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Dengue Fever/ Breakbone fever/ Dandy fever/ Hemorrhagic fever/ Infectious Thrombocytopenic purpura:
is an acute febrile disease caused by infection with one of the stereotypes of dengue virus, which is transmitted by mosquito genus Aedes.
(+) fever, accompanied with rash and pain in the joints, and behind the ear.
Dengue hemorrhagic fever:
- -severe, fatal manifestation of the dengue virus.
- -(+) bleeding diathesis and hypovolemic shock.
- *FLAVIVIRUS 1,2,3,4 and a family of TOGAVIRDAE (small viruses that contain single-stranded RNA).
- *ARBOVIRUSES GROUP B
- bite of AEDES AEGYPTI:
- AA: day-biting mosquito (2 hours after sunrise and 2 hours before sunset); breeds in stagnant water; limited, low flying; has fine white dots at the base of the wings and white bands on the legs.
- AEDES ALBOPICTUS:
- -transmission of the dengue virus in the RURAL AREAS.
- OTHER CONTRIBUTORY MOSQUITOES:
- Aedes polynensis
- Aedes scutellaris simplex
three to 14 days; COMMON: 7-10 days.
- *patients are usually infective to the mosquito from a day BEFORE the febrile to the end of it.
- *the mosquito becomes infective from day 8-12 after the blood meal and remain infective throughout its life.
Sources of infection:
- 1. INFECTED PERSON:
- present in the blood of pt in the ACUTE PHASE of the disease and will become reservoir of the virus, sucked by mosquitoes, which may then transmit the disease.
- 2. STANDING WATER:
- any stagnant water in the household and its premises are usual breeding places of these mosquitoes.
- age: usual-ages 4-9 y/o.
- season: during the rainy season.
- location: urban communities.
PATHOGENESIS and PATHOLOGY:
- DENGUE FEVER:
- 1. prodromal sx characterized by:
- -malaise and anorexia up to 12 hours.
- -fever and chills accompanied by severe frontal headache, ocular pain, myalgia (pain in muscles) with severe backache, arthralgia (pain in joints).
- 2. N&V
- 3. fever> non-remitting (3-7 days)
- 4. rash- prominent on the extremities and the trunk (may involve in the face in some isolated cases)
- 5. petechiae usually appear near the end of the febrile period and most commonly in the lower ext.
- DENGUE HEMORRHAGIC FEVER:
- -(+) fever, hemorrhagic diathesis, hepatomegaly and hypovolemic shock.
PHASES OF ILLNESS:
- I. INITIAL FEBRILE PHASE (2-3 days)
- -fever (39-40)+headache
- -palms and soles are flushed
- -(+)torniquet test
- -anorexia, vomiting, myalgia
- -maculopapular or petechial rash may be present and usually starts in the distal portion of the extremities (sparing the axilla and chest), the skin appears purple, with blanched areas of varying size (Herman's sign, pathognomic sign)
- -generalized or abdominal pain
- -hemorrhagic manifestations: (+) torniquet test, purpura, epistaxis, and gum bleeding.
- II. CIRCULATORY PHASE:
- -(+) fall of temperature + profound circulatory changes (third or fifth day)
- -restless, with cool, clammy skin.
- -(+) cyanosis
- -profound thrombocytopenia (deficiency of platelets in the blood) + onset of shock
- -severe bleeding diathesis, can lead to GIT hemorrhage.
- -pulse is rapid and weak; narrow PP, drop BP.
- -untreated shock-COMA; met. acidosis and death may occur within 2 days.
CLASSIFICATION ACCDG TO SEVERITY:
- GRADE I:
- -fever with non-specific constitional sx + (+)torniquet test (hemorrhage)
- GRADE II:
- -all signs of grade I + spontaneous bleeding from the nose, gums and GIT.
- GRADE III:
- -(+) circulatory failure (weak pulse, narrow PP, hypotenstion, cold, clammy skin and restlessness)
- GRADE IV:
- -(+) SHOCK + undetectable BP and pulse.
- -epistaxis; menorrhagia
- -GIT bleeding
- -peptic ulcer
- -met acidosis
- -tissue anoxia
- -hemorrhage into the CNS or adrenal glands
- -utering bleeding
- *DENGUE ENCEPHALOPATHY:
- -restlessness, apprehension or anxiety, disturbed sensorium, convulsion, spacity and hyporeflexia
- 1. TORNIQUET TEST:
- occlude arm for five mins to detect capillary fragility.
- 2. PLATELET COUNT:
- decreased, CONFIRMATORY!!!
- 3. HEMOCONCENTRATION:
- increase of 20% in HCT or a steady rise.
- 4. OCCULT BLOOD
- 5. HgB DETERMINATION
- Analgesics EXCEPT ASPIRIN (relief pain)
- INITIAL PHASE-IV (px dehydration and replace plasma)
- Severe bleeding-BT
- O2 therapy-SHOCK
- Sedatives-anxiety and apprehension
- -mosquito-free enviroenment
- -monitor VS
- -nose bleeding- keep trunk elevated; apply ice bag to the bridge of the nose and to the forehead.
- -WOF: signs of SHOCK (slow pulse, cold, clammy skin, prostration and fall of BP)
- -restore blood volume: TRENDELENBURG POSITTION (provide blood vol at the head part)
- -isolation is NOT required (not infectious)