Dengue fever Epidemiology - pathogenesis - symptoms - diagnosis - Management - Complications

A mosquito-borne viral disease occurring in tropical and subtropical areas.
Spreads by animals or insects
Requires a medical diagnosis
Lab tests or imaging often required
Short-term: resolves within days to weeks

Those who become infected with the virus a second time are at a significantly greater risk of developing severe disease.
Symptoms include high fever, headache, rash and muscle and joint pain. In severe cases there is serious bleeding and shock, which can be life threatening.
Treatment includes fluids and pain relievers. Severe cases require hospital care.

1. Presenter: Dr.Arun Vasireddy Dengue Fever Subject Seminar - 6 th July,2015

2. Introduction Epidemiological Scenarios & Demographics Etio -pathogenesis Pathophysiology Clinical picture Evaluation & Diagnosis Management of DF/DHF/DSS Prevention & Control Future Directions Overview

3. Dengue fever, a.k.a,Breakbone fever - identified as the most common arboviral (arthropod-borne) disease worldwide by WHO . Transmitted by female mosquitoes of the genus Aedes , subtropical and tropical geographical distribution. 5 antigenically distinct serotypes – (DENV 1-5) 5 TH serotype was discovered in October 2013 in malaysia .(sylvatic) Introduction

4. GLOBAL SCENARIO ( WHO , 2014) 30-fold increase in global incidence over the last five decades . According to WHO, recent estimate indicates 390 million dengue infections annually ,of which 96 million manifest clinically. 3.5-5 lakh cases of DHF/DSS per year About 3900 million people, in 128 countries, are at risk of infection.   75% of global disease burden is in Asia-Pacific region. A ctual no. of dengue cases are underreported/misclassified . Source: http ://www.who.int/mediacentre/factsheets/fs117/en/

5. INDIAN SCENARIO Dengue virus was isolated in India for the first time in 1945 . The first recorded epidemic of clinically Dengue like illness occurred at Madras in 1780 . The first evidence of occurrence of dengue fever in the country was reported in 1956 from Vellore district in Tamil Nadu. The first dengue hemorrhagic fever(DHF) outbreak occurred in Calcutta in 1963 . All 4 serotypes are found in Indian population Since 1996, the area of endemicity is increasing with about 450 million population at risk At present, dengue is endemic in 23 states Mortality rates are 10-20% (40% in case of DSS)

6. CDC Outbreak Report (southern asia ) 2012-14

7. REASON FOR CHANGE IN EPIDEMIOLOGY Incidence increased 30-fold in last 50 years due to :

8. Epidemiology It depends on 3 factors : Agent – virus. Environment . Host – man & mosquito.

9. Agent - Dengue virus Dengue virus belongs the genus flavivirus . These viruses contain a single stranded RNA as its genome and are small in size (30-45nm). There are five antigenically distinct serotypes (DENV 1-5) with abundant genetic variation. These serotypes may be in circulation either in singular, or more than one can be in circulation in any geographical area at the same time. Antigens can cross react with other members in the same genus. Infection with any one serotype confers lifelong immunity to the virus serotype.

10. The genome encodes only 10 proteins. Out of ten, 3 are structural proteins that form the coat of the virus and deliver the RNA to target cells – 1k4r ,the nucleocapsid of core protein , 1ok8 , a membrane associated protein (M), 2r6p6, an envelope protein(E ). 7 are non-structural (NS) proteins that orchestrate the production of new viral antigens once the virus invades the cell - NS1, NS2A, NS2B, NS3, NS4A, NS4B and NS5 In dengue virus infection, pts have measurable levels of NS1 protein in the blood, a diagnostic marker of the infection . Dengue virus Ref: Goodsell DS. RCSB Protein Data Bank. July, 2008.

