People who eat beef and bovine spinal cord contaminated by mad cow disease may be infected with fatal Creutzfeldt-Jakob disease (referred to as Creutzfeldt-Jakob disease), and its typical clinical symptoms are dementia or insanity, blurred vision, balance disorder and muscle contraction. The patient finally died of insanity.
The pathogenesis of Creutzfeldt-Jakob disease has been inconclusive in the medical field, and no effective treatment has been found.
The disease first occurred after the natives of an island ate the internal organs of the deceased. Because the aborigines on the island have the custom of eating the viscera of the dead, diseases are high. Later, because European and American countries have fed beef cattle with "bovine bone meal", cattle have the same symptoms and lead to large-scale spread, so Creutzfeldt-Jakob disease is called "mad cow disease". Its pathogens are called prions and prions, and prions are a small group of protein. The process of replication in normal cells using protein with the same amino acid sequence is not clear. It is a biological form different from bacteria and viruses. It has no DNA or RNA to replicate, and there is no targeted treatment at present. Because of its simple structure, prions replicate and spread faster than bacteria and viruses.
Discovery of prion
As early as 300 years ago, people have noticed the "itching disease" of sheep and goats. Its symptoms are: loss of coordination, instability, irritability, itching, and even paralysis and death. In 1960s, British biologist Alpine destroyed DNA and RNA by radiation, but its tissues were still infectious. Therefore, it is considered that the pathogenic factor of scrapie is not nucleic acid, but protein. Because this inference did not conform to the general understanding at that time and lacked strong experimental support, it was not recognized and even regarded as heresy. 1947 found mink encephalomalacia with symptoms similar to "sheep scratching injury". Later, chronic wasting diseases (atrophy) of red deer and deer and spongiform encephalopathy of cats were discovered one after another. The most shocking thing is that 1996 spring "mad cow disease" caused unprecedented panic in Britain and even the whole world, and even triggered political and economic turmoil. For a time, people "talk about the color change of cattle."
1997, the Nobel Prize in Physiology and Medicine was awarded to American biochemist Stanley? Stanley Prusiner, because he discovered a new organism-Peron. "Prion" was first put forward by Prusiner of the University of California. Before that, it had many different names, such as unusual virus, lentivirus, infectious encephalomyelitis and so on. Many years' experimental research shows that it is a group of protein particles with strong resistance to various physical and chemical actions and strong infectivity, with a molecular weight of 27,000 ~ 30,000, which can cause diseases of people and animals.
[Edit this paragraph] There are new discoveries in the study of mad cow disease.
The latest preliminary research report of mad cow disease published by American scientists on June 5438+09 shows that the abnormal protein, which is considered as the cause of mad cow disease, exists not only in the nerve and lymph tissues of cattle, but also in the muscles of cattle.
According to the research results of Dr. stanley prusiner and his colleagues at the University of California, San Francisco, a large number of deformed protein can be collected in animal muscle tissues, at least in mice.
Prusiner won the 1997 Nobel Prize in Medicine for his research on the etiology of mad cow disease. He said that this latest research is only preliminary, and it is not certain whether this deformed protein is naturally formed in animal muscles.
It is also reported that according to the latest research results of Prusiner, the French Food Safety Bureau is going to test the muscle of a cow infected with mad cow disease to see if there is a deformed protein in the muscle tissue of this cow that causes mad cow disease. Researchers have taken samples from cattle and will get the results within a week.
[Edit this paragraph] The death toll from mad cow disease will rise steadily.
A scientist of the British government's advisory committee on spongiform encephalopathy warned that the number of people who died of mad cow disease will increase by about 30% every year, which will eventually lead to thousands of deaths every year. So far, 69 people have died from this epidemic, and another 7 deaths may be related to mad cow disease. Scientists believe that people can be infected by eating beef infected with Creutzfeldt-Jakob disease virus, but this fatal disease can only be diagnosed by examining the victim's brain after death.
[Edit this paragraph] There are three difficulties in handling the crisis of mad cow disease.
