DENGUE

 Introduction:

                        Dengue is the world's most rapidly spreading viral mosquito-borne infection. Most cases of dengue are A-symptomatic or they have very mild symptoms which can be managed at home. The most important complication of dengue is not the low platelet count but the capillary leak syndrome. Capillary leak syndrome leads to loss of fluid from the plasma which results in hypotension and shock.

Epidemiology:

                        While dengue is seen throughout the year, it is most common during September and October right after the rainy season.

Definitions:

Febrile Phase:

1. The initial phase of the infection is characterized by high fever for 2-7 days, often associated with facial flushing, skin erythema, generalized body ache, myalgia, arthralgia, and headache.
2. Mild hemorrhagic manifestations such as petechiae and mucosal membrane bleeding can be seen.  

Critical phase: 

1. This occurs on days 3-7 of the illness, around the time that the fever starts to break. This period is characterized by an increase in capillary permeability, which is manifested by an increasing hematocrit level.
2. Pasma leakage continues for about 24-48 hours. 
3. The degree of plasma leakage is varying and can be determined by pleural effusion and ascites. The increase of hematocrit above the baseline is an accurate and quick method of assessing the severity of plasma leakage. In severe cases, shock and multiorgan failure may occur.  
4. Dropping white blood cell count and platelet count could easily precede the plasma leakage. The start of the critical phase can easily be detected by warning signs.

Recovery phase:

1. This usually lasts for 36-72 hours and during this time the leaked plasma is reabsorbed.
2. Pulmonary edema may occur if too much fluid was given away in the previous 2 phases.

Severe dengue: 

                               Severe dengue is identified by one or more of the following.

1. Plasma leak that may lead to shock or /and fluid accumulation, with or without respiratory diseases.
2. Severe bleeding 
3. Severe organ impairment. 

Warning signs of severe dengue: 

1. Abdominal pain or tenderness
2. Persistent vomiting  
3. Clinical fluid accumulation
4. Mucosal blood
5. Lethargy, restlessness
6. Liver enlargement
7. Increase in hematocrit with a rapid decrease in platelet count.

Managing dengue as an outpatient:

Step1: Overall assessment:

The history should include

1. Date of onset of fever/illness
2. Quantity of oral intake
3. Assessment for warning signs
4. Diarrhea
5. Change in mental state/seizures/dizziness
6. Urine output (Frequency, volume, and time of the last voiding)
7. Other important relevant histories, such as family or neighborhood dengue, co-existing conditions (e.g: Infancy, pregnancy, obesity, diabetes Mellitus, and hypertension).

Physical examination: 

                                                 The physical examination should include an assessment of 

1. Mental state
2. hydration status
3. Hemodynamic status
4. Tachypnea/ acidotic breathing/ pleural effusion
5. Abdominal tenderness/ hepatomegaly/ ascites
6. Rash and bleeding manifestations
7. Tourniquet test. 

A tourniquet test is performed by inflating the blood pressure cuff between the diastolic and systolic pressures for 5-10 minutes. A positive test is when 10 or more petechiae develop per square inch.  

Investigations:

                        A complete blood count should be done at the first visit.

1. A hematocrit test in the early febrile phase establishes the patient's own baseline hematocrit.
2. A decreasing white blood cell count makes dengue very likely. 
3. A rapid decrease in the platelets and an increase in the hematocrit compared to the baseline is indicative of the progress of the plasma leakage/ critical phase of dengue.
4. In the absence of the patient's baseline, age-specific population hematocrit levels could be used as a surrogate during the critical phase.

Laboratory tests should be performed to confirm the diagnosis.

1. Dengue antigen NS1 will be positive in the first 5 days of fever.
2. Dengue IgM will be positive 5-6 days after the initial infection and IgG antibodies will rise slowly.
3. In secondary infection, the IgG antibodies will rise rapidly after around 2-3 weeks.
4. During an outbreak, it is not necessary to test serology for the acute management of every patient, except in the case of unusual symptoms or undifferentiated diagnoses.

Additional tests are optional are to be given according to one's health condition for e.g:

1. Liver function
2. Glucose
3. Serum electrolytes
4. Urea and creatinine
5. Bicarbonate
6. Lactate
7. Cardiac enzymes
8. ECG
9. Urine specific gravity.

Step 2: Diagnosis, assessment of disease phase and severity:

Based on the evaluation of the history, physical examination, and/or full blood count and hematocrit, determine whether the disease is dengue, which stage is it in, Whether there are warning signs, the hydration and hemodynamic status of the patient, and whether the patient requires admission. 

Step 3 management:

                                  Dengue without warning signs: Most cases should be handled at home and the caretakers should be given advice and proper instructions; however if the management seems to be complicated or patients lives far away or cannot be monitored at home or can not tolerate oral fluid, then refer to hospital for admission. 

