Download Rift Valley Fever

Rift Valley Fever
Sherine Shawky, MD, Dr.PH
Assistant Professor
Department of Community
Medicine & Primary Health Care
College of Medicine
King Abdulaziz University
[email protected]
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
1950-1951
1967-1970
1969
1976-1977
1977-1980
1987
1990-1991
1993
1997
1999
2000-2001
Country
Kenya
Nigeria
Central African Republic
Sudan
Egypt
Mauritania
Madagascar
Egypt – Senegal
Kenya – Somalia
South Africa
Saudi Arabia - Yemen
Glycoprotein
spikes
G1
G2
RVF Virus
S
Coiled nucleocapsid
RNA+N protein
L
M
Lipid
envelope
transcriptase
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
–Retinitis
• Presentation
–Localized pain
–Blurred vision
–Loss of vision:
1.0-10.0%
–Retinal
detachment
• Death: rare
2- Meningoencephalitis
• Rate: < 1.0% • Presentation:
• Onset: 1-3 weeks –Severe headache
–Vertigo
• Death: rare
–Seizures
–Coma
3- Haemorrhagic fever
• Rate: < 1.0% • Lesions:
• Onset: 2-4 days –Acute fulminant
hepatitis
• Presentation:
–DIC
–hemorrhagic
–Hemolytic
phenomenon
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
• Urea
• Creatinine
• AST, ALT
• ALP,Bilirubin
• Albumin
• PT & PTT
• LDH & CPK
• Hepatitis A IgM &
IgG, HBsAg,
HBcAB, HCV Ab
• 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
• Thrombocytopenia<
• Shock
3
100,000/mm
• Decreased urine
• Anaemia< 8gm/dL
output
• AST & ALT > • Creatinine>150mol/L
• Confusion or other
200U/mL
• Bilirubin>100 CNS manifestation
• Evidence of DIC
mol/L
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