Lecture Dengue (Febrile hemorrhagic Dengue)
Dengue viruses have many antigens, have type-specific antigens, and have common antigens of the subgroup and groups.
Dengue is an acute infectious disease caused by dengue virus caused by the blood-borne disease; the vector is Aedes aegypti mosquito. The disease has clinical manifestations mainly acute and haemorrhagic fever with many other forms, but severe with shock due to decreased blood circulation.
Dengue fever was first described by Spaniards in 1764. The cause was Dengue viruses discovered by Ashburn and Graig in 1907. In 1953 an outbreak of dengue occurred in the Philippines. In 1958 a similar outbreak occurred in Thailand, the cause of which was Dengue viruses was identified. Due to the epidemic spreading more and more to Southeast Asian countries, such as Vietnam in 1958-1960, Singapore, Laos, Cambodia ... and the Western Pacific countries in the following years, the World Health Organization (WHO) in 1964 has agreed on the name of the disease is dengue.
Until now, almost every country in the world can have dengue patients. Many studies on this disease have been conducted. However, there are still many problems such as contraction of the pathogenesis of the disease, treatment of serious diseases and prevention of dengue fever epidemic have not been fully studied.
Dengue virus belongs to Flavivirus group (Arbovirus group of group B or Flaviviridae) Dengue virus has 4 serotypes: 1,2,3 and 4. With RNA nucleus, there are 3 genes Protein with structure Protein C (core), Protein M (membrane Protein (shell) and 7 Unstructured Proteins. Protein E functions to neutralize and interact with receptors.
Dengue viruses have many antigens, have type-specific antigens, and have common antigens of the subgroup and groups. All 4 dengue virus serotypes have cross-reactive relatives. However, antibodies obtained after infection with one serotype have a positive response but cannot completely neutralize the other types.
An attention-seeking patient is an important source of mild illness with little management. Studies in Malaysia have demonstrated that wild monkeys are the source of the pathogen, but there is no evidence that the disease can be transmitted from monkeys to humans.
The disease is spread by blood through Aedes mosquito.
Main Mosquito: Urban A. aegypti.
Secondary mosquito: A. albopictus in the countryside, in the A. Polynesiensis forest in the South Pacific. Some other mosquitoes such as A. Scultellaris, A. niveus, A. cooki… are secondary vectors.
Aedes aegypti are striped mosquitoes that are found in cities and towns, and live indoors and outdoors and breed well in artificial mosquito containers near home. The favourable temperature for mosquito eggs to develop is over 260 C (11-18 days) at 32-330 C, only need 4-7 days. Aedes aegypti mosquito likes to sting, stubbornly, burn many times to full blood, only during the day. After they are full of blood, mosquitoes sit in a dark place with an altitude of 2 meters or less, and can fly 400 meters away
Sense of the body
The epidemic areas have been circulating for many years, children are susceptible to the disease, and the age of the disease tends to be smaller and smaller.
The first epidemic in the locality, all ages can become infected.
No gender differences.
Dengue epidemic often occurs in the hot, rainy season. The high density of A. aegypti mosquitoes (³ 1 / house and ³ 50% of neighbouring houses have mosquitoes) in our country, dengue haemorrhagic disease is divided into 3 regions.
Region 1: There are diseases all year round, developing the epidemic in the summer-autumn, mainly encountered in children, in areas with temperatures over 200 C, the Mekong River Delta, Central Coast.
Region 2: No disease in cold months, epidemic occurs in rainy, hot months, both adults and children get sick, is the northern delta region 4
Region 3: The disease spreads in the rainy, hot months, often does not become serious epidemic, in the Central Highlands in the northern mountainous region
Mechanism of pathogenesis and pathology
Mechanism of pathogenesis
The mechanism of the pathogenesis of dengue has not been fully studied. Dengue virus can cause many different diseases. Currently there are two main theories:
The virulence hypothesis of the virus, according to this hypothesis, the highly virulent Dengue virus types can cause severe illness with haemorrhagic shock.
Clinical hypothesis: Patients infected with dengue virus have haemorrhage and shock due to re-infection with dengue virus of different type and pathological immune response of the body (Hal Stead SB), this hypothesis is widely supported. households.
It was found that: Antibodies to one Serotype Dengue react to the remaining Serotype Dengue, but cannot neutralize them.
