I. Overview

Rabies is a zoonotic disease caused by rabies virus, and it is an infectious disease that specifically attacks the central nervous system. Once the disease 100% dies, the transmission route is between animals and people, between animals, not between people.

Rabies virus, rhabdoviridae, rabies virus. It infects almost all warm-blooded animals and its natural hosts are dogs and wild animals. It mainly damages the central nervous system. After being bitten, people or animals move along nerve fibers to the CNS (central nervous system). See figure 1 for the transmission process. The virus has no resistance to the environment and is sensitive to fatty solvents (soapy water, chloroform, acetone, etc.). ), 70% ethanol, iodine preparation and quaternary ammonium compound. It is also easy to be inactivated by pasteurization, ultraviolet rays, acid (below PH 4) and alkali (above PH 10). But not easily killed by phenol or lysol solution. Related experiments have found that the virus inactivation in infected tissues is usually slow in crude tissue extracts or neutral glycerol, and the infectivity is very stable in frozen or freeze-dried tissue extracts.

Fig. 1: the transmission process of rabies virus in human (animal) body.

Second, the clinical manifestations

Clinical manifestations of animal rabies

(1) dogs (see figure 2 for the infection process)

Precursor stage: depressed, restless, sensitive to sound and light, often hiding in the dark, salivating, scratching his tail; Limb weakness; Abnormal appetite, like to eat foreign bodies; Looking up at the sky and biting, it is worse, sexual desire is hyperactive, and the sexual organs of yourself or other dogs are sniffed; Sick dogs often change their habits. In the early stage of illness, they often escape or avoid, unwilling to get close to others or not listen to the call. The sick dog may come back after missing for a few days, when it loses weight, is covered in mud and may have blood on its fur. The owner is often bitten when he caresses or forcibly pulls to clean.

Excited period (manic period): intense behavior, obvious aggression, trying to break free from the rope to attack people or animals, sometimes running for dozens of kilometers, and may bite people and all kinds of livestock encountered at any time along the way; Some dogs with rabies sometimes become conscious and get to know their owners again. Rage and depression often alternate. The sick dog was very tired and lay motionless, but soon stood up again, showing a particularly squinting and frightened expression. When it is stimulated by the outside world again, it has a new attack. Sick dogs also bite their limbs and tails; Drooling a lot, sometimes the chin won't close; Change voice; Not afraid of water, but addicted to water.

Paralysis stage ("dumb rabies"): With the development of the disease, it quickly enters paralysis stage. At this time, the sick dog's jaw drooped, his tongue blurted out, his salivation was obvious, his hindquarters and limbs were paralyzed and he could not afford to lie down. Finally, he died of respiratory center paralysis or failure.

Fig. 2: The infection process of rabies in dogs.

(2) cattle

Become restless, dig with forelimbs, growl loudly, have paroxysmal excitement and attack actions, such as trying to break free from the rope, hitting the wall, jumping on the feeding trough, and salivating. Sometimes attacks on people and animals occur. When the excitement attacks, it often stops for a short time, then attacks again, and gradually appears paralysis symptoms, such as swallowing paralysis, neck stretching, salivation, breath holding, internal urgency and then heaviness, and finally falls to the ground. He died 3~6 days after onset.

(3) horses

The bitten part is itchy, and often bites or rubs the bitten part at the beginning of the disease, resulting in friction bleeding. Easy to panic, dull eyes, dilated pupils and hypersexuality. When excited and angry, they also attack other animals or people, sometimes biting themselves and eating sawdust and feces. After a brief rampage, he developed progressive paralysis with symptoms similar to tetanus, and finally his hind legs became stiff and he died of incomplete paralysis.

(4) Sheep

Cases are rare. Symptoms are similar to those of cattle, but most of them have no excitement symptoms or short excitement period. Show fidgeting, hypersexuality and attack other animals. Always lick and bite the wound to make it last for a long time. He finally died of paralysis.

5] pigs

It is characterized by excitement, rage, hoarse voice, salivation, repeated digging with nose arch and attacking people and animals. During the intermission, I often get into the mat, jump up at the slightest noise, run aimlessly, and finally have paralysis symptoms. The course of the disease is about 2 ~ 4 days.

[6] cats

Rabies is generally violent, with symptoms similar to those of dogs, but the course of disease is short, and it dies 2-4 days after symptoms appear. Attacking other animals and people during the outbreak of disease.

2. Clinical manifestations of human rabies

The clinical manifestations of human rabies are generally divided into four stages: incubation period, prodromal period, excitement period and coma period:

Incubation period: average about 10~90 days. It has been reported that the incubation period is greater than 1 year, but it is rare. The length of incubation period and onset time may depend on the location and degree of injury. During the incubation period, the infected person has no symptoms.