11. DENV is transmitted by the bite of female aedes mosquito. In India, Aedes aegypti is the main vector in most urban areas. Rarely by Ae.Albopictus , Ae.polynesiensis , Ae.niveus in some states. P opulation & Lifespan depends on - rainfall , water storage, temperature and humidity. Year round breeding - ( 10⁰ C Isotherm). 30 N to 40 S latitude distribution - Tropics and sub-tropics survives best between 16 ⁰ C and 30 ⁰ C and a relative humidity of 60–80%. Altitude is also a limiting factor for the distribution and is restricted to between sea level and 1000 ft above sea level. Vector/Intermediate Host

12. To find a host, these mosquitoes are attracted to chemical compounds emitted by mammals. These compounds include  ammonia ,  carbon dioxide ,  lactic acid , and  octenol . most commonly bite at dusk and dawn, indoors & in shady areas. Breed in areas of  stagnant water , such as flower vases, uncovered barrels, buckets, and discarded tires, but the most dangerous areas are wet shower floors and toilet tanks, as they allow the mosquitos to breed in the residence. Research has shown that certain chemicals (fatty acids associated with bacteria involved in the degradation organic matter in water) stimulate the female mosquitoes to lay their eggs. Can transmit the infection trans- ovarially . Peculiarities of A.aegypti

13. Host - Primates The DENV infects humans and several species of lower primates. People of all ages and both genders are at risk. (more in <15 yrs age groups & in females) Secondary dengue infection is a risk factor for DHF, including passively acquired antibodies in infants. Travel to dengue endemic areas is a most important risk factor. Migration of a patient during viremia to a non-endemic area may introduce dengue into that area. The geographical spread of dengue has been reported to occur mainly by people travelling from endemic areas to non-endemic areas .

14. How dengue is transmitted? Because of the high level of viraemia resulting from DENV infection of humans, the viruses are efficiently transmitted between mosquitoes and humans without the need for an enzootic/ s ylvantic amplification host. Whitehead SS, Blaney JE, Durbin AP, Murphy BR. Prospects for a dengue virus vaccine. Nature Reviews Microbiology 5, 518-528 (1 July 2007) Available from: http:// www.nature.com / nrmicro /journal/v5/n7/full/nrmicro1690. html

15. Transmission & Pathogenesis Viremia Viremia Extrinsic incubation period DAYS 5 8 12 16 20 24 28 Human #1 Human #2 Illness Mosquito feeds / acquires virus Mosquito refeeds / transmits virus Intrinsic incubation period Illness

16. Increased Probability of DHF Hyper- endemicity Increased circulation of viruses Increased probability of secondary infection Increased probability of occurrence of virulent strains Increased probability of immune enhancement Increased probability of DHF

17. Neutralizing antibody to Dengue 1 virus 1 1 Dengue 1 virus 1 Pathogenesis of DHF (ADE ) STEP 1- Homologous Antibodies Form Non-infectious Complexes Non-neutralizing antibody 1 1 Complex formed by neutralizing antibody and virus

18. Non-neutralizing antibody to Prior DENV infection Dengue 2 virus 2 2 2 2 2 STEP 2- Heterologous Antibodies of first serotype infection form Infectious Complexes with second serotype Ag- Ab Complex formed by non-neutralizing antibody and virus 2

19. 2 2 2 2 2 2 2 2 2 2 STEP 3 - Heterologous Complexes Enter More Monocytes & macrophages, Where Virus Replicates Non-neutralizing antibody Dengue 2 virus 2 Complex formed by non-neutralizing antibody and Dengue 2 virus 2

20. STEP 4 –DHF pathogenesis The affected macrophages release vasoactive mediators that increase vascular permeability, leading to vascular leakage, hypovolemia , and shock. Infants born to mothers who have had dengue, as maternally derived dengue neutralizing IgGs wane, are also thought to be at risk for enhanced disease . Activation of classic complement pathway & Cross reactivity at T-cell level results in increased production of IFN- γ & TNF- α leading to Increased vascular permeability & bleeding Antibody dependent enhancement (ADE) & inappropriate memory T-cell response are central to pathogenesis of DHF/DSS

