epidemiology of DENGUE.pptx..................

Dengue (break-bone fever) is a viral infection that is spread from mosquitoes to people. It is more common in tropical and subtropical than in temperate climates

1. EPIDEMIOLOGY OF DENGUE Prepared By Krupa mathew.M , Associate professor

2. DENGUE Dengue fever is a self limiting disease caused by Dengue viruses (ARBOVIRUS).

3. Is a single-stranded RNA viruses that belong to the family Flaviviridae and the genus Flavivirus single-stranded RNA viruses that belong to the family Flaviviridae and the genus Flavivirus Aedes aegypti and Aedes Albopictus are the two most important vectors of dengue. A PREVALENCE OF Aedes aegypti and Aedes albopictus together with the dengue virus tends to be associated with the outbreaks.

4. AGENT The dengue virus belongs to a distinct complex within the genus flavivirus based on antigenic and biological characteristics. Four serotypes DENV 1, DENV 2, DENV 3, DENV 4 VECTORS Aedes aegypti and Aedes Albopictus are the two most important vectors of dengue. Both the mosquitoes carry vectorial competency for dengue virus (high susceptibility to infecting virus, ability to replicate the virus and ability to transmit the virus to another host. Aedes aegypti is a highly domesticated, strongly anthropophilic , nervous feeder (it bites more than one host to complete one blood meal)

5. Host factors All the age groups and both sexes are affected ENVIRONMENTAL FACTORS Rainy season Water stagnation

6. The population of Ae.aegypti fluctuates with rainfall and water storage. It’s life span is influenced by temperature and humidity. The mosquito survives best between 16 to 30 degree C, and a relative humidity of 60-80%. It breeds in the containers in and around the houses. Being a domestic feeder, it is a endophagic and endophilic . The failure of urban authorities to provide civil amenities and poor public health infrastructure raises the potential for the vector to breed at high level and makes the environment transmission conducive.

7. TRANSMISSION Vector borne transmission Dengue virus is transmitted by female mosquitoes

8. Aedes aegypti mosquito becomes infective by feeding on a patient from the day before onset of the fifth day (viraemia stage) of illness. After an extrinsic incubation period of 8 to 10 days, the mosquito becomes infective, and is able to transmit the infection. Once the mosquito becomes infective it remains so for life. The genital tract of the mosquito gets infected and transovarian transmission of dengue virus occurs when enters fully developed egg at the time of oviposition.

9. HIGH RISK PATIENTS Infants and elderly. Obesity. Pregnancy. Peptic ulcer disease. Women in mensturation who have an abnormal bleeding. Haemolytic diseases. Congenital heart Diseases. Chronic diseases. Patients on steroids.

10. Also is a discordant species(it needs more than one feed for the completion of the genotropic cycle). This habit results in the generation of multiple cases in the cities.

11. CLINICAL MANIFESTATION Dengue virus infection may be Asymptomatic or may cause Symptomatic Undifferentiated febrile illness (viral syndrome) Dengue fever (DF) Dengue haemorrhagic Fever (DHF) including Dengue Shock Syndrome (DSS).

12. UNDIFFERENTIATED FEVER Infants, children and adults who have been infected with dengue virus, especially for the first time may develop a simple undistinguishable fever from other viral infection. Maculopapular rashes may accompany the fever or may appear during defervescence . Upper respiratory and gastrointestinal symptoms are common.

13. CLASSICAL DENGUE FEVER The illness is characterized by an incubation period of 3 to 10 days (commonly 5 to 6 days). The onset is sudden, with chills and high fever , intense headache, muscle and joint pains which prevent all movement. Within 24 hours retro-orbital pain, particularly on eye movements or eye pressure and photophobia develops. Fever is usually between 39 and 40 degree C. Other symptoms include extreme weakness, anorexia, constipation, altered taste sensation, colicky pain, abdominal tenderness, sore throat, general depression

14. The skin eruptions appear in 80% of cases during the remission or during the second febrile phase, which lasts for 1- 2 days. The rash may be diffuse, flushing, mottling or fleeting pin – point eruptions on the face, neck and chest during the first half of the febrile period and a conspicuous rash, that may be maculopapular on the third or the fourth day. It starts on the chest and trunk and may spread to the extremities rarely to the face. It may be accompanied by itching and hyperaesthesia . The rash lasts for 2 hours to several days and may be followed by desquamation. Fever lasts for about 5 days, rarely more than a week after which recovery is usually complete although convalescence may be protracted.

