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Dengue Fever Prevention and Management


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									Centre of Research for
Public Health            Dengue Fever – Prevention and

                          Dr. Amir Riaz
                          M.B.B.S, F.C.P.S (Med)
                          Consultant Physician & Gastroenterologist
                          Scientific Chair, Centre of Research for Public Health
                          Assistant Professor
                          Lahore College of Pharmaceutical Sciences Lahore, Lahore,
Dengue Prevalence
      Programs to minimize the impact of
• Teaching medical community how to diagnose and manage
  dengue hemorrhagic fever (DHF)

• Implementing an emergency contingency plan to anticipate
  the logistical issues of hospitalizing large numbers of patients
  and to outline measures for community-wide vector control

• Educating the general public to encourage and enable them to
  carry out vector control in their homes and neighborhoods
       What is dengue fever?
• Dengue fever is a virus infection caused by the dengue virus.
   There are 4 kinds of dengue viruses.

Aedes Aegypti                    Aedes Albopictus
     Do you know?
• Dengue fever and dengue haemorrhagic fever are the most
  common mosquito-borne viral disease in the world.
• Only the female mosquito feeds on blood. This is because
  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.
• The female Aedes mosquito searches for suitable places to lay
  their eggs.
• Aedes are day-biters, most active during dawn and dusk.
Life cycle of Aedes mosquito
Extrinsic life cycle in Aedes mosquito
Intrinsic life cycle in human subjects
Transmission of dengue virus by
Aedes Aegypti
     Important points learned

• Aedes aegypti & Aedes Albopictus - vectors

• Dengue transmitted by infected female mosquito

• Primarily a daytime feeder

• Lives around human habitation

• Lays eggs and produces larvae preferentially in artificial
  Why prevention is stressed?

• No specific treatment is available for virus

• DF & DHF has significant morbidity & mortality

• Disease is endemic & become epidemic in many parts
  of world population

• Treatment is only supportive & symptomatic.

• No effective vaccine is yet developed which is effective
  against all four types of viruses causing DF & DHF
    Purpose of control
• Reduce female vector density to a level below which
  epidemic vector transmission will not occur

• Based on the assumption that eliminating or reducing the
  number of larval habitats in the domestic environment will
  control the vector

• Prevent vector bites in humans to control spread of virus to
  vectors & humans

• The minimum vector density to prevent epidemic
  transmission is unknown
Reproduction of Aedes mosquito
Common mosquito breeding grounds
Potential breeding grounds
Potential breeding grounds
Potential breeding grounds
Potential breeding grounds
Potential breeding grounds
Potential breeding grounds
Potential breeding grounds
Potential breeding grounds
Potential breeding grounds
Potential breeding grounds
The 10-minute Mozzie Wipe-Out
The 10-minute Mozzie Wipe-Out
The 10-minute Mozzie Wipe-Out
The 10-minute Mozzie Wipe-Out
The 10-minute Mozzie Wipe-Out
What else can you do?
      Personal prevention
• Avoid travel to areas where dengue is endemic.
• Wear N,N-diethyl-3-methylbenzamide (DEET)–containing
  mosquito repellant.
• Wear protective clothing, preferably impregnated with
  permethrin insecticide.
• Remain in well-screened or air-conditioned places.
• The use of mosquito netting is of limited benefit, as Aedes are
  day-biting mosquitoes.
• Eliminate the mosquito vector using indoor sprays.
      Control of infection mosquitoes
• Application of appropriate insecticides to larval habitats or
  use of fish in ponds

• During outbreaks, emergency vector control measures like
  broad application of insecticides as space sprays using
  portable or truck-mounted machines or even aircraft

• Regular monitoring of the vectors' susceptibility to widely
  used insecticide chemicals.

• Active monitoring and surveillance of the natural mosquito
• If the patient has no hemorrhagic manifestations and is well-
  hydrated, he or she can be sent home with instructions for

• If there are hemorrhagic manifestations or hydration status is
  borderline, the patient should be observed, either in an
  outpatient observation center or in the hospital

• If warning signs are present even without evidence of shock,
  or if DSS is present, the patient should be hospitalized
      Treatment – Patient follow-up
• Patients being treated at home should be instructed regarding
  the appearance of danger signs and told to return should any

• Repeat clinical evaluation should be considered, with timing
  based on the physician's judgment, remembering that DSS
  most commonly occurs at 3-6 days after symptom onset.

• Patients with bleeding manifestations should have serial
  hematocrit and platelet levels checked at least daily until their
  temperature is normal for 1-2 days.
      Treatment – Patient follow-up
• If the blood sample was taken the first five days after the
  onset of symptoms, a convalescent-phase sample to measure
  IgM antibody is needed between 6-30 days after the onset of

• A blood sample should be taken from all hospitalized patients
  at the time of discharge or death
• Rest, in a vector protected envoirment.

