Rift Valley Fever

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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_at_hotmail.com

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Rift Valley Fever

• Acute febrile viral disease
• Affecting animals humans
• Causes influenza-like illness
• May lead to high morbidity, mortality economic
  loss

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Geographic Location Geologic Feature of Rift
Valley

• Length 6,000miles
• Site Lebanon to Mozambique
• Largest part Kenya
• Development Subterranean forces
• Feature Dambos

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Causes of Outbreaks
Rainfall or Inundation
Wetlands Stagnant water
Vegetation Growth
Flourishing of mosquitoes
Transmission of Infection
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Outbreaks in the Last Half Century
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RVF Virus
Glyco- protein spikes
Lipid envelope
L
S
G1
M
G2
transcriptase
Coiled nucleocapsid RNAN protein
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Mode of Transmission

• Mosquitoes
• Other blood suckling insects
• Contact with blood or other body fluids of
  infected animals
• Consumption of infected milk

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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

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Target

• Liver focal necrosis
• RBCs haemagglutination
• Brain necrotic encephalitis

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Clinical Picture 1- Non-Human Host

• Fever
• Hepatitis
• Abortion
• Death
• Adults 10-30
• Neonates 100

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2- Human Host

• Incubation period of 2-6 days
• Asymptomatic
• Flu-like illness
• Abdominal pain
• Photophobia
• Recovery in 2-7days

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Complications of RVF 1- Ocular Lesions

• Rate 0.5-2.0
• Onset 1-3 weeks
• Presentation
• Localized pain
• Blurred vision
• Loss of vision 1.0-10.0

• Lesions
• Macular lesions
• Retinitis
• Retinal detachment
• Death rare

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2- Meningoencephalitis

• Rate lt 1.0
• Onset 1-3 weeks
• Death rare

• Presentation
• Severe headache
• Vertigo
• Seizures
• Coma

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3- Haemorrhagic fever

• Lesions
• Acute fulminant hepatitis
• DIC
• Hemolytic anemia
• CFR 50.0

• Rate lt 1.0
• Onset 2-4 days
• Presentation
• hemorrhagic phenomenon

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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

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High Risk Groups (cont.)

• Doctors and nurses in contact with infected cases
  at late stages of the disease
• Laboratory technicians
• Travellers visiting epidemic areas

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Diagnosis of RVF

• Antibody detection
• ELISA
• EIA
• Virus detection
• Virus isolation
• Antigen detection
• PCR

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Prevention ControlI. Animal

• Vaccination of unaffected animals
• Live attenuated vaccine
• Killed vaccine
• Notification of affected animals
• Application of safe insecticides to eradicate
  blood suckling insects

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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

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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

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III- Humans 1- General Measures

• Sleeping indoors
• Using bed nets during sleep
• Putting screens on windows
• Wearing clothes that protects whole body

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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

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III- Humans1-General Measures (cont.)

• Avoiding direct contact with animals
• Washing hands after contact with animals, their
  blood or other body fluids
• Avoid drinking raw milk

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III- Humans 2- Community Measures

• Health education
• Epidemiologic research program
• Active disease surveillance
• Check measures at air, sea and land entry points

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III- Humans3- Occupational Measures

• Wearing masks, gloves, gowns and other barriers
  according to infected hosts condition
• Laboratory samples should be handled by trained
  staff

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III- Humans3- Occupational Measures (cont.)

• Application of water, soap and antiseptic
  solution on exposed parts
• Application of copious water and eye wash
  solution on exposed conjunctiva

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Management of Suspected Cases

• Notification
• Ascertainment of cases
• Identification, screening and surveillance of
  contacts

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Recommended Investigations For Suspected Cases

• CBC
• Urea
• Creatinine
• AST, ALT
• ALP,Bilirubin
• Albumin

• PT PTT
• LDH CPK
• Hepatitis A IgM IgG, HBsAg, HBcAB, HCV Ab
• RFV seriology viral culture

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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

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Indications For Hospitalisation

• Thrombocytopenialt 100,000/mm3
• Anaemialt 8gm/dL
• Creatininegt150mol/L
• Confusion or other CNS manifestation
• Evidence of DIC

• Shock
• Decreased urine output
• AST ALT gt 200U/mL
• Bilirubingt100 mol/L

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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

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Management of Hospitalised Patients (cont.)

• Ribavirin, Interferon, Immune Modulators
  Convalescent Phase Plasma give promising results
• Introduction to ICU or haemodialysis unit if
  indicated

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• 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

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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