Rabies, also known as rabies, is an acute viral infectious disease that invades the central nervous system. All warm-blooded animals, including humans, may be infected. It is mostly obtained through the bite of infected animals. It is generally believed that a mad dog with white foam on its mouth is contagious. In fact, cats, ferrets, raccoons, skunks, foxes or bats may also get sick and infected. Sick animals often become very savage, and the virus in saliva enters the next patient from the bitten wound.
It is extremely rare for rabies to spread from one person to another. Most human rabies patients will get sick and die. 197 1 year, cured cases 1 case. In 2004, after an undiagnosed rabies patient died in the United States, three donors died of rabies.
Pathogen: The pathogen causing rabies is RabiesVirus, which belongs to Rhabdoviridae. The complete rabies virus is bullet-shaped, with a length of about 200 nanometers and a diameter of about 70 nanometers. The whole virus consists of the outermost lipid bilayer outer membrane, structural protein shell and RNA molecules loaded with genetic information. At present, it is generally believed that rabies virus has four different serotypes. Rabies virus is very weak, and it will die quickly in the environment of surfactant, formaldehyde, mercury chloride and acid and alkali, and it is sensitive to heat and ultraviolet rays.
Clinical Stages and Manifestations: The clinical manifestations of rabies can be divided into four stages.
1, incubation period: (the average is about 4-6 weeks, and the shortest can reach 10 days -8 months). The incubation period varies from a few days to several years according to the individual's physique, and the infected person has no symptoms during the incubation period.
2, prodromal stage: the infected person began to have symptoms such as general malaise, fever, fatigue, anxiety, pain in the bitten part, abnormal sensation and so on.
3. Excited period: People: The patient's symptoms reach a peak, and symptoms such as mental tension, general spasm, hallucination, delirium, fear of light, sound, water and wind appear. Therefore, rabies is also called hydrophobia, and patients often suffocate because of throat spasm.
4. Coma period: If the patient can survive the excitement period, he will enter the coma period. During this period, patients are in a deep coma, but the symptoms of rabies are no longer obvious, and most patients who enter this period will eventually fail and die.
Pathology: rabies virus first infects muscle cells, passes through the incubation period in muscle cells, then enters nerve cells through acetylcholine receptors between muscle cells and nerve cells, and then enters the spinal cord along the same path, and enters the brain without delaying blood diffusion. The virus infects the hippocampus, cerebellum, brain stem and even the whole central nervous system in the brain, and replicates in a large number in the gray matter, reaching salivary gland, cornea, nasal mucosa, lung, skin and other parts along the nerve. The damage of rabies virus to the host mainly comes from the endosome, that is, the eosinophilic particles formed by the aggregation of its discarded protein shell in cells. Endosomes are widely distributed in patients' central nerve cells, which is also a laboratory diagnostic index of the disease.
Diagnosis: The diagnosis of rabies can be made by clinical symptoms or laboratory examination.
1, clinical diagnosis: mainly based on the above clinical symptoms.
2, laboratory diagnosis:
Examine the matrix in brain tissue;
The antibody was detected by fluorescence immunoassay.
Secretion animal inoculation experiment;
Serological antibody examination;
Detection of viral RNA by reverse transcription polymerase chain reaction.
Prevention and treatment:
1 to control the spread among wild animals;
2. Feeding bait containing oral rabies vaccine;
3. Control the spread between pets;
4. Compulsory rabies vaccination for pets;
5. Preventive immunization of susceptible population;
6. Vaccinate people who are easily exposed to rabies virus with rabies vaccine.
Preventive treatment after exposure: rinse thoroughly with 3%-5% soapy water or 0. 1% bromogeramine or clean water. When cleaning the deep wound, use a syringe to pierce the deep wound for perfusion cleaning, so as to be comprehensive and thorough. Disinfect with 75% ethanol, and then wipe with concentrated iodine tincture. The sooner local wounds are treated, the better. Even if the delay is 1-2 days or even 3-4 days, local treatment cannot be ignored. At this time, if the wound has scabbed, it should be removed as mentioned above. Vaccinate rabies vaccine and inject rabies virus immune serum near the wound.