• Fluids, encouraged to take small, frequent sips of fluids. If the
  patient cannot be rehydrated by mouth, fluids should be
  administered intravenously. At times large amounts of intravenous
  fluids are needed.

• Antipyretics—aspirin & NSAIDs drugs such as ibuprofen should be
  avoided to prevent platelet dysfunction & bleeding diathesis.

• Monitor blood pressure, urine output, hematocrit, platelet count,
  and level of consciousness
• Patients often develop dengue hemorrhagic fever after their fever
  disappears. So providers should continue monitoring vital signs and
  hydration status for 24 to 48 hours after defervescence.

• If any doubt, provide intravenous fluids, guided by serial
  hematocrits, blood pressure, and urine output

• The volume of fluid needed is similar to the treatment of diarrhea
  with mild to moderate isotonic dehydration (5%-8% deficit).

• Volume required for rehydration is twice the recommended
  maintenance requirement.

• Formula for calculating maintenance volume:
  1500 + 20 x (weight in kg - 20).

• For example, maintenance volume for 55 kg patient is: 1500 +
  20 x (55-20) = 2200 ml.

• For this patient, the rehydration volume would be
  2 x 2200, or 4400 ml (4.5 liters).

• Avoid invasive procedures when possible.

• Unknown if the use of steroids, intravenous immune
  globulin, or platelet transfusions to shorten the duration
  or decrease the severity of thrombocytopenia is effective

• Patients in shock may require treatment in an intensive
  care unit
• Avoid invasive procedures when possible.

• Patients in shock may require treatment in intensive care unit.
      Indications for hospital discharge
• Absence of fever for 24 hours (without anti-fever therapy) and
  return of appetite.

• Visible improvement in clinical picture.

• Stable hematocrit.

• 3 days after recovery from shock.

• Platelets >50,000/mm³.

• No respiratory distress from pleural effusions/ascites
      Common misconceptions about
      Dengue Hemorrhagic Fever
• One common belief is that dengue plus bleeding equals
  dengue hemorrhagic fever?
• There are four established criteria for defining DHF, and the
  critical difference between dengue fever and DHF is not
  bleeding, but the increased vascular permeability that occurs
  in DHF—this causes shock and death.
• DHF kills only by hemorrhage?
• Patient dies as a result of shock.
• Poor management turns dengue into DHF?
• Poorly managed dengue can be more severe, DHF is a distinct
  condition, that can develop even in well-treated patients.
     Common misconceptions about
     Dengue Hemorrhagic Fever
• Positive tourniquet test = DHF?
• No Tourniquet test is a nonspecific indicator of
  capillary fragility
• DHF is a pediatric disease?
• All age groups are involved in the Americas
• DHF is a problem of low income families?
• All socioeconomic groups are affected
• Tourists will certainly get DHF with second infection?
• Tourists are at low risk to acquire DHF
•   A. Guidelines and manuals
•   Dengue haemorrhagic fever: diagnosis, treatment, prevention and control. 2nd edition.
    Geneva : World Health Organization. 1997
•   Dengue Haemorrhagic Fever: early recognition, diagnosis and hospital management An
    audiovisual guide for health care workers responding to outbreaks
    Download video http://terrance.who.int:85/streaming/dhf.wmv
    DHF video transcript http://www.who.int/csr/don/archive/disease/dengue_fever/dengue.pdf
•   Guidelines for Treatment of Dengue Fever/Dengue Haemorrhagic Fever in Small Hospitals
•   Manual for Indoor Residual Spraying: Application of Residual Sprays for Vector Control
•   Guidelines for Integrated Vector Management
•   Planning Social Mobilization and Communication for Dengue Fever Prevention and Control:
    A Step-by-Step Guide
•   B. Strategies and Best Practices
•   Strengthening implementation of the global strategy for dengue fever/dengue
    haemorrhagic fever
•   The International Dengue Task Force: Dedicated to the Fight against Dengue
•   Best Practices for Dengue Control - Environmental Health Project
    Best Practices for Dengue Control in the Americas
•   C. Contacts
•   − Network of PAHO/WHO Collaborating Centres and National Reference Laboratories for
    Dengue in the Americas http://www.paho.org/english/ad/dpc/cd/den-cc.htm
•   − WHOCCNet Global Network of WHO Collaborating Centres for Epidemic infectious and
    zoonotic diseases.
               Thank you
For comments and remarks: feedback@crph.org.pk

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