dengue hemorrhagic fever
Introduction
Introduction to Dengue Haemorrhagic Fever Dengue hemorrhagic fever is a serious clinical type of dengue fever. The onset is similar to typical dengue fever. After 2 to 5 days of fever, the condition suddenly increases, and a large amount of bleeding and shock occurs in multiple organs. Blood concentration, thrombocytopenia, leukocytosis, and hepatomegaly occur. . More common in adolescent patients, the mortality rate is higher. In 1950, dengue hemorrhagic fever was first discovered in Thailand, and the disease was followed in Southeast Asia, the Pacific Islands and the Caribbean. Dengue hemorrhagic fever can be divided into two types: simple dengue hemorrhagic fever and heavier dengue shock syndrome. 1, dengue hemorrhagic fever: early clinical manifestations of typical dengue fever, often on the 2nd to 5th day of the disease course, the condition suddenly aggravated, manifested as cold skin, pulse speed, lethargy or irritability, sweating, liver, skin Defects or ecchymoses, positive beam test, etc. 2, dengue shock syndrome: on the basis of bleeding, the patient's blood pressure and pulse pressure showed a progressive decline, and then entered a state of shock. The minds of early patients can still be awake. basic knowledge The proportion of illness: 0.005% Susceptible people: no special people Mode of infection: insect vector infection Complications: acute respiratory distress syndrome
Cause
The cause of dengue hemorrhagic fever
1, the cause of the disease
The dengue virus belongs to the Flavivirus family of Flaviviridae. The diseased grain is dumbbell-shaped, rod-shaped or spherical, with a diameter of 40-50 nm. The genome is a single-stranded positive-strand RNA with a length of about 11 kb and encodes 3 The structural protein and seven non-structural proteins, the genome and the nuclear protein are assembled into a icosahedral symmetry virus particle, and the outer layer has a capsule composed of lipoprotein, and the envelope contains a type and a group-specific antigen.
Depending on the difference in antigenicity, dengue virus can be divided into four serotypes, with partial cross-reactivity between each type and with Japanese encephalitis virus.
In the first infection, specific antibodies can be detected in the serum on the 4th to 5th day of the disease, reaching a peak at 2 to 4 weeks, and can be maintained at a low titer for several years.
Dengue virus grows well in the brains of Aedes striata muscle cells, monkey kidney cells and newborn mice. The replication of viruses in cells can lead to cytopathic changes. The cell line most commonly used to isolate dengue virus is from the muscles of Aedes albopictus. C6/36 cell line.
Dengue virus is resistant to low temperature, can survive for 5 years in human serum at -20 °C, and survive for more than 8 years at -70 °C. However, dengue virus is not heat resistant and can be extinguished at 60 ° C for 30 min or 100 ° C for 2 min. It is also sensitive to acid, detergent, ether, ultraviolet light, formaldehyde, etc. It is easy to be inactivated.
Dengue virus infection can temporarily inhibit the replication of human immunodeficiency virus type 1 (HIV-1) in AIDS patients.
2, the pathogenesis
Type 4 dengue virus can cause dengue hemorrhagic fever, but the second type is the most common. In 1985, the dengue hemorrhagic fever in Hainan Province of China was also caused by the second type of dengue virus. Hemorrhagic fever is more common in children aged 1 to 4 years. In Hainan Province of China, the majority of patients aged 15 to 30 years old.
The pathogenesis of this disease has not yet been fully elucidated. The current pathogenesis is only a hypothesis that humans can produce specific antibodies after being infected with dengue virus, and infants can obtain antibodies from the mother through the placenta. These low titers have higher antibodies. Weak neutralization and strong promotion of dengue virus replication, it is called an enhance antibody, which promotes the binding of dengue virus to Fc receptors on the surface of monocytes or phagocytic cells, and promotes The dengue virus replicates, releasing activated vasoactive factors such as tumor necrotic factor-alpha (TNF-) and interleukin-2 by activated CD4+ T lymphocytes and monocytes. , IL-2), interleukin-6 (IL-6), interleukin-8 (IL-8), interleukin-10 (IL-10), interleukin-12 (IL-12) and interference Interferon (IFN-), etc., lead to increased vascular permeability, plasma protein exudation from microvessels, causing blood concentration and shock, and activation of the coagulation system can cause disseminated intravascular coagulation (DIC) ), aggravating shock, and with The reduction of small plates leads to bleeding in various systems. It has been found that dengue fever in children caused by type 2 dengue virus is likely to develop into a plasma free dengue virus non-structural protein NS1 level >600ug/L within 3 days of onset. Dengue hemorrhagic fever.