The treatment of serum began at 1899, and the effective treatment time was within 24 hours after being bitten.
The preparation methods of rabies vaccine include animal brain tissue culture and human diploid cell vaccine (HDCV). The vaccine produced by animal brain tissue has strong immune response and may cause encephalitis.
Symptoms of dogs
Rabies, also known as mad dog disease, is hydrophobia. It is a direct contact infectious disease between people and all warm-blooded animals (people, dogs, cats, etc.) caused by rabies virus. ). Once a person is bitten by a dog containing rabies virus, the mortality rate is 100%. Therefore, dogs as pets must pay attention to rabies immunity. The clinical manifestations of dogs suffering from rabies are extreme excitement, mania, salivation, loss of consciousness, and finally they die of paralysis.
Symptoms: the incubation period of the disease varies, usually 15 days, and the elderly can reach several months or more than a year ago. The incubation period is related to the virulence and location of infection.
There are two kinds of clinical manifestations: one is violent and the other is paralytic.
Violent type: divided into three stages, precursor stage, excitement stage and paralysis stage.
In the prodromal stage, depression, photophobia and darkness, slow response, unwillingness to listen to the master's call, unwillingness to contact with people, abnormal appetite, preference for biting foreign bodies, difficulty swallowing, difficulty stretching the neck, increased saliva, weakness in posterior driving and dilated pupils. The duration of this period is generally 1-2 days. After the prodromal stage, it enters the excited stage, which is characterized by intense anxiety, active attack on people and other animals, confusion and laryngeal muscle paralysis. After going on the rampage, you look depressed, tired and inactive. After a little recovery, you can stand up crazily, squint and bite your limbs and hindquarters with a little external stimulation. As soon as he left the house, the dog refused to recognize his home and wandered around, with hoarse voice, jaw paralysis and salivation. This kind of sick dog is very harmful to people and other livestock. Once found, it shall immediately notify the relevant departments to implement it.
Paralysis period: paralysis symptoms are the main symptoms, including general muscle paralysis, difficulty in standing, inability to lie flat, convulsions, drooping tongue, salivation, and finally death due to paralysis or failure of respiratory center.
Prevention: Rabies can be prevented by inoculating inactivated or improved rabies live vaccine. The immunization program is the first immunization for dogs vaccinated with live vaccine at the age of 3-4 months, and then every 2-3 years. Dogs aged 3-4 months are immunized with inactivated vaccine for the first time, and the second immunization is carried out 3-4 weeks after the first immunization, and every other year after the second immunization.
Rabies is very harmful to people. Once people are bitten by rabies, if they are not vaccinated within 24 hours, once rabies symptoms appear, the mortality rate is10o%. Therefore, animal owners must regularly vaccinate other animals according to immunization procedures to prevent being bitten by dogs. For domestic large dogs, they must be kept in captivity and chained to prevent others from being bitten by free-range dogs. Once a person is bitten by an unknown dog, he should immediately go to the epidemic prevention department for emergency immunization. Control measures should be taken immediately after the discovery of ownerless dogs and wild dogs.
Treatment: At present, there is no medicine to treat this disease.
Rabies knowledge question and answer
1. What is rabies?
Rabies, also known as rabies, is an acute infectious disease caused by rabies virus, which mainly invades the central nervous system of people and animals.
Second, what is the drug resistance of rabies virus?
Generally speaking, the resistance of mad virus is not strong, and sunlight, ultraviolet rays and ultrasonic waves can destroy it. Strong alkali, strong acid, potassium permanganate and iodine can all make it die, and it will die quickly in 1% formalin or 70% alcohol. After drying, it gradually loses its appeal.
Sensitive to temperature, the virus can be completely killed at 56℃ for one hour, at 60℃ 10- 15 minutes, and at 100℃ for only 2 minutes. But low temperature is a good living condition for viruses. The virus in brain block can be preserved for several months at 4℃, and its infectious characteristics can still be maintained for several years at -70℃. .