Last year, from June 5438 to 10, a new round of mad cow disease crisis broke out in Europe. The EU has spared no effort to introduce a series of measures to try to eliminate people's "cow phobia" and prevent the crisis from developing further. Several months have passed and the crisis has not eased. On the contrary, the cattle industry in the EU is getting deeper and deeper in the crisis, and consumers are even more afraid to care about beef. The meeting of EU agriculture ministers recently concluded that the economic and social pressure of the mad cow disease crisis on the EU has reached a "state of emergency".
At present, the European Union faces three major problems in the contest with mad cow disease. First of all, "bullfighting" measures are difficult to implement. According to the relevant plan of the European Union, from June 5438+1 October1this year, all cows over 30 months should be tested for mad cow disease, because mad cow disease has an incubation period, and generally only cows over 30 months can be diagnosed with mad cow disease. There are about 7 million two-year-old cows in EU countries, which is a very heavy test. According to the estimation of the European Commission, only 2 million cows can be tested this year. As for the prohibition of animal bone meal as feed, the European Commission also acknowledged the difficulty of its implementation. Some member countries disapprove of this decision, so there is no guarantee that cattle farmers will not continue to use animal bone meal. The European Commission is very dissatisfied with the slow implementation of new measures by member States.
Second, the economic burden is difficult to cope with. In response to the BSE crisis, the EU decided to use1200 million euros to buy slaughtered cattle, subsidize the losses of cattle farmers and detect BSE. However, due to the continuous spread of mad cow disease, the original budget has been unable to cope with the current crisis. Fischle, Commissioner for Agriculture of the European Commission, said that due to the sharp drop in beef consumption in EU countries, serious damage to exports, and more and more cases of mad cow disease, it is necessary to destroy sick cattle and a large number of cattle raised in the same column to restore consumer confidence. He stressed that the EU needs 3 billion euros this year to deal with this crisis. EU Agriculture Ministers129 met in Brussels, but failed to come up with a final plan to solve the economic burden.
Third, social pressure is increasing. When the mad cow disease crisis broke out, the EU and its member states faced multiple social pressures. On the one hand, the growing dissatisfaction of consumers led to the resignation of government ministers in some member countries, forcing the government to take more stringent measures to control mad cow disease; On the other hand, cattle farmers have been hit by the shrinking market and suffered heavy losses. They strongly urge the EU and member governments to protect their interests. In addition, farmers in the EU are on pins and needles at present, fearing that the EU will reduce subsidies to them to cope with the crisis of mad cow disease. On February 2nd, Belgian farmers put pressure on the European Union and the Belgian government to park 1 200 tractors in expressway, Europe, temporarily interrupting the traffic to Germany, Luxemburg and France.
Analysts here believe that the pressure and influence of the mad cow disease crisis on the EU economy and society may be further intensified, and people's fear of mad cow disease will be difficult to eliminate for a while. How the EU responds to the crisis has become the focus of European society.
[Edit this paragraph] Infection and prevention of mad cow disease
The infection process of cattle is usually: feed made of meat and bone marrow infected by the pathogen of mad cow disease is digested and absorbed by the stomach, and then enters the brain through blood, destroying the brain, making it lose its function and become spongy, leading to mad cow disease.
Human infection is usually due to the following factors:
1, eating beef infected with mad cow disease and its products can also lead to infection, especially the meat with the spine removed (generally German beef sausages are made of this meat);
2. Some cosmetics use animal raw materials in addition to plant raw materials, so the cosmetics may also contain mad cow disease virus (the organs or tissues of cattle and sheep used in cosmetics include placenta, amniotic fluid, collagen, brain sugar, etc.);
3. Some scientists believe that the reason why human "mad cow disease" suddenly changed into "Creutzfeldt-Jakob disease" is not because of eating beef infected with mad cow disease, but directly caused by environmental pollution. It is considered that the excessive manganese content in the environment may be the cause of "mad cow disease" and "Creutzfeldt-Jakob disease"
At present, there is no effective treatment for mad cow disease, which can only prevent and control the spread of this virus in livestock. Once cows are found to be infected with mad cow disease, they can only be resolutely slaughtered, burned and buried deep. However, some people think that even if the cattle infected with BSE are incinerated, there is still BSE virus in the ashes. If the ashes are dumped in landfills, the virus may spread.