Precursor period of symptoms: the infected person begins to feel general malaise; Fever, headache, nausea, fatigue and anxiety; The bitten part is red, swollen and painful, and there are ants walking.

Excited period: The patient's symptoms reach the peak, with symptoms such as mental stress, general spasm, hallucination, delirium, fear of light, sound, water and wind, so rabies is also called water phobia, and patients often suffocate due to throat spasm.

Coma: If the patient can survive the excitement, he will enter coma. 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.

Third, epidemiology.

1. spread

The spread of rabies is roughly from wild animals to domestic animals (mainly dogs), and then from domestic animals to humans (see Figure 3).

Figure 3: Rabies transmission circle

? Step 2 distribute

Animal rabies exists in most countries except New Zealand and Brunei. According to statistics, since the discovery of human rabies, 56% of cases have occurred in Asia (90% of which are in rural areas), 44% in Africa (75% of which are in rural areas), and the total number of cases in other regions is less than 500.

The distribution of human rabies in China is mainly concentrated in rural areas south of the Yangtze River (see Figure 4).

Figure 4: Distribution of human rabies in China.

3. Prevalence

① Infected dogs are still the main source of rabies infection in China, accounting for an absolute advantage in human rabies epidemic.

② Dog bites are frequent.

③ Dog rabies is still highly sporadic, but the epidemic situation is still difficult to count.

④ The morbidity and mortality of domestic animals and wild animals increased: pigs, sheep, goats, buffaloes, cows, weasels, badgers and raccoons. Such as 20 13 Xinjiang sheep and Inner Mongolia cattle and sheep epidemic.

⑤ There have been cases of transmission from domestic animals and wild animals to people, such as pig/human transmission in Zhejiang in 2007; Bat/human transmission; Weasel badger/human transmission.

⑥ Infected animals: Rabies in wild animals gradually appeared.

Dogs: Most of them are rural dogs and stray dogs, not pet dogs.

Livestock: pigs, sheep, cows and buffaloes.

Economic animals: sika deer, raccoon dog.

Wild animals: mice, bats, badgers, foxes, wolves, etc.

Fourth, rabies control.

1. feature

Rabies is one of the most easily controlled infectious diseases, because it can't spread through the air, but only through the biting of healthy animals by sick animals, so it is relatively difficult to spread. In addition, its vaccine has excellent effect and can prevent rabies well.

Rabies is one of the most difficult infectious diseases to eradicate, mainly because it infects almost all warm-blooded animals, which makes its host range very wide, so it is very difficult to eradicate it completely.

Rabies is an infectious disease that must be controlled and eliminated by vaccine. Because of the wide range of rabies hosts, uncertain incubation period, short time from onset to death, and the mortality rate after onset is 100%, its vaccine effect is excellent, so vaccination is the simplest and most successful method to control and eliminate rabies.

? 2. Three strategies to eliminate rabies.

(1) Legislation, management and education are the social basis for controlling rabies epidemic.

① Dog license and registration system (including rural areas).

② Control and eliminate stray dogs or wild dogs.

③ Strict immunization measures.

(4) Establish the rabies laboratory detection capacity of the provincial animal disease control center, and carry out the diagnosis, epidemiological investigation and monitoring of animal rabies all the year round.

⑤ Administrative and economic support from the government.

⑥ Technical training: Training rabies prevention and control technicians (provinces, cities, counties and townships).

⑦ Popularize rabies prevention and control knowledge in community and rural education.

Management of stray dogs and cats: culling or sending to a special animal adoption center.

Pet-name ruby birth control of dogs and cats.

⑵ Epidemiological monitoring: it is the premise of controlling rabies epidemic.

① Understand the species, distribution and cross-border flow of natural hosts and virus-carrying hosts in this area. Monitoring the virus carrying status of important hosts and virus strain typing in high-incidence areas.

(2) Establish an animal epidemic monitoring system, and embed the emergency report telephone of animal epidemic and death into the public alarm telephone system to facilitate the acceptance of public reports.

③ Cultivate the public's awareness of paying attention to dead animals, find dead cats, dead dogs and dead wild animals and take the initiative to declare for inspection, so as to improve the sample inspection rate.

④ Village epidemic prevention staff: establish awareness, actively publicize, take the initiative to pay attention and report in time.

⑤ In case of human rabies epidemic, conduct targeted epidemiological investigation immediately.

⑶ Immunity: It is the core of rabies control.

① immunization of rural dogs: attenuated vaccine can be used to curb the epidemic as soon as possible. Oral bait vaccine is urgently needed in rural areas.

