodies against the virus. This active vaccination is relatively painless and is given into the arm in multiple doses a few days or a week apart. The exact vaccination schedule depends on the preparation and is specified by the manufacturer. This usually includes 3 doses on days 0, 7, 21 or 28. The vaccination must be repeated after one year and then every 3-5 years.
-> See also: Vaccinations for adults
Prognosis / rehabilitation
Only at 30 to 40% of the infected, the disease breaks out, which, if left untreated, is fatal. Most often death occurs through respiratory failure. However, if the simultaneous vaccination is carried out on time and in accordance with the regulations, the likelihood of contracting rabies is very low.
Summary
The rabies is a life-threatening infectious disease caused by viruses that usually occurs through contact with saliva or by the bite transmitted from an infected animal. Without treatment, the onset of the disease always results in death. The cause of death is usually the Respiratory arrest due to paralysis of the Respiratory muscles. The closer the virus entry point to the central nervous system (CNS) is located, the faster the disease breaks out. The virus attacks the central nervous system and thus causes paralysis, cramps, and abnormal sensations in the skin, but also states of anxiety, confusion and the tendency to quickly develop tantrums. Simultaneous vaccination with rabies vaccine and rabies antibodies can prevent the onset of the disease after infection if done in time.
