malaria
Introduction
Introduction to malaria Malaria is an infectious disease caused by parasitic parasites in the human body. It is infected by bites of malaria or imported from the blood of people with malaria parasites. Different malaria parasites cause vivax malaria, three-day malaria, falciparum malaria and oval malaria. The main manifestations of the disease are periodic regular attacks, body chills, fever, hyperhidrosis, long-term multiple episodes, can cause anemia and splenomegaly, malaria is prevalent in 102 countries and regions, according to World Health Organization (WHO) estimates, There are 2 billion people living in endemic areas, especially in Africa, Southeast Asia and some countries in Central and South America, where the mortality rate of falciparum malaria is extremely high. basic knowledge The proportion of illness: 0.0005% Susceptible people: no special people Mode of transmission: insect-borne blood transmission Complications: pulmonary edema, anemia, coma, hypertension, proteinuria, hematuria
Cause
Malaria cause
Epidemiology
1. Patients with malaria infection and those with malaria parasites.
2, the transmission route malaria vector is Anopheles, mosquito bites the skin as the main route of transmission, a very small number of cases can be caused by the blood of the Plasmodium, the most important thing to spread malaria is Anopheles sinensis, for the plain interval of malaria The main medium of transmission is the transmission of malaria in the mountains to the micro-Anopheles mosquitoes. In the hilly areas, the Anopheles sinensis subspecies is an important medium. In the mountainous areas of Hainan Island, the malaria vector is found to be Anopheles sinensis.
3, people susceptible to malaria are generally susceptible to malaria, although there is a certain immunity after infection, but not persistent, there is no cross-immunity between various types of malaria, after repeated infections, the symptoms can be lighter when re-infected Even asymptomatic, and foreigners from non-endemic areas are often more susceptible to infection and have more severe symptoms.
4. Epidemic characteristics Malaria is mainly prevalent in the tropics and subtropics, followed by temperate zones. This is mainly due to the fact that the disease is closely related to the ecological environment and media factors. The endemic areas are the most widespread, and the falciparum malaria is mainly prevalent in the tropics. Three-day malaria and ovarian malaria are relatively rare. In addition to the mixed epidemic of vivax malaria and falciparum malaria in Yunnan and the two provinces, China is mainly dominated by vivax malaria, and the incidence is more in summer and autumn. It is not subject to seasonal restrictions.
(1) Causes of the disease
Plasmodium is taxonomically belonging to the genus Hematopoi, Plasmodium, Plasmodium, and four parasitic parasites in the human body, causing vivax malaria, falciparum malaria, three-day malaria and oval malaria. Although there are four malaria parasites in China, they are mainly Plasmodium vivax and Plasmodium falciparum. Plasmodium malaria is rare, and Plasmodium ovale is only found. example.
1. Morphology found in red blood cells is an important basis for the identification of malaria and insect species. The parasitic period of erythrocytes in the red blood cells is called the red inner phase. This stage is different with the growth, development and breeding period of the worms. The morphological changes are very large (polymorphism), which can be generally divided into three main developmental stages, namely the trophozoic stage, the schizont stage and the gametophyte stage. When observing the morphology of the malaria parasite by optical microscopy, the thin film should be used for smear. Stained by Wright or Ji's solution, the stained Plasmodium nucleus is purplish red, the cytoplasm is blue, and the malaria pigment is still brown without being affected by dyeing.
1 Trophozoite: The first stage of feeding and growth of Plasmodium in the cell, according to its development, there are early trophozoites and late trophozoites. The cytoplasm of early trophozoites is less slender. The ring shape, the middle is a vacuole, quite like the ring of the ring, the cell nucleus is small, located on one side of the ring, quite like the gem on the ring, so it is also called the signet ring at this time, and the worm body is obviously growing. Large, sometimes protruding pseudopods, the nucleus also increased, the final product of malarial pigments after digestion and decomposition of hemoglobin began to appear in the cytoplasm, and the morphology of infected red blood cells changed again, and different forms of small cells may appear. Point, this time is called late trophozoite (also known as large trophozoites).