However, quantitative competitive reverse transcription polymerase chain reaction (QC-RT-PCR) was used to detect dengue virus RNA in patients' plasma. It was found that there was no significant difference in plasma virus levels between patients with dengue fever and dengue hemorrhagic fever, suggesting that dengue The pathogenesis of hemorrhagic fever is more complicated, not only due to the higher replication rate of dengue virus.
In addition, it has been found that dengue hemorrhagic fever is more likely in men with dengue fever in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency.
Pathological changes are mainly systemic capillary endothelial damage, increased permeability, leading to extravasation of plasma proteins, perivascular hemorrhage, edema and lymphocyte infiltration, mononuclear macrophage system hyperplasia.
Prevention
Dengue hemorrhagic fever prevention
1. Control the source of infection: In the endemic areas or areas that may be endemic, it is necessary to do a good job in monitoring and forecasting the dengue epidemic situation, early detection, early diagnosis, timely isolation and treatment of patients, and at the same time, specific laboratory tests should be carried out on suspicious cases as soon as possible. Identify light patients and strengthen frontier health quarantine.
2, improve the population's disease resistance: pay attention to diet balanced nutrition, work and rest, appropriate exercise, enhance physical fitness, dengue vaccine is still in development, experimental stage, has developed dengue virus type 1 and 2 protein and DNA gene vaccine Animal experiments are being carried out, but they have not been promoted and applied in the population. Because low titer anti-dengue virus type 1 antibody may become a promoting antibody, it induces the occurrence of dengue hemorrhagic fever, thus increasing vaccine development and application. Difficulty.
Complication
Dengue hemorrhagic fever complications Complications, acute respiratory distress syndrome, myocarditis
It is the same as dengue fever, but the incidence is higher and the condition is more serious.
Symptom
Dengue haemorrhagic fever symptoms common symptoms rash fever lymph node swelling shock liver hemorrhage tends to lethargy hem blood beam arm test positive body sweating
The incubation period is the same as dengue fever, which can be divided into two types: simple dengue hemorrhagic fever and heavier dengue shock syndrome.
1, dengue hemorrhagic fever: early clinical manifestations of typical dengue fever, often on the 2nd to 5th day of the disease course, the condition suddenly aggravated, manifested as cold skin, pulse speed, lethargy or irritability, sweating, liver, skin Defects or ecchymoses, positive beam arm test, bleeding gums, nose bleeding, gastrointestinal bleeding, hemoptysis, hematuria, vaginal bleeding or chest, abdominal bleeding.
2. Dengue shock syndrome: On the basis of bleeding, the patient's blood pressure and pulse pressure are progressively decreased, and then enter the state of shock. The early patients' mentality can still be awake. If not treated in time, the patient can gradually become fear. , irritability, paralysis and coma, can die within 4 to 24 hours.
Examine
Dengue hemorrhagic fever check
First, the general routine inspection
1, blood routine examination.
2, urine routine can have a small amount of protein, red blood cells, white blood cells, and sometimes tube type.
3, the total number of white blood cells in patients with dengue fever is reduced at the onset of the disease, especially to the rash period; the percentage of neutrophils is also reduced, and there is a clear left shift phenomenon, abnormal lymphocytes, 1 week after fever The blood picture returned to normal.
Second, the virus is isolated from the blood of the early patients, inoculated in Aedes albopictus cell line (C6/36), after isolation of the virus must be identified by type-specific neutralization test or hemagglutination inhibition test.
Third, serum immunological examination Take two sera for complement fixation test, neutralization test or hemagglutination inhibition test, the hemagglutination inhibition test is more sensitive, and the combination test is the most specific. In the recovery period, the complement antibody-binding antibody titer of 1:32 or more has diagnostic significance; the double serum titer is more than 4 times higher than that.
Diagnosis
Diagnosis and diagnosis of dengue hemorrhagic fever
Diagnostic criteria
1. Epidemiological data is the same as dengue fever.
2, clinical manifestations of typical dengue fever clinical manifestations, bleeding tendency, such as skin defects, ecchymosis, channel bleeding, such as bleeding gums, nose bleeding, gastrointestinal bleeding, hemoptysis, hematuria, vaginal bleeding, or chest, abdominal cavity Hemorrhage, etc., patients with dengue shock syndrome have a progressive decline in blood pressure and pulse pressure. When the systolic blood pressure <12.0 kPa (90 mmHg) and pulse pressure <2.7 kPa (20 mmHg), the patient enters a shock state.