At present, it is not clear how this toxin spreads in domestic animals and how it is transmitted to humans.
Brief introduction of SARS
Severe acute respiratory syndrome is a kind of atypical pneumonia. After the pathogen of the disease was determined, the World Health Organization (WHO) named it "Severe Acute Respiratory Syndrome" according to the characteristics of the disease. Until the cause is found out, it is called "atypical pneumonia".
Atypical pneumonia refers to pneumonia caused by mycoplasma, chlamydia, Legionella, rickettsia, adenovirus and other unknown microorganisms. Typical pneumonia refers to lobar pneumonia or bronchopneumonia caused by common bacteria such as Streptococcus pneumoniae.
In fact, in the medical field, the name of this infectious disease was controversial in 2003, because it has been found that this disease is actually not the "atypical pneumonia" often mentioned in medicine, but the "infectious coronavirus pneumonia".
For this kind of infectious diseases, people's understanding has gradually deepened and their concepts have gradually become correct. At first, people thought chlamydia virus was the cause of the disease, and it was not until March 2003 that the pathogen was identified as "coronavirus". Doctors in Guangdong, China first used "atypical pneumonia" on June 22nd, 65438. According to its clinical symptoms, such as fever, cough and shadow in the lungs. However, compared with pneumonia caused by Streptococcus pneumoniae and other bacteria, the symptoms are atypical, the pathogen is not completely clear, and it is highly contagious, so the use of antibacterial drugs is ineffective. The World Health Organization also confirmed its drug. At the end of February, Carlo, an Italian infectious disease expert at the World Health Organization? According to the information available at that time, Dr. carlo urbani named it Severe Acute Respiratory Syndrome (SARS for short), and it was officially replaced by the World Health Organization on March 15.
In fact, the name of severe acute respiratory syndrome does not fully reflect the essential characteristics of the disease. It has long been suggested to name it "infectious coronavirus pneumonia" (if so, it can be called "coronary lung" for short). Although this suggestion has not been accepted by the society and medical circles, it is enough to prove that SARS, like SARS, reflects people's understanding of the distinctive characteristics of things at a certain stage.
A cure has been found so far. Scientists from China and the European Union have jointly found 15 compounds which can effectively kill SARS virus, providing a new method for synthesizing SARS therapeutic drugs. On June 9, 2005, Chinese and European scientists announced this achievement at the annual meeting of the project "SARS diagnosis and virus research in China and Europe".
Recent research by the University of Hong Kong shows that bats may be the wild hosts of SARS virus.
Zhou Gang, an expert in computer Chinese character input, proposed in 2003 that "atypical pneumonia" can be called "tuberculosis".
However, it is still suggested to call it SARS in the medical field according to the naming principle of the World Health Organization (WHO). Like WHO, the Hong Kong medical community changed its name to SARS and Chinese mainland at the first time. Because people have always referred to it as "SARS", it is not recommended to change the entry itself.
-
In traditional medicine, atypical pneumonia is relative to typical pneumonia, which is usually caused by common bacteria such as pneumococcus. Typical symptoms, such as fever, chest pain, cough and expectoration. Laboratory tests show that white blood cells increase and antibiotic treatment is effective. Atypical pneumonia itself is not a newly discovered disease, it is mostly caused by viruses, mycoplasma, chlamydia, rickettsia and other pathogens. Symptoms, lung signs and blood test results are not as obvious as SARS infection, and some viral pneumonia antibiotics are ineffective.
SARS refers to a group of diseases caused by the above atypical pathogens, not a definite diagnosis. Its clinical characteristics are that the onset is hidden, mostly dry cough, occasional hemoptysis, and less positive signs of auscultation in the lungs; X-ray chest film mainly shows interstitial infiltration; Its pathogenesis is usually mild, and patients rarely die because of it.