2 schizont stage: After the late trophozoites mature, the shape of the worm becomes round, the cytoplasmic vacuoles disappear, the nucleus begins to divide, called the schizont pre- or immature schizonts, and the nucleus of the schizont cytoplasm continues to divide. The cytoplasm is also divided, and the malaria pigment is gradually concentrated. Finally, every small part of the cytoplasm that surrounds a nucleus forms many small individuals called merozoite, a merozoite-containing worm. The body is called a schizont or mature schizon.
3 gametocyte (gametocyte): After the passage of several generations of schistosomiasis in the red blood cells, some merozoites do not undergo splitting after entering the red blood cells, the nucleus increases, the cytoplasm increases, and finally develops into a circle, oval Or crescent-shaped individuals, called gametophytes, have male and female (or size) points, larger worms, dense cytoplasm, malarial pigmentation and large, nuclear dense and biased to one side of the worm body is female gametophyte ( Large gametophyte); loose and located in the center of the worm body is the male gametophyte (small gametophyte), parasitic in the human red blood cells, the four morphogens of the larvae are smaller, the cytoplasm is thin, the malaria pigment is small and small, the nuclear identification is shown in Table 1. .
2. The four malaria parasites whose life history is parasitic in the human body have the same life history process. They need to pass through two generations of asexual reproduction and sexual reproduction. They are divided into three stages: red blood cell phase, red blood cell inner phase and spore proliferation phase. Both need human and Anopheles two hosts, first enter the liver cell development (erythroblastic phase) in the human body, then proliferate in the red blood cells and multiply (intraerythrocytic phase), finally differentiate the gametophyte, complete asexual reproduction , began the initial development of sexual reproduction, sexual reproduction of gametogenesis and spore proliferation in the anopheles (spy growth period), asexual reproduction is completed in the human body, sexual reproduction is completed in the mosquito, so the artificial malaria parasite The intermediate host, the mosquito is its terminal host.
(two) pathogenesis
The pathogenic stage of Plasmodium life history is mainly the intraerythrocytic stage, all clinical signs and symptoms of malaria, including the periodic episodes of typical malaria, secondary anemia and splenomegaly, severe malaria caused by severe malaria, malaria nephropathy, Black urine fever, etc., are caused by the Plasmodium proliferating in the red internal fissure and its pathophysiological changes. Although the extracellular red blood cells have damage to the liver cells, but no obvious clinical symptoms, however, it has an incubation period and recurrence with malaria. Related to, from the whole process of malaria incidence, the sporozoites in the mosquito salivary glands invade the human body and go through a period of incubation before the clinical attack, followed by clinical seizures; if not thoroughly treated, the long or short dive Re-ignition or recurrence occurred in the latent period.
1. The incubation period is caused by the invasion of the malaria parasite into the human body until the onset of malaria, such as the spread of malaria mosquitoes. The incubation period includes the development of the infrared phase and the proliferation of the intracytoplasmic protozoa to a certain amount of time; The method of directly injecting the red endogenous malaria parasite into the human body is only caused by the proliferative period of the red endogenous Plasmodium to a certain amount of time.
2. A typical episode of malaria episodes, reburning and recurrent malaria is three consecutive stages of chills, fever, and sweating. The whole process is about 8 to 10 hours. After the episode, the patient's body temperature returns to normal, and the malaria episodes are red. The intraplasia of Plasmodium falciparum is related to the proliferation cycle, and also has a certain relationship with the number of erythrocytic parasites. The cause of the attack is due to the rupture of erythrocytes by schizonts, merozoites, protozoal metabolites, residues and denaturation. Hemoglobin and red blood cell debris enter the bloodstream together. Some of these substances are engulfed by macrophages, stimulating macrophages to produce endogenous pyrogens, which interact with the malaria parasite metabolites in the hypothalamic thermoregulatory center. The regulation mechanism of the nervous system causes chills and fever. After the blood stimuli are cleared, the body temperature begins to return to normal. The typical interval of the attack coincides with the fission cycle of the Plasmodium red endogenous period. Protozoa produce immunity, or after incomplete treatment, most of the erythrocytic parasites are eliminated, no clinical symptoms, but no clinical symptoms, but In a few weeks or months, in the absence of reinfection, the remaining Plasmodium may evade immunity for some reason (such as antigenic variation) and the general resistance and specific immunity of the body decline, re-breeding Once again, it is called recrudescence. After the onset of malaria, the erythrocytic plaque has been completely eliminated by human immunity or sclerotherapy drugs, but due to the presence of latent sporozoites in the infrared phase of the malaria parasite After the end of dormancy, the merozoites that began to proliferate in the splitting body re-invade the red blood cells and then multiply, which causes the protozoosis to cause malaria, which is called relapse. Because the body has certain immunity during recurrence, Symptoms are generally lighter than initial, and the number of episodes is also small.