15. DHF DHF is a severe form of dengue fever. The course of dengue illness can be divided into three febrile phases 1. FEBRILE PHASE. 2. CRITICAL PHASE. 3. RECOVERY PHASE

16. FEBRILE PHASE Following an incubation of 4 to 6 days, the illness commonly begins abruptly with a high fever accompanied by facial flushing and headache. Anorexia, vomiting, epigastric discomfort, tenderness at the right costal margin and generalized abdominal pain are common. During the first phase of the illness usually resembles classical DF, but maculopapular rash is less common. It may appear early or late in the course of illness. Occasionally, the temperature may be 40 degree to 41 degree C and febrile convulsions may occur particularly in infants

17. A positive tourniquet test is the most common haemorrhagic phenomenon. The test is performed by inflating a blood pressure cuff to a mid point between systolic and diastolic pressure for 5 min. The test is considered positive when 10 or more petechiae per 2.5 x 2.5 cm -1 inch square) are observed. In DHF, the test usually gives a definite positive with 20 petechiae or more

18. CRITICAL PHASE The critical phase of dengue begins at defervescence and typically lasts 24–48 hours. Most patients clinically improve during this phase, but those with substantial plasma leakage can , within a few hours, develop severe dengue as a result of a marked increase in vascular permeability. Initially, physiologic compensatory mechanisms maintain adequate circulation, which narrows pulse pressure as diastolic blood pressure increases. Patients with severe plasma leakage may have pleural effusions, ascites, hypoproteinemia , Patients may appear to be well despite early signs of shock. However, once hypotension develops, systolic blood pressure rapidly declines, and irreversible shock and death may ensue despite resuscitation. Patients can also develop severe hemorrhagic manifestations, including hematemesis, bloody stool, or menorrhagia, especially if they have been in prolonged shock . Uncommon manifestations include hepatitis, myocarditis, pancreatitis, and encephalitis.

19. RECOVERY PHASE If the patient survives the 24-48 hour critical phase, a gradual re absorption of extra vascular compartment fluid takes place in the following 48-72 hours. General wellbeing improves, appetite returns, gastro intestinal symptoms abate, haemodynamic status stabilizes and diuresis ensues. Some may experience generalized pruritis Bradycardia and ECG changes are common during this stage. The haematocrit stabilizes or may be lower due to the dilution effect of reabsorbed fluid. Some patients may have a rash of “isles of white in the sea of red”.

20. WBC count starts to rise soon after defervescence ., but the recovery of platelet count is typically later than that of WBC count. Respiratory distress from massive pleural effusion and ascitis will occur any time if excessive IV fluids have been administered. Often due to fluid therapy pulmonary oedema or Congestive Heart Failure may be reported during the treatment

21. SEVERE DENGUE Severe dengue is defined by one of the following: 1. Plasma leakage that may lead to shock 2. Severe bleeding 3. Severe organ impairment. As dengue vascular permeability progresses, hypovolaemia worsens and results in shock. It usually takes place during defervescence usually on day 4 or 5 (range 3-7 days) of illness. This condition is preceded by the warning signs.

22. LABORATORY DIAGNOSIS Rapid and accurate dengue diagnosis is very important for the following reasons. 1. Clinical management. 2. Epidemiological surveillance. 3. Research. 4. Vaccine trials. Epidemiological surveillance requires early determination of dengue virus infection during the outbreak for urgent public health action towards control

23. DIAGNOSIS BY : Virus Isolation. Viral Nucleic Acid Detection. Immunological Response & Serological Tests. Viral Antigen Detection. Rapid Diagnostic Test. Analysis Of Haematological Parameters

24. CLINICAL MANAGEMENT It is important to classify the severity of dengue infection The presence of thrombocytopenia with concurrent haemoconcentration differenciates grade I and grade II DHF from DF.