The name of atypical pneumonia originated at the end of 1930, which corresponds to typical pneumonia, mainly lobar pneumonia or bronchopneumonia caused by bacteria. In 1960s, Mycoplasma pneumoniae was considered as the main pathogen of atypical pneumonia, but other pathogens were later discovered, especially Chlamydia pneumoniae. At present, it is believed that the main pathogens of atypical pneumonia are mycoplasma pneumoniae, Chlamydia pneumoniae, Chlamydia psittaci, Legionella and Rickettsia (causing Q fever pneumonia), especially the first two, which account for almost 1/3 of hospitalized adults with community-acquired pneumonia every year. Most of these pathogens are intracellular parasites without cell walls, so broad-spectrum antibiotics (mainly macrolides and tetracyclines) that can penetrate into cells are effective for their treatment, while β -lactams are ineffective. Antibiotics are ineffective for SARS caused by virus.
-
Huang Xingchu, the first SARS patient reported in China (commonly known as "SARS patient" in Chinese mainland), is also the first case in the world.
-
Clinical diagnosis of symptoms and signs of SARS
1. Epidemiological history
1. 1 had close contact with similar patients two weeks before onset or had clear evidence of infecting others.
1.2 lived in epidemic area or SARS epidemic area 2 weeks before onset.
2. Symptoms and signs
Fever (> 38℃), cough, rapid breathing, shortness of breath, or respiratory distress syndrome, lung rales or more than one sign of lung consolidation.
3. Laboratory inspection
Early white blood cell count does not increase or decrease.
4. Lung imaging examination
Patchy and patchy infiltrative shadows or reticular changes in the lung to varying degrees.
5. The effect of antibacterial drugs is not obvious.
Clinical diagnosis of SARS
According to the comprehensive judgment of epidemiological data, symptoms and signs, laboratory examination and pulmonary imaging examination, the clinical diagnosis was made. Once the pathogen is identified and the detection method is specific, the definition of confirmed cases is established.
Suspected cases: 1. 1+2+3 or 1.2+2+3+4.
Clinically diagnosed cases: 1. 1+2+3+4 or 1.2+2+3+4+5.
Diagnostic criteria for severe acute respiratory syndrome cases
SARS cases meet the following criteria, among which 1 can be diagnosed as severe SARS cases:
1. Multi-leaf lesion or X-ray chest film progress within 48 hours >: 50%
2. dyspnea, respiratory frequency >; 30 times/minute;
3. In hypoxemia, when the oxygen uptake is 3-5 liters/minute, Sao 2
4. Shock, ARDS or MODS (multiple organ dysfunction syndrome) occurs.
-
Obviously, because SARS is caused by virus, any antibiotic drugs that are effective for bacteria have no obvious effect on this disease.
Traditional "atypical pneumonia" may be caused by pathogens such as mycoplasma, chlamydia, rickettsia, or rare bacteria, so it may be sensitive to macrolide antibiotics, that is, macrolide antibiotics (erythromycin) can be used as specific drugs.
But if "atypical pneumonia" in the traditional sense is also caused by viruses, antibiotics are also ineffective. At this point, if you use antibiotics, it is actually abusing antibiotics.
-
Prevent atypical pneumonia
-natural ventilation should be preferred in public places, schools and nurseries, and doors and windows should be opened for ventilation as much as possible.
-Ensure the air supply safety of air conditioning system and sufficient fresh air volume. All waste gas should be discharged directly to the outside. When the air conditioner is not used, the return air duct should be closed.
-Disinfect floors, walls, elevators and other surfaces regularly. During disinfection, spray disinfection should be carried out in turn according to the method of first up and then down, first left and then right. During spray disinfection, 0. 1% ~ 0.2% peracetic acid solution or dibromohydantoin solution with effective bromine of 500mg/L ~ 1000mg/L or chlorine-containing disinfectant solution with effective chlorine of 500mg/L ~ 1000mg/L can be sprayed. Dosage: liquid absorption of earth wall 150mg/m2 ~ 300ml/m2, liquid absorption of cement wall, wood wall and lime wall 100 ml/m2. The ground disinfection spraying amount is 200 ml/m2 ~ 300 ml/m2. Spray disinfection should be carried out from the inside out for no less than 60 minutes.