3. Anemia and liver spleen
(1) Anemia: After recurrent episodes of malaria, the number of red blood cells decreases rapidly, hemoglobin decreases, causing different degrees of anemia. The anemia of falciparum malaria is more serious, because Plasmodium falciparum invades various red blood cells, the number of reproduction is large, the destruction of red blood cells is more serious, malaria The more episodes, the longer the course of the disease, the heavier the anemia.
(2) Liver and spleen: patients with malaria may have large liver, especially in children with falciparum malaria. Splenomegaly is an early appearance of malaria patients with significant features. The initial splenomegaly begins 3 to 4 days after the onset of seizures. The reason is hyperemia and macrophage proliferation.
(3) malaria nephrotic syndrome: malaria can be complicated by glomerulonephritis acute renal failure or nephrotic syndrome during the attack. It is generally considered to be an immunopathological phenomenon, which is type III allergic reaction. The kidney disease caused by acute malaria is temporary. The reversible lesions can be cured by antimalarial treatment. Some patients with long-term unhealed may have nephrotic syndrome. Malaria nephropathy is more common in patients with falciparum malaria and three-day malaria.
(4) Dangerous malaria: refers to the possibility of finding Plasmodium falciparum in the blood and eliminating other diseases. It has one of the following manifestations: super-pelletiasis (infection rate of Plasmodium falciparum in the peripheral blood>5 %); coma or other conscious disturbances lasting more than 6 hours; severe anemia (hemoglobin <71g/L); jaundice; water, electrolyte or acid-base balance disorders; renal failure (24h urine volume less than 400ml); high fever or other Inclusions, sinister malaria usually occurs during the epidemic period of falciparum malaria, or in a non-immune population, this type of patient begins to have more symptoms than the general case, but after the first or second episode, the condition suddenly becomes severe, the symptoms Intricate, erratic, rapid and sinister disease development, high mortality, more than 80% of the clinical manifestations of sinister malaria are seen in patients with falciparum malaria, classified according to clinical symptoms into brain type, ultra-high heat type, cold type, gastrointestinal type, etc. Most of the brain type malaria.
Prevention
Malaria prevention
1. Control the infection source to improve the epidemic report, cure patients with malaria and patients with malaria parasites.
2. Cut off the transmission route mainly to eliminate Anopheles mosquitoes, prevent bites by Anopheles mosquitoes, remove Anopheles larvae breeding sites and use insecticides, personal protection can be applied with repellents or mosquito nets to avoid being bitten by mosquitoes.
3. Improve the population's disease resistance Malaria vaccination may reduce the incidence and mortality of the disease, but due to the diversity of Plasmodium antigens, it has brought great difficulties to the development of vaccines. Currently, the main development is sporozoite protein and gene. The vaccine has not been available for field use.
Malaria vaccine, AIDS vaccine and tuberculosis vaccine have become the top three vaccines in the world. The "recombinant malaria vaccine" independently developed by China has been approved by the State Drug Administration and the World Health Organization to enter clinical trials.
Chemical drug prevention is a commonly used measure at present. It can be used as appropriate for healthy and foreign populations in high malaria areas. Frequent use of chloroquine, oral 0.3g/time, once/week, in the chloroquine-resistant malaria endemic area, available mefloquine 0.25g / time, once / week, can also use pyrimethamine 25mg / time, or doxycycline 0.2g / time, once / week.