25. MANAGEMENT OF DENGUE FEVER For the patients who are able to tolerate adequate volumes of oral fluids and pass urine every 6 hours, and do not have any warning signs adhere to the following plan. Encourage intake of ORS, fruit juice and other fluids containing electrolytes and sugar to replace losses from fever and vomiting Adequate oral fluid intake may be able to reduce the number of hospitalizations. Administer Paracetamol for high fever if the patient is uncomfortable. The interval of Paracetamol dosing should not be less than six hours.

26. Tepid sponge if the patient still has high fever. Do not give Asprin ( Acetylsalicilic acid), ibuprofen or other non steroidal anti inflammatory agents (NSAIDs) as these drugs may aggravate gastritis or bleeding. Instruct the care givers that the patients should be brought to hospital immediately if any of the following occur: No clinical improvement Deterioration around the time of defervescence . Severe abdominal pain. Persistent vomiting or cold and clammy extremities. Lethargy or irritability, restlessness, bleeding (black stools or coffee-ground vomiting). Not passing urine for more than 4-6 hours.

27. Patients who are discharged should be monitored daily by the health care providers for temperature pattern. Paracetamol is administered to keep the temperature below 39 degree celcius . Copious amount of fluids should be give to main fluid and electrolyte imbalance. Patients should be monitored for initial signs of shock The critical period is during the transition from the febrile to the afebrile stage and usually occurs after the third day of illness Serial haematocrit determinants are essential guide for treatment, since they reflect the degree of plasma leakage and need for IV therapy.

28. MANAGEMENT OF DHF Grade I and Grade II

29. A person with dengue haemorrhagic fever with thrombocytopenia and haemoconcentration presents with abdominal pain, black tarry stools, epistaxis, bleeding from gums and infection. All these patients should be observed for signs of shock. The critical period for development of shock is transition from febrile to afebrile phase of illness which usually occurs in the third day of illness. A rise of haemoconcentration indicates the need for IV fluid therapy. Despite this treatment, if the patient’s Bp falls with a decrease in urine output, the management for Grade III/IV DHF/DSS should be instituted. Oral dehydration should be given along with antipyrectics like paracetamol , sponging.

30. MANAGEMENT OF DHF GRADE III AND IV

31. Common signs of complications are observed during the afebrile phase of DHF. Following hospitalization, the haematocrit , platelet count and vital signs should be examined to assess the patient’s condition and intravenous fluid therapy should be started. The patient requires a regular and sustained monitoring. If the patient has already received about 1000 ml of IV fluid, it should be changed to colloidal solution preferably Dextran 40/ haemaccele or if haematocrit is decreasing, fresh whole blood transfusion ml/kg/hour should be given In case of persistent shock, after initial fluid replacement and resuscitation with plasma or plasma expanders, the haematocrit continues to decline, internal bleeding should be suspected. It is thus recommended to give fresh whole blood in small volumes of 10ml/kg/hour for all patients in shock as a routine precaution. Oxygen should be given to all patients in shock.

32. DISEASE NOTIFICATION In dengue-endemic countries, cases of suspected, probable and confirmed dengue should be notified as soon as possible so that appropriate health measures can be initiated.

33. CONTROL MEASURES MOSQUITO CONTROL - The vectors of DF and DHF ( A.aegypti ) breed in and around houses and in principle controlled by individual and community action, using antiadult and antilarval measures. VACCINES - So far there is no satisfactory vaccine and no immediate prospect of preventing the disease by immunization OTHER MEASURES Isolation under bed-nets during the first few days; individual protection against mosquitoes. Other personal prophylactic measures. Environmental measures

34. PREVENTION OF WATER STAGNATION

35. ROLE OF ALTERNATIVE MEDICINE

36. THANK YOU

37. REFERENCES 1.Park’s Textbook of Preventive & Social Medicine, Banarsidas Bhanot publishers,22 Ed 2. Basawanthappa B.T, Community Health Nursing, Jayapee publications 3. Neelam Kumari , Text book of Community Health Nursing, S. Vikas Publisher, First Edn 4. Rao.B sridhar , Book of Community Health Nursing,AITBS publisher, New Delhi