21. Vasculopathy Thrombopathy with impaired platelet function & moderate-severe thrombocytopenia ( due to interaction of virus with platelets through IgM antiplatelet antibody ) Coagulopathy, with activation of coagulation & fibrinolysis, and later in severe disease,DIC . Bone Marrow depression – reduced megakaryocyte production Mechanism – Suppressed megakaryocytopoiesis & increased platelet clearance by DENV induced apoptosis & antiplatelet antibodies. Pathogenesis of DHF –Abnormal Haemostasis

22. FACTORS RESPONSIBLE FOR DHF/DSS Presence of enhancing and non neutralising antibodies Age : susceptibility to DHF/DSS drops significantly after 12 yrs of age Sex : females more often affected than males Race : Caucasians more often affected than blacks Nutritional status : malnutrition is protective Sequence of infection : example, serotype 1 followed by serotype 2 is more dangerous than serotype 4 followed by serotype 2 Infecting serotype : type 2 more dangerous than others Infecting genotype : Asian type 2 causes DHF/DSS while American type is not responsible for the illness

23. Dengue Clinical Syndromes Undifferentiated fever Classic dengue fever Dengue hemorrhagic fever Dengue shock syndrome

24. Natural course The clinical course of illness passes through 3 phases : • Febrile phase • Critical phase • Convalescent phase

25. Febrile phase The onset of dengue fever is usually with sudden rise in temperature which may be biphasic, lasting 5-8 days and commonly associated with headache, flushing and rash . There may be pain in retro-orbital area, muscles, joint or bone. Rash may be maculopapular or rubelliform and usually appear after 3 or 4 day of fever and commonly seen in face, neck and other part of the body which generally fades away in the later part of the febrile phase. Localized cluster of petechiae may appear over upper and lower limbs.

26. Febrile rash of dengue which blanches upon pressure. Convalescent rash of dengue – "White islands in the sea of red". During the first 24-48 hours of fever, children may develop a transient generalized macular erythematous rash which blanches upon pressure . The convalescent rash of dengue fever appears about 2-3 days after defervescence . It is characterized by generalized confluent petechial rash which does not blanch upon pressure, with multiple small round islets of normal skin. It is otherwise called "white islands in a sea of red ".

27. Critical phase DF/DHF patients usually go to critical phase after 3 to 4 days of onset of fever. During this critical phase plasma leakage and high haemoconcentration are documented and patients may develop hypotension. Abnormal haemostasis and leakage of plasma leads to shock,bleeding , accumulation of fluid in pleural and abdominal cavity. High morbidity and mortality in DHF/DSS are commonly associated with various organ involvements and metabolic derangement . The period of plasma leakage usually persists for 36-48 hrs.

28. Convalescent phase (recovery) During the recovery phase the extracellular fluid which was lost due to capillary leakage returns to the circulatory system and signs and symptoms improve. This phase occurs after 6-7 days of fever and last for 2-3 days. (48-72 hours) Longer convalescence may be expected in some of the patients with severe shock, organ involvement and other complications which may require specific treatment. Patient may develop pulmonary oedema due to fluid overload if the fluid replacement is not optimized carefully.

29. Clinical Manifestations of DENV Infection John ALS, Abraham SN, Gubler DJ. Barriers to preclinical investigations of anti-dengue immunity and dengue pathogenesis Nature Reviews Microbiology 11 , 420–426 (2013) Available from: http://www.nature.com/nrmicro/journal/v11/n6/full/nrmicro3030.html

30. Clinical Evaluation in Dengue Fever Blood pressure Evidence of bleeding in skin or other sites Hydration status Evidence of increased vascular permeability-- pleural effusions, ascites Tourniquet test

31. Tourniquet Test Inflate blood pressure cuff to a point midway between systolic and diastolic pressure for 5 minutes Positive test: 20 or more petechiae per 1 inch 2 (6.25 cm 2 )

32. WORK UP OF A PATIENT WITH DENGUE Laboratory diagnosis Virus isolation Genome detection Antigen detection Serological diagnosis Supportive investigations