Tafenoquine is an 8-aminoquine antimalarial drug. A randomized, double-blind study of the prevention of falciparum malaria in G6 PD normal and non-pregnant women was performed in Ghana with placebo. Within 13 weeks of administration, the preventive effect of oral administration of 25 mg per week was 32%, that of the 50 mg group was 84%, that of the 100 mg group was 87%, and that of the 200 mg group was 86%. The adverse reactions were few and light, which was considered to be a better malignancy. Malaria prevention medication.
Artesunate, which is currently widely used in clinical case treatment, should not be used as a malaria prevention drug to prevent Plasmodium from becoming resistant to it, thereby shortening its clinical application cycle.
Complication
Malaria complications Complications pulmonary edema anemia coma hypertension protein hematuria
1. The initial symptoms of malaria are similar to those of a cold, with intermittent fever, chills and headaches, and can lead to complications such as pulmonary edema, liver and kidney failure, anemia, and even coma.
2. If left untreated, serious complications such as brain abuse, black fever, and even death may occur.
Black urine fever This is a sudden acute hemolysis in falciparum malaria patients, with a serious complication of hemoglobinuria and hyperthermia. It is more common in cases of falciparum malaria that repeatedly and repeatedly take quinine.
3. Plasmodium malaria can cause serious complications and affect the kidneys, liver, brain, and blood.
High blood pressure, proteinuria, hematuria and edema are the main clinical manifestations of the disease. Four malarias can be complicated by this disease, but it is more common in three-day malaria.
Splenomegaly, large liver, blood cell changes, pseudo acute abdomen, etc. are also common complications.
Symptom
Malaria symptoms Common symptoms High fever diarrhea periodic chills fever... Intermittent chills alternating hot and cold abdominal pain low heat nausea joint pain sore blood marrow or sputum smear...
1. General symptoms The typical clinical episodes of four human malaria are generally similar and can be divided into prodromal phase, chills (chilling), fever, sweating and intermittent.
(1) Prodromal period: the patient has fatigue, headache, discomfort, anorexia, chills and low fever. This period is equivalent to the development of mature merozoites in the hepatocytes (schizont bodies), but due to peripheral blood. The density of protozoa within the sample is too low, and the microscopic examination is mostly negative.
(2) chill period or chill period: lasts for several minutes to 1 hour, often accompanied by headache, nausea and vomiting. At this time, the body temperature has exceeded 38 °C. When the microscopic examination of Plasmodium, most of them are schizont and ring.
(3) fever period: generally lasts for 3 to 4 hours, headache is aggravated, the body temperature can be higher than 40 °C, patients with multiple recurrences, only mild and low fever, or dizziness, headache, muscle and joint pain and trigeminal neuralgia There is no obvious high fever, and the protozoa seen in the fever period is mainly small trophozoites.
(4) Sweating period: It can be slightly sweaty to sweating. During this period, the body temperature quickly returns to normal, and the above symptoms gradually disappear.
(5) Intermittent period: refers to the interval between two episodes before and after. The length of time depends on the species and immunity. In the interim period of typical cases, the cases of falciparum malaria are very irregular, only a few hours, up to 24 48h, vivax malaria and ovarian malaria were about 48h, and malaria was 72h. The microscopic trophozoites were mainly found in the protozoa except for falciparum malaria.
(6) Latent period and recurrence: vivax malaria and ovarian malaria also have latent period and recurrence; falciparum malaria and three-day malaria have only re-ignition, no recurrence, initial and recurrence, and the time between two recurrences, They are called the first and second latent periods, respectively, and similar situations seen after the treatment of sufficient high-efficiency intracranial sclerotial drugs are collectively called re-ignition. The clinical manifestations of various malaria are as follows:
1 vivax malaria: There are many prodromal periods in vivax malaria. The clinical acute episodes are based on body temperature above 38 °C. The fever begins around noon and before 9 pm, and occasionally in the middle of the night, the first and second symptoms are lighter and the heat is lower. Low, and then increasing, the common herpes simplex in the daily malaria episodes, more common around the lips, can also extend to the nose and ears, occasionally around the anus and genital area, the prognosis of vivax malaria is good, early years have the name of benign malaria.