3. How many kinds of rabies virus are there?
There are two types of rabies virus:
1. Rabies virus isolated from patients and sick animals has the characteristics of neurotropic and salivary glands, which can make people or animals suffer from rabies. Its symptoms are mainly madness, which is called manic rabies.
2. Rabies virus isolated from bats in Central and South America can cause rabies after infecting people and animals. But its symptoms are mainly paralysis. It is called paralytic rabies. This virus is characterized by both neuroticism and visceral, and its invasion is relatively weak. But it can be spread by air, and the formation of endosomes in the brain is atypical.
4. What are the sources of rabies infection?
Rabies infection comes from two sources.
1. Animals and people suffering from rabies
All warm-blooded animals can be infected with rabies, but the sensitivity is different, and mammals are the most sensitive. In nature, rabies has been found in domestic dogs, wild dogs, cats, wolves, foxes, jackals, badgers, pigs, cows, sheep, horses, camels, bears, deer, elephants, rabbits, squirrels, weasels, bats and other animals. Birds are not sensitive. Rabies can also occur in chickens, ducks, geese and peacocks. However, the disease develops slowly and is usually paralyzed. Ducks are very resistant to rabies virus, only 29% can have neurological symptoms, and many can survive. All cold-blooded animals such as fish, frogs and turtles can resist rabies virus infection.
In people with rabies, the virus can be isolated from their saliva. Although there are few cases of human-to-human transmission, it should be noted that infection through corneal transplantation can also occur.
2. "Healthy" dogs and animals carrying rabies virus
Some animals are bitten by mad dogs, but they have no symptoms and will not die. It's just that there is a lot of rabies virus in saliva, and people who bite people will get seriously ill and die. And this "healthy" animal is still alive. This kind of recessive virus-carrying animals accounts for 15.2%, the virus-carrying rate of domestic animals is not high, and puppies are the most dangerous source of infection among dogs. Because these are often overlooked, they are worse than typical mad dogs. The greatest harm should be highly valued.
5. Why are dogs the main source of rabies?
Because there is a habit of keeping dogs all over the world, dogs have the closest contact with people among animals. In addition, dogs are mobile and have the characteristics of biting behavior, so dogs have become the main link of rabies epidemic. According to statistics, the proportion of people bitten by various animals suffering from rabies is: 80.07% by dogs, 9.25% by cats, 0.64% by wolves, 0.03% by foxes and 0.64% by farm animals. Dogs account for the highest proportion, so dogs are the main source of infection.
What are the modes of transmission of rabies?
Rabies has the following three modes of transmission:
1. Infected by being bitten or scratched by dogs or other animals or licking mucous membranes. Rabies virus invades nerves through wounds and mucous membranes. This is the main mode of infection.
2. Inadvertently stabbing hand infection during slaughter or peeling. According to statistics, among 86 cases of rabies, 78 people were bitten and 8 people were infected by slaughtering dogs.
3. Infection through the digestive tract. Animals that died of rabies were buried underground, frozen in winter, pulled out by wild dogs or other animals, ate meat and became infected with rabies.
Seven, suffering from rabies dogs or pigs and other livestock meat, processed into mature meat. Will it be infected if you eat it?
The meat of an animal suffering from rabies will not get rabies even if it is cooked, because the rabies virus has died after boiling at 100℃ and is not contagious. However, animals suffering from rabies are prohibited from slaughtering, skinning and eating meat. In order to prevent peeling or knife cutting from stabbing hands or infecting chapped hands, it is very easy to get infected by touching the blood and saliva of sick animals.
8. Who are susceptible to rabies?
People are generally susceptible to rabies, but different people have different infection rates. There are more men than women, and there are more people below 14, accounting for about 52% of the total number. In the population below 14, the ratio of male to female is 2.37: 1. The reason why men are higher than women is that men are generally considered to be more active and have more opportunities to go out and be bitten. Children aged 5- 14, especially boys, are active, love to play with dogs, tease dogs and pick fights, so they are easy to be bitten. This age is also called "onset age" and is prone to rabies.