Pathophysiological disorders in dengue
Increased vascular permeability: Due to antigen-antibody reaction and Dengue virus reproduction in monocytes leads to:
Release of vasomotor mediators (Anaphylatoxin, Histamine, Kinin, Serotonin ...)
Organized Thromboplastin release.
The vessel wall increases permeability, fluid from the lumen drains out into the intercellular space, resulting in a decrease in circulating blood volume, her blood and shock.
According to Guyton, when the circulating volume is lost 10-15%, the body can compensate, 20-30% loss of shock occurs, 35-40% loss of blood pressure is 0.
Dengue haemorrhagic fever coagulation disorder is caused by:
The vessel wall is damaged and the permeability increases.
Coagulation factors decrease due to consumption during hypercoagulation.
Impaired liver function: Decreased synthesis of clotting factors, this issue needs to be further studied.
In Dengue patients the two above disorders interact, leading to the severe clinical symptoms of the disease, namely, shock and haemorrhage.
Injury from pathological surgery
Common damage is haemorrhage with different levels in organs: Skin organized under the skin, mucous membrane of the gastrointestinal tract, heart and liver haemorrhagic brain and meninges are less common peritoneal pleura containing much fluid.
Lymphocyte haemorrhage and peri-capillary infiltrating mononuclear cells in damaged organ walls. In small capillaries, blood clots form
Liver: Necrosis of hepatocytes and Kuffer cells. Mononuclear and polymorphonuclear leucocytosis in the hepatic sinuses, sometimes in the portal space.
Divide the clinical bodies
Dengue virus infection has clinical manifestations
Dengue (Classic Dengue) Sauce.
Dengue haemorrhagic fever is moderate.
Dengue haemorrhagic fever is shocking.
Dengue haemorrhagic fever may cause visceral haemorrhage.
Other diseases: Dengue fever with hemoglobin, acute liver failure, brain.
Dengue has 4 degrees: Dengue I, II, III and IV (Grade III and IV are Dengue Dengue with Shock: Dengue Shock Syndrome - DSS).
Symptoms study according to each clinical form
Typical common dengue
Incubation period: Average 4-10 days (3-15 days).
Onset: Usually sudden with high fever, usually short onset.
Syndrome of toxic infections:
Fever: Onset suddenly, often high fever continuously, average 4-7 days (seldom less than 2 days, but some patients have fever up to 15-19 days). The temperature is usually continuously high and sometimes fluctuates with the lowering of the fever, the temperature often drops suddenly, with the blood pressure decreasing. Some (17-20%) of patients have biphasic fever, after 2-3 days of reducing fever, the temperature increases for 3-5 days.
Patients often have pain all over the body, headaches continuously, on both sides of the temple, feeling cold, sweating, nausea and vomiting, much less tired.
Peripheral blood leukocytes are normal or decreased, Lymphocyte streptococcus increases, blood sedimentation rate does not increase.
Meet in all common patients on day 4 to 7 of illness while having a high or low fever. If there is no natural bleeding, the ligation test (Tourmquet Tes) is positive from day 1 to 3 of the disease.
Common types of bleeding are:
Subcutaneous haemorrhage: There are dots, nodular haemorrhagic bands larger than haemorrhagic plaques may have "tumours" or "wrap" haemorrhage under the skin. Haemorrhagic spots are often scattered throughout the body in thin skin areas (inside arms, inner thighs, sides of ribs), thickened in the legs, forearms (signs of socks). Places of impact such as blood pressure measurement sites, wind blowing, needle sticking, and pinching of the skin often leave bands or patches of bleeding.
Mucous haemorrhage: The most common is nosebleeds, most bleeding at Kisselbach vascular points, root bleeding, bleeding under the eye conjunctiva is less common.
Visceral bleeding: Commonly gastrointestinal bleeding, followed by urinary, respiratory, cerebral haemorrhage, meningitis ... common women.
Cardiovascular: During heavy bleeding, dehydration or rapid, weak pulse. Adult patients may have high fever and dissociation temperature. Blood pressure is usually reduced in some cases with changes on the cardiogram mainly conduction disturbances.
Gastrointestinal: Common abdominal pain in children with liver pain, hepatomegaly, jaundice and mucosa rarely occur, blood biochemical tests on liver have many changes ... Some cases have digestive disorders with diarrheal bloating.