33. LABORATORY DIAGNOSIS Virus isolation : - cultured mosquito cells /mammalian cells used - “gold standard” - low sensitivity and long detection time Genome detection : nested RT-PCR single step RT-PCR NASBA assay

34. Antigen detection : E/M antigen NS I antigen Serological diagnosis : ELISA IgM & IgG antibody detection

35. APPROXIMATE TIME-LINE OF PRIMARY AND SECONDARY DENGUE INFECTIONS & DIAGNOSTIC METHODS THAT CAN BE USED TO DETECT INFECTION -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16-20 21-40 41-60 61-80 90 >90 Days ONSET OF SYMPTOMS (IN DAYS) NS1 DETECTION VIRUS ISOLATION RNA DETECTION VIRAEMIA IgM PRIMARY IgM SECONDARY IgG PRIMARY IgG SECONDARY

36. COMPARISON OF DIAGNOSTIC TESTS ACCORDING TO THEIR ACCESSIBILITY AND CONFIDENCE DIRECT METHODS INDIRECT METHODS ACCESSIBILITY CONFIDENCE VIRUS ISOLATION GENOME DETECTION NS1 ANTIGEN SEROLOGY IgM SEROLOGY IgG

37. INTERPRETATION OF DENGUE DIAGNOSTIC TESTS Highly suggestive Confirmed One of the following: IgM + in a single serum sample IgG + in a single serum sample with a HI titre of 1280 or greater One of the following: PCR + Virus culture + IgM seroconversion in paired sera IgG seroconversion in paired sera or fourfold IgG titer increase in paired sera

38. ROUGH GUIDE FOR INTERPRETATION OF DENGUE SEROLOGY REPORTS IgM IgG INTERPRETATION Negative Negative Early sample/not dengue Negative Positive (low titre ) Past dengue infection Negative Positive (high titre ) Secondary dengue infection Positive Negative Primary dengue infection Positive Positive (low titre ) Recent primary dengue infection Positive Positive (high titre ) Secondary dengue infection

39. SUPPORTIVE INVESTIGATIONS Complete blood count (CBC) Metabolic panel Serum protein and albumin levels Liver panel Disseminated intravascular coagulation (DIC) panel Chest X-Rays - Effusion USG Abdomen - Ascites

40. Characteristic findings in dengue fever : Thrombocytopenia (platelet count < 100 x 109/L) Leukopenia Mild to moderate elevation of aspartate aminotransferase and alanine aminotransferase values In patients with dengue hemorrhagic fever : Increased hematocrit level secondary to plasma extravasation and/or third-space fluid loss Hypoproteinemia Prolonged prothrombin time Prolonged activated partial thromboplastin time Decreased fibrinogen Increased amount of fibrin split products

41. MARKERS FOR SEVERE DISEASE Increased urinary levels of heparan sulphate Increased plasma levels of pentraxin 3 Decreased serum albumin Increased levels of vascular endothelial growth factor (VEGF) Increased levels of soluble vascular cell adhesion molecule – 1 (VCAM-1)

42. DIFFERENTIAL DIAGNOSIS Dengue-like diseases [ Chikungunya fever , West Nile fever (with rash) & Colorado tick fever, sandfly fever, Rift Valley fever, and Ross River fever (without rash )] Early stages of malaria Mild yellow fever Viral hepatitis Leptospirosis Viral respiratory and influenza like diseases

43. MANAGEMENT OF DF/DHF/DSS

44. OUTPATIENT MANAGEMENT OF A PATIENT WITH DENGUE Advise bed rest Encourage plenty of oral fluid intake (of oral rehydration solution (ORS), fruit juice and other fluids containing electrolytes and sugar) Give paracetamol for high fever if the patient is uncomfortable. Inform the patient about the warning signs

