Epidemic meningitis is an acute infectious disease caused by meningococcus. When healthy children inhale dust with bacteria, the pathogen first invades the respiratory mucosa, showing cold symptoms such as fever, cough and runny nose, which is not easy to distinguish from common colds. Some children are under control during upper respiratory tract infection. If it can't be controlled, bacteria will enter the blood circulation and form bacteremia. At this time, it is characterized by high fever, nausea, vomiting, and petechiae and ecchymosis on the skin, which are mainly distributed in the easily oppressed parts such as shoulders, elbows and buttocks. Pathogens can eventually invade the meninges and develop into meningitis, leading to meningeal irritation and increased intracranial pressure, such as restlessness or lethargy, convulsions, aggravated headache, frequent vomiting and persistent high fever. Babies are characterized by refusing to eat milk, staring at their eyes, screaming loudly, full anterior fontanel and meningeal irritation. Due to adrenal cortical hemorrhage, fulminant epidemic cerebrospinal meningitis may present symptoms of acute adrenal cortical insufficiency, such as severe shock, pallor, cold limbs, undetectable pulse, decreased or undetectable blood pressure, increased heart rate, dull heart sound and coma. If found and treated early, the cure rate of this disease is very high. Generally, most deaths are explosive, and they die of severe shock or cerebral hernia in a short time.
Ordinary children can be completely cured if they are treated properly in the early stage. The symptoms in infancy are often atypical and difficult to diagnose. If the treatment is delayed, even if you survive, it is easy to have sequelae. The common complications of epidemic meningitis are arthritis, subdural effusion or empyema. Sequelae include deafness, blindness, limb paralysis, intellectual and mental changes, hydrocephalus and so on. Comprehensive measures should be taken to prevent meningitis, so as to achieve early detection, early diagnosis, early treatment and early isolation. In the epidemic season (February-April) and regions, we should be alert to the occurrence of meningitis, and never treat it as a cold to avoid delaying the illness. Those who have symptoms of upper respiratory tract infection or close contact with bleeding spots on the skin should be treated according to this disease. In epidemic areas, drug prevention should be carried out for contacts. Compound sulfamethoxazole, 50 mg per kilogram of body weight per day, can be taken orally twice. At present, the group A meningococcal polysaccharide vaccine used in some areas has a certain preventive effect on the disease.
epidemiology
The disease is prevalent or distributed all over the world, with an average annual incidence rate of 2.5/65438+ 10,000, with the highest prevalence rate in Central Africa.
(a) the source of infection is the only source of infection of this disease, and the pathogen exists in the nasopharynx of the carrier or patient. In the epidemic period, the population carrying rate can be as high as 50%. If the population carrying rate exceeds 20%, it indicates that there is a possibility of epidemic. The bacteria-carrying flora in non-epidemic period is mainly group B, and the proportion of group A is high in epidemic period. After getting sick, the carrier is about 10% ~ 20%, and the bacteria can be excreted for several weeks to two years. Those who have been carrying bacteria for more than 3 months are called chronic carriers, mostly drug-resistant strains, which often exist in the deep lymphoid tissue of the carrier's nasopharynx. Carriers are more dangerous to people around them than patients.
(2) Transmission route Pathogens are directly transmitted by air through droplets. Because the viability of pathogenic bacteria in vitro is extremely weak, there is little chance of indirect transmission through daily necessities. Close contact is of great significance to the onset of infants under 2 years old. Whether sporadic or epidemic, the incidence rate increases with the arrival of winter, generally starting from 1 1, reaching the peak in February-April, and respiratory virus infection in May is conducive to the spread of the disease. There are fewer opportunities for indirect dissemination of daily necessities.
(3) The susceptibility of the population to this disease is rare among newborns. Infants after 2-3 months have this disease, and infants aged 6 months -2 years have the highest incidence rate, and then gradually decline. Newborns are born with bactericidal antibodies from their mothers, so they seldom get sick. The antibody level dropped to the lowest point at 6 ~ 24 months, and then gradually increased, reaching the adult level around the age of 20. The susceptibility of the population is closely related to the antibody level. Due to the different immunity of different age groups, the incidence rate in different regions is also different. The incidence in big cities is scattered, and the incidence under 2 years old is the highest; In small and medium-sized cities, the highest age is 2 ~ 4 years old or 5 ~ 9 years old; In remote mountainous areas, once there is an infectious source involved, it often leads to an outbreak, and people over the age of 15 can account for more than half of the total incidence. The incidence of male and female is roughly the same. There is an epidemic peak every 10 year on average, which is due to the decline of population immunity after a certain period of time and the gradual accumulation and increase of new susceptible population. In recent years, two main epidemiological problems are the change of flora and the increase of sulfa-resistant strains.
clinical picture
The condition of epidemic cerebrospinal meningitis is complex and changeable, with different severity. There are generally three clinical manifestations, namely, common type, fulminant type and chronic septicemia type. The incubation period is 1 ~ 7 days, usually 2 ~ 3 days.
(1) Common type accounts for about 90% of all patients. According to its development process, it can be divided into three stages: upper respiratory tract infection stage, sepsis stage and meningitis stage. But there is no obvious boundary between clinical stages.
1. The infection period of upper respiratory tract is about 1 ~ 2 days. Most patients have no symptoms, and some patients have symptoms such as sore throat, hyperemia of nasopharyngeal mucosa and increased secretion. Pathogens can be found in nasopharyngeal swab culture, which is generally difficult to diagnose.