2 falciparum malaria: incubation period of 6 to 27 days, an average of 11 days, more sudden onset, no chills, only chills, high fever are more common, often accompanied by headache, body aches, nausea, vomiting, anemia, etc., sweating period Not obvious, the heat type is complex, and some are like vivax malaria, which occurs once every other day, which is consistent with the proliferative cycle of a malignant malaria endophytic period at 48h; some have fever every day, and the heat type is intermittent type, relaxation type or Irregular; some continue to have high fever, the fever period is often as long as 20 ~ 36h; the interval between the two episodes is very short, resulting in a body temperature curve of "M" type, falciparum malaria with high-efficiency sclerotium killing medicine sufficient treatment After that, it can be cured. If it can be treated in time, the prognosis is good in most cases.
3 ovate disease: clinical symptoms similar to vivax malaria, most of them occur after 5 pm or at night, the symptoms are mild, no obvious chills, the number of attacks is generally less than 6 times, easy to self-heal, less recurrence in the long-term, common no Symptoms of the worms, more than half of the cases from the beginning of the typical inter-day heat type, the heat is low.
4 three-day malaria: incubation period of 18 to 35 days, an average of 28 days, usually no prodromal period, 3 to 4 days before the onset of fatigue, muscle and joint pain, cold and headache, often not easy to detect and ignored, mostly in the afternoon, It can also be seen at noon, chills, fever and sweating are more obvious in three periods, because the fever is too fast, there is the possibility of collapse, because the developmental synchronization of Plasmodium is strong, every 72h is a period of attack The rule is that there is no recurrence of malaria on the third day, and sufficient chloroquine and quinine can be cured.
2. Sinister malaria is mainly found in falciparum malaria, and the other three types of malaria are rarely seen as sinister.
(1) Brain type: more common in patients without immunity and not treated in time, clinically divided into three levels of lethargy, lethargy and coma.
(2) Ultra-high heat type: It is characterized by rapid onset of illness, rapid rise in body temperature to above 41 °C and continuous non-return.
(3) cold type: the patient is weak, the skin is wet and cold, pale or mildly bun, may have paroxysmal upper abdominal pain, often accompanied by intractable vomiting or watery stool, quickly collapsed and even coma, mostly due to circulation Death and death.
(4) Gastrointestinal type: There is obvious abdominal pain, diarrhea and sensation after urgency. This type is a type with a good prognosis and a low case fatality rate.
Examine
Malaria check
1. Examination of pathogens in the blood. The four malaria parasites in the human body are only falciparum malaria. Only the ring body and the gametophyte are seen in the surrounding blood, and there are more chances to be detected during the attack period. Most of the protozoa enter the visceral capillaries during the intermittent period, such as the gametophyte at that time. If it has not yet appeared, the blood test may be temporarily negative. Therefore, it is most appropriate to check blood during the onset of falciparum malaria. The blood tests of the other three malarias are not limited by time. Protozoa can be seen in both the attack and intermittent periods, which is clinically similar to malaria. Those who are negative for blood test protozoa should insist on checking blood twice a day for several days. The thick blood film is carefully examined according to the regulations. Its power is many times higher than that of thin blood film. Any malaria will eventually be found in the surrounding blood. Plasmodium, a blood smear from the earlobe or fingertips of the patient, staining, microscopic examination, is still the most reliable method for the diagnosis of malaria, such as the discovery of erythrocytic parasites.
In view of the fact that the accuracy of the microscopy method is affected by the density of protozoa in the blood, the production and dyeing techniques, the deformation or density of protozoa after taking the drug, and the experience of microscopic examination, in recent years, some improvements have been made to the traditional blood test method. For the Becton Dickinson QBC method (quantitative buffy coat), take the capillary containing the anticoagulant and acridine orange, take 60l of the patient's blood, add a floater, and after centrifugation, the Plasmodium is concentrated in the upper layer of red blood cells and the lower layer of white blood cells, due to the tube There is a pontoon in the center. Pushing the above two layers of cells and Plasmodium to the wall of the tube, you can directly check the fluorescing Plasmodium under the fluorescence microscope. This method has a concentration effect, which can improve the sensitivity and eliminate the need for dyeing, saving time. The second is 0.5% to 1.0% saponin solution instead of ordinary water hemolysis, and then microscopically stained with Gibber's solution. The advantage is that the saponin-treated thick blood membrane bottom plate is clear, no red blood cell debris and platelet interference, help Detection of Plasmodium.