45. INDICATIONS OF HOSPITALISATION Suspect severe dengue and the need for hospitalisation when patient develops : Giddiness cooler extremities compared to trunk & extremities Oliguria with dark urine Rt. hypochondriac pain or severe abdominal pain Bleeding from any site Persistent vomiting Lethargy or irritability/restlessness

46. MANAGEMENT PRIORITIES OF A PATIENT WITH SEVERE DENGUE Replacement of plasma losses Recognition & management of hemorrhage Prevention and management of fluid overload Prevention of iatrogenic infections

47. INITIAL INPATIENT MANAGEMENT Establish IV access Collect samples for blood group, Hb , PCV and platelets Monitor : Pulse volume Blood pressure Abdominal girth Urine output

48. Choice of fluids: Crystalloid vs colloid Colloids provide volume expansion over and above actual fluid volume infused. Crystalloids have no added volume effect. Major concerns with use of colloids are impact on coagulation and allergic reaction. Hence, crystalloids are ideal for initial resuscitation & colloids better serve in severe shock with undetectable blood pressure.

49. Choice of fluids: NS vs RL NS preferred over RL due to risk of worsening tissue acidosis and lactate accumulation when large volumes of RL is infused repeatedly Large volumes of 0.9% saline may lead to hyperchloraemic acidosis (this may aggravate or be confused with lactic acidosis from prolonged shock) When serum chloride level the normal range, it is advisable to change to Ringer’s Lactate.

50. APPROACH TO A PATIENT OF SEVERE DENGUE & COMPENSATED SHOCK - Stabilise ABC Fluid resuscitation (with 1-3 ml/ kg/h of NS/RL over 1 hr ) Observe for improvement (2 hours) Algorithm 1 Algorithm 2 yes no

51. APPROACH TO A PATIENT OF SEVERE DENGUE & HYPOTENSION - Stabilise ABC Fluid resuscitation (with 10-20 ml/kg of isotonic crystalloid /colloid over 15 min ; 1-2 bolus Obtain baseline HCT (before fluids) Correct hypoglycemia & hypocalcemia Observe for improvement Algorithm 1 Algorithm 2 yes no

52. ALGORITHM 1 (for improving patient) Maintainance IV crystalloid / colloid @ 1-3ml /kg/hr after every 2-4 hrs Monitor HCT 6 hrly Check for recurrence of clinical instability & review HCT HCT increases HCT decreases Bolus fluid or increase IV fluid rate Consider fresh BT

53. ALGORITHM 2 (for deteriorating patient) If shock persists inspite of 2-3 rounds of algorithm 2, then the patient is said to be in refractory shock Review baseline HCT High Low Improvement Whole blood/PRBC Algorithm 1 Recheck hematocrit Algorithm 2* Yes No Give 2 nd bolus of crystalloid (colloid in hypotensive shock)

54. APPROACH IN REFRACTORY SHOCK Evaluate for unrecognised morbidities Consider CVP if expertise available CVP low / HCT high CVP normal or high with continuing shock , HCT normal Titrate fluid with care consider ventilation /nasal CPAP in cases with respiratory distress Consider ionotropes / vasopressors Consider ionotrope support depending on SBP - Dopamine/adrenaline(for low SBP) - Dobutamine (for normal/high SBP) Check intra abdominal pressure

55. UNRECOGNISED MORBIDITIES THAT MAY CONTRIBUTE TO REFRACTORY SHOCK CLINICAL CONDITION TREATMENT Occult bleed Co-existing bacterial septic shock /malaria Myocardial dysfunction Elevated intra-abdominal pressure Positive pressure ventilation contributing to poor CO Widespread hypoxic ischemic injury with terminal vasoplegic shock Whole blood/PRBC transmission Antibiotics/ antimalarial plus BT plus cardiovascular support ECHO plus cadiovascular support Cautious drainage Titrated fluid plus cardiovascular support No treatment effective