② Immunization of urban pets: use inactivated vaccine.

③ Wild animal immunization: oral attenuated or genetically engineered bait vaccine.

④ WHO research shows that 75% dog immunization rate can effectively block the transmission chain of RV.

⑤ Dogs and cats are exempted at the beginning of March, one year old and two years old, and they are immunized once a year.

3. Principles of handling animal rabies

(1) All suspected cases of animal rabies should be culled and diagnosed immediately, and the polluted environment should be disinfected.

(2) If an uninmunized animal is bitten by a suspected sick animal, it shall be culled and destroyed immediately in principle. If it is really impossible to cull and destroy, it should be kept in isolation for 6 months. If it is sick, it can be regarded as a sick animal and killed. If there are no symptoms, they can be regarded as healthy, released from isolation and raised normally.

(3) If the immunized animals are bitten, they should be vaccinated again immediately and observed in isolation for 45 days.

4. Handling principles of dogs that hurt people

(1) All healthy dogs with the appearance of their owners should restrict their activities after biting and observe for 10 days. If there are suspected rabies symptoms during the observation period, they should be reported immediately, executed and sent to a professional laboratory for diagnosis.

2 stray or ownerless canines, wild animals, bats, etc. If you can catch it, you should kill it immediately and send it to a professional laboratory to collect brain tissue for virology detection.

5. Problems in rabies control

(1) Backward concept of keeping dogs:

① Lack of dog responsibility: Many people will choose to donate or abandon dogs after they feel fresh about raising dogs, which leads to a high number of stray dogs, thus increasing the risk of dogs spreading rabies.

(2) Neglect of dog hygiene: In rural areas, dogs are basically scattered, and dogs move freely in villages and fields, which increases the risk of transmission; In addition, many dog owners will keep dogs and livestock together, which is very easy to cause the spread of rabies between dogs and livestock except for feeding.

(2) lack of immunity:

At present, due to the shortage of special funds for epidemic prevention in China, only some provinces and cities have carried out limited dog immunization work, with low immunization coverage and no continuous dog immunization work. The immune level of dogs varies from place to place. Even many provinces, cities and counties without epidemics have no immunity. National average immunization coverage rate

(3) The awareness of epidemic prevention is not strong;

(1) only killing dogs does not pay attention to the supervision and immunity of dogs, and there is a lack of lasting prevention work.

(2) The state has no special funds.

③ The veterinary work is ineffective, the prevention and control of animal rabies is not included in the focus of veterinary epidemic prevention work, professional and technical personnel are lacking, and laboratory testing is rarely carried out.

④ The prevention and control of animal rabies in each province is unbalanced, and there are not many areas where timely sampling and inspection can be standardized.

⑤ People don't know enough, don't report the epidemic situation, and are unwilling to accept animal immunization.

6. Animal carcasses will not be sent for inspection. It is difficult to carry out canine immunization in rural areas.

Five, after the injury treatment measures

1. Wound treatment:

(1) should be treated immediately (it should not exceed 24 hours), even if it exceeds 24 hours, it should be thoroughly cleaned.

(2) Treatment method:

① The bitten wound should be quickly wiped clean with 20% soapy water or 0. 1% fresh clean or washed repeatedly with clean water for about 15 minutes. When the wound is deep, it should be perfused and cleaned.

② Immediately after washing, wipe the inside and outside of the wound with 75% alcohol or iodine for thorough disinfection.

? 2. Vaccination:

(1) immunization program

① Classic immunization program: 1 dose vaccine was injected into deltoid muscle of arm on 0, 3, 7, 14 and 28, and children could also be injected into anterolateral thigh muscle.

② Alternative immunization program: 2- 1- 1 program recommended by WHO. At day 0, both deltoid muscles were injected with 1 dose vaccine at the same time, and at day 7 and 2 1 day, respectively.

③ Economical immunization scheme: WHO recommended intradermal injection, which greatly reduced the dosage of vaccine and the cost of vaccine by 60%-80%. China is evaluating it.

(2) the degree of injury

① General injury: that is, second exposure, and vaccination should be given.

② Percutaneous injury and severe bite: that is, third-degree exposure, we should follow the principle of paying equal attention to cleaning the wound in time, injecting anti-rabies immunoglobulin and vaccinating. Recently, WHO once again recommended that immunoglobulin (RIG) should be applied to any broken skin bite.

③ Immunoglobulin: The total dose should be controlled at 40 IU/kg body weight. The subcutaneous muscles around the wound should be injected with more infiltration to neutralize rabies virus. After treatment, the wound should not be bandaged and sutured, and should be exposed as much as possible. At the same time, the vaccine was injected five times according to the above procedures.