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					   Rift Valley Fever
 Sherine Shawky, MD, Dr.PH
      Assistant Professor
  Department of Community
Medicine & Primary Health Care
      College of Medicine
  King Abdulaziz University
   shshawky@hotmail.com
    Rift Valley Fever
• Acute febrile viral disease
• Affecting animals & humans
• Causes influenza-like illness
• May lead to high morbidity,
  mortality & economic loss
  Geographic Location &
   Geologic Feature of
       Rift Valley
• Length: 6,000miles
• Site: Lebanon to Mozambique
• Largest part: Kenya
• Development: Subterranean forces
• Feature: Dambos
Causes of Outbreaks
  Rainfall or Inundation
Wetlands & Stagnant water

    Vegetation Growth
Flourishing of mosquitoes
 Transmission of Infection
Outbreaks in the Last Half Century
   Date        Country
   1950-1951   Kenya
   1967-1970   Nigeria
   1969        Central African Republic
   1976-1977   Sudan
   1977-1980   Egypt
   1987        Mauritania
   1990-1991   Madagascar
   1993        Egypt – Senegal
   1997        Kenya – Somalia
   1999        South Africa
   2000-2001   Saudi Arabia - Yemen
Glyco-    RVF Virus
protein
                               Lipid
spikes
                               envelope
                S      L
  G1
                      M
  G2

                           transcriptase
Coiled nucleocapsid
RNA+N protein
  Mode of Transmission
• Mosquitoes
• Other blood suckling insects
• Contact with blood or other
  body fluids of infected animals
• Consumption of infected milk
  Mode of Transmission
         (cont.)
• Contact with blood or other
  body fluids of infected humans
  in late stages of disease
• Airborne transmission
• Inoculation through broken skin
           Target
• Liver: focal necrosis
• RBCs: haemagglutination
• Brain: necrotic encephalitis
      Clinical Picture
   1- Non-Human Host
• Fever
• Hepatitis
• Abortion
• Death
  –Adults: 10-30%
  –Neonates: 100%
       2- Human Host
• Incubation period of 2-6 days
• Asymptomatic
• Flu-like illness
• Abdominal pain
• Photophobia
• Recovery in 2-7days
  Complications of RVF
    1- Ocular Lesions
• Rate: 0.5-2.0% • Lesions:
• Onset: 1-3 weeks –Macular lesions
• Presentation     –Retinitis
 –Localized pain      –Retinal
                       detachment
 –Blurred vision
 –Loss of vision:   • Death: rare
  1.0-10.0%
 2- Meningoencephalitis
• Rate: < 1.0%    • Presentation:
• Onset: 1-3 weeks –Severe headache
• Death: rare       –Vertigo
                   –Seizures
                   –Coma
  3- Haemorrhagic fever
• Rate: < 1.0% • Lesions:
• Onset: 2-4 days –Acute fulminant
• Presentation:     hepatitis
  –hemorrhagic     –DIC
   phenomenon      –Hemolytic
                    anemia
                 • CFR: 50.0%
      High Risk Groups
• People who sleep outdoors at night
• Slaughterhouse workers, butchers
  veterinarians and others who
  handle blood, other body fluids or
  tissues of infected animals
     High Risk Groups
          (cont.)
• Doctors and nurses in contact
  with infected cases at late stages
  of the disease
• Laboratory technicians
• Travellers visiting epidemic
  areas
   Diagnosis of RVF
• Antibody detection
    -ELISA
    -EIA
• Virus detection
    -Virus isolation
    -Antigen detection
    -PCR
   Prevention & Control
        I. Animal
• Vaccination of unaffected animals
  –Live attenuated vaccine
  –Killed vaccine
• Notification of affected animals
• Application of safe insecticides to
  eradicate blood suckling insects
            I- Animal
              (cont.)
• Periodic surveillance of susceptible
  animals to assess immune status
• Application of quarantine measures
  for testing of imported animals
• Rapid burial of dead bodies
           II- Vector
• Removal of stagnant water
• Weekly treatment of water
  collections using insecticides
• Application of insecticides every
  other day in all gardens
• Removal of objects that can act
  as possible water containers
       III- Humans:
   1- General Measures
• Sleeping indoors
• Using bed nets during sleep
• Putting screens on windows
• Wearing clothes that protects
  whole body
      III- Humans:
1-General Measures (cont.)
• Applying mosquito repellents
• Using spray on clothes
• Avoiding peaks of mosquito
  activity
• Avoiding presence near vegetations
  in the evening
      III- Humans
1-General Measures (cont.)
• Avoiding direct contact with
  animals
• Washing hands after contact with
  animals, their blood or other body
  fluids
• Avoid drinking raw milk
      III- Humans
 2- Community Measures
• Health education
• Epidemiologic research program
• Active disease surveillance
• Check measures at air, sea and
  land entry points
      III- Humans
3- Occupational Measures
• Wearing masks, gloves, gowns and
  other barriers according to infected
  host’s condition
• Laboratory samples should be
  handled by trained staff
          III- Humans
    3- Occupational Measures
             (cont.)
• Application of water, soap and
  antiseptic solution on exposed parts
• Application of copious water and
  eye wash solution on exposed
  conjunctiva
    Management of
    Suspected Cases
• Notification
• Ascertainment of cases
• Identification, screening and
  surveillance of contacts
Recommended Investigations
    For Suspected Cases
• CBC             • PT & PTT
• Urea            • LDH & CPK
• Creatinine      • Hepatitis A IgM &
• AST, ALT          IgG, HBsAg,
• ALP,Bilirubin     HBcAB, HCV Ab
• Albumin         • RFV seriology &
                    viral culture
     Management of
  unhospitalised Patients
• Isolation at home
• Contacts should wear masks, gloves
  and protective clothes
• Safe disposal of patients linens &
  clothes
• Close follow-up for 6 weeks
Indications For Hospitalisation
• Shock         • Thrombocytopenia<
                  100,000/mm  3
• Decreased urine
  output        • Anaemia< 8gm/dL
• AST & ALT > • Creatinine>150mol/L
  200U/mL       • Confusion or other
• Bilirubin>100 CNS manifestation
  mol/L         • Evidence of DIC
      Management of
    Hospitalised Patients
• General Supportive Measures
• Isolation in negative airway
  pressure room
• Safe disposal of soiled linens
• Safe disposal of solid medical waste
• Safe sewage disposal
     Management of
   Hospitalised Patients
          (cont.)
• Ribavirin, Interferon, Immune
  Modulators & Convalescent Phase
  Plasma give promising results
• Introduction to ICU or
  haemodialysis unit if indicated
• Hospital discharge after:
  – Improvement in general status
  –Decline in liver symptoms
  –Recovery from DIC
• Follow-up in ophthalmology and
  medical clinics for 6 weeks
• Safe burial practice for dead
  cases
         Conclusion
• RVF is spreading outside Africa
• Although often mild, may lead to
  high morbidity and mortality
• No vaccine for humans
• No specific treatment
• Preventive measures are crucial

				
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posted:8/1/2010
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