Rift Valley Fever Sherine Shawky, MD, Dr.PH Assistant Professor Department of Community Medicine & Primary Health Care College of Medicine King Abdulaziz University

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

RVF Virus Coiled nucleocapsid RNA+N protein Glyco- protein spikes transcriptase Lipid envelope S L M G1 G2

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: % Onset: 1-3 weeks Presentation –Localized pain –Blurred vision –Loss of vision: % Lesions: –Macular lesions –Retinitis –Retinal detachment Death: rare

2- Meningoencephalitis Rate: < 1.0% Onset: 1-3 weeks Death: rare Presentation: –Severe headache –Vertigo –Seizures –Coma

3- Haemorrhagic fever Rate: < 1.0% Onset: 2-4 days Presentation: –hemorrhagic phenomenon Lesions: –Acute fulminant hepatitis –DIC –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 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 Shock Decreased urine output AST & ALT > 200U/mL Bilirubin>100 mol/L Thrombocytopenia< 100,000/mm 3 Anaemia< 8gm/dL Creatinine>150mol/L Confusion or other CNS manifestation 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