After being bitten by mad dogs and animals, what factors are related to the onset?
The incidence of being bitten by mad dogs or other animals is related to the following six factors:
1. It is related to the bitten part. In the epidemic situation of children bitten by 1- 14 years old, the incidence of bite sites was: head accounted for 25.6%, upper limbs accounted for 29.7%, trunk accounted for 2. 1%, lower limbs accounted for 27.8%, and multiple bites accounted for 14.8%. The incidence of head and limbs is the highest.
2. It is related to the order of being bitten. People who are bitten first are more likely to get sick than those who are bitten later, which may be related to the amount of virus infected. For example, a rabid dog bit 12 people in a certain place, and three of them who were bitten first died of illness.
3. It is related to the depth and number of wounds. The incidence of deep wounds, large wounds and a large number of wounds is high.
It has something to do with whether you have clothes or not. The incidence of wearing clothes is the highest; Compared with wearing cotton-padded clothes in winter, the incidence of wearing single clothes in summer is higher. This is because the infected teeth and saliva enter the narrowed edge of the wound after being wiped by clothes.
5. It is related to whether the wound is treated in time. The incidence of wounds treated in time is significantly lower than that of untreated wounds.
6. Related to vaccination. Timely injection of rabies vaccine on the day of being bitten has the lowest incidence.
X. What factors are related to the prevalence of rabies?
The prevalence of rabies is mainly related to the following three factors.
1, the incidence of human rabies is mainly related to the surrounding dog environment. Because dogs are the main source of rabies infection, if there are more dogs and the density of dogs increases, it is very easy to cause the epidemic of infectious diseases among dogs, which directly poses a great threat to people and increases the possibility of epidemic.
2. It is related to region and season. In the southern region with warmer climate, rabies epidemic can occur all year round. In the cold area of the north, although rabies occurs all year round, the incidence rate is higher in warmer seasons because of less clothing. In the cold season, dogs don't want to go out and people wear cotton-padded clothes, so the incidence rate drops.
3. It is related to the importance of local government and the preventive measures taken. If the local government vigorously kills wild dogs, or takes measures to restrict the raising of dogs, the density of dogs can be greatly reduced and the epidemic of rabies can be reduced. Or stipulate that dogs must be injected with rabies vaccine on time, which can also effectively control the rabies epidemic.
XI。 What is the pathogenesis of rabies?
There are a lot of viruses in the saliva of sick animals. When biting a person, the virus invades the wound and becomes infected, and propagates in the surrounding tissues. To some extent, it is introduced into the central nervous system and brain along the peripheral nerves. The spread speed of the virus is about 3 nanometers per hour. When the virus reached the nerve roots on the dorsal side of the spinal cord, it began to multiply. It invades the joint segment of the spinal cord and spreads to the whole central nervous system within 24 hours. The virus mainly invades neurons in many parts. Recent studies have proved that rabies virus not only spreads to the cardiac nerve, but also spreads to the centrifugal nerve, causing many peripheral nerve tissues to be involved. Among them, olfactory nerve infection is more serious than salivary gland infection. Viruses can also be isolated from dead heart muscle, skeletal muscle, lung, liver, kidney and other internal organs, which may be related to centrifugal transmission. Many organs of patients will be damaged to varying degrees.
Twelve, what is the incubation period? How long is the incubation period of rabies?
After any infectious disease is infected by bacteria or viruses, it takes some time to get sick, which is called incubation period.
The incubation period of rabies fluctuates the most, from 6 days, 12 days to more than 1 year, the shortest 6 days, the longest 10 years, and even very special 30 to 40 years. According to statistics, the incubation period of about 84% and 4% cases is 12-99 days.
Thirteen, what are the symptoms of rabies?
The symptoms of rabies can be divided into: prodromal period. Manic period. Paralysis has three stages.