2. Immunological testing
1 detection of Plasmodium antigen; can detect protozoa, so the clinical diagnosis of patients with current disease and the source of infection can be used to check the efficacy, the main methods are agarose diffusion test, convective immunoelectrophoresis, enzyme-linked Immunosorbent assay, direct fluorescence or enzyme immunostaining.
2 detection of Plasmodium antibodies: can be used in epidemiological investigations, trace the source of infection; to determine the prevalence of malaria by measuring the level of antibodies in the epidemic population; to screen blood donors to prevent malaria transfusion infection, and to assess antimalarial measures The effect, etc., in addition to the multiple episodes and no reason to identify, detection of malaria antibodies is helpful for diagnosis, detection of antibodies are more commonly used indirect fluorescent antibody test, indirect hemagglutination test, enzyme-linked immunosorbent assay.
3. Nucleic acid probe detection There are several different nucleic acid probes for the detection of Plasmodium at home and abroad. Due to its unique high specificity, the sensitivity can be higher than that of microscopic examination. It is considered that nucleic acid probe technology is very promising. Conventional microscopy, and a large number of samples can be processed in batches in a short period of time. It has been considered to be able to quantify and estimate the level of malaria parasemia. It is a potential diagnostic tool for malaria epidemiological investigation and evaluation of antimalarial measures. There are still some technical problems to be solved in the mass production of nucleic acid probes and large-scale field use.
4. PCR detection It is recognized that among the various malaria detection methods, the sensitivity and specificity of the PCR method are the highest, in order to further improve the sensitivity and specificity of the PCR technology, and to facilitate the promotion in practical work, on this basis In addition, nested PCR (PCR) and PCR-ELISA methods have been carried out. In addition to the direct detection of Plasmodium in anticoagulant samples, the detection of Plasmodium on PCR dried blood droplets has matured. It is convenient to monitor malaria in remote areas by PCR technology. Because of its high requirements on experimental techniques and conditions, it limits its application in the field. At present, the conditions of most malaria areas are still good after returning blood on site. Conditional laboratories perform further analytical processing.
5. Dipstick method Currently, the World Health Organization recommends the application of the Dipstick method, which is based on the principle that Plasmodium falciparum can synthesize and secrete a stable water-soluble antigen, histidine rich protein II (HRPII), The cloned antibody was dropped on the immunochromatographic strip, and after adsorption, washing and color development, the presence of histone-rich protein II in the blood was detected. According to foreign reports comparing Dipstick and several other methods, the sensitivity of Dipstick method for diagnosis of malaria was 84.2%~ 93.9%) and specificity (81.1%99.5%) are high; and it is easy to operate, fast and stable, easy to learn, suitable for microscopic examination or laboratory technology quality is difficult to guarantee, and the prevalence of malaria to be determined, malaria In areas with low spread and need to avoid drug abuse to reduce the development of resistance, it must be pointed out that the application of Dipstick method also has certain limitations. It is difficult to detect falciparum malaria that is still in the latent period or contains only mature gametophytes in the blood. protozoan.
Diagnosis
Malaria diagnosis and identification
diagnosis
The four malarias in the human body have many commonalities in the clinical manifestations, the course of the disease, and the response to the drugs, and each has its own particularity. Therefore, the type of malaria in the patient should be clearly identified in the diagnosis.
1. Clinical diagnosis points
1 Most cases have chills or chills of varying lengths before fever.
2 body temperature rises rapidly in a short time, lasts for several hours, then drops quickly, and then there are different degrees of sweating, measuring body temperature once every 2 to 4 hours, analyzing the body temperature curve, you can find that the body temperature at night often falls to normal Or below normal temperature.
3 seizures have timing, the fever period and the non-heat period overlap, and there is a certain regularity.
4 patients in the intermittent period of fatigue, weakness and slight discomfort, generally feel good.
5 The incidence was more common around noon and afternoon, and fewer authors started at night.
6 The clinical symptoms are more serious than once, and after repeated episodes, they gradually reduce, and there is a tendency of self-healing.
