Dengue

Dengue– Arbovirus transmitted to humans by the bite of a mosquito (Aedes). It operates in sporadic fashion and / or epidemic (Southeast Asia, Pacific, Africa,

Caribbean and Central and South America). There are 4 different dengue serotypes.

– Primary infection by the dengue virus may be asymptomatic or present with classic dengue. Secondary infection with a different serotype can cause dengue hemorrhagic fever, characterized by increased vascular permeability with plasma leakage from the vascular compartment and hemoconcentration.

– Dengue haemorrhagic fever may be complicated by shock (dengue shock syndrome) at the time of defervescence if a large plasma leakage was not compensated.

Clinical signs:

Dengue fever:

• fever with headache, retro-orbital pain, myalgia, arthralgia

• maculopapular rash of the lower limbs

• signs of bleeding in the skin, frequent and mild (petechiae and signs of lace 1), rarely mucosal (epistaxis, gingival bleeding)

Dengue haemorrhagic fever:

• high fever (39-41 ° C) sudden onset and during 2-7 days (sometimes 2 pics)

• haemorrhagic signs: signs of constant positive tourniquet test1, skin bleeding (purpura, petechiae, bruising), mucosal (epistaxis, gingival bleeding), gastrointestinal (haematemesis, melena), bleeding at injection sites

• hepatomegaly

Dengue shock syndrome:

The risk period is the time of the disappearance of fever, to J3-J7. The warning signs of shock are: persistent vomiting, severe abdominal pain, agitation or confusion, sudden hypothermia; ascites and pleural effusion possible.

Signs of shock:

• Rapid, weak pulse and stunning

• coldness, sweating

• pinch of BP, hypotension

1* yaw sign: inflating a blood pressure monitor and maintain between the minimum and maximum for 5 minutes. The sign is positive if there are at least 20 petechiae in a square 2.5 cm.

Laboratory:

– Count and blood count with platelet count: leukopenia, thrombocytopenia with platelet frequent ≤ 100,000 / mm3.

– The hematocrit is the only examination to highlight haemoconcentration and thus differentiating classic dengue and dengue hemorrhagic fever (hematocrit increased by 20% from the mean for age and sex: for example, if the average hematocrit in the target population is 35%, a hematocrit of 42% corresponds to an increase of 20%).

– Confirmation of diagnosis:

Confirm etiology early in the epidemic by serology (ELISA or rapid tests): titles of IgG and IgM high in a sample to diagnose recent infection. The IgM / IgG ratio can differentiate a primary infection (high ratio) of a secondary infection (low ratio), only to risk of shock. An increase in antibody between two samples (beginning and end of the disease) allows to pose a diagnosis of acute infection. Serotypes are identified by serology or PCR.

Treatment:

Dengue fever:

• Give paracetamol PO; fresh wrap. Acetylsalicylic acid (aspirin) is formally against-indicated.

• Prevention or treatment of moderate dehydration (plenty of fluids, oral rehydration salts, monitor plans A or B to prevent or treat dehydration, WHO).

Dengue haemorrhagic fever (levels I and II)

• Admit observation for children under 15 years, patients with significant or repeated bleeding or have less than 20,000 platelets / mm 3 and all patients who have difficulty drinking or eating. Monitor vital signs (pulse, BP, FR, diuresis) every 3 hours and hematocrit every 6 hours.

Watch out for warning signs of shock.

• Infuse Ringer lactate: 7 ml / kg / hour for 6 hours to be adapted according to the clinical course and hematocrit.

If improved: gradually reduced to 5 ml and 3 ml / kg / hour and stop after 24 to 48 hours.

If no improvement: increase to 10 ml and 15 ml / kg / hour.

• Place the patient under a mosquito net.

• IM injections are against inappropriate.

Dengue shock syndrome: Emergency +++ (degrees III and IV):

• Infuse Ringer lactate: 10 to 20 ml / kg in less than 20 minutes. Repeat if necessary until a cumulative volume of 30 ml / kg.

If improvement of vital signs and hematocrit: move to 10 ml / kg / hour and then adapt.

If no improvement in vital signs: give oxygen and perform emergency hematocrit:

– If the hematocrit is still high or increased: fluid modified gelatin 10 to 20 ml / kg in less than 10 minutes. Repeat if needed until a cumulative volume of 30 ml / kg. Continue with 10 to 20 ml / kg / hour until improvement of vital signs.

– A sudden drop in hematocrit without clinical improvement reflects a hemorrhage (usually digestive or internal): transfuse 10 to 20 ml / kg of fresh blood (previously tested blood for HIV, hepatitis B and C, etc.).

• Monitor vital signs every 15 to 30 minutes and hematocrit every 2 hours during the first 6 hours, then every 4 hours.close monitoring for the next 48 hours as the shock may recur.

• Stop the infusion when the vital signs are normal and stable, appetite income and normalized hematocrit, generally 48 hours after the shock.

Attention to fluid overload: eyelid edema is the first sign of overload. Suspend infusion until disappearance of edema.If signs of edema (laryngeal crackles, dyspnea, increased FR, cough with or without frothy sputum, distress, crackles in 2 fields, tachycardia), give IV furosemide, repeated after 1-2 hours if necessary :

Children: 1 mg / kg / injection

Adult: 40 mg / injection

• In case of febrile seizures in infants See convulsions.

Prevention:

– In endemic areas, there is a risk of an epidemic: report probable or confirmed cases.

– Personal protection: mosquito net, repellent.

– Vector control: essential, especially during epidemics (destruction of breeding sites with insecticide sprayage).

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Editor-in-chief of the Medical Actu website; general practitioner graduated from the Faculty of Medicine of Algiers in 2005 currently practicing as a liberal.

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