Respiratory: Inflammation of the upper respiratory tract during onset, pleural effusion or superinfection pneumonia.
Swollen nodules: More common in dengue.
Maculopapular rash: May be present in dengue patients before petechiae or common dengue in dengue patients.
Dehydration manifestations: Her blood, Haematocrit increased, electrolyte disturbance, decreased Na +
Coagulation disorders: Platelet reduction, Prothrombin rate decreased, Fibrinogen blood decreased, clotting factors VIII, XII, V, VII, IX.
Clinical manifestations caused by dengue virus
Dengue fever (Dengue fever) is a constant high fever, generalized musculoskeletal pain, swollen lymph nodes all over the body, and maculopapular rash. Haemorrhage is rare, ligation test negative, no shock, no visceral bleeding without coma, and normal Haematocrit and platelet jaundice.
Mild (grade I) dengue fever is persistent, no spontaneous haemorrhage, ligation test (+), decreased blood pressure, no shock.
Typical dengue (as described above, equivalent to grade II).
Dengue shock-type haemorrhagic fever (Dengue shock) occurs on day 3 to 7 of the disease, small tachycardia, stuck blood pressure, falling or not measured cold, sweaty, tired skin. It is necessary to detect pre-shock signs for timely treatment. There are 5 signs of pre-shock according to World Health Organization in 1980 struggling or severe abdominal pain, cold, head, skin congestion and little urination. Some of the other signs of pre-shock with value visceral haemorrhage and mucosal haemorrhage more increased skin congestion, but cold hands and feet, signs of prolonged "finger press" ...
Shock has a bad prognosis when: High fever, rapid pulse, visceral hemorrhage accompanied by brain symptoms (coma) shock with severe decreased platelet anuria, ECG disorders, coagulopathy Severe blood, severe liver damage, intravascular clotting (DIC) with electrolyte disorders ... shock in children is often worse than in adults.
Dengue haemorrhagic fever visceral haemorrhage is common bleeding from the gastrointestinal tract, uterus, urinary tract, which can cough up blood and brain haemorrhage.
The test usually shows a decreased red blood cell Haematocrit.
Dengue haemorrhagic fever with haemoglobinuria: Mechanism unknown, possibly a complication of the disease, or drug allergy in patients with G6PD deficiency.
Dengue haemorrhagic fever can be acute liver failure: Dengue haemorrhagic fever patients with enlarged liver or atrophy SGOT and SGPT have increased jaundice of Bilirubin high mucosal jaundice, low Prothrombin ratio, high NNH3, consciousness disorder due to severe liver failure ... The cause can be due to disorders of microcirculation in the liver and acute hepatitis caused by Dengue virus (Dengue Hepatitis).
Dengue fever: There are criteria for diagnosis of dengue with diffuse acute encephalopathy, less likely to develop early coma (other than secondary after shock, or severe haemorrhage). Caused by disorders of microcirculation in the brain haemorrhage scattered in the brain organization due to dehydration and electrolyte disorders.
The main complication is due to increased vascular permeability and blood clotting disorders
Severe visceral bleeding, late stage due to scattered intravascular coagulation (DIC).
Coma and encephalopathy, severe brain edema.
Heart: Pericardial effusion, coronary insufficiency, conduction disturbances, edema of the heart slot, myocardial haemorrhage.
Lung: Pleural effusion, acute pulmonary edema.
Kidney: Acute renal failure.
Peritoneal effusion, epidural effusion, minimal edema, premature birth miscarriage in pregnant women.
Classification of disease levels
According to the regulations of the World Health Organization Dengue Dengue divided into 4 degrees:
Grade I: Fever + ligation sign (+), no spontaneous bleeding.
Grade II: Fever + natural bleeding under the skin or mucous membranes.
Grade III: As grade I, II + small rapid pulse blood pressure stuck or dropped, cold skin, struggling.
Grade IV: Deep shock, unrecognized blood pressure, pulse not captured.
Acute fever shows fever from 2 to 7 days.
Haemorrhage, at least the method of ligation (+).
Platelet reduction ≤ 100,000 / mm3.
Haematocrit increased by 20% or more compared to normal or there is evidence of increased vascular permeability.
Virus isolation: Need to do early in the early days of the disease.
