Rabies, commonly known as mad dog disease, is a common infectious disease of human and animal. The pathogen is rabies virus, which can cause acute encephalitis and peripheral nerve inflammation in animals. The infected persons who have not received vaccine immunity will almost certainly die when the neurological symptoms appear. The common cause of death is that the central nervous system (brain spinal cord) is destroyed by the virus, and eventually die of autonomic nervous system damage Organ failure. But as long as timely vaccination, generally can induce the body to produce enough immunity to eliminate the virus.
Among mammals, primates, carnivores, Chiroptera and other animals can become diseases, such as humans, cats, dogs, ferrets, raccoons, skunks, foxes, wolves, bears, bats and horses; rodents (except beavers) are rarely infected, such as squirrels, chipmunks, rabbits, etc., but for the sake of safety, rabies should be injected after being bitten by rodents such as rats Vaccines.
The virus is widely distributed in the cerebrospinal fluid, saliva and body fluid of the patients. Most of the virus is transmitted through bite. Many people or animals who are infected are especially active. They attack without infuriation and show other unusual behaviors. Rabies can also appear in the form of paralysis, making the patient appear silent and introverted. There are also unconfirmed cases that the virus can be transmitted by aerosol through mucous membrane or respiratory tract, and is infected by aerosol containing bat feces when exploring caves with rabies bats. Rabies from one person to another is rare, once appeared in organ transplantation, rarely out of human bite or kiss. In 2004, after the death of a patient who was not diagnosed as rabies in the United States, he donated internal organs, and four people who received donations died of rabies.
The clinical manifestations of rabies can be divided into four stages (average 20-90 days, the shortest 3 days, the longest 19 years ). According to the individual constitution, the incubation period varies from several days to several years. In the incubation period, the infected person has no symptoms and is not infectious.
Prodromal stage (lasting about 1-4 days)
Most patients began to appear general discomfort, fever, fatigue, restlessness, nausea and other symptoms, sensitive to pain, sound, wind, light and other stimuli, throat tightness. More than half of the patients felt numbness, itching, tingling or creeping sensation near the wound because the virus propagated in the wound.
Excitatory phase (spasmodic phase). This period lasts about 1-3 days.) Patients with various symptoms reached the peak, appeared mental tension, general spasm, hallucinations, delirium, fear of light, sound, water and wind, so rabies is also known as hydrophobia, patients often because of throat spasm and suffocation to death. The patient gradually entered into a highly excited state with extremely horrible, irritable and frightened expression, and had a premonition of imminent disaster and imminent death. More rational people, when they feel unable to control their own behavior, can still take the initiative to ask the medical staff to tie themselves up (bind up), and intermittently give orders to their families about the aftermath. The tragic scene of their parting in life and death is appalling. Most of the patients stare at everything around them with startled and despairing eyes. Sometimes they are restless, rushing, shouting and shouting. They are powerful and superhuman. They are very afraid of death. As the vagus nerve nucleus, glossopharyngeal nucleus and hypoglossal nerve nucleus are damaged, the respiratory muscle and swallowing muscle spasm occur, and fear of water, wind, dysphagia, dyspnea and so on.
Hydrophobia is one of the most unique symptoms of rabies (some patients are not typical and may not appear in the early stage). Hydrophobia is very symptomatic and has not been seen in other diseases except rabies hysteria. Drinking water, hearing the sound of running water, seeing water or just mentioning the word "water" can lead to severe spasm of pharyngeal muscles. It is difficult to swallow, so although the patient is extremely thirsty, he does not dare to drink water, even if he drinks, he cannot swallow. Others use a large cotton swab dipped in water and sent to the mouth to help solve the pain of thirst, but they still can't swallow, cough and aggravate pharyngeal muscle spasm. With the development of the course of disease, the symptoms of autonomic nervous dysfunction appeared, sweating profusely, saliva secretion increased, a large number of saliva, especially in children, because of pharyngeal pain and obstruction, more irritable, with both hands to tear their own throat, neck, and spit around.