Precursor stage: At the early stage of onset, children often say that they have nervous system symptoms such as headache, anxiety and fear, and may also have symptoms such as nausea and vomiting. The body temperature is as high as 37.5-38℃. Children's personality or behavior will change, such as depression, depression, anxiety, and some are easy to get angry. The bitten part is red, and there is tingling or numbness around the wound, swelling, accompanied by ants walking and strong itching. The change of wound is an important difference between madness and serious illness, which is very helpful for early diagnosis. In addition, there may be a sense of urgency in the pharynx, anorexia and dysphagia. This time is usually 1-3 days, and sometimes it can be 7 days.
Manic period: also known as exciting period, there may be symptoms unique to rabies, such as hydrophobia, paroxysmal mania, salivation attack, etc. When the patient wants to drink water, it causes severe spasm in the pharynx, difficulty in breathing and great pain. In the future, whenever you see or hear water, or even think of water, it will cause reflex attacks, so it is also called "water phobia". Pharyngeal spasm can also spread to the respiratory muscles, leading to dyspnea. Patients may have cyanosis and dilated pupils. During the intermission, patients are conscious, and with the aggravation of paroxysmal spasm, patients always have manic behavior. Due to the excitement of sympathetic nerve, the patient appeared sweating and salivation, accompanied by vomiting and eating and drinking disorders, and soon appeared dehydration. The body temperature is as high as 39-40℃. This cycle takes 1-3 days.
Paralysis period: after experiencing mania period, the patient turns from mania to quietness, the spasm gradually stops, the reaction is slow, and a small amount of food can be eaten. The average family member often thinks that the condition is improving. In fact, paralysis of the brain and limbs soon appeared, and eventually he died of respiratory and circulatory failure. This period is relatively short, generally 15-20 hours.
Fourteen, how to diagnose and identify rabies?
When prodromal symptoms are not obvious, it is generally difficult to diagnose. Asking if there is a history of bite, or if there is abnormal feeling at the wound, is helpful for diagnosis. If there is a typical fear of water or pharyngeal spasm, it is not difficult to diagnose.
In the diagnosis, it is necessary to distinguish it from other diseases:
(1) Rabies phobia: These patients are often people who have rabies knowledge or have seen rabies patients attack. This kind of person is very afraid of rabies, and the surface pain of the bitten part produces symptoms of mental terror. However, these patients have no low fever, no real throat muscle spasm when encountering water, and no fear of water.
(2) Tetanus: The symptoms are similar, but the incubation period of tetanus is short, 6- 14 days, with a history of trauma. Typical symptoms such as clenching teeth, hunchback and long-term tonic general spasm appear, while rabies is mainly local spasm with short duration.
(3) Meningitis and encephalitis are often confused with precursor symptoms of rabies. However, there is no history of biting, and the mental state appears dull, drowsy, coma and convulsion, which is different from sobriety, panic and anxiety of rabies. In addition, rabies should be distinguished from polio, central nervous system drug poisoning and uremia.
Fifteen, how to prevent rabies?
If you want to get rid of rabies, you should do the following:
(1) Publicity should be strengthened to make every parent, especially children, aware of the dangers of rabies. We should increase our knowledge of rabies prevention. In particular, we should educate children, especially young children, to love them, not to play with dogs, tease dogs, and not to contact dogs. Dogs and small animals that are not crazy and look healthy may carry rabies virus. Children's resistance is weak, and they are easily thrown down by dogs and bite their heads and upper limbs, with the highest incidence and the most dangerous.
(2) Dogs are the main source of rabies infection. If a mad dog is found, it must be resolutely caught, isolated or killed and buried. Dog owners must lock up their dogs according to regulations to prevent infection and injury. And regularly inject veterinary vaccines into dogs.
(3) After being bitten, go to the hospital in time. Because the wound is the portal of virus invasion. After treatment, infection can be prevented directly and the incubation period can be prolonged.
(4) After being bitten or treated, rabies vaccine should be injected in time. Because once it happens, there is no way to treat it. According to the regulations, you should always be vaccinated. This is the most effective way to prevent rabies.