Dengue with warning signs:

                                               Refer to the hospital for admission.

Severe dengue:

                         Urgent referral to the emergency.

Case no.1 Dengue without warning signs:

                                                                                          A 16-year-old boy, otherwise well, presents to your clinic with sudden onset of high fever, chills, and pain in his lower back and thigh, nausea, and vomiting that started 5 days back. He has a diffuse pinkish rash all over the trunk and the extremities.

On examination, he is febrile but not ill-appearing. B.P is 110/70 mm His skin is flushed red. You press the skin of his back and upper arms with your thumb and it leads to an impression for a few seconds. The rest of his examination is normal. His CBC shows Hb 13 gram, (PCV 40%) TLC 3,500/cmm, platelet count is 65,000/cmm, ALT is 72 I.U, malarial parasite smear-negative.

Blanching of normal skin is due to displacement of subcutaneous fluid. If this patient can tolerate adequate volumes of oral fluids and can pass urine at least once every 6 hours. he should be reviewed daily for disease progression until he is out of the critical period.

Patients with stable hematocrit can be sent home but are advised to the hospital as quickly as they can if they develop any warning signs and to adhere to the action plan provided to them by your doctor.

instruct the caregiver to bring the patient to the hospital immediately if he develops any one of these symptoms. 

1. No clinical improvement.
2. Deterioration around the time of defervescence
3. Severe abdominal pain
4. Persistent vomiting
5. Cold and clammy extremities 
6. lethargy or irritability/ restlessness
7. Bleeding
8. Not passing urine for more than 4-6 hours.
9. People who are sent home should be regularly checked by the health care provider for temperature patterns, the volume of fluid intake or losses, urine output, warning signs, signs of plasma leakage, bleeding, hematocrit, and white blood cell, and platelets count.

Remember:

1. Not all features may be present in the same patient.
2. Rule out malaria and sepsis.
3. The single most important test is a hematocrit.
4. Platelets should not be given unless the patient is actively bleeding.

Case no.2 Dengue with warning signs:

                                                          A 15-year-old girl has been running a fever for a week. On day 5 she has a pink, macular rash on her trunk and extremities. She has a slight nose bleed and her gums are bleeding. Although she is afebrile, her face is puffy, her legs edematous and she has a distended ad tender abdomen. BP is 110/74 mm. and she is alert and cooperative. Lab tests Hb 15.5 gm/dl, Htc 45%, TLC 3.5/cmm, platelets 35,000/cmm, ALT is 95 I.U. 

This patient should be referred for inpatient care where fluid resuscitation is provided. IV dextrose, normal saline, Ringer's lactate should be given in a bolus and then sufficiently to measure blood pressure and adequate urine output platelets should not be given unless the patient is actively bleeding.

Case no. 3 Severe dengue:

                                           A middle-aged man present with a week of high fever flushed skin, and today has petechiae and bruises on the limbs, nose bleed, and black stools. His B.P is steadily falling. By profession, he is a butcher and he has been slaughtering goats and sheep for the past week for Bakra eid. You notice blood oozing from venipuncture sites.

This patient has severe dengue. This is defined as one or more of the following.

1. Plasma leakage may lead to shock and/or fluid accumulation, with or without respiratory distress.
2. Severe bleeding
3. Severe organ impairment

These patients must be referred immediately to a tertiary care center where adequate fluids can be given. This patient should be transfused with platelets. All cases of severe dengue should also be evaluated for Crimean Congo hemorrhagic fever.

Prevention of dengue:

                                  Dengue enters the body through the bite of an Aedes aegyptii mosquito which typically breeds in clean, stagnant water. The only known prevention of dengue is to save yourself from mosquito bites, removing all mosquito breeding sites by keeping a clean and dry environment in the household.

1. Cover your arms and legs in the evenings by wearing long leggings and long sleeves.
2. Reinforce door/ window settings to prevent the entry of mosquitos. 
3. Use mosquito repellant such as coils, mats, etc.
4. Apply mosquito repellant cream: only DEET is effective in the strength of 24% in up to 5 hours
5. Cover kitchen utensils used for storing water
6. Indoor plants may serve as breeding spots
7. Drain stagnant water in empty plots and gardens after rainfall to prevent larva breeding.

Pearls of wisdom:

1. Majority of patients with dengue recover without complications
2. Avoid panic, reassure the patient and family.
3. Dengue without warning signs can be treated at home
4. Raised hematocrit, indicates dehydration secondary plasma leakage.
5. Refer to the hospital when there are warning signs
6. The mainstay is fluid balance
7. Many patients receive platelet transfusion out of fear