-Articles and appliances that are frequently used or touched should be disinfected regularly. Counter, desk and chair, door handle, faucet, etc. 0.2% ~ 0.5% peracetic acid solution or chlorine-containing disinfectant with effective chlorine of 1000 mg/L ~ 2000 mg/L can be used for spraying or wiping 15 ~ 30 minutes. Tableware can be disinfected with circulating steam for 20min (temperature:100℃); Boiling disinfection 15 ~ 30 minutes; Disinfect cabinets with far infrared rays. The temperature reaches 125℃ for 15 minutes. After disinfection, the temperature should be reduced to below 40℃ before use. Chemical disinfection can be used in units without thermal disinfection or eating utensils that cannot be disinfected by thermal disinfection. For example, soak in chlorine-containing disinfectant with available chlorine content of 250mg/L-500mg/L, dibromohydantoin solution with available bromine content of 250-500mg/L, chlorine dioxide solution of 200mg/L and 0.5% peracetic acid solution for 30 min. Rinse with clean water after disinfection and dry for later use.
-Wash and dry clothes and bedding frequently. You can also use disinfectant washing powder and detergent to wash clothes.
-Toilets, kitchens and living rooms should be cleaned frequently. Sanitary ware can be soaked and wiped with chlorine-containing disinfectant with effective chlorine content of 500mgL for 30 minutes.
Guide to terminal disinfection measures when suspected SARS patients are found;
-For air disinfection and surface disinfection of small houses, use 7 ml 15% peracetic acid solution per cubic meter (that is, use 1 g peracetic acid per cubic meter), put it in porcelain or glassware, heat and evaporate the bottom with alcohol lamp, add appropriate amount of alcohol, seal and fumigate for 2 hours, and then open the doors and windows for ventilation. Pay attention to fire prevention during fumigation and disinfection, and pay attention to the strong corrosiveness of peracetic acid.
-for large houses, 0.3% ~ 0.5% peracetic acid solution or 3% hydrogen peroxide solution should be used after sealing, and aerosol spray disinfection should be carried out according to the amount of 20ml per cubic meter. 1 hour later, you can open the doors and windows for ventilation.
-Stop the regulating system, and soak or wipe the whole gas supply equipment and gas supply pipeline with chlorine-containing disinfectant solution with effective chlorine of 500 ~1000 mg/L. ..
-When disinfecting floors, walls, elevator surfaces, etc. Spray disinfection should be carried out according to the method of first up and then down, first left and then right. Spray disinfection can be carried out with 500mg/L ~ 1000mg/L of 0.3% ~ 0.5% peracetic acid solution or 1000mg/L ~ 2000mg/L of effective chlorine-containing disinfectant solution ... The liquid absorption of the earth wall is150 mg/m2 ~ 300. Spraying disinfectant solution on the above walls should not exceed its liquid absorption. Ground disinfection is sprayed once from outside to inside, and the spraying amount is 200ml/m2 ~ 300ml/m2. After indoor disinfection is completed, repeat spraying from the inside out. The above disinfection treatment should last for not less than 60 minutes.
-If the tableware and contaminated clothes used by the patient cannot be concentrated in the disinfection station for disinfection, they can be boiled or soaked in the epidemic area for disinfection. When soaking for disinfection, the disinfectant must be soaked in the disinfected articles. It can be soaked in 0.5% peracetic acid solution or dibromohydantoin solution or chlorine-containing disinfectant solution with effective chlorine of 250 mg/L ~ 500 mg/L for 30 minutes, and then rinsed with clear water. Articles and wastes with heavy pollution and little economic value should be burned with the consent of patients.
-Disinfect toilets, garbage, sewers, tap water, tank water and domestic sewage when necessary.