Serum reaction: Using the HI) technique is done twice, the first time on the first week of disease, the second time is the first time for 7- 14 days.
Tests: ELISA, Mac- ELISA, PCR ...
The epidemic usually occurs in the hot rainy season in the locality where dengue fever is circulating.
There is no specific treatment.
The principles of treatment
Additional fluid early depending on disease severity.
Cool down when a high fever sedates.
Well manage all bleeding, fresh blood transfusion when heavy visceral bleeding.
Early detection and management of shock.
Nurture and take good care of the patient's nurse.
Grade I: Mainly drink.
Grade II: oral combined with infusion.
Grade III: Mainly transmitting.
Grade IV: Fast transfer speed.
The oral and infusion types of fluid are isotonic:
Oral solution: ORESOL (Nal3,5g + Trisodium citrate 2.9 g + KCL 1,5g + Glucose 20g) mixed with 1 litter of boiling water to cool.
Infusion: Ringer lactate + 5% glucose or 0.9% sodium chloride + 5% glucose at the rate of 2/1; 3/1 or 1/1 in acidosis, add isotonic sodium bicarbonate (1.4%).
Amount of additional fluid with degree I and II: The amount of additional fluid should be based on temperature, perspiration, vomiting, urine volume and Haematocrit on average 2 litters / 24 hours for adults and 1000ml / 24 hours for children. According to the World Health Organization in 1997 there were cases of dehydration but no shock.
Supplement lost volume of fluid: 10ml / kg when losing 1% of body weight.
Then the infusion maintains the amount of fluid calculated according to the formula Halliday and Segar.
The amount of infusion is maintained for 24 hours
10 - 20 Kg
1000ml + 50ml for 1 Kg above 10 Kg weight
1500ml + 20ml for 1 Kg above weight 20 Kg
Early liquid supplementation is the number one measure to prevent shock, all patients even mildly (grade I) also need to drink water (ORESOL), juice, water.
Dengue shock first aid (grades III, IV):
Add solution amount 1- 20 ml / kg for <20 minutes.
If shock persists: Give oxygen and measure the Haematocrit.
If the Haematocrit remains high, continue infusion rapidly, using multiple infusions. Addition of plasma glue solution, dextran, fluid volume 30ml / kg when blood pressure is up to 80mmHg, then decrease gradually to 10-20ml / Kg.
If Haematocrit is very low with shock capable of visceral haemorrhage, fresh blood transfusion is 10ml / Kg. When blood pressure = 100mmHg, the infusion is maintained for hours, when the blood pressure vessel is stable, the diabetic patient has an appetite ... then the infusion is stopped.
Once the fluid has been fully compensated, the central venous pressure is 8cm of water, but the patient still has not recovered from the shock of intravenous dopamine.
After the fever is gone: There is a process of resorption of plasma into the lumen causing acute pulmonary edema (OAP), so attention should be paid to patient monitoring and CVP.
Treatment of bleeding:
Haemorrhage under the skin: Without treatment, Vitamin C, P, Rutin, antihistamines can be used to protect the vessel wall, limit allergic reactions.
Mucous haemorrhage: Nosebleeds using cotton absorbent antipyrine 20% of vasoconstrictor to tighten the nostrils or use gelaspon. When there is a lot of nosebleeds, specialist intervention is ENT specialist.
Visceral haemorrhage: Fresh blood transfusion when Haematocrit is low. Plasma infusion, platelet block when Haematocrit is high.
Reducing fever in case of high fever, sedative:
It is best to physically cool down, loosen your clothes in cool water without ice.
Antipyretics: Only single paracetamol can be used. Dosage 10-15 mg / Kg weight 4-6 hours apart, total dose should not exceed 60mg / Kg / 24 hours.
Do not use other antipyretic drugs such as acetyl sacylicacid, Analgin, Ibu-Profen ... to reduce fever because the body causes haemorrhage and acidosis.
Sedatives: Calcium bromide, Diazepam ...
Cardiovascular support when needed.
Nourishing: eat liquid, enough nutrients, enough vitamins.
Kill Aedes mosquitoes by spraying mosquito repellent to eliminate standing water nests around the house from developing larvae (note Aedes aegypti mosquito has shown resistance to some drugs).
Specific disease prevention
Currently, there is no vaccine for dengue fever.