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Clerkship > Dengue - Nelson 21 > Flashcards

Dengue - Nelson 21 Flashcards

1
Q

Characteristics of dengue fever

A 
Biphasic fever
Myalgia / arthralgia
Rash
Leukopenia
Lymphadenopathy
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2
Q

Characteristics of dengue hemorrhagic fever

A

Capillary permeability
abnormalities of hemostasis
Severe: protein-losing shock syndrome DSS

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3
Q

Severe dengue includes

A 
Fluid loss leading to shock
Fluid loss w respi distress
Liver damaged (^ALT AST >100U/L)
Severe bleeding 
Altered consciousness 
Significant heart abnormalities
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4
Q

Family of dengue virus

A

Flaviviridae

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5
Q

Dengue like diseases and their virus

A

Chikungunya - Togavirus
O’nyong-nyong - Togavirus
West nile fever - Flavivirus

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6
Q

Principal Vector of Dengue

A

Mosquito - Stegomyia family, Aedes aegypti

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7
Q

Where does A. aegypti breeds

A

Water stored for drinking and rainwater collected in a y container

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8
Q

These species breed in water trapped in vegetation; caused of Hawaiian epidemics

A

Aedes albopictus

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9
Q

Explain the urban transmission cycle

A

viremic humans –> bitten by vector mosquito –> virus multiplies during extrinsic incubation period –> bite is passed on to a susceptible human

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10
Q

Since A. aegypti has limited flight ranged, spread of the virus is possible through?

A

through viremic human beings and follows the main lines of transportation

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11
Q

Dengue-like diseases may occur in epidemics. Epidemiologic features depend on what 2 factors?

A

vectors

their geographic distribution

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12
Q

Occurs where multiple types of dengue virus are simultaneously or sequentially transmitted. It is endemic in tropical America, Asia, the Pacific Islands, and parts of Africa, where warm temperatures and the practices of water storage in homes plus outdoor breeding sites result in large, permanent populations of A. aegypti

A

Dengue Hemorrhagic Fever

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13
Q

In areas of high endemicity, this infections are frequent.

A

secondary infections

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14
Q

This infection is relatively mild in the majority of instances, ranging from an inapparent infection through an undifferentiated upper respiratory tract or dengue-like disease, but may also progress to dengue
hemorrhagic fever

A

Secondary dengue infections

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15
Q

Dengue hemorrhagic fever can occur during primary dengue infections, most frequently in ?

A

Infants whose mothers are immune to dengue

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16
Q

Dengue hemorrhagic fever or severe dengue occurs rarely in individuals of what ancestry because of an as yet incompletely described resistance gene

A

African ancestry

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17
Q

Pathogenesis of DHF

A

usually associated with second heterotypic infections with dengue types 1-4 or
in infants born to mothers who have had two or more lifetime dengue infections

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18
Q

Retrospective studies of sera from human mothers whose infants acquired DHF and in children acquiring sequential dengue infections have shown that the circulation of ___ at the time of infection is the strongest risk factor for development of severe disease

A

infection-enhancing antibodies

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19
Q

best correlates of risk for dengue hemorrhagic fever

A

(-) crossreactive neutralizing antibodies

(+) enhancing antibodies from passive transfer or active production

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20
Q

Pathology of Dengue

A

When dengue virus immune complexes attach to monocyte/macrophage Fc receptors, a signal is sent that suppresses innate immunity, resulting in enhanced viral production

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21
Q

In the Americas, DHF and DSS have been associated with these strains of recent Southeast Asian origin

A

dengue types 1-4 strains

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22
Q

Outbreaks of DHF in all areas of the world are correlated with___ while recent outbreaks in India, Pakistan, and Bangladesh are related to ___

A

secondary dengue infections

imported dengue strains

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23
Q

Early in the acute stage of secondary dengue infections, there is rapid activation of ___

A

complement system

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24
Q

Shortly before or during shock, blood levels of these (3) are elevated

A

soluble tumor necrosis factor receptor
interferon-γ
interleukin-2

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25
Q

These are depressed at times of DHF

A

C1q, C3, C4, C5-C8, and C3 proactivators are depressed

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26
Q

Catabolic rates of these are elevated

A

C3 catabolic rates are elevated

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27
Q

This is a viral toxin that activates myeloid cells to release cytokines by attaching to toll receptor 4. It also contributes to increased vascular permeability by activating complement, interacting with and damaging endothelial cells, and interacting with blood clotting factors and platelets

A

Circulating viral nonstructural protein 1 (NS1)

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28
Q

Capillary damage allows fluid, electrolytes, small proteins, and, in some instances, RBC to leak into extravascular spaces. This internal
redistribution of fluid, together with deficits caused by fasting, thirsting, and vomiting, results in ____ (6)

A 
hemoconcentration
hypovolemia
increased cardiac work
tissue hypoxia
metabolic acidosis
hyponatremia
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29
Q

In rare instances, death may be a result of

A

gastrointestinal or intracranial hemorrhages

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30
Q

Pathologic lesion in GI tract (death)