2. Septic patients will suddenly have high fever, chills and chills, accompanied by symptoms of poisoning such as headache, loss of appetite and apathy. The child has crying, noise, irritability, skin allergy and convulsions. A few patients have joint pain or arthritis. 70% patients have petechiae (or ecchymosis) on their skin and mucosa, and the size is about 1 ~ 2 mm to 1cm. In severe cases, petechiae and ecchymosis can expand rapidly, and a large area of skin necrosis appears in the center due to thrombosis. About 10% patients can see herpes simplex around their lips, which mostly occurs about two days after illness. A few patients have splenomegaly. Most patients developed meningitis within 1 ~ 2 days.
3. Meningitis patients have persistent high fever and toxemia, and there are still petechiae and ecchymosis all over the body, but the symptoms of the central nervous system are aggravated. Due to the increase of intracranial pressure, patients have a splitting headache, frequent vomiting, high blood pressure and slow pulse, and often have skin allergies, fear of light, mania, convulsions and other symptoms. 1 ~ 2 days later, the patient went into delirium coma and may have respiratory or circulatory failure.
Infantile epilepsy is mostly atypical. In addition to high fever, refusal to eat, irritability and crying, convulsions, diarrhea and cough are more common than adults, but meningeal irritation is not necessary, and most patients with anterior fontanel are prominent, which is very helpful for diagnosis. But sometimes due to frequent vomiting and dehydration, anterior fontanel subsidence may occur.
(2) A small number of fulminant patients have sudden onset and dangerous condition. If not rescued in time, they often die within 24 hours.
1. fulminant septicemia is common in children, but adult cases are not uncommon. Began to have a high fever, headache, vomiting, severe poisoning symptoms, and extreme depression. There may be different degrees of disturbance of consciousness and convulsions. Within 12 hours, extensive ecchymosis and ecchymosis often appear all over the body, which quickly expand and merge into large ecchymosis with subcutaneous necrosis. Circulation failure is the main manifestation of this type, with pale face, cold limbs, cyanosis of lips and fingers, rapid pulse, obvious drop in blood pressure and low pulse pressure. Many patients' blood pressure can drop to zero, and their urine output is reduced or there is no urine. Meningeal irritation was absent, cerebrospinal fluid was clear, and only the number of cells increased slightly. Blood and petechiae cultures are mostly positive, and laboratory examination can confirm the existence of DIC. Thrombocytopenia and white blood cell count below1000 /mm3 usually indicate poor prognosis.
2. Fulminant meningoencephalitis is also common in children. The clinical symptoms of brain parenchymal damage are obvious. The patient quickly went into a coma, twitched frequently, and often showed positive push-body bundle sign, unequal bilateral reflexes, continuous increase in blood pressure and edema of fundus papillae. Some patients have brain hernia. The tentorial hiatus hernia is caused by the temporal lobe gyrus or hippocampus hernia hooking into the tentorial fissure, which can compress the diencephalon and oculomotor nerve, resulting in ipsilateral pupil dilation, light reaction disappearing, eyeball fixation or abduction, paraplegia of the contralateral limb, and then respiratory failure. When the foramen magnum hernia occurs, the cerebellar tonsil hernia enters the foramen magnum and compresses the medulla oblongata. At this time, the patient's coma is deepened, the pupil is obviously narrowed or enlarged, or the pupil edge is irregular, the muscle tension of both limbs is increased or stiff, the upper limbs are mostly in the pronation position, the lower limbs are stiff, the breathing is irregular, fast and slow, deep and shallow, or apnea, or sobbing or nodding, which becomes tidal waves. Before respiratory failure, patients may have the following symptoms: ① pale face, frequent vomiting, severe headache and restlessness; (2) Sudden coma, convulsions, and continuous increase in muscle tension; ③ The pupils are unequal in size, obviously narrowed or enlarged, with irregular edges, slow or disappearing response to light and fixed eyeballs; ④ Changes of respiratory rhythm; ⑤ Blood pressure rises.
3. Mixed type has both the above two types of clinical manifestations, and often appears at the same time or successively, which is the most serious type of this disease.
(3) Chronic meningococcal septicemia is rare, and there are more adult patients. The course of this disease often lasts for several months. Patients often have intermittent chills, chills and fever attacks, which are relieved after 12 hours each time, and recur after 1 ~ 4 days. Eczema, macula, knee and wrist pain may occur during the attack. The diagnosis is mainly blood culture in fever period, and it often needs many tests to be positive. The positive rate of differential smear is not high. Sometimes it can develop into purulent meningitis or endocarditis in the course of the disease, which makes the condition deteriorate sharply.
prevent
(a) early detection of patients, on-site isolation treatment.
(2) During the epidemic, do a good job in health promotion and try to avoid large gatherings and collective activities. Don't take children to public places, don't take children to public places, and wear masks when going out.
(3) Drug Prevention Sulfonamides are still used in China. Close contacts can use iodopyrimidine (SD), 2g/ day for adults, with the same amount of sodium bicarbonate taken twice for 3 days; The daily dose for children is 100mg/kg. During the epidemic of epidemic cerebrospinal meningitis, everyone has: ① fever with headache; ② listlessness; ③ Acute pharyngitis; (4) Two of the four items, such as skin and oral mucosal bleeding, can be treated with enough sulfonamides, which can effectively reduce the incidence and prevent the epidemic. Prevention with rifampicin or minocycline abroad. Rifampicin is 600mg daily for 5 days, and the daily dose for children aged 1 ~ 12 is 10mg/kg.
(IV) Vaccine prevention At present, two groups of capsular polysaccharide vaccines, A and C, are widely used at home and abroad. The protection rate of group A polysaccharide vaccine purified by ultracentrifugation was 94.9%, and the average antibody titer increased by 14. 1 fold after immunization. Polysaccharide vaccine is still used as "emergency" prevention in China. In June 5438+0 ~ February, if the incidence of meningitis is more than 10/65438+ 10,000, or the incidence is higher than the same period of last year, vaccination can be carried out in the population.
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