3, laboratory examination: can be found that the total number of white blood cells decreased from a slight increase, neutrophils slightly increased, thrombocytopenia, can be as low as 30 × 109 / L, blood concentration, hematocrit increased by more than 20%, blood coagulation Decreased factors, decreased complement levels, elevated fibrin degradants, decreased plasma albumin, elevated serum transaminases, prolonged bleeding time and prothrombin time, decreased fibrinogen, serological examination and virus isolation with dengue fever.
If the patient has epidemiological data and typical clinical manifestations for dengue diagnosis, the serum is positive for anti-dengue virus IgM antibody; or double serum, the recovery-specific IgG antibody titer is 4 times or higher than the acute phase. , or the isolation of dengue virus in serum, plus the occurrence of large amounts of bleeding in multiple organs, liver, hematocrit increased by more than 20%, diagnosed as dengue hemorrhagic fever, if the patient is based on dengue hemorrhagic fever At the same time with shock, the diagnosis is dengue shock syndrome.
Differential diagnosis
Dengue hemorrhagic fever and dengue shock syndrome should be differentiated from the following diseases:
1, leptospirosis rash: skin defects are less common with gastrocnemius pain, subconjunctival hemorrhage, early kidney damage, protein, cells and casts in the urine, peripheral blood leukocytes, if delayed diagnosis and treatment, Hemorrhage and multiple organ damage often occur in severe cases later, and the serum leptospirosis agglutination test is positive.
2, sepsis: more primary infections, peripheral blood leukopenia, nuclear left shift, shock common, if delayed diagnosis and treatment, severe cases can occur bleeding and multi-organ damage later, migratory purulent lesions, blood culture has bacterial growth.
3, epidemic hemorrhagic fever: pain during the course of the disease, high blood volume syndrome, renal damage is more significant, peripheral blood leukopenia, often up to 20 × 109 / L, atypical lymphocytes accounted for more than 10%, more than fever Shock, the condition worsened, followed by oliguria or anuria. If the diagnosis was delayed, severe bleeding and multiple organ damage occurred in the late stage of severe cases, and the serum anti-epidemic hemorrhagic fever virus antibody was positive.
4, epidemic cerebrospinal meningitis: more than winter and spring onset, headache, vomiting, meningeal irritation positive, cerebrospinal fluid showed purulent changes, sputum, cerebrospinal fluid centrifugal precipitation smear after Gram staining microscopic examination can be in neutral Rhodobacter sphaericus is found in the cytoplasm of cells, and blood and cerebrospinal fluid culture may have meningococcal growth.
5, tsutsugamushi disease: severe cases can also lead to bleeding and multiple organ damage in the late stage, can be found in most cases of skin eschar or ulceration, serovar agglutination test (external - Fei reaction), OXK agglutination antibody positive, effective At a price of 1:160 or above, blood is inoculated into the peritoneal cavity of the mouse to isolate the rickettsia tsutsugamushi.
6, typhoid fever: slow onset, body temperature gradually rising, expression is indifferent, rose rash is common, peripheral blood leukopenia, eosinophils reduce or disappear, if delayed diagnosis and treatment, severe cases can also occur bleeding and multiple organ damage, serum The fat test can be positive, and the blood culture can have the growth of Salmonella typhi.
7, heavy drug allergy: reaction has a history of application of sensitizing drugs, rash can be polymorphic, such as maculopapular rash, urticaria, sputum, ecchymosis, etc., severe cases can occur exfoliative dermatitis, extensive skin congestion, edema, Itching is common. If the diagnosis is delayed, shock, bleeding and multiple organ damage may occur in the late stage of severe cases. The total number of white blood cells is often increased; eosinophils are increased.
8, acute poisoning: history of toxic poisons, such as poisonous mushrooms, puffer fish, fish gall, insecticides, poison rats, methanol, etc., acute onset, sudden headache, abdominal pain, vomiting, visual impairment, limb weakness or paralysis , coma, if delayed diagnosis and treatment; severe cases can also occur in the later stages of shock, bleeding and multiple organ damage, residuals after eating, blood and urine analysis can help to confirm the diagnosis.
9, acute leukemia: the onset is slow, mainly for fever, anemia, bleeding and prone to infection, physical examination can find sternal tenderness, liver, splenomegaly, if delayed diagnosis and treatment, late can also occur shock, bleeding and multiple organ damage There are naive white blood cells in the peripheral blood, and bone marrow examination helps to confirm the diagnosis.