7 has clinical manifestations of hemolytic anemia, the degree of which is consistent with the number of episodes.
8 splenomegaly, the extent of which is related to the course of the disease, and some cases also see liver enlargement.
Infants and young children, falciparum malaria and new infections, the first and second episodes, clinical symptoms are often atypical, in addition, some patients with higher immunity, a large number of protozoa in the blood, clinical symptoms are not obvious or not at all, In particular, a medical examination and laboratory examination are required to determine the diagnosis.
2. Laboratory diagnosis
(1) Examination of pathogens in the blood: The four malaria parasites in the human body are only falciparum malaria. Only the ring body and the gametophyte are seen in the surrounding blood, and there are more chances to be detected during the attack period. Most of the protozoa enter the visceral capillaries during the intermittent period. At that time, the gametophyte has not yet appeared, the blood test may be temporarily negative, so it is most appropriate to check the blood during the onset of falciparum malaria; the blood test of the other three malaria is not limited by time, the protozoa can be seen in both the attack and the intermittent period, clinically Similar to malaria, blood test protozoa negative, should insist on a blood test 2 times a day, for several days, carefully check the thick blood membrane according to the regulations, its power is many times higher than the thin blood film, all malaria, eventually will be in the surrounding blood Plasmodium is detected, blood smears are taken from the earlobe or fingertips of the patient, staining, and microscopic examination are still the most reliable methods for the diagnosis of malaria. If the red endogenous Plasmodium is found, it can be diagnosed.
In view of the fact that the accuracy of the microscopy method is affected by the density of protozoa in the blood, the production and dyeing techniques, the deformation or density of protozoa after taking the drug, and the experience of microscopic examination, in recent years, some improvements have been made to the traditional blood test method. For the Becton Dickinson QBC method (quantitative buffy coat), take the capillary containing the anticoagulant and acridine orange, take 60l of the patient's blood, add a floater, and after centrifugation, the Plasmodium is concentrated in the upper layer of red blood cells and the lower layer of white blood cells, due to the tube There is a pontoon in the center. Pushing the above two layers of cells and Plasmodium to the wall of the tube, you can directly check the fluorescing Plasmodium under the fluorescence microscope. This method has a concentration effect, which can improve the sensitivity and eliminate the need for dyeing, saving time. The second is 0.5% to 1.0% saponin solution instead of ordinary water hemolysis, and then microscopically stained with Gibber's solution. The advantage is that the saponin-treated thick blood membrane bottom plate is clear, no red blood cell debris and platelet interference, help Detection of Plasmodium.
(2) Immunological testing:
1 detection of Plasmodium antigen; can detect protozoa, so the clinical diagnosis of patients with current disease and the source of infection can be used to check the efficacy, the main methods are agarose diffusion test, convective immunoelectrophoresis, enzyme-linked Immunosorbent assay, direct fluorescence or enzyme immunostaining.
2 detection of Plasmodium antibodies: can be used in epidemiological investigations, trace the source of infection; to determine the prevalence of malaria by measuring the level of antibodies in the epidemic population; to screen blood donors to prevent malaria transfusion infection, and to assess antimalarial measures The effect, etc., in addition to the multiple episodes and no reason to identify, detection of malaria antibodies is helpful for diagnosis, detection of antibodies are more commonly used indirect fluorescent antibody test, indirect hemagglutination test, enzyme-linked immunosorbent assay.
(3) Nucleic acid probe detection: At present, there are several different nucleic acid probes for the detection of Plasmodium at home and abroad. Due to its unique high specificity, the sensitivity can be higher than that of microscopic examination. It is hoped that it can replace the routine microscopy and can process a large number of samples in a short time. It has been considered to be able to quantify and estimate the level of malaria parasemia. It is a potential diagnostic tool for malaria epidemiological investigation and evaluation of antimalarial measures. At present, there are still some technical problems to be solved in the mass production of nucleic acid probes and large-scale on-site use.