56. TREATMENT OF HEMORRHAGIC COMPLICATIONS OF DF/DHF/DSS Give 5–10ml/kg of fresh-packed red cells or 10–20 ml/kg of fresh whole blood at an appropriate rate and observe the clinical response Infusion of 600 ml FFP may contribute to a significant increase in platelet count in the first 12 hours, but not thereafter . (Fc receptor blocade inhibiting Immune-mediated platelet destruction) Consider repeating the blood transfusion if there is further blood loss or no appropriate rise in haematocrit after blood transfusion. Factor VIIIa (100 microg / kg) - effective in restoring hemostasis in a limited series of patients with Dengue Shock Syndrome exhibiting life-threatening bleeding episodes. There is little evidence to support the practice of transfusing platelet concentrates and/or fresh-frozen plasma for severe bleeding. It is being practised when massive bleeding can not be managed with just fresh whole blood/fresh-packed cells, but it may exacerbate the fluid overload.

57. MANAGEMENT OF CONGESTIVE PHASE Change over to hypotonic fluid Decrease infusion rate to 3-5 ml/kg BW/hr Diuretics & digitalisation needed in patients with cardiac overload due to regurgitant fluid

58. DOs & DON’Ts OF DF/DHF/DSS DOs DON’Ts Avoid IM injections Administer paracetamol for high fever Use isotonic intravenous fluids for severe dengue Give intravenous fluid volume just sufficient to maintain effective circulation during period of plasma leakage for severe dengue Tight glycemic control Administer aspirin or ibuprofen for fever Use hypotonic intravenous fluids for severe dengue Excessive or prolonged intravenous fluid during severe dengue

59. SPECIAL CONSIDERATIONS Insertion of following carries risk of hemorrhage Nasogastric tube – Orogastric tube preferred Intercostal drain - Judicious use of I.V fluids and furosemide avoids ICDs Central venous line– Intra osseous route preferable Corticosteroids are of no benefit in reducing complications. Efficacy of heparin not documented.

60. SIGNS OF RECOVERY Stable pulse, BP & breathing rate Normal temperature No evidence of external/internal bleeding Return of appetite No vomiting Good urinary output Stable hematocrit Convalescent confluent petechial rash

61. PROGNOSIS Poor prognostic indicators include : Early & profound shock with no detectable diastolic pressure or unrecordable BP. Delayed admission to hospital DSS with gastrointestinal hemorrhage Causes of death in a case of DHF/DSS : Failing to recognize that a patient is in shock Hemorrhages Failing to recognize that patient has entered congestive phase

62. HOW TO PREVENT DENGUE? There is no vaccine for preventing dengue. (Currently, a tetravalent live attenuated CYD dengue vaccine is in stage III of trial in over 30,000 volunteers in >10 countries of asia & america ) B est preventive measure – Eliminate Mosquito breeding spots.

63. Change water in vases on alternate days Remove water from flower-pot plates on alternate day Turn over water storage containers Clear blockages and put insecticide in roof gutters monthly

64. Proper application of mosquito repellents containing 20% to 30% DEET as the active ingredient on exposed skin and clothing decreases the risk of being bitten by mosquitoes Biologic & Genetic manipulation of mosquitoes to reduce life span. The risk of dengue infection for international travelers appears to be small. There is increased risk if an epidemic is in progress or visitors are in housing without air conditioning or screened windows and doors.

65. Dengue is one of the world’s most imp emerging diseases Rising global incidence & explosive epidemics – Major challenge. Further advances : Further understand immunopathogenisis & pathophysiology Identification of better therapeutic agents. Improved diagnostics – early detection to guide evidence based practice. To Predict epidemics early. Develop an effective & balanced functional Vaccine for all serotypes. To address the public about the disease as a global threat. Conclusion & Future Directions

66. References: Harrison’s principles of Internal Medicine 18 th Ed. Manson's Tropical Infectious Diseases 23rd Ed. Park's Textbook of Preventive and Social Medicine 22/ e Api textbook of medicine 10 th Ed. Ferri's Clinical Advisor 2015 Online Source: WHO & CDC Factsheets (2013-15) Medscape reference.