A

Minimal to moderate hemorrhages are seen in the upper gastrointestinal tract

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31
Q

Pathologic lesion in the heart (death)

A

petechial hemorrhages are common in the interventricular septum and pericardium

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32
Q

Pathologic lesion in the liver (death)

A

usually enlarged, often with fatty changes

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33
Q

Incubation period of Dengue fever

A

1-7 days

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34
Q

CM in infants and young children

A

fever for 1-5 days
pharyngeal inflammation
rhinitis
mild cough

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35
Q

CM in older children and adults

A

Sudden onset of fever (39.4 - 41.1°C)
frontal or retroorbital pain,
occasionally, severe back pain precedes the fever (back-break fever)

36
Q

may be seen during the first 24-48 hr of dengue fever

A

transient, macular, generalized rash that blanches under pressure
pulse rate may be slow
myalgia and arthralgia occur soon after the onset of fevers and increase in severity

37
Q

2nd to 6th day of dengue fever

A 
fever
nausea
vomiting
generalized lymphadenopathy
cutaneous hyperesthesia or hyperalgesia
taste aberrations
pronounced anorexia
38
Q

1-2 days after defervescence, what is seen in dengue fever and disappears after how many days?

A

a generalized, morbilliform, maculopapular rash appears that spares the palms and soles
1-5 days

39
Q

Rarely there is _____ of the palms and soles.
About the time this second rash appears, the body temperature, which has previously decreased to normal, may become slightly elevated and demonstrate the characteristic _____

A

edema

biphasic temperature pattern

40
Q

Describe the first phase of Dengue Hemorrhagic Fever and Dengue Shock Syndrome (DHF/DSS)

A 
Mild first phase with abrupt onset of 
fever
malaise
vomiting
headache
anorexia
cough 
may be followed after 2-5 days by rapid clinical deterioration and collapse
41
Q

In rapid clinical deterioration and collapse in DHF/DSS or the second phase, the patient usually has

A 
cold, clammy extremities
warm trunk
flushed face
diaphoresis
restlessness
irritability
midepigastric pain
decreased urinary output
42
Q

In second phase of DHF/DSS, skin is affected by

A

scattered petechiae on the forehead and extremities spontaneous ecchymoses
easy bruising and bleeding at sites of venipuncture
macular or maculopapular rash
circumoral and peripheral cyanosis

43
Q

In second phase of DHF/DSS, lungs is affected by

A

Respirations are rapid and often labored

44
Q

In second phase of DHF/DSS, heart is affected by

A

Pulse is weak, rapid, and thready

heart sounds are faint

45
Q

In second phase of DHF/DSS, liver is affected by

A

Liver may enlarge to 4-6 cm below the costal margin and is usually firm and somewhat tender

46
Q

Approximately 20– 30% of cases of dengue hemorrhagic fever are complicated by

A

shock (dengue shock syndrome)

47
Q

Dengue shock can be subtle, arising in patients who are fully alert, and is accompanied by (2)

A

increased peripheral vascular resistance

raised diastolic blood pressure

48
Q

(DHF/DSS) Shock is not from congestive heart failure but from

A

venous pooling

49
Q

(DHF/DSS) With increasing cardiovascular compromise, the diastolic pressure _____ the systolic level and the _____ narrows

A

diastolic pressure RISES TOWARD the systolic level pulse pressure narrows

50
Q

(DHF/DSS) In uncorrected shock, <10% of patients usually have (2)

A

gross ecchymosis or gastrointestinal bleeding

51
Q

(DHF/DSS) After a 24- to 36-hr period of crisis,
convalescence is fairly rapid in the children who recover. The temperature may return to normal before or during the stage of shock. _____ and _____ are common during convalescence.

A

Bradycardia and ventricular extrasystoles

52
Q

Clinical diagnosis derives from these 2 factors

A

High index of suspicion

Knowledge on geographic distribution and environmental cycles of causal virus s

53
Q

This term should be used until a specific diagnosis of dengue is established

A

Dengue-like diseases

54
Q

Dengue Case is confirmed through (3)

A

1 Isolation of virus viral antigen and genome by PCR analysis
2 IgM dengue antibodies detection
3 4 fold increase in antibody titers

55
Q

WHO criteria for DHF

A 
1 Fever (2-7d biphasic)
2 Minor or major hg manif
(6)
Tourniquet test positive
Thrombocytopenia <100,000/uL
Hct >20% (inc cap perm)
Pleural effusion
Ascites
Hypoalbuminemia
56
Q

DSS criteria

A 
DHF criteria
Hypotension
Tachycardia
Narrow pulse pressure =20mmHg
Poor perfusion (cold extremities)
57
Q

Probable dengue

A 
Live/ travel to endemic area
Fever and 2 of ff
1 NAusea
2 Rash
3 Aches and pains
4 TT positive
5 Leukopenia
6 Any warning sign
58
Q

Dengue with warning signs

A 
Abdominal pain or tenderness
Persistent vomiting
Mucosal bleed
Clinical fluid accumulation
Lethargy, restlessness
Liver enlargement >2cm
Labs 
-inc in Hct w rapid dec in platelets
59
Q

Severe dengue

A

Severe plasma leakage
Shock DSS
Fluid accumulation w Respi distress

Severe bleeding
as evaluated by clinician

Severe organ involvement
Liver AST or ALT >/= 1000
CNS Altered consciousness
Heart other organs

60
Q

Virologic dx can be established by serologic tests by (2)

A

Detection of viral proteins or viral RNA

Isolation of virus from blood leukocytes or acute phase serum

61
Q

Following primary and secondary infections, there is an appearance of what Antibodies that disappears after 6-12wks a feature that can be used to date a dengue infection

A

Antidengue IgM antibodies

62
Q

In secondary infections most dengue antibody is this and serologic studies depends on four fold increase in this antibody titer

A

IgG

IgG antibody titer

63
Q

This is a viral nonstructural protein released by infected cells into the circulation and can be detected in acute stage blood samples

A

NS1

64
Q

Ddx

A 
Dengue like dses
Viral respi and influenza-like dses
Early stages of malaria
Mild yellow fever
Scrub thypus
Viral hepatitis 
Leptospirosis
65
Q

Lab findings (5)

A 
1 pancytopenia (after 3-4d)
2 neutropenia <2,000/uL
3 platelets rarely fall below 100,000/uL
4 normal ranges
Venous clotting
BT and PTT 
Plasma fibrinogen 
5 TT positive
66
Q

Lab findings that may occur during primary dengue (4)

A

Mild acidosis
Hemoconcentration
Inc transaminase
Hypoproteinemia

67
Q

ECG

A

1 sinus bradycardia
2 ectopic ventricular foci
3 flattened T waves
4 prolongation of PR interval

68
Q

Mc hg abnormalities during DHF and DSS

A 
Hemoconcentration
Inc in HCt >20%
Thrombocytopenia
Prolong BT
Mod dec Prothrombin level
69
Q

Other lab abnormalities

A

-moderate elevations of serum transaminase levels
-consumption of complement
-mild metabolic acidosis with hyponatremia,
occasionally hypochloremia, slight elevation of serum urea nitrogen, and hypoalbuminemia

70
Q

Roentgenograms of the chest reveal in nearly all patients with dengue shock syndrome

A

pleural effusions (right >left)

71
Q

Can be used to detect serosal effusions of the thorax or abdomen

A

Ultrasonography

72
Q

Characteristic signs of increased vascular permeability

A

Thickening of the gallbladder wall and the presence of perivesicular fluid

73
Q

Treatment

A

Supportive

  • Bed rest - febrile period
  • Antipyretics < 40°C
  • Analgesics or mild sedation - pain
  • Fluid and electrolyte replacement
74
Q

2 drugs C/I and should not be used because of their effects on hemostasis/blood clotting

A

Aspirin

Salicylates

75
Q

A medical emergency that may occur in any child

who lives in or has a recent travel history to a tropical destination

A

Dengue shock syndrome

76
Q

Management of dengue hemorrhagic fever and dengue shock syndrome includes

A

1 evaluation of
VS
hemoconcentration
dehydration
electrolyte imbalance
2 close monitoring for 48 hr
3 O2 for cyanotic patients
4 Rapid IV replacement of fluids and electrolytes
5 Normal saline > Ringer lactated (shock)
6 Plasama/colloid preparations if ≤10 mmHg or when elevation of hct persists after replacement of fluids
7 Oral rehydration

77
Q

Care must be taken to avoid this which may contribute to cardiac failure

A

Overhydration

78
Q

May be required to control bleeding but should NOT be given DURING HEMOCONCENTRATION but only after evaluation of hg or hct values

A

Transfusions of fresh blood

79
Q

may be required for children who are markedly agitated

A

Sedation

80
Q

Complications. During the fluid reabsorptive phase, this may be life-threatening and is heralded by a decrease in hematocrit with wide pulse pressure
What are necessary to give/do during this situation?

A

Hypervolemia

Diuretics and digitalization

81
Q

Most frequent complications in infants and young children of primary infections with dengue fever and dengue-like diseases

A

Fluid and electrolyte losses
hyperpyrexia
febrile convulsions

82
Q

Uncommon complications but may occur at any

stage

A

Epistaxis
petechiae
purpuric lesions

83
Q

May occur during a high temperature (complication)

A

Convulsions

84
Q

Infrequently, after the febrile stage these complications may occur in children (4)

A

prolonged asthenia
mental depression
bradycardia
ventricular extrasystoles

85
Q

Prevention

A

1 Dengue vaccines (Dengvaxia) - 9 above in highly endemic areas
2 Avoiding daytime mosquito bites
-insecticides
-repellents
-body covering with clothing
-screening of houses
-destruction of A. aegypti breeding sites
3 tight-fitting lid or thin layer of oil
4 larvicide
5 ultra-low-volume spray equipment (adulticide malathion)

86
Q

4S laban sa

A

Search and destroy breeding sites
Self protection measures
Seek early consultation
Say no to indiscriminate fogging

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