(4) PCR detection: It is currently recognized that among various malaria detection methods, the sensitivity and specificity of PCR methods are the highest, in order to further improve the sensitivity and specificity of PCR technology, and to facilitate the promotion in practical work, On the basis of this, nested PCR (PCR) and PCR-ELISA methods were carried out. In addition to the direct detection of Plasmodium in anticoagulant samples, the detection of Plasmodium on PCR dried blood drops was also mature. In order to facilitate the monitoring of malaria in remote areas by PCR technology, due to its high requirements on experimental techniques and conditions, which limits its application in the field, the conditions of most malaria areas are still returned to the site after blood collection. The better conditions of the laboratory for further analysis and processing.
(5) Dipstick method: At present, the World Health Organization recommends the application of the Dipstick method, which is based on the principle that Plasmodium falciparum can synthesize and secrete a stable water-soluble antigen, histidine rich protein II (HRPII), for its preparation. The monoclonal antibody was dropped on the immunochromatographic strip, and after adsorption, washing and color development, the presence of histein II in the blood was detected. According to foreign reports comparing Dip-stick and several other methods, the sensitivity of Dipstick method for diagnosis of malaria was diagnosed. (84.2%93.9%) and specificity (81.1%99.5%) are high; and it is easy to operate, fast and stable, easy to learn. It is suitable for microscopic examination or laboratory technology quality is difficult to guarantee, and malaria is to be determined. The prevalence range, malaria is low-spread, and it is necessary to avoid drug abuse to reduce the development of resistance. It must be pointed out that the application of Dipstick method also has certain limitations. It is difficult to detect that it is still in the incubation period or that the blood only contains maturity. Plasmodium falciparum.
Differential diagnosis
Clinical manifestations of typical malaria, diagnosis is not difficult, for the so-called atypical cases accounting for more than 1/3, must be differentiated from other diseases characterized by fever, splenomegaly and hepatomegaly, so as not to delay treatment, spread malaria, or neglect Other diseases in which malaria coexists.
1. Acute schistosomiasis has a history of exposure to schistosomiasis and a history of dermatitis, common digestive symptoms such as diarrhea and mucous membranes, and dry cough. Unlike malaria, more than 90% of the liver is large. More significant, increased white blood cell count, eosinophilia, cerebral palpebral reaction, ring egg precipitation test or stool incubation positive.
2. Most of the filariasis has a history of previous episodes, white blood cells and eosinophils, no anemia and splenomegaly, and blood microbes are more positive than sputum.
3. Black fever has a history of living in the epidemic area of kala-azar, fever is generally irregular, and can develop into a complete blood cell reduction in the later stage, nose bleeding or gum bleeding, liver and spleen, bone marrow puncture can be found in Lidu body.
4. Amoebic liver abscess liver is obviously swollen and painful, no spleen, irregular heat type, white blood cells increased significantly, mainly neutrophils, ultrasound and X-ray examination can find abscess.
5. Typhoid fever is a heat retention, with rash symptoms such as rose rash, abdominal distension and other symptoms of systemic poisoning, blood, bone marrow, stool and other bacterial cultures and typhoid serum agglutination reaction.
6. Septicemia has irregular body temperature, and white blood cells and neutrophils are significantly increased. Generally, the cause of infection can be found, and blood or bone marrow bacteria culture is positive.
7. Brucellosis fever is periodic, the general symptoms are not heavy, a series of neurological symptoms can be seen later, and intradermal and serological tests can be performed.
8. The body temperature of leptospirosis is continuous heat or relaxation heat, with conjunctival hyperemia, gastrocnemius pain, lymph node swelling, skin mucosal hemorrhage, liver function damage and lung symptoms, etc., can be tested for serum immunology and examination. Leptospira is diagnosed and penicillin is effective.
9. Acute pyelonephritis fever is irregular, with backache, frequent urination, urgency and dysuria, urine test, red, white blood cells and protein, positive bacterial culture.
10. Cerebral malaria This disease is easily confused with epidemic encephalitis, toxic dysentery, and heat stroke. It is usually necessary to carefully search for malaria parasites. Toxic mites should also be used for faecal routines, culture, and can not be used for a while. Antimalarial treatment to wait for results.
11. Others such as miliary tuberculosis, long-term fever caused by biliary tract infection should also pay attention to identification.