Due to vocal cord spasm, unclear articulation, hoarseness and even loss of voice, children cry with open mouth, hoarse voice and can not cry out. Some people mistakenly think it is "learning from dog barking". Fear of wind is also a special symptom of rabies patients. Even if it is a breeze: blowing the fan in front of the patient with hand, gently blowing on his face with his mouth, the wind driven by pedestrians passing by or the ventilation caused by opening and closing the doors and windows can stimulate the pharyngeal muscle spasm of patients. Patients hiding in the house, curled up in the dark corner, sound, light, pain and even doctors touch the limbs and other stimuli are particularly sensitive, can stimulate the pharyngeal muscle spasm. Patients are extremely painful, not only unable to eat and drink, but also often accompanied by spasm of auxiliary respiratory muscles, resulting in dyspnea and hypoxia. The main symptoms were sniveling split mouth breathing, facial muscle twitch, face and mouth blue purple, nail bed cyanosis, and may appear limb twitch, and even the whole body showed painful convulsions. The patient's hypoxia is so serious, but it is very difficult to inhale oxygen. Because of restlessness, it is difficult to place and fix oxygen with nasal catheter or nasal plug or even mask.
If it is fixed by force, the oxygen catheter may be pulled off by itself at any time. Even if the oxygen supply catheter does not directly contact the skin and mucosa, small flow of oxygen may stimulate the pharyngeal muscle spasm. In addition, due to autonomic nervous hyperfunction, sweating, salivation, central fever, body temperature as high as 38-40 ℃. Heart rate increased, blood pressure increased, pupil dilation, expression of extreme panic, anxiety, pain, but most of the conscious. Very few patients spit on others, trying to escape from the outdoor, have the behavior of attacking or biting others. With the aggravation of excitement symptoms, there are mental disorders, delirium, auditory hallucinations, hallucinations, howling or murmuring. The patient may die of mixed respiratory failure or circulatory failure mainly due to central respiratory failure.
Coma (paralysis). This period lasts for 6-18 hours.) After the exciting period, the convulsions gradually stop, and the patients seem to gradually become quiet. A few patients have a transient state of mind. They can cooperate with medical treatment, simply answer questions, or barely drink water and eat a little. The disease seems to have improved. This is the so-called "back light reflection" phenomenon. But the reaction quickly weakened to disappear, appeared all kinds of delayed paralysis symptoms, especially limb paralysis. Paralysis of eye, face and masticatory muscles is characterized by strabismus, eye movement disorder, jaw drop, mouth cannot be closed, facial expression numbness, aphasia and hypoesthesia. Abdominal wall, testis, knee tendon and other physiological reflex disappeared, quickly from quiet into coma.
Breathing gradually weakened, slowed, irregular, tidal breathing. The pulse is weak, irregular and even untouchable. The heart sound is low and dull, and the heart rate is disordered. The breathing sounds of both lungs were thick, and a large number of phlegm sounds and roaring phlegm were heard. The blood pressure gradually drops, the skin is wet and cold, the pattern appears, and the finger tip is gray. Pupil dilation, mouth and nose out of brown liquid, quickly died of respiratory, circulatory and systemic failure. This period lasted only 6-18 hours.
Pathology: after rabies virus enters the human body, it first infects muscle cells or skin cells, and passes through the incubation period. Then, it enters nerve cells through acetylcholine receptors between muscle cells, skin cells and nerve cells. It slowly ascends along the axons of nerve cells, reaches the spinal cord, and then enters the brain. It does not spread along the blood. The virus infects the hippocampus, cerebellum, brain stem and even the whole central nervous system in the brain, and replicates in the gray matter, and reaches salivary gland, cornea, nasal mucosa, lung and skin along the peripheral nerve.
The main damage of rabies virus to host comes from Negri bodies, which is the eosinophilic particles formed by the waste protein shell in the cells. The inner base bodies are widely distributed in the central nervous cells of patients, which is also a guide for laboratory diagnosis of rabies virus. The average moving rate of rabies virus in the peripheral nerve tissue is 3 mm / h. It can propagate and spread to the whole central nervous system within one day after it reaches the central nerve tissue (brain spinal cord). Therefore, the farther the wound is from the brain to the spinal cord, the longer the incubation period is, and the more likely the vaccine will take effect in time to effectively prevent rabies attacks.
Methods of prevention:
1. Controlling the spread of wildlife
By feeding bait containing oral rabies vaccine to control the transmission among pets, compulsory vaccination of rabies vaccine for pets, vaccination for susceptible people, vaccination of rabies vaccine for people easily exposed to rabies virus, prophylactic treatment after being bitten by disinfectants, such as hydrogen peroxide, iodine based disinfectant, 0.1% Bromogeramine, or 3% - 5% soapy water, is unavoidable It makes sense to even wash with water. But pay attention not to suck the wound with your mouth, because the tiny damage in the mouth may shorten the distance between rabies virus and brain! When the deep wound was washed, the syringe was inserted into the deep part of the wound for perfusion cleaning, so that it was completely and thoroughly disinfected with 75% ethanol, and then smeared with concentrated iodine tincture. The earlier the local wound treatment is, the better. Even if it is delayed for 1, 2 or even 3 or 4 days, the local treatment should not be ignored. If the wound has scab, the scab should be removed and treated according to the above method. After cleaning the wound, rabies vaccine should be injected; at the same time, rabies virus antiserum can be infiltrated and injected near the wound. However, if antiserum is used, it is necessary to increase the dosage of vaccine to avoid reducing the effect of vaccine by antiserum.
2. Prevention and treatment of modern medicine
Prevention of rabies is the use of rabies vaccine, trying to stimulate the immune system to produce enough antibodies before rabies virus destroys the central nervous system. The rabies vaccine was invented by Louis Pasteur in 1885. He successfully tried it on a 9-year-old child bitten by a rabid wolf. This achievement is known as "the most outstanding item in the scientific record". Rabies vaccine preparation methods include the use of animal brain tissue culture or human diploid cell vaccine (hdcv). The vaccine produced by animal brain tissue is cheap, but the human immune response is large, which may cause encephalitis; and rabies virus antiserum is usually prepared from the blood of infected horses or sheep.
The best time to vaccinate is within 24 hours after being bitten (the faster the better). Generally speaking, rabies vaccine can induce the production of antibody in lymphoid B cells faster than the propagation and destruction of rabies virus. Therefore, even if the virus has invaded, vaccination before the attack is still effective. In order to be cautious, general doctors will use antiviral serum to infiltrate around the wound or inject it to reduce the number of rabies virus in the body as much as possible, and strive for long enough response time for the immune system. If the virus has invaded the central nervous system, it is difficult to save life even after receiving passive immunity, because immune cells rarely enter the central nervous system (caused by the barrier of blood-brain barrier).
Treatment after onset: Milwaukee therapy reports that patients are cured after the onset of the disease. Many cases are generally considered to be "rabies hysteria" rehabilitation due to lack of solid evidence. In other cases, the virus was removed from the body by the immune system, but the central nervous system was seriously damaged. The patient entered a clinical "coma period". Laboratory tests showed that there was no virus in the body, and eventually died of organ failure caused by nerve injury.
It is worth noting that in 2004, an associate professor of Wisconsin Medical School led a medical team to successfully cure a 15-year-old female high school student with rabies, Jeanna Giese She is the first rabies patient in the world with a clear record of not being vaccinated and having a rabies attack, but eventually being cured. Moreover, her nervous system is not seriously damaged. The experimental treatment was named "Milwaukee therapy". The idea of Milwaukee therapy is called "induced coma": it inhibits the activity of the central nervous system, delays the spread of virus between nerve cells, and waits for the immune system to play its own role.
Therefore, sedatives: midazolam, phenobarbital, ketamine and amantadine, inhibitors of virus transmission, and biopterin, which may be lacking after rabies, were used. But there is no vaccine, because the immune system can detect and respond when the virus attacks, but usually the nervous system is damaged before the virus is cleared In addition, although ribavirin was used, it was generally not believed that ribavirin had obvious effect on rabies. It was a bat that transmitted the virus to Jeanna, and some scholars believe that the rabies virus carried by bats is a weak pathogenic mutation, so she is so lucky. In recent years, associate professor Willoughby's method has been tried by some doctors to treat several patients.
