Presentation on theme: "A Sudden Seizure by a Demon…"— Presentation transcript:
1 A Sudden Seizure by a Demon… Dengue The DangerA Sudden Seizure by a Demon…Group no. 20 , 3rd yearI.Ya. Horbachevsky Ternopil State Medical University.
2 INTRODUCTIONDengue is caused by 4 flavivirus serotypes (DEN1-4). The incidence of dengue fever (DF) & dengue hemorrhagic fever (DHF) has increased 30 fold globally in the last 4 decades and more than half the world’s population is now threatened with it’s infection. According to WHO 100 million attacks of DF, 2,50,000 DHF occur annually with 25,000 unfortunate deaths.
3 Epidemiological evidences show that DHF & DSS (dengue shock syndrome) occur more frequently on re-infection with a second serotype.
4 EpidemiologySince the 18th. Century, dengue has caused repeated epidemics worldwide. H.Graham in 1903 implicated Aedes aegypti as the vector for the disease and the virus was isolated in 1944 by Albert Sabin. DHF gained nosologic status in 1954 and subsequently became endemic in many areas of tropical world. Dengue now affects >100 countries all over the world except Europe.
6 Some important datal In India, the first recorded outbreak was in 1812.l 60 outbreaks have been reported during the period 1956 to 2001.l cases and 423 deaths in the year 1996 in Delhi.l India, 2006: cases, 217 deaths
7 Dengue cases reported in india in september 2006 STATESNumber of cases reported.
9 A child with dengue hemorrhagic fever or dengue shock syndrome may present severely hypotensive with disseminated intravascular coagulation (DIC)
10 Etiology Causative agent: 4 dengue viruses within the genus flavivirus are found in India.Dengue virions are small particles with lipoprotein envelope containing E proteins and nucleocapsid of single stranded RNA genome.There is a close antigenic similarity among the 4 serotypes but cross protection in human is at best partial and transient.DEN-2 is more virulent than other 3 serotypes.
13 A TEM micrograph showing dengue virus Virus classificationGroup:Group IV ((+)ssRNA)Family:FlaviviridaeGenus:FlavivirusSpecies:Dengue virus
14 B) Transmission: Reservoir of infection is both man & mosquito. The transmission cycle is “Man-Mosquito-Man”.Aedes aegypti is the principal vector, other less important vectors being Aedes albopictus, Aedes polynesiensis and several species of Aedes scutellaris complex.
15 Incubation periodE3-14 days with mosquitoes remaining infected for life. The outbreaks coincide with the monsoon.
19 PathogenesisAfter the bite by an infected mosquito, the virus replicates in the regional lymph nodes of the affected individual and is disseminated via the lymph and blood to the other tissues.DHF & DSS are characterised by abnormally increased capillary permeability and disordered haemostasis. The DHF/DSS are primarily seen in the young(<12yrs.) & mostly in secondary infection.
20 Pathology The pathologic findings include: Depression of all haemopoietic cells including megakaryocytes in bone marrow.Active proliferation and lymphocytolysis in germinal centers in lymph nodes & spleen.Focal mid-zonal necrosis and fatty changes in liver.Occasionally glomerulonephritis ( immune- complex deposition).
22 Clinical features Classic Dengue (“Break-bone fever”) Abrupt onset of fever ĉ chill, headache, retro-orbital pain & low backache. The fever is typically high and occasionally followed by remission lasting for a few hours to 2 days, comes again following appearance of rash (saddle-back fever) & lasts for 5-7 days.Transient generalized erythematous flush like or typical morbilliform rash appears on trunk spreading to face & extremities sparing palms &soles. It may be accompanied by itching.
23 Generalised myalgia, arthralgia. Constitutional symptoms like anorexia, nausea, vomiting may be present.Relative bradycardia, generalized lymphadenopathy.Convalescence may be accompanied by asthenia & bradycardia.
26 Clinical feature (contd.) B) Dengue haemorrhagic fever (DHF):The critical stage is reached after 2-7 days when fever subsides & circulatory disturbances start appearing as -Ascites.Petechiae, purpura, echymoses.Epistaxis, gum bleeding, GI haemorrhage etc.Generalized abdominal pain with tenderness over right costal margin.Hepatomegaly.
27 Clinical feature (contd.) C) Dengue shock syndrome (DSS)Some patients of DHF manifest signs of restlessness, abdominal pain and shock (rapid weak pulse, cold clammy extremities, diaphoresis, circumoral cyanosis, irritability or drowsiness). These cases, known as DSS, are characterised by severe hypotension or undetectable BP & pulse.The duration of shock is very short & the patient may die ĉ in hrs.
29 ..Investigation.. A) Virus isolation From blood during febrile phase. Newer diagnostic techniques:RT-PCR (Reverse transcriptase polymerase chain reaction). Very sensitive & specific for detection of viral RNA.Hybridization probe- identification of viral nucleic acids.Immuno-cytochemical methods- for detecting Dengue virus antigen.
30 B) SerologyHemagglutination inhibition assays:- It is the WHO recommended reference test for dengue virus infection. Disadvantages of these tests areTime consumingCannot identify specific serotypesCross-reaction with other related flaviviruses.
31 Interpretation of hemagglutination inhibition test S1 (1st.sample taken on adm.)S2 (2nd.sample taken after days)Interpretation<1:20<1:1280Primary Dengue>1:20>1:1280Secondary Dengue---Presumptive e/oSecondary Dengue
32 Commercial Dengue blot assay: It is a rapid diagnostic test, which is as sensitive as haemagglutination inhibition assay in diagnosing a secondary dengue infection but not so in case of primary infection.
33 ELISAThe IgM antibody– Capture ELISA (MAC-ELISA) is specially useful in diagnosis of recent infection.IgG ELISA has results and interpretation same as haemagglutination inhibition assay.
34 GUAIAC TESTSigns of early coagulopathy may be as subtle as a guaiac test positive for occult blood in the stool. This test should be performed on all patients in whom dengue virus infection is suspected.
35 Other associated lab. Findings WBC count- May be normal but leucopenia is common. Neutropenia occurs towards end of febrile phase. Relative lymphocytosis ĉ >15% atypical lymphocytes is common in DHF/DSS.ThrombocytopeniaRising haematocritHypoproteinaemia/ mild albuminuria
36 ..Treatment.. A) Classical Dengue Treatment of dengue fever is symptomatic only. Bed rest, sponging, Paracetamol,oral rehydration, which is most important from day1.B) Dengue haemorrhagic fever (grade I & II)The patient should be hospitalized.Management of fever is same as classic dengueFluid replacement is through IV line.
37 PrognosisThe case fatality rate varies greatly on the condition of the patient at admission and the quality of available treatment. However, most DHF/DSS patients respond well to supportive therapy, and overall mortality in an experienced center is as low as 1%.
38 Measures to control outbreaks Initiate vector control measures (eg. Residual spraying).Ensure community participation.Assess facilities for case management of patients with haemorrhagic shock.Alert health personnel to report increase /clustering of cases.Measures for prevention of mosquito bites to be conveyed to general population:
39 Measures (contd.) Wear clothes that cover full arms & legs Mandatory use of mosquito nets/repellantsKeep patients protected from mosquito bite in acute phaseElimination of mosquito breeding places:Empty water tanks once a weekCover & seal septic tanks and soak away pits.Regular removal of rubbishChange water of coolers & other stagnant domestic water sources etc.
41 Eradication of mosquito breeding grounds by spraying of insecticides
42 ..Immunisation..Tetravalent vaccines are in advanced stage (phase III) of development in Thailand and are expected to be available in near future (within 5-10yrs).
43 ..Conclusion..Though Dengue fever is usually a self-limiting disease, lack of proper monitoring and adequate volume replacement may lead to fatal outcome.In view of emerging outbreaks of dengue fever in various states of India, it becomes imperative for primary care physicians to have an updated knowledge of its early diagnosis and recent management guidelines.