Children with Dengue fever, Dengue haemorrhagic fever and ...
Dengue fever
Transcript of Dengue fever
DENGUE FEVER
Dr. Anita LamichhaneDeptt. Of pediatrics
Shaikh Zayed Hospital
Etiological AgentEtiological Agent
Dengue virus Dengue virus • Single stranded RNA virus,Arbovirus belonging to flaviviridae
family
• 4 antigenically distinct serotypes-DEN 1, 2,3, 4.
• DEN-1, DEN-2 were prevalent until 1980s
• DEN-3 is predominant in recent outbreak
• DEN-4 primarily detected in secondary dengue infections
• Serotype provides specific life time immunity and short term
cross immunity
Dengue virus transmission • Two general patterns
• Epidemic Dengue – dengue virus is introduced into a region
as an isolated event that involves a single viral
strain(Asia,Africa,America)
• Hyperendemic Dengue-continuous circulation of multiple
viral serotypes in an area where a large pool of susceptible
hosts & a competent vector are constantly
present,predominant pattern of global transmission.
The vector-Aedes aegypti
• Transmitted by the infected female Aedes aegypti
• Can be identified by the white bands or scale patterns on its legs and thorax
• Primarily a daytime feeder• Found in tropical & subtropical
region• Lives around human habitation• Lays egg & produces larvae
preferentially in artificial containers
Vector & its transmission
0 5 8 12 16 20 24 28 DAYS
Illness Illness Human #1 Human #2
Mosquito feeds/acquires virus
Mosquito refeeds/transmits
virus
Viremia Viremia
Intrinsic incubation
period
Intrinsic incubation
period
Extrinsic incubation
period
Extrinsic incubation
periodViremia
Replication & transmission of Dengue virus
• Virus inoculated into a human being with mosquito saliva
• The virus localizes and replicates in various target organs-
local lymph nodes & liver released spreads through
the blood infect the WBCs & reticuloendothelial
system(dendritic cells,hepatocytes,endothelial cells)
• The mosquito ingests blood containing the viruses (on
biting an infective person)
• Virus replicates in the midgut,ovaries,nerve tissue, fat body
of the mosquito
• It then escapes into the body cavity and later on infects the
salivary glands
• In the salivary glands, the virus replicates
• When the mosquito bites another human ,the life cycle
continues
• Humans are the primary reservoir of infection
Vector
• Aedes aegypti/Aedes albopictusAedes aegypti/Aedes albopictus
• The female mosquito feeds on blood ( they need the
protein found in blood to produce eggs)
• Male mosquitoes feed only on plant nectar.
• The mosquito is attracted by the body odours, carbon
dioxide and heat emitted from the animal or humans.
Aedes aegypti Mosquito life cycle
• Eggs are laid on the walls of water-filled containers in the
house and patio.
• The eggs can survive for months and hatch when
submerged in water.
• Female mosquitoes lay dozens of eggs up to 5 times
during their life time.
• The mosquito life cycle, takes 8 days and occurs in water.
Adult mosquitoes live for one month.
• Adult mosquitoes “usually” rest indoors in dark areas (closets, under beds, behind curtains); only female mosquitoes bite humans.
• The dengue mosquito can fly several hundred yards looking for water-filled containers to lay their eggs.
• The dengue mosquito does not lay eggs in ditches, drainages, canals, wetlands, rivers or lakes
Aedes aegypti
Aedes albopictus
PATHOPHYSIOLOGY
• Rapid activation of the complement system
• Blood level of soluble TNF receptor, interferon-
gamma,& IL-2 are
• C1q,C3,C4,C5-8 & C3 proactivators are
• These factors interact at the endothelial cell to
produce vascular permeability through the nitric
oxide final pathway
• The blood clotting & fibrinolytic system are & levels of
factor XII are
• Capillary damage allows fluid, electrolytes & small
proteins ,red cells to leak into extravascular spaces
• This internal redistribution of fluid together with deficits
caused by fasting, thirst,vomiting results in
hemoconcentration,hypovolaemia, increase cardiac work,
tissue hypoxia, metabolic acidosis & hyponatremia
CLINICAL MANIFESTATIONSCLINICAL MANIFESTATIONS
Four dengue clinical syndrome
• Undifferentiated fever
• Classic dengue fever
• Dengue hemorrhagic fever(DHF)
• Dengue Shock Syndrome (DSS)- a severe form of
DHF
Undifferentiated fever
• Most common presentation
• Silent transmission
• Incubation period of 3-14 days(average 4-7 days)
• Sudden onset of fever, biphasic
• Severe headache(retro-orbital)
• Myalgias & arthalgias that may be severe
• Nausea & vomiting
• Rash may be present at the different stages of
illness- maculpapular, petechial, erythematous
• Hemorrhagic manifestations
DENGUE HEMORRHAGICDENGUE HEMORRHAGIC FEVERFEVER
Dengue Hemorrhagic Fever
• Usually develops around 3rd -7th day of illness
• There is rapid onset of plasma leakage, altered hemostasis,
and damage to the liver, resulting in severe fluid losses and
bleeding
• Skin hemorrhage-petechiae, purpura, ecchymosis
• Gingival & nasal bleeding,Hematuria
• GI bleeding- haetamesis,melena,haematochezia
• Plasma leakage is due to increased capillary
permeability ;manifest as hemoconcentration, pleural
effusion & ascites.
• Bleeding due to capillary fragility & thrombocytopenia
• Liver damage manifests as increases in levels liver
enzymes, low albumin levels, and deranged coagulation
parameters(PT,PTT)
3 phases of DHF
• Febrile phase : 2-7 days Sudden onset fever
Severe headache
Epigastric discomfort,anorexia, vomiting
Arthralgia, myalgia
Flushing
Tender hepatomegaly, splenomegaly
Maculopapular rash
Leakage phase
• 1ST 24-48 HOURS• Pleural effusion• Ascities• Pericardial effusion• Haemorrhagic menifestation• Haematemesis,malena ,epistaxis & menorrhagia
Convalescent phase
Short & uneventful
• Short & uneventful• Return of appetite• Bradycardia• Recovery rash• Severe itching on palms & soles• of appetiteBradycardiaRecovery z
Criteria to label Dengue Criteria to label Dengue Hemorrhagic FeverHemorrhagic Fever
WHO case definition of DHF• Fever-sudden onset 2-7 days
• Hemorrhagic manifestations with positive tourniquet test
• Low platelet count(1,00,000/mm3 or less)
• Objective evidence of plasma leak syndrome
– Hematocrit ≥ 20% above baseline
– Low albumin
– Pleural/pericardial effusions
Four grades of DHF
• Grade I- Fever & non-specific constitutional symptoms
Positive tourniquet test is only hemorrhagic manifestations
• Grade II- Grade I manifestations + spontaneous bleeding
• Grade III-signs of circulatory failure• Grade IV- profound shock (undetectable pulse &
BP)
Danger signs in Dengue Hemorrhagic Fever
• Abdominal pain-intense & sustained
• Persistent vomiting
• Abrupt change from fever to hypothermia, with
sweating
• Change in mental status of the patient
Unusual presentation of Severe Dengue Fever
• Encephalopathy
• Liver failure or fulminant hepatitis
• Demonstrated by Increase aminotransferas,
increase bilirubin, incresae PT,APTT
• Cardiomyopathy-conduction defects, myocarditis
• Severe GI hemorrhage
Risk Factors
• Age: all groups are affected
• Pre-existing anti –dengue antibody,either caused by
previous infection or to maternal antibodies passed to
infants
• Higher risk in secondary infections
• Higher risk inlocations with two or more seroypes
circulating simultaneously at high levels
TOURNIQUET TESTTOURNIQUET TEST
• Inflate BP cuff to a point midway between SBP & DBP
for 5 minute
• After deflating the cuff, wait for the skin to return to its
normal colour ,then count the number of petechiae
visible in one inch-square area on the ventral surface of
the forearm
• Positive test:Positive test:20 0r more petechiae per one inch2
Positive Tourniquet Test• A typical positive result from a tourniquet test may look like. This patient has more than 20 petechiae per square inches.
Dengue Shock Dengue Shock SyndromeSyndrome
Four criteria • Evidence of circulatory failure, manifested indirectly by all
of the following
– Rapid & weak pulse
– Narrow pulse pressure (≤ 20 mm Hg or hypotension for
age)
– Cold, clammy skin & altered mental status
– Frank shock
Laboratory tests in Dengue Fever
• Complete blood count:– WBC-leucopenia,lymphocytosis– Platelets-thrombocytopenia– Hematocrit:≥20% of the baseline
• Liver function tests:– serum aminotransferases:deranged– Serum bilirubin:increased– serum albumin:low
• Coagulation studies –PT,APTT:prolongrd
• Serum electrolytes:deranged
• Blood gases:metabolic acidosis
• Tourniquet test:positive
• Complement levels:low
• Blood urea:raised
• Chest X-ray- for effusions
• ECG- sinus bradycardia, prolonged PR interval
• Serological diagnosiso ELISA Anti dengue IgM & IgG Ab Sensitivity 84-98% Specificity 100%o Haemagglutination inhibition testo Complement fixation test
• Virus isolation• Molecular detection - PCR
Treatment
• Mainly Supportive
• No hemorrhagic manifestations & well hydrated:
patient sent home with instructions for “follow up”
• If hemorrhagic manifestations/hydration status
borderline-patient observed in hospitals
• If warning signs are present even without evidence
of shock or if DSS present-hospitalized
• Intravenous fluids with Electrolyte balance
• Antipyretics-acetaminophen(aspirin and NSAIDS should be
avoided as they interfere with platelet function)
• H2 blockers,antiemetics(Domperidone)
• Platelet and FFP transfusion when needed
• Monitoring of BP, urine output, platelet count and
hematocrit
• Soft,balanced nutritious diet
Mosquito barrier
• Needed until fever subsides(to prevent Aedes
aegypti mosquito from biting patients &
acquiring virus)
• Patients should be kept ideally in screened room
or under mosquito net
Treatment of DHF & DSS• A medical emergency
• Admit in ICU
• Keep the patient in supine position
• Immediate evaluation of vital signs & degrees of
hemoconcentration, dehydration & electrolyte imbalance
• Rapid I/v replacement with wide bore cannula –N/S ideal
fluid of choice
• Monitor CBC, LFTs, S/E, PT/APTT
• When pulse pressure is ≤ 10 mmHg or when elevation of
Hct persists after replacement of fluids; plasma or colloids
are indicated
• FFP & platelets for bleeding
• No role of corticosteroids
• Look for evidence of complications
• Avoid hypervolaemia
Complications
• Fluid & electrolyte losses• Myocarditis • Hepatic dysfunction• Febrile convulsions• Residual brain damage• Encephalopathy • Disseminated Intravascular coagulation• Dengue shock syndrome
Indications for hospital discharge
• Absence of fever for 24 hours(without anti-fever
therapy) & return of appetite
• Visible improvement in clnical picture
• Stable haematocrit
• 3 das after recovery from shock
• platelets ≥ 50,000/mm3
• No respiratory distress from pleural effusion/ascites
Return IMMEDIATELY to clinic or emergency department if
any of the following warning signs appear:
• Severe abdominal pain or persistent vomiting
• Red spots or patches on the skin
• Bleeding from nose or gums , Vomiting blood
• Black, tarry stools
• Drowsiness or irritability
• Pale, cold, or clammy skin
• Difficulty breathing
Dengue Vaccine
• No licensed vaccine at present• Effective vaccine must be tetravalent
• Field testing of an attenuated tetravalent
vaccine currently underway
PREVENTION PREVENTION
Vector control
• Chemical control-
– Larvicides may be used to kill the immature aquatic stages
– Ultra-low volume fumigation is effective against adult mosquitoes
– Mosquitoes may have resistance to commercial aerosols spray
• Biological controlBiological control-largely experimental-Placing fish in containers to eat the larvae
• Environmental controlEnvironmental control– Elimination of larval habitats– Most likely method to be effective in the long
term
Prophylaxis • Avoiding mosquito bites– Use of insecticides– Repellents– Body covering with clothing– Screening of house– Destruction of the vector breeding sites– Using mosquito nets
• If storage is mandatory, a tight fitting lid or a thin layer of oil may prevent egg laying or hatching
• A larvicide (Abate) available as a 1% sand –
granule formations may be added safely to
drinking water
Why to control??/Purpose of control
• Reduce female vector density to a level below
which epidemic vector transmission will not
occur
• The minimum vector density to prevent epidemic
transmission is unknown
Program to minimize the impact of epidemic
• Teaching the medical community how to
diagnose and mange DHF
• Educating the general public to encourage &
enable them to carry out vector control in their
home and neighborhood
Common containers in which eggsdevelop into adult dengue
mosquitoes:
Recent advances
• Gene-modified mosquitos could stop dengue fever : genetically modified mosquitoes wee released last year at sites in Malaysia and the Cayman Islands.
Key MessageKey MessageDengue infection is preventable diseaseNo direct person to person transmissionPrevent Man – Mosquito contact to
prevent the disease