DENGUE MD.KABIUL AKHTER ALI Vector Borne Disease Consultant NVBDCP, NRHM District Heath & Family Welfare Samiti Uttar Dinajpur
Distribution Endemic in more than 100 tropical and subtropical countries Pandemic began in South East Asia after WW II with subsequent global spread Several epidemics since 1980s Distribution is comparable to malaria
EpidemiologyIn India first outbreak of dengue was recorded in1812A double peak hemorrhagic fever epidemicoccurred in India for the first time in Calcuttabetween July 1963 & March 1964In New Delhi, outbreaks of dengue fever reportedin 1967,1970,1982, &1996
Burden of disease in S.E. AsiaCATEGORY-A(INDONESIA,MYANMAR & THAILAND)CATEGORY-B(INDIA,BANGALADESH,MALDIVES & SRILANKA)CATEGORY-C(BHUTAN, NEPAL)CTEGORY-D(DPR KOREA)
Dengue Endemic Areas(1996 to 2010 = 29 States/UTs) Risk factors: •Construction activities • Water storage practice •Population movement •Heavy rainfall •Vector abundance
Dengue Fever Dengue endemic in 29 States/UTs, upsurge observed in 2010 States reported higher numbers of cases in 2010 (as on Dec 31) Dengue being reported from newer areas (Assam, Meghalaya, Chhattisgarh, Jharkhand, Manipur, Nagaland, Uttarakhand ,A&N Islands)
WHAT IS DENDUE ?•Dengue is a viral disease•It is transmitted by the infective bite of female Aedes Aegypti mosquito•Man develops disease after 5-6 days of being bitten by an infectivemosquito•It occurs in two forms: Dengue Fever and Dengue HaemorrhagicFever(DHF)•Dengue Fever is a severe, flu-like illness (Influenza)•Dengue Haemorrhagic Fever (DHF) is a more severe form ofdisease, which may cause death•Person suspected of having dengue fever or DHF must see a doctor at once
Dengue clinical syndromeThere are actually four dengue clinical syndromes:1. Undifferentiated fever;2. Classic dengue fever;3. Dengue hemorrhagic fever, or DHF; and4. Dengue shock syndrome, or DSS.Dengue shock syndrome is actually a severe form of DHF.
CLASSIS DENGUE Acute febrile illness with headache, retro-orbital pain, myalgia, arthralgia “Break-bone fever” High fever 5-7 days Second fever for 1-2 days in 5% patients Followed by marked fatigue days to weeks Classic dengue 15-60% of infections Nausea, vomiting, diarrhea (30%) Macular or maculopapular rash (50%) Respiratory symptoms: cough, sore throat (30%)
SIGNS & SYMPTOMS OF DENGUE FEVER•Abrupt onset of high fever•Severe frontal headache•Pain behind the eyes which worsens with eye movement•Muscle and joint pains•Loss of sense of taste and appetite•Measles-like rash over chest and upper limbs•Nausea and vomiting
Dengue Hemorrhagic FeverWHO classification of DHF Usually occurs in secondary infections after actively or passively Thrombocytopenia (platelet count (maternal) acquired immunity to a <100,000) different viral serotype Only 2-4% of secondary infections Fever 2-7 days result in severe disease Hemorrhagic manifestations with a Mortality is 10-20% if untreated, positive tourniquet test but decreases to <1% if adequately Hemoconcentration or evidence of treated plasma leakage Plasma leakage may progress to dengue shock syndrome
SIGNS & SYMPTOMS OF DENGUEHAEMORRHAGIC FEVER AND SHOCK SYNDROM• Symptoms similar to dengue fever•Severe continuous stomach pains•Skin becomes pale, cold or clammy•Bleeding from nose, mouth & gums and skin rashes•Frequent vomiting with or without blood•Sleepiness and restlessness•Patient feels thirsty and mouth becomes dry•Rapid weak pulse•Difficulty in breathing
AGENT FACTORS•The dengue viruses are the members of the genusflavivirus. These small (50nm)viruses contain single strandedRNA.•There are four virus serotypes, which are designated asDEN-1, DEN-2, DEN-3 and DEN-4.•Although all four serotypes are antigenicaly similar, theyare different enough to elicit cross-protection only for a fewmonths after infection by any one of them. Infection withany one serotype confers lifelong immunity to the virusserotype.•Man and mosquito are reservoirs of infection. Transovariantransmission (infection carried over to next progeny ofmosquitoes through eggs) has made the control morecomplicated.•At present DEN1 and DEN2 serotypes are widespread inIndia
VECTOR OF DENGUE• Dengue is transmitted by the bite of female Aedes mosquito• In India Ae. aegypti is the main vector in most urban areas; however, Ae albopictus is also found as vector in few areas of southern India.• Female Aedes mosquito deposits eggs singly on damp surfaces justabove the water line. Under optimal conditions the life cycle of aquaticstage of Ae. Aegypti (the time taken from hatching to adultemergence) can be as short as seven days• The eggs can survive one year without water. At low temperature,however, it may take several weeks to emerge. Ae. aegypti has anaverage adult survival of fifteen days. During the rainy season, whensurvival is longer, the risk of virus transmission is greater. It is a day timefeeder and can fly up to a limited distance of 400 meters. To get one fullblood meal the mosquito has to feed on several persons, infecting all ofthem.
TRANSMISSION CYCLE OF DENGUE##There is evidence that vertical transmission of dengue virus from infectedfemale mosquitoes to the next generation occurs through eggs, which is known astransovarian transmission.
TRANSMISSION CYCLE OF DENGUE1.The virus is inoculated into humans with themosquito saliva.2.The virus localizes and replicates in various targetorgans, for example, local lymph nodes and theliver.3.The virus is then released from these tissues andspreads through the blood to infect white bloodcells and other lymphatic tissues.4.The virus is then released from these tissues andcirculates in the blood.5.The mosquito ingests blood containing the virus.6.The virus replicates in the mosquito midgut, theovaries, nerve tissue and fat body. It then escapesinto the body cavity, and later infects the salivaryglands.7.The virus replicates in the salivary glands andwhen the mosquito bites another human, the cyclecontinues.
Few common and favouredbreeding places/sites ofAe. aegypti
LABORATORY DIAGNOSIS OF DENGUE Haemagglutination inhibition (HI) test Compliment Fixation Test (CFT) Neutralization test (NT) IgM-capture Enzyme-Linked Immunosorbent Assay (MAC-ELISA) ndvbcp recommended IgG-ELISA Rapid Diagnostic tests (NS 1)
Management of Dengue Fever (DF)• No specific therapy, management of Dengue fever is symptomatic andsupportivei. Bed rest is advisable during the acute phase.ii. Use cold sponging to keep temperature below 39o C.iii. Antipyretics may be used to lower the body temperature. Aspirin/NSAID likeIbuprofen etc should be avoided since it may cause gastritis, vomiting, acidosisand platelet disfunction.Paracetamol is preferable in the doses as follows:1-2 years: 60 -120 mg/doses 3-6 years: 120 mg/dose 7-12 years: 240 mg/doseAdult : 500mg/doseIn children the dose is calculated as per 10mg/KG Body Weight per dosewhich can be repeated at the interval of 6hrsiv. Oral fluid and electrolyte therapy are recommended for patients withexcessive sweating or vomiting.v. Patients should be monitored in DHF endemic area until they becomeafebrile for one day without the use of antipyretics and after platelet andhaematocrit determinations are stable, platelet count is >50,000/ cumm.
Vaccination No current dengue vaccine Estimated availability in 5-10 years Vaccine development is problematic as the vaccine must provide immunity to all 4 serotypes Lack of dengue animal model Live attenuated tetravalent vaccines under phase 2 trials New approaches include infectious clone DNA and naked DNA vaccines
PreventionPersonal: clothing to reduce exposed skin insect repellent especially in early morning, late afternoon. Bed netting important mosquito repellants(pyrethroid based) coils, sanitation measuresEnvironmental: reduced vector breeding sites solid waste management public education empty water containers and cut weed/tall grass
PreventionBiological: Target larval stage of Aedes in large water storage containers Larvivorous fish (Gambusia), endotoxin producing bacteria (Bacillus), copepod crustaceans (mesocyclops)Chemical:Thermal fogging-malathion,pyrethrum Insecticide treatment of water containers Space spraying (thermal fogs) Indoor space spraying(2% pyrethrum), organophosphorus compounds
Social IssuesAlthough the goal of disease control is to prevent epidemictransmission, if an epidemic does occur, ways to minimize itsimpact include:•Teaching the medical community how to diagnose and managedengue and dengue hemorrhagic fever (DHF), so they are betterprepared to effectively manage and treat large numbers of cases.Mortality from DHF will thus be minimized.•Implementing an emergency contingency plan to anticipate thelogistical issues of hospitalizing large numbers of patients and tooutline measures for community-wide vector control activities.Such plans should be prepared with the participation of all partiesand agencies involved, and should be ready for implementationprior to the emergence of an epidemic.•Educating the general public to encourage and enable them tocarry out vector control in their homes and neighborhoods.
Public Health Major and escalating global public health problem Global demographic changes: urbanization and population growth with substandard housing, water, and waster management systems Deteriorating public health infrastructure with limited resources resulting in “crisis management” not prevention Increased travel Lack of effective mosquito control
Initiatives Strategic action plan Guidelines on clinical management 13 centers identified for Apex Referral laboratories for diagnosis/treatment and surveillanceICMR Virus Unit, Kolkata. 137 sentinel surveillance hospitals amongst them in west bengal 1.Burdwan Medical College Hospital. 2. School of Tropical Medicine, Calcutta NIV Pune to supply ELISA kits Contingency grant